crossterm support (#331)

* crossterm v2

* patch crossterm

* fix-version

* no more tui dependency

* lints

20 files changed, 4399 insertions, 136 deletions

diff --git a/src/command/client/search.rs b/src/command/client/search.rs
index 53471ec1..9321f117 100644
--- a/src/command/client/search.rs
+++ b/src/command/client/search.rs
@@ -13,7 +13,6 @@ use super::history::ListMode;
 
 mod cursor;
 mod duration;
-mod event;
 mod history_list;
 mod interactive;
 pub use duration::{format_duration, format_duration_into};
diff --git a/src/command/client/search/event.rs b/src/command/client/search/event.rs
deleted file mode 100644
index 0e791c96..00000000
--- a/src/command/client/search/event.rs
+++ /dev/null
@@ -1,70 +0,0 @@
-use std::{thread, time::Duration};
-
-use crossbeam_channel::unbounded;
-use termion::{event::Event as TermEvent, event::Key, input::TermRead};
-
-pub enum Event<I> {
-    Input(I),
-    Tick,
-}
-
-/// A small event handler that wrap termion input and tick events. Each event
-/// type is handled in its own thread and returned to a common `Receiver`
-pub struct Events {
-    rx: crossbeam_channel::Receiver<Event<TermEvent>>,
-}
-
-#[derive(Debug, Clone, Copy)]
-pub struct Config {
-    pub exit_key: Key,
-    pub tick_rate: Duration,
-}
-
-impl Default for Config {
-    fn default() -> Config {
-        Config {
-            exit_key: Key::Char('q'),
-            tick_rate: Duration::from_millis(250),
-        }
-    }
-}
-
-impl Events {
-    pub fn new() -> Events {
-        Events::with_config(Config::default())
-    }
-
-    pub fn with_config(config: Config) -> Events {
-        let (tx, rx) = unbounded();
-
-        {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                let tty = termion::get_tty().expect("Could not find tty");
-                for event in tty.events().flatten() {
-                    if let Err(err) = tx.send(Event::Input(event)) {
-                        eprintln!("{err}");
-                        return;
-                    }
-                }
-            })
-        };
-
-        thread::spawn(move || loop {
-            if tx.send(Event::Tick).is_err() {
-                break;
-            }
-            thread::sleep(config.tick_rate);
-        });
-
-        Events { rx }
-    }
-
-    pub fn next(&self) -> Result<Event<TermEvent>, crossbeam_channel::RecvError> {
-        self.rx.recv()
-    }
-
-    pub fn try_next(&self) -> Result<Event<TermEvent>, crossbeam_channel::TryRecvError> {
-        self.rx.try_recv()
-    }
-}
diff --git a/src/command/client/search/history_list.rs b/src/command/client/search/history_list.rs
index d74221d8..f4725b02 100644
--- a/src/command/client/search/history_list.rs
+++ b/src/command/client/search/history_list.rs
@@ -1,12 +1,12 @@
 use std::time::Duration;
 
-use atuin_client::history::History;
-use tui::{
+use crate::tui::{
     buffer::Buffer,
     layout::Rect,
     style::{Color, Modifier, Style},
     widgets::{Block, StatefulWidget, Widget},
 };
+use atuin_client::history::History;
 
 use super::format_duration;
 
diff --git a/src/command/client/search/interactive.rs b/src/command/client/search/interactive.rs
index e0ceb091..c8ceab58 100644
--- a/src/command/client/search/interactive.rs
+++ b/src/command/client/search/interactive.rs
@@ -1,19 +1,22 @@
-use std::io::stdout;
-
-use eyre::Result;
-use semver::Version;
-use termion::{
-    event::Event as TermEvent, event::Key, event::MouseButton, event::MouseEvent,
-    input::MouseTerminal, raw::IntoRawMode, screen::AlternateScreen,
+use std::{
+    io::{stdout, Write},
+    time::Duration,
 };
-use tui::{
-    backend::{Backend, TermionBackend},
+
+use crate::tui::{
+    backend::{Backend, CrosstermBackend},
     layout::{Alignment, Constraint, Direction, Layout},
     style::{Color, Modifier, Style},
     text::{Span, Spans, Text},
     widgets::{Block, BorderType, Borders, Paragraph},
     Frame, Terminal,
 };
+use crossterm::{
+    event::{self, Event, KeyCode, KeyEvent, KeyModifiers, MouseEvent},
+    execute, terminal,
+};
+use eyre::Result;
+use semver::Version;
 use unicode_width::UnicodeWidthStr;
 
 use atuin_client::{
@@ -26,7 +29,6 @@ use atuin_client::{
 
 use super::{
     cursor::Cursor,
-    event::{Event, Events},
     history_list::{HistoryList, ListState, PREFIX_LENGTH},
 };
 use crate::VERSION;
@@ -62,42 +64,69 @@ impl State {
         Ok(results)
     }
 
-    fn handle_input(
+    fn handle_input(&mut self, settings: &Settings, input: &Event, len: usize) -> Option<usize> {
+        match input {
+            Event::Key(k) => self.handle_key_input(settings, k, len),
+            Event::Mouse(m) => self.handle_mouse_input(*m, len),
+            _ => None,
+        }
+    }
+
+    fn handle_mouse_input(&mut self, input: MouseEvent, len: usize) -> Option<usize> {
+        match input.kind {
+            event::MouseEventKind::ScrollDown => {
+                let i = self.results_state.selected().saturating_sub(1);
+                self.results_state.select(i);
+            }
+            event::MouseEventKind::ScrollUp => {
+                let i = self.results_state.selected() + 1;
+                self.results_state.select(i.min(len - 1));
+            }
+            _ => {}
+        }
+        None
+    }
+
+    fn handle_key_input(
         &mut self,
         settings: &Settings,
-        input: &TermEvent,
+        input: &KeyEvent,
         len: usize,
     ) -> Option<usize> {
-        match input {
-            TermEvent::Key(Key::Char('\t')) => {}
-            TermEvent::Key(Key::Ctrl('c' | 'd' | 'g')) => return Some(RETURN_ORIGINAL),
-            TermEvent::Key(Key::Esc) => {
+        let ctrl = input.modifiers.contains(KeyModifiers::CONTROL);
+        let alt = input.modifiers.contains(KeyModifiers::ALT);
+        match input.code {
+            KeyCode::Char('c' | 'd' | 'g') if ctrl => return Some(RETURN_ORIGINAL),
+            KeyCode::Esc => {
                 return Some(match settings.exit_mode {
                     ExitMode::ReturnOriginal => RETURN_ORIGINAL,
                     ExitMode::ReturnQuery => RETURN_QUERY,
                 })
             }
-            TermEvent::Key(Key::Char('\n')) => {
+            KeyCode::Enter => {
                 return Some(self.results_state.selected());
             }
-            TermEvent::Key(Key::Alt(c @ '1'..='9')) => {
+            KeyCode::Char(c @ '1'..='9') if alt => {
                 let c = c.to_digit(10)? as usize;
                 return Some(self.results_state.selected() + c);
             }
-            TermEvent::Key(Key::Left | Key::Ctrl('h')) => {
+            KeyCode::Left => {
                 self.input.left();
             }
-            TermEvent::Key(Key::Right | Key::Ctrl('l')) => self.input.right(),
-            TermEvent::Key(Key::Ctrl('a') | Key::Home) => self.input.start(),
-            TermEvent::Key(Key::Ctrl('e') | Key::End) => self.input.end(),
-            TermEvent::Key(Key::Char(c)) => self.input.insert(*c),
-            TermEvent::Key(Key::Backspace) => {
+            KeyCode::Char('h') if ctrl => {
+                self.input.left();
+            }
+            KeyCode::Right => self.input.right(),
+            KeyCode::Char('l') if ctrl => self.input.right(),
+            KeyCode::Char('a') if ctrl => self.input.start(),
+            KeyCode::Char('e') if ctrl => self.input.end(),
+            KeyCode::Backspace => {
                 self.input.back();
             }
-            TermEvent::Key(Key::Delete) => {
+            KeyCode::Delete => {
                 self.input.remove();
             }
-            TermEvent::Key(Key::Ctrl('w')) => {
+            KeyCode::Char('w') if ctrl => {
                 // remove the first batch of whitespace
                 while matches!(self.input.back(), Some(c) if c.is_whitespace()) {}
                 while self.input.left() {
@@ -108,8 +137,8 @@ impl State {
                     self.input.remove();
                 }
             }
-            TermEvent::Key(Key::Ctrl('u')) => self.input.clear(),
-            TermEvent::Key(Key::Ctrl('r')) => {
+            KeyCode::Char('u') if ctrl => self.input.clear(),
+            KeyCode::Char('r') if ctrl => {
                 pub static FILTER_MODES: [FilterMode; 4] = [
                     FilterMode::Global,
                     FilterMode::Host,
@@ -120,19 +149,24 @@ impl State {
                 let i = (i + 1) % FILTER_MODES.len();
                 self.filter_mode = FILTER_MODES[i];
             }
-            TermEvent::Key(Key::Down | Key::Ctrl('n' | 'j'))
-            | TermEvent::Mouse(MouseEvent::Press(MouseButton::WheelDown, _, _)) => {
-                if self.results_state.selected() == 0 && input.eq(&TermEvent::Key(Key::Down)) {
-                    return Some(RETURN_ORIGINAL);
-                }
+            KeyCode::Down if self.results_state.selected() == 0 => return Some(RETURN_ORIGINAL),
+            KeyCode::Down => {
+                let i = self.results_state.selected().saturating_sub(1);
+                self.results_state.select(i);
+            }
+            KeyCode::Char('n' | 'j') if ctrl => {
                 let i = self.results_state.selected().saturating_sub(1);
                 self.results_state.select(i);
             }
-            TermEvent::Key(Key::Up | Key::Ctrl('p' | 'k'))
-            | TermEvent::Mouse(MouseEvent::Press(MouseButton::WheelUp, _, _)) => {
+            KeyCode::Up => {
+                let i = self.results_state.selected() + 1;
+                self.results_state.select(i.min(len - 1));
+            }
+            KeyCode::Char('p' | 'k') if ctrl => {
                 let i = self.results_state.selected() + 1;
                 self.results_state.select(i.min(len - 1));
             }
+            KeyCode::Char(c) => self.input.insert(c),
             _ => {}
         };
 
@@ -303,6 +337,45 @@ impl State {
     }
 }
 
+struct Stdout {
+    stdout: std::io::Stdout,
+}
+
+impl Stdout {
+    pub fn new() -> std::io::Result<Self> {
+        terminal::enable_raw_mode()?;
+        let mut stdout = stdout();
+        execute!(
+            stdout,
+            terminal::EnterAlternateScreen,
+            event::EnableMouseCapture
+        )?;
+        Ok(Self { stdout })
+    }
+}
+
+impl Drop for Stdout {
+    fn drop(&mut self) {
+        execute!(
+            self.stdout,
+            terminal::LeaveAlternateScreen,
+            event::DisableMouseCapture
+        )
+        .unwrap();
+        terminal::disable_raw_mode().unwrap();
+    }
+}
+
+impl Write for Stdout {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        self.stdout.write(buf)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        self.stdout.flush()
+    }
+}
+
 // this is a big blob of horrible! clean it up!
 // for now, it works. But it'd be great if it were more easily readable, and
 // modular. I'd like to add some more stats and stuff at some point
@@ -312,15 +385,10 @@ pub async fn history(
     settings: &Settings,
     db: &mut impl Database,
 ) -> Result<String> {
-    let stdout = stdout().into_raw_mode()?;
-    let stdout = MouseTerminal::from(stdout);
-    let stdout = AlternateScreen::from(stdout);
-    let backend = TermionBackend::new(stdout);
+    let stdout = Stdout::new()?;
+    let backend = CrosstermBackend::new(stdout);
     let mut terminal = Terminal::new(backend)?;
 
-    // Setup event handlers
-    let events = Events::new();
-
     let mut input = Cursor::from(query.join(" "));
     // Put the cursor at the end of the query by default
     input.end();
@@ -343,27 +411,6 @@ pub async fn history(
     let mut results = app.query_results(settings.search_mode, db).await?;
 
     let index = 'render: loop {
-        let initial_input = app.input.as_str().to_owned();
-        let initial_filter_mode = app.filter_mode;
-
-        // Handle input
-        if let Event::Input(input) = events.next()? {
-            if let Some(i) = app.handle_input(settings, &input, results.len()) {
-                break 'render i;
-            }
-        }
-
-        // After we receive input process the whole event channel before query/render.
-        while let Ok(Event::Input(input)) = events.try_next() {
-            if let Some(i) = app.handle_input(settings, &input, results.len()) {
-                break 'render i;
-            }
-        }
-
-        if initial_input != app.input.as_str() || initial_filter_mode != app.filter_mode {
-            results = app.query_results(settings.search_mode, db).await?;
-        }
-
         let compact = match settings.style {
             atuin_client::settings::Style::Auto => {
                 terminal.size().map(|size| size.height < 14).unwrap_or(true)
@@ -376,6 +423,24 @@ pub async fn history(
         } else {
             terminal.draw(|f| app.draw(f, &results))?;
         }
+
+        let initial_input = app.input.as_str().to_owned();
+        let initial_filter_mode = app.filter_mode;
+
+        if event::poll(Duration::from_millis(250))? {
+            loop {
+                if let Some(i) = app.handle_input(settings, &event::read()?, results.len()) {
+                    break 'render i;
+                }
+                if !event::poll(Duration::ZERO)? {
+                    break;
+                }
+            }
+        }
+
+        if initial_input != app.input.as_str() || initial_filter_mode != app.filter_mode {
+            results = app.query_results(settings.search_mode, db).await?;
+        }
     };
 
     if index < results.len() {
diff --git a/src/main.rs b/src/main.rs
index 2f81f4fc..3004e0b1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,6 +6,7 @@ use eyre::Result;
 
 use command::AtuinCmd;
 mod command;
+mod tui;
 
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
diff --git a/src/tui/LICENSE b/src/tui/LICENSE
new file mode 100644
index 00000000..7a0657cb
--- /dev/null
+++ b/src/tui/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Florian Dehau
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/src/tui/README.md b/src/tui/README.md
new file mode 100644
index 00000000..506bdf8f
--- /dev/null
+++ b/src/tui/README.md
@@ -0,0 +1,5 @@
+# tui-rs
+
+A fork of https://crates.io/crates/tui/0.19.0 since it is now unmaintained.
+
+Some parts have been removed or modified for simplicity, but it is currently mostly equivalent.
diff --git a/src/tui/backend/crossterm.rs b/src/tui/backend/crossterm.rs
new file mode 100644
index 00000000..2cbfd6e0
--- /dev/null
+++ b/src/tui/backend/crossterm.rs
@@ -0,0 +1,221 @@
+use crate::tui::{
+    backend::Backend,
+    buffer::Cell,
+    layout::Rect,
+    style::{Color, Modifier},
+};
+use crossterm::{
+    cursor::{Hide, MoveTo, Show},
+    execute, queue,
+    style::{
+        Attribute as CAttribute, Color as CColor, Print, SetAttribute, SetBackgroundColor,
+        SetForegroundColor,
+    },
+    terminal::{self, Clear, ClearType},
+};
+use std::io::{self, Write};
+
+pub struct CrosstermBackend<W: Write> {
+    buffer: W,
+}
+
+impl<W> CrosstermBackend<W>
+where
+    W: Write,
+{
+    pub fn new(buffer: W) -> CrosstermBackend<W> {
+        CrosstermBackend { buffer }
+    }
+}
+
+impl<W> Write for CrosstermBackend<W>
+where
+    W: Write,
+{
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.buffer.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.buffer.flush()
+    }
+}
+
+impl<W> Backend for CrosstermBackend<W>
+where
+    W: Write,
+{
+    fn draw<'a, I>(&mut self, content: I) -> io::Result<()>
+    where
+        I: Iterator<Item = (u16, u16, &'a Cell)>,
+    {
+        let mut fg = Color::Reset;
+        let mut bg = Color::Reset;
+        let mut modifier = Modifier::empty();
+        let mut last_pos: Option<(u16, u16)> = None;
+        for (x, y, cell) in content {
+            // Move the cursor if the previous location was not (x - 1, y)
+            if !matches!(last_pos, Some(p) if x == p.0 + 1 && y == p.1) {
+                map_error(queue!(self.buffer, MoveTo(x, y)))?;
+            }
+            last_pos = Some((x, y));
+            if cell.modifier != modifier {
+                let diff = ModifierDiff {
+                    from: modifier,
+                    to: cell.modifier,
+                };
+                diff.queue(&mut self.buffer)?;
+                modifier = cell.modifier;
+            }
+            if cell.fg != fg {
+                let color = CColor::from(cell.fg);
+                map_error(queue!(self.buffer, SetForegroundColor(color)))?;
+                fg = cell.fg;
+            }
+            if cell.bg != bg {
+                let color = CColor::from(cell.bg);
+                map_error(queue!(self.buffer, SetBackgroundColor(color)))?;
+                bg = cell.bg;
+            }
+
+            map_error(queue!(self.buffer, Print(&cell.symbol)))?;
+        }
+
+        map_error(queue!(
+            self.buffer,
+            SetForegroundColor(CColor::Reset),
+            SetBackgroundColor(CColor::Reset),
+            SetAttribute(CAttribute::Reset)
+        ))
+    }
+
+    fn hide_cursor(&mut self) -> io::Result<()> {
+        map_error(execute!(self.buffer, Hide))
+    }
+
+    fn show_cursor(&mut self) -> io::Result<()> {
+        map_error(execute!(self.buffer, Show))
+    }
+
+    fn get_cursor(&mut self) -> io::Result<(u16, u16)> {
+        crossterm::cursor::position()
+            .map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))
+    }
+
+    fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()> {
+        map_error(execute!(self.buffer, MoveTo(x, y)))
+    }
+
+    fn clear(&mut self) -> io::Result<()> {
+        map_error(execute!(self.buffer, Clear(ClearType::All)))
+    }
+
+    fn size(&self) -> io::Result<Rect> {
+        let (width, height) =
+            terminal::size().map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))?;
+
+        Ok(Rect::new(0, 0, width, height))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.buffer.flush()
+    }
+}
+
+fn map_error(error: crossterm::Result<()>) -> io::Result<()> {
+    error.map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))
+}
+
+impl From<Color> for CColor {
+    fn from(color: Color) -> Self {
+        match color {
+            Color::Reset => CColor::Reset,
+            Color::Black => CColor::Black,
+            Color::Red => CColor::DarkRed,
+            Color::Green => CColor::DarkGreen,
+            Color::Yellow => CColor::DarkYellow,
+            Color::Blue => CColor::DarkBlue,
+            Color::Magenta => CColor::DarkMagenta,
+            Color::Cyan => CColor::DarkCyan,
+            Color::Gray => CColor::Grey,
+            Color::DarkGray => CColor::DarkGrey,
+            Color::LightRed => CColor::Red,
+            Color::LightGreen => CColor::Green,
+            Color::LightBlue => CColor::Blue,
+            Color::LightYellow => CColor::Yellow,
+            Color::LightMagenta => CColor::Magenta,
+            Color::LightCyan => CColor::Cyan,
+            Color::White => CColor::White,
+            Color::Indexed(i) => CColor::AnsiValue(i),
+            Color::Rgb(r, g, b) => CColor::Rgb { r, g, b },
+        }
+    }
+}
+
+#[derive(Debug)]
+struct ModifierDiff {
+    pub from: Modifier,
+    pub to: Modifier,
+}
+
+impl ModifierDiff {
+    fn queue<W>(&self, mut w: W) -> io::Result<()>
+    where
+        W: io::Write,
+    {
+        //use crossterm::Attribute;
+        let removed = self.from - self.to;
+        if removed.contains(Modifier::REVERSED) {
+            map_error(queue!(w, SetAttribute(CAttribute::NoReverse)))?;
+        }
+        if removed.contains(Modifier::BOLD) {
+            map_error(queue!(w, SetAttribute(CAttribute::NormalIntensity)))?;
+            if self.to.contains(Modifier::DIM) {
+                map_error(queue!(w, SetAttribute(CAttribute::Dim)))?;
+            }
+        }
+        if removed.contains(Modifier::ITALIC) {
+            map_error(queue!(w, SetAttribute(CAttribute::NoItalic)))?;
+        }
+        if removed.contains(Modifier::UNDERLINED) {
+            map_error(queue!(w, SetAttribute(CAttribute::NoUnderline)))?;
+        }
+        if removed.contains(Modifier::DIM) {
+            map_error(queue!(w, SetAttribute(CAttribute::NormalIntensity)))?;
+        }
+        if removed.contains(Modifier::CROSSED_OUT) {
+            map_error(queue!(w, SetAttribute(CAttribute::NotCrossedOut)))?;
+        }
+        if removed.contains(Modifier::SLOW_BLINK) || removed.contains(Modifier::RAPID_BLINK) {
+            map_error(queue!(w, SetAttribute(CAttribute::NoBlink)))?;
+        }
+
+        let added = self.to - self.from;
+        if added.contains(Modifier::REVERSED) {
+            map_error(queue!(w, SetAttribute(CAttribute::Reverse)))?;
+        }
+        if added.contains(Modifier::BOLD) {
+            map_error(queue!(w, SetAttribute(CAttribute::Bold)))?;
+        }
+        if added.contains(Modifier::ITALIC) {
+            map_error(queue!(w, SetAttribute(CAttribute::Italic)))?;
+        }
+        if added.contains(Modifier::UNDERLINED) {
+            map_error(queue!(w, SetAttribute(CAttribute::Underlined)))?;
+        }
+        if added.contains(Modifier::DIM) {
+            map_error(queue!(w, SetAttribute(CAttribute::Dim)))?;
+        }
+        if added.contains(Modifier::CROSSED_OUT) {
+            map_error(queue!(w, SetAttribute(CAttribute::CrossedOut)))?;
+        }
+        if added.contains(Modifier::SLOW_BLINK) {
+            map_error(queue!(w, SetAttribute(CAttribute::SlowBlink)))?;
+        }
+        if added.contains(Modifier::RAPID_BLINK) {
+            map_error(queue!(w, SetAttribute(CAttribute::RapidBlink)))?;
+        }
+
+        Ok(())
+    }
+}
diff --git a/src/tui/backend/mod.rs b/src/tui/backend/mod.rs
new file mode 100644
index 00000000..1a197e79
--- /dev/null
+++ b/src/tui/backend/mod.rs
@@ -0,0 +1,20 @@
+use std::io;
+
+use crate::tui::buffer::Cell;
+use crate::tui::layout::Rect;
+
+mod crossterm;
+pub use self::crossterm::CrosstermBackend;
+
+pub trait Backend {
+    fn draw<'a, I>(&mut self, content: I) -> Result<(), io::Error>
+    where
+        I: Iterator<Item = (u16, u16, &'a Cell)>;
+    fn hide_cursor(&mut self) -> Result<(), io::Error>;
+    fn show_cursor(&mut self) -> Result<(), io::Error>;
+    fn get_cursor(&mut self) -> Result<(u16, u16), io::Error>;
+    fn set_cursor(&mut self, x: u16, y: u16) -> Result<(), io::Error>;
+    fn clear(&mut self) -> Result<(), io::Error>;
+    fn size(&self) -> Result<Rect, io::Error>;
+    fn flush(&mut self) -> Result<(), io::Error>;
+}
diff --git a/src/tui/buffer.rs b/src/tui/buffer.rs
new file mode 100644
index 00000000..38307980
--- /dev/null
+++ b/src/tui/buffer.rs
@@ -0,0 +1,732 @@
+use crate::tui::{
+    layout::Rect,
+    style::{Color, Modifier, Style},
+    text::{Span, Spans},
+};
+use std::cmp::min;
+use unicode_segmentation::UnicodeSegmentation;
+use unicode_width::UnicodeWidthStr;
+
+/// A buffer cell
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Cell {
+    pub symbol: String,
+    pub fg: Color,
+    pub bg: Color,
+    pub modifier: Modifier,
+}
+
+impl Cell {
+    pub fn set_symbol(&mut self, symbol: &str) -> &mut Cell {
+        self.symbol.clear();
+        self.symbol.push_str(symbol);
+        self
+    }
+
+    pub fn set_char(&mut self, ch: char) -> &mut Cell {
+        self.symbol.clear();
+        self.symbol.push(ch);
+        self
+    }
+
+    pub fn set_fg(&mut self, color: Color) -> &mut Cell {
+        self.fg = color;
+        self
+    }
+
+    pub fn set_bg(&mut self, color: Color) -> &mut Cell {
+        self.bg = color;
+        self
+    }
+
+    pub fn set_style(&mut self, style: Style) -> &mut Cell {
+        if let Some(c) = style.fg {
+            self.fg = c;
+        }
+        if let Some(c) = style.bg {
+            self.bg = c;
+        }
+        self.modifier.insert(style.add_modifier);
+        self.modifier.remove(style.sub_modifier);
+        self
+    }
+
+    pub fn style(&self) -> Style {
+        Style::default()
+            .fg(self.fg)
+            .bg(self.bg)
+            .add_modifier(self.modifier)
+    }
+
+    pub fn reset(&mut self) {
+        self.symbol.clear();
+        self.symbol.push(' ');
+        self.fg = Color::Reset;
+        self.bg = Color::Reset;
+        self.modifier = Modifier::empty();
+    }
+}
+
+impl Default for Cell {
+    fn default() -> Cell {
+        Cell {
+            symbol: " ".into(),
+            fg: Color::Reset,
+            bg: Color::Reset,
+            modifier: Modifier::empty(),
+        }
+    }
+}
+
+/// A buffer that maps to the desired content of the terminal after the draw call
+///
+/// No widget in the library interacts directly with the terminal. Instead each of them is required
+/// to draw their state to an intermediate buffer. It is basically a grid where each cell contains
+/// a grapheme, a foreground color and a background color. This grid will then be used to output
+/// the appropriate escape sequences and characters to draw the UI as the user has defined it.
+///
+/// # Examples:
+///
+/// ```
+/// use tui::buffer::{Buffer, Cell};
+/// use tui::layout::Rect;
+/// use tui::style::{Color, Style, Modifier};
+///
+/// let mut buf = Buffer::empty(Rect{x: 0, y: 0, width: 10, height: 5});
+/// buf.get_mut(0, 2).set_symbol("x");
+/// assert_eq!(buf.get(0, 2).symbol, "x");
+/// buf.set_string(3, 0, "string", Style::default().fg(Color::Red).bg(Color::White));
+/// assert_eq!(buf.get(5, 0), &Cell{
+///     symbol: String::from("r"),
+///     fg: Color::Red,
+///     bg: Color::White,
+///     modifier: Modifier::empty()
+/// });
+/// buf.get_mut(5, 0).set_char('x');
+/// assert_eq!(buf.get(5, 0).symbol, "x");
+/// ```
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct Buffer {
+    /// The area represented by this buffer
+    pub area: Rect,
+    /// The content of the buffer. The length of this Vec should always be equal to area.width *
+    /// area.height
+    pub content: Vec<Cell>,
+}
+
+impl Buffer {
+    /// Returns a Buffer with all cells set to the default one
+    pub fn empty(area: Rect) -> Buffer {
+        let cell = Cell::default();
+        Buffer::filled(area, &cell)
+    }
+
+    /// Returns a Buffer with all cells initialized with the attributes of the given Cell
+    pub fn filled(area: Rect, cell: &Cell) -> Buffer {
+        let size = area.area() as usize;
+        let mut content = Vec::with_capacity(size);
+        for _ in 0..size {
+            content.push(cell.clone());
+        }
+        Buffer { area, content }
+    }
+
+    /// Returns a Buffer containing the given lines
+    pub fn with_lines<S>(lines: &[S]) -> Buffer
+    where
+        S: AsRef<str>,
+    {
+        let height = lines.len() as u16;
+        let width = lines
+            .iter()
+            .map(|i| i.as_ref().width() as u16)
+            .max()
+            .unwrap_or_default();
+        let mut buffer = Buffer::empty(Rect {
+            x: 0,
+            y: 0,
+            width,
+            height,
+        });
+        for (y, line) in lines.iter().enumerate() {
+            buffer.set_string(0, y as u16, line, Style::default());
+        }
+        buffer
+    }
+
+    /// Returns the content of the buffer as a slice
+    pub fn content(&self) -> &[Cell] {
+        &self.content
+    }
+
+    /// Returns the area covered by this buffer
+    pub fn area(&self) -> &Rect {
+        &self.area
+    }
+
+    /// Returns a reference to Cell at the given coordinates
+    pub fn get(&self, x: u16, y: u16) -> &Cell {
+        let i = self.index_of(x, y);
+        &self.content[i]
+    }
+
+    /// Returns a mutable reference to Cell at the given coordinates
+    pub fn get_mut(&mut self, x: u16, y: u16) -> &mut Cell {
+        let i = self.index_of(x, y);
+        &mut self.content[i]
+    }
+
+    /// Returns the index in the Vec<Cell> for the given global (x, y) coordinates.
+    ///
+    /// Global coordinates are offset by the Buffer's area offset (`x`/`y`).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use tui::buffer::Buffer;
+    /// # use tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// // Global coordinates to the top corner of this buffer's area
+    /// assert_eq!(buffer.index_of(200, 100), 0);
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// Panics when given an coordinate that is outside of this Buffer's area.
+    ///
+    /// ```should_panic
+    /// # use tui::buffer::Buffer;
+    /// # use tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// // Top coordinate is outside of the buffer in global coordinate space, as the Buffer's area
+    /// // starts at (200, 100).
+    /// buffer.index_of(0, 0); // Panics
+    /// ```
+    pub fn index_of(&self, x: u16, y: u16) -> usize {
+        debug_assert!(
+            x >= self.area.left()
+                && x < self.area.right()
+                && y >= self.area.top()
+                && y < self.area.bottom(),
+            "Trying to access position outside the buffer: x={}, y={}, area={:?}",
+            x,
+            y,
+            self.area
+        );
+        ((y - self.area.y) * self.area.width + (x - self.area.x)) as usize
+    }
+
+    /// Returns the (global) coordinates of a cell given its index
+    ///
+    /// Global coordinates are offset by the Buffer's area offset (`x`/`y`).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use tui::buffer::Buffer;
+    /// # use tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// assert_eq!(buffer.pos_of(0), (200, 100));
+    /// assert_eq!(buffer.pos_of(14), (204, 101));
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// Panics when given an index that is outside the Buffer's content.
+    ///
+    /// ```should_panic
+    /// # use tui::buffer::Buffer;
+    /// # use tui::layout::Rect;
+    /// let rect = Rect::new(0, 0, 10, 10); // 100 cells in total
+    /// let buffer = Buffer::empty(rect);
+    /// // Index 100 is the 101th cell, which lies outside of the area of this Buffer.
+    /// buffer.pos_of(100); // Panics
+    /// ```
+    pub fn pos_of(&self, i: usize) -> (u16, u16) {
+        debug_assert!(
+            i < self.content.len(),
+            "Trying to get the coords of a cell outside the buffer: i={} len={}",
+            i,
+            self.content.len()
+        );
+        (
+            self.area.x + i as u16 % self.area.width,
+            self.area.y + i as u16 / self.area.width,
+        )
+    }
+
+    /// Print a string, starting at the position (x, y)
+    pub fn set_string<S>(&mut self, x: u16, y: u16, string: S, style: Style)
+    where
+        S: AsRef<str>,
+    {
+        self.set_stringn(x, y, string, usize::MAX, style);
+    }
+
+    /// Print at most the first n characters of a string if enough space is available
+    /// until the end of the line
+    pub fn set_stringn<S>(
+        &mut self,
+        x: u16,
+        y: u16,
+        string: S,
+        width: usize,
+        style: Style,
+    ) -> (u16, u16)
+    where
+        S: AsRef<str>,
+    {
+        let mut index = self.index_of(x, y);
+        let mut x_offset = x as usize;
+        let graphemes = UnicodeSegmentation::graphemes(string.as_ref(), true);
+        let max_offset = min(self.area.right() as usize, width.saturating_add(x as usize));
+        for s in graphemes {
+            let width = s.width();
+            if width == 0 {
+                continue;
+            }
+            // `x_offset + width > max_offset` could be integer overflow on 32-bit machines if we
+            // change dimenstions to usize or u32 and someone resizes the terminal to 1x2^32.
+            if width > max_offset.saturating_sub(x_offset) {
+                break;
+            }
+
+            self.content[index].set_symbol(s);
+            self.content[index].set_style(style);
+            // Reset following cells if multi-width (they would be hidden by the grapheme),
+            for i in index + 1..index + width {
+                self.content[i].reset();
+            }
+            index += width;
+            x_offset += width;
+        }
+        (x_offset as u16, y)
+    }
+
+    pub fn set_spans(&mut self, x: u16, y: u16, spans: &Spans<'_>, width: u16) -> (u16, u16) {
+        let mut remaining_width = width;
+        let mut x = x;
+        for span in &spans.0 {
+            if remaining_width == 0 {
+                break;
+            }
+            let pos = self.set_stringn(
+                x,
+                y,
+                span.content.as_ref(),
+                remaining_width as usize,
+                span.style,
+            );
+            let w = pos.0.saturating_sub(x);
+            x = pos.0;
+            remaining_width = remaining_width.saturating_sub(w);
+        }
+        (x, y)
+    }
+
+    pub fn set_span(&mut self, x: u16, y: u16, span: &Span<'_>, width: u16) -> (u16, u16) {
+        self.set_stringn(x, y, span.content.as_ref(), width as usize, span.style)
+    }
+
+    #[deprecated(
+        since = "0.10.0",
+        note = "You should use styling capabilities of `Buffer::set_style`"
+    )]
+    pub fn set_background(&mut self, area: Rect, color: Color) {
+        for y in area.top()..area.bottom() {
+            for x in area.left()..area.right() {
+                self.get_mut(x, y).set_bg(color);
+            }
+        }
+    }
+
+    pub fn set_style(&mut self, area: Rect, style: Style) {
+        for y in area.top()..area.bottom() {
+            for x in area.left()..area.right() {
+                self.get_mut(x, y).set_style(style);
+            }
+        }
+    }
+
+    /// Resize the buffer so that the mapped area matches the given area and that the buffer
+    /// length is equal to area.width * area.height
+    pub fn resize(&mut self, area: Rect) {
+        let length = area.area() as usize;
+        if self.content.len() > length {
+            self.content.truncate(length);
+        } else {
+            self.content.resize(length, Cell::default());
+        }
+        self.area = area;
+    }
+
+    /// Reset all cells in the buffer
+    pub fn reset(&mut self) {
+        for c in &mut self.content {
+            c.reset();
+        }
+    }
+
+    /// Merge an other buffer into this one
+    pub fn merge(&mut self, other: &Buffer) {
+        let area = self.area.union(other.area);
+        let cell = Cell::default();
+        self.content.resize(area.area() as usize, cell.clone());
+
+        // Move original content to the appropriate space
+        let size = self.area.area() as usize;
+        for i in (0..size).rev() {
+            let (x, y) = self.pos_of(i);
+            // New index in content
+            let k = ((y - area.y) * area.width + x - area.x) as usize;
+            if i != k {
+                self.content[k] = self.content[i].clone();
+                self.content[i] = cell.clone();
+            }
+        }
+
+        // Push content of the other buffer into this one (may erase previous
+        // data)
+        let size = other.area.area() as usize;
+        for i in 0..size {
+            let (x, y) = other.pos_of(i);
+            // New index in content
+            let k = ((y - area.y) * area.width + x - area.x) as usize;
+            self.content[k] = other.content[i].clone();
+        }
+        self.area = area;
+    }
+
+    /// Builds a minimal sequence of coordinates and Cells necessary to update the UI from
+    /// self to other.
+    ///
+    /// We're assuming that buffers are well-formed, that is no double-width cell is followed by
+    /// a non-blank cell.
+    ///
+    /// # Multi-width characters handling:
+    ///
+    /// ```text
+    /// (Index:) `01`
+    /// Prev:    `コ`
+    /// Next:    `aa`
+    /// Updates: `0: a, 1: a'
+    /// ```
+    ///
+    /// ```text
+    /// (Index:) `01`
+    /// Prev:    `a `
+    /// Next:    `コ`
+    /// Updates: `0: コ` (double width symbol at index 0 - skip index 1)
+    /// ```
+    ///
+    /// ```text
+    /// (Index:) `012`
+    /// Prev:    `aaa`
+    /// Next:    `aコ`
+    /// Updates: `0: a, 1: コ` (double width symbol at index 1 - skip index 2)
+    /// ```
+    pub fn diff<'a>(&self, other: &'a Buffer) -> Vec<(u16, u16, &'a Cell)> {
+        let previous_buffer = &self.content;
+        let next_buffer = &other.content;
+        let width = self.area.width;
+
+        let mut updates: Vec<(u16, u16, &Cell)> = vec![];
+        // Cells invalidated by drawing/replacing preceeding multi-width characters:
+        let mut invalidated: usize = 0;
+        // Cells from the current buffer to skip due to preceeding multi-width characters taking their
+        // place (the skipped cells should be blank anyway):
+        let mut to_skip: usize = 0;
+        for (i, (current, previous)) in next_buffer.iter().zip(previous_buffer.iter()).enumerate() {
+            if (current != previous || invalidated > 0) && to_skip == 0 {
+                let x = i as u16 % width;
+                let y = i as u16 / width;
+                updates.push((x, y, &next_buffer[i]));
+            }
+
+            to_skip = current.symbol.width().saturating_sub(1);
+
+            let affected_width = std::cmp::max(current.symbol.width(), previous.symbol.width());
+            invalidated = std::cmp::max(affected_width, invalidated).saturating_sub(1);
+        }
+        updates
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn cell(s: &str) -> Cell {
+        let mut cell = Cell::default();
+        cell.set_symbol(s);
+        cell
+    }
+
+    #[test]
+    fn it_translates_to_and_from_coordinates() {
+        let rect = Rect::new(200, 100, 50, 80);
+        let buf = Buffer::empty(rect);
+
+        // First cell is at the upper left corner.
+        assert_eq!(buf.pos_of(0), (200, 100));
+        assert_eq!(buf.index_of(200, 100), 0);
+
+        // Last cell is in the lower right.
+        assert_eq!(buf.pos_of(buf.content.len() - 1), (249, 179));
+        assert_eq!(buf.index_of(249, 179), buf.content.len() - 1);
+    }
+
+    #[test]
+    #[should_panic(expected = "outside the buffer")]
+    fn pos_of_panics_on_out_of_bounds() {
+        let rect = Rect::new(0, 0, 10, 10);
+        let buf = Buffer::empty(rect);
+
+        // There are a total of 100 cells; zero-indexed means that 100 would be the 101st cell.
+        buf.pos_of(100);
+    }
+
+    #[test]
+    #[should_panic(expected = "outside the buffer")]
+    fn index_of_panics_on_out_of_bounds() {
+        let rect = Rect::new(0, 0, 10, 10);
+        let buf = Buffer::empty(rect);
+
+        // width is 10; zero-indexed means that 10 would be the 11th cell.
+        buf.index_of(10, 0);
+    }
+
+    #[test]
+    fn buffer_set_string() {
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buffer = Buffer::empty(area);
+
+        // Zero-width
+        buffer.set_stringn(0, 0, "aaa", 0, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["     "]));
+
+        buffer.set_string(0, 0, "aaa", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["aaa  "]));
+
+        // Width limit:
+        buffer.set_stringn(0, 0, "bbbbbbbbbbbbbb", 4, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["bbbb "]));
+
+        buffer.set_string(0, 0, "12345", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["12345"]));
+
+        // Width truncation:
+        buffer.set_string(0, 0, "123456", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["12345"]));
+    }
+
+    #[test]
+    fn buffer_set_string_zero_width() {
+        let area = Rect::new(0, 0, 1, 1);
+        let mut buffer = Buffer::empty(area);
+
+        // Leading grapheme with zero width
+        let s = "\u{1}a";
+        buffer.set_stringn(0, 0, s, 1, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["a"]));
+
+        // Trailing grapheme with zero with
+        let s = "a\u{1}";
+        buffer.set_stringn(0, 0, s, 1, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["a"]));
+    }
+
+    #[test]
+    fn buffer_set_string_double_width() {
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buffer = Buffer::empty(area);
+        buffer.set_string(0, 0, "コン", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["コン "]));
+
+        // Only 1 space left.
+        buffer.set_string(0, 0, "コンピ", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(&["コン "]));
+    }
+
+    #[test]
+    fn buffer_with_lines() {
+        let buffer = Buffer::with_lines(&["┌────────┐", "│コンピュ│", "│ーa 上で│", "└────────┘"]);
+        assert_eq!(buffer.area.x, 0);
+        assert_eq!(buffer.area.y, 0);
+        assert_eq!(buffer.area.width, 10);
+        assert_eq!(buffer.area.height, 4);
+    }
+
+    #[test]
+    fn buffer_diffing_empty_empty() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::empty(area);
+        let next = Buffer::empty(area);
+        let diff = prev.diff(&next);
+        assert_eq!(diff, vec![]);
+    }
+
+    #[test]
+    fn buffer_diffing_empty_filled() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::empty(area);
+        let next = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let diff = prev.diff(&next);
+        assert_eq!(diff.len(), 40 * 40);
+    }
+
+    #[test]
+    fn buffer_diffing_filled_filled() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let next = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let diff = prev.diff(&next);
+        assert_eq!(diff, vec![]);
+    }
+
+    #[test]
+    fn buffer_diffing_single_width() {
+        let prev = Buffer::with_lines(&[
+            "          ",
+            "┌Title─┐  ",
+            "│      │  ",
+            "│      │  ",
+            "└──────┘  ",
+        ]);
+        let next = Buffer::with_lines(&[
+            "          ",
+            "┌TITLE─┐  ",
+            "│      │  ",
+            "│      │  ",
+            "└──────┘  ",
+        ]);
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![
+                (2, 1, &cell("I")),
+                (3, 1, &cell("T")),
+                (4, 1, &cell("L")),
+                (5, 1, &cell("E")),
+            ]
+        );
+    }
+
+    #[test]
+    #[rustfmt::skip]
+    fn buffer_diffing_multi_width() {
+        let prev = Buffer::with_lines(&[
+            "┌Title─┐  ",
+            "└──────┘  ",
+        ]);
+        let next = Buffer::with_lines(&[
+            "┌称号──┐  ",
+            "└──────┘  ",
+        ]);
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![
+                (1, 0, &cell("称")),
+                // Skipped "i"
+                (3, 0, &cell("号")),
+                // Skipped "l"
+                (5, 0, &cell("─")),
+            ]
+        );
+    }
+
+    #[test]
+    fn buffer_diffing_multi_width_offset() {
+        let prev = Buffer::with_lines(&["┌称号──┐"]);
+        let next = Buffer::with_lines(&["┌─称号─┐"]);
+
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![(1, 0, &cell("─")), (2, 0, &cell("称")), (4, 0, &cell("号")),]
+        );
+    }
+
+    #[test]
+    fn buffer_merge() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 2,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        assert_eq!(one, Buffer::with_lines(&["11", "11", "22", "22"]));
+    }
+
+    #[test]
+    fn buffer_merge2() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 2,
+                y: 2,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        assert_eq!(one, Buffer::with_lines(&["22  ", "22  ", "  11", "  11"]));
+    }
+
+    #[test]
+    fn buffer_merge3() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 3,
+                y: 3,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 1,
+                y: 1,
+                width: 3,
+                height: 4,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        let mut merged = Buffer::with_lines(&["222 ", "222 ", "2221", "2221"]);
+        merged.area = Rect {
+            x: 1,
+            y: 1,
+            width: 4,
+            height: 4,
+        };
+        assert_eq!(one, merged);
+    }
+}
diff --git a/src/tui/layout.rs b/src/tui/layout.rs
new file mode 100644
index 00000000..369e10f9
--- /dev/null
+++ b/src/tui/layout.rs
@@ -0,0 +1,537 @@
+use std::cell::RefCell;
+use std::cmp::{max, min};
+use std::collections::HashMap;
+
+use cassowary::strength::{REQUIRED, WEAK};
+use cassowary::WeightedRelation::{EQ, GE, LE};
+use cassowary::{Constraint as CassowaryConstraint, Expression, Solver, Variable};
+
+#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
+pub enum Corner {
+    TopLeft,
+    TopRight,
+    BottomRight,
+    BottomLeft,
+}
+
+#[derive(Debug, Hash, Clone, PartialEq, Eq)]
+pub enum Direction {
+    Horizontal,
+    Vertical,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Constraint {
+    // TODO: enforce range 0 - 100
+    Percentage(u16),
+    Ratio(u32, u32),
+    Length(u16),
+    Max(u16),
+    Min(u16),
+}
+
+impl Constraint {
+    pub fn apply(&self, length: u16) -> u16 {
+        match *self {
+            Constraint::Percentage(p) => length * p / 100,
+            Constraint::Ratio(num, den) => {
+                let r = num * u32::from(length) / den;
+                r as u16
+            }
+            Constraint::Length(l) => length.min(l),
+            Constraint::Max(m) => length.min(m),
+            Constraint::Min(m) => length.max(m),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Margin {
+    pub vertical: u16,
+    pub horizontal: u16,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Alignment {
+    Left,
+    Center,
+    Right,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Layout {
+    direction: Direction,
+    margin: Margin,
+    constraints: Vec<Constraint>,
+    /// Whether the last chunk of the computed layout should be expanded to fill the available
+    /// space.
+    expand_to_fill: bool,
+}
+
+thread_local! {
+    static LAYOUT_CACHE: RefCell<HashMap<(Rect, Layout), Vec<Rect>>> = RefCell::new(HashMap::new());
+}
+
+impl Default for Layout {
+    fn default() -> Layout {
+        Layout {
+            direction: Direction::Vertical,
+            margin: Margin {
+                horizontal: 0,
+                vertical: 0,
+            },
+            constraints: Vec::new(),
+            expand_to_fill: true,
+        }
+    }
+}
+
+impl Layout {
+    pub fn constraints<C>(mut self, constraints: C) -> Layout
+    where
+        C: Into<Vec<Constraint>>,
+    {
+        self.constraints = constraints.into();
+        self
+    }
+
+    pub fn margin(mut self, margin: u16) -> Layout {
+        self.margin = Margin {
+            horizontal: margin,
+            vertical: margin,
+        };
+        self
+    }
+
+    pub fn horizontal_margin(mut self, horizontal: u16) -> Layout {
+        self.margin.horizontal = horizontal;
+        self
+    }
+
+    pub fn vertical_margin(mut self, vertical: u16) -> Layout {
+        self.margin.vertical = vertical;
+        self
+    }
+
+    pub fn direction(mut self, direction: Direction) -> Layout {
+        self.direction = direction;
+        self
+    }
+
+    pub(crate) fn expand_to_fill(mut self, expand_to_fill: bool) -> Layout {
+        self.expand_to_fill = expand_to_fill;
+        self
+    }
+
+    /// Wrapper function around the cassowary-rs solver to be able to split a given
+    /// area into smaller ones based on the preferred widths or heights and the direction.
+    ///
+    /// # Examples
+    /// ```
+    /// # use tui::layout::{Rect, Constraint, Direction, Layout};
+    /// let chunks = Layout::default()
+    ///     .direction(Direction::Vertical)
+    ///     .constraints([Constraint::Length(5), Constraint::Min(0)].as_ref())
+    ///     .split(Rect {
+    ///         x: 2,
+    ///         y: 2,
+    ///         width: 10,
+    ///         height: 10,
+    ///     });
+    /// assert_eq!(
+    ///     chunks,
+    ///     vec![
+    ///         Rect {
+    ///             x: 2,
+    ///             y: 2,
+    ///             width: 10,
+    ///             height: 5
+    ///         },
+    ///         Rect {
+    ///             x: 2,
+    ///             y: 7,
+    ///             width: 10,
+    ///             height: 5
+    ///         }
+    ///     ]
+    /// );
+    ///
+    /// let chunks = Layout::default()
+    ///     .direction(Direction::Horizontal)
+    ///     .constraints([Constraint::Ratio(1, 3), Constraint::Ratio(2, 3)].as_ref())
+    ///     .split(Rect {
+    ///         x: 0,
+    ///         y: 0,
+    ///         width: 9,
+    ///         height: 2,
+    ///     });
+    /// assert_eq!(
+    ///     chunks,
+    ///     vec![
+    ///         Rect {
+    ///             x: 0,
+    ///             y: 0,
+    ///             width: 3,
+    ///             height: 2
+    ///         },
+    ///         Rect {
+    ///             x: 3,
+    ///             y: 0,
+    ///             width: 6,
+    ///             height: 2
+    ///         }
+    ///     ]
+    /// );
+    /// ```
+    pub fn split(&self, area: Rect) -> Vec<Rect> {
+        // TODO: Maybe use a fixed size cache ?
+        LAYOUT_CACHE.with(|c| {
+            c.borrow_mut()
+                .entry((area, self.clone()))
+                .or_insert_with(|| split(area, self))
+                .clone()
+        })
+    }
+}
+
+#[allow(clippy::too_many_lines)]
+fn split(area: Rect, layout: &Layout) -> Vec<Rect> {
+    let mut solver = Solver::new();
+    let mut vars: HashMap<Variable, (usize, usize)> = HashMap::new();
+    let elements = layout
+        .constraints
+        .iter()
+        .map(|_| Element::new())
+        .collect::<Vec<Element>>();
+    let mut results = layout
+        .constraints
+        .iter()
+        .map(|_| Rect::default())
+        .collect::<Vec<Rect>>();
+
+    let dest_area = area.inner(&layout.margin);
+    for (i, e) in elements.iter().enumerate() {
+        vars.insert(e.x, (i, 0));
+        vars.insert(e.y, (i, 1));
+        vars.insert(e.width, (i, 2));
+        vars.insert(e.height, (i, 3));
+    }
+    let mut ccs: Vec<CassowaryConstraint> =
+        Vec::with_capacity(elements.len() * 4 + layout.constraints.len() * 6);
+    for elt in &elements {
+        ccs.push(elt.width | GE(REQUIRED) | 0f64);
+        ccs.push(elt.height | GE(REQUIRED) | 0f64);
+        ccs.push(elt.left() | GE(REQUIRED) | f64::from(dest_area.left()));
+        ccs.push(elt.top() | GE(REQUIRED) | f64::from(dest_area.top()));
+        ccs.push(elt.right() | LE(REQUIRED) | f64::from(dest_area.right()));
+        ccs.push(elt.bottom() | LE(REQUIRED) | f64::from(dest_area.bottom()));
+    }
+    if let Some(first) = elements.first() {
+        ccs.push(match layout.direction {
+            Direction::Horizontal => first.left() | EQ(REQUIRED) | f64::from(dest_area.left()),
+            Direction::Vertical => first.top() | EQ(REQUIRED) | f64::from(dest_area.top()),
+        });
+    }
+    if layout.expand_to_fill {
+        if let Some(last) = elements.last() {
+            ccs.push(match layout.direction {
+                Direction::Horizontal => last.right() | EQ(REQUIRED) | f64::from(dest_area.right()),
+                Direction::Vertical => last.bottom() | EQ(REQUIRED) | f64::from(dest_area.bottom()),
+            });
+        }
+    }
+    match layout.direction {
+        Direction::Horizontal => {
+            for pair in elements.windows(2) {
+                ccs.push((pair[0].x + pair[0].width) | EQ(REQUIRED) | pair[1].x);
+            }
+            for (i, size) in layout.constraints.iter().enumerate() {
+                ccs.push(elements[i].y | EQ(REQUIRED) | f64::from(dest_area.y));
+                ccs.push(elements[i].height | EQ(REQUIRED) | f64::from(dest_area.height));
+                ccs.push(match *size {
+                    Constraint::Length(v) => elements[i].width | EQ(WEAK) | f64::from(v),
+                    Constraint::Percentage(v) => {
+                        elements[i].width | EQ(WEAK) | (f64::from(v * dest_area.width) / 100.0)
+                    }
+                    Constraint::Ratio(n, d) => {
+                        elements[i].width
+                            | EQ(WEAK)
+                            | (f64::from(dest_area.width) * f64::from(n) / f64::from(d))
+                    }
+                    Constraint::Min(v) => elements[i].width | GE(WEAK) | f64::from(v),
+                    Constraint::Max(v) => elements[i].width | LE(WEAK) | f64::from(v),
+                });
+            }
+        }
+        Direction::Vertical => {
+            for pair in elements.windows(2) {
+                ccs.push((pair[0].y + pair[0].height) | EQ(REQUIRED) | pair[1].y);
+            }
+            for (i, size) in layout.constraints.iter().enumerate() {
+                ccs.push(elements[i].x | EQ(REQUIRED) | f64::from(dest_area.x));
+                ccs.push(elements[i].width | EQ(REQUIRED) | f64::from(dest_area.width));
+                ccs.push(match *size {
+                    Constraint::Length(v) => elements[i].height | EQ(WEAK) | f64::from(v),
+                    Constraint::Percentage(v) => {
+                        elements[i].height | EQ(WEAK) | (f64::from(v * dest_area.height) / 100.0)
+                    }
+                    Constraint::Ratio(n, d) => {
+                        elements[i].height
+                            | EQ(WEAK)
+                            | (f64::from(dest_area.height) * f64::from(n) / f64::from(d))
+                    }
+                    Constraint::Min(v) => elements[i].height | GE(WEAK) | f64::from(v),
+                    Constraint::Max(v) => elements[i].height | LE(WEAK) | f64::from(v),
+                });
+            }
+        }
+    }
+    solver.add_constraints(&ccs).unwrap();
+    for &(var, value) in solver.fetch_changes() {
+        let (index, attr) = vars[&var];
+        let value = if value.is_sign_negative() {
+            0
+        } else {
+            value as u16
+        };
+        match attr {
+            0 => {
+                results[index].x = value;
+            }
+            1 => {
+                results[index].y = value;
+            }
+            2 => {
+                results[index].width = value;
+            }
+            3 => {
+                results[index].height = value;
+            }
+            _ => {}
+        }
+    }
+
+    if layout.expand_to_fill {
+        // Fix imprecision by extending the last item a bit if necessary
+        if let Some(last) = results.last_mut() {
+            match layout.direction {
+                Direction::Vertical => {
+                    last.height = dest_area.bottom() - last.y;
+                }
+                Direction::Horizontal => {
+                    last.width = dest_area.right() - last.x;
+                }
+            }
+        }
+    }
+    results
+}
+
+/// A container used by the solver inside split
+struct Element {
+    x: Variable,
+    y: Variable,
+    width: Variable,
+    height: Variable,
+}
+
+impl Element {
+    fn new() -> Element {
+        Element {
+            x: Variable::new(),
+            y: Variable::new(),
+            width: Variable::new(),
+            height: Variable::new(),
+        }
+    }
+
+    fn left(&self) -> Variable {
+        self.x
+    }
+
+    fn top(&self) -> Variable {
+        self.y
+    }
+
+    fn right(&self) -> Expression {
+        self.x + self.width
+    }
+
+    fn bottom(&self) -> Expression {
+        self.y + self.height
+    }
+}
+
+/// A simple rectangle used in the computation of the layout and to give widgets a hint about the
+/// area they are supposed to render to.
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, Default)]
+pub struct Rect {
+    pub x: u16,
+    pub y: u16,
+    pub width: u16,
+    pub height: u16,
+}
+
+impl Rect {
+    /// Creates a new rect, with width and height limited to keep the area under max u16.
+    /// If clipped, aspect ratio will be preserved.
+    pub fn new(x: u16, y: u16, width: u16, height: u16) -> Rect {
+        let max_area = u16::max_value();
+        let (clipped_width, clipped_height) =
+            if u32::from(width) * u32::from(height) > u32::from(max_area) {
+                let aspect_ratio = f64::from(width) / f64::from(height);
+                let max_area_f = f64::from(max_area);
+                let height_f = (max_area_f / aspect_ratio).sqrt();
+                let width_f = height_f * aspect_ratio;
+                (width_f as u16, height_f as u16)
+            } else {
+                (width, height)
+            };
+        Rect {
+            x,
+            y,
+            width: clipped_width,
+            height: clipped_height,
+        }
+    }
+
+    pub fn area(self) -> u16 {
+        self.width * self.height
+    }
+
+    pub fn left(self) -> u16 {
+        self.x
+    }
+
+    pub fn right(self) -> u16 {
+        self.x.saturating_add(self.width)
+    }
+
+    pub fn top(self) -> u16 {
+        self.y
+    }
+
+    pub fn bottom(self) -> u16 {
+        self.y.saturating_add(self.height)
+    }
+
+    pub fn inner(self, margin: &Margin) -> Rect {
+        if self.width < 2 * margin.horizontal || self.height < 2 * margin.vertical {
+            Rect::default()
+        } else {
+            Rect {
+                x: self.x + margin.horizontal,
+                y: self.y + margin.vertical,
+                width: self.width - 2 * margin.horizontal,
+                height: self.height - 2 * margin.vertical,
+            }
+        }
+    }
+
+    pub fn union(self, other: Rect) -> Rect {
+        let x1 = min(self.x, other.x);
+        let y1 = min(self.y, other.y);
+        let x2 = max(self.x + self.width, other.x + other.width);
+        let y2 = max(self.y + self.height, other.y + other.height);
+        Rect {
+            x: x1,
+            y: y1,
+            width: x2 - x1,
+            height: y2 - y1,
+        }
+    }
+
+    pub fn intersection(self, other: Rect) -> Rect {
+        let x1 = max(self.x, other.x);
+        let y1 = max(self.y, other.y);
+        let x2 = min(self.x + self.width, other.x + other.width);
+        let y2 = min(self.y + self.height, other.y + other.height);
+        Rect {
+            x: x1,
+            y: y1,
+            width: x2 - x1,
+            height: y2 - y1,
+        }
+    }
+
+    pub fn intersects(self, other: Rect) -> bool {
+        self.x < other.x + other.width
+            && self.x + self.width > other.x
+            && self.y < other.y + other.height
+            && self.y + self.height > other.y
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_vertical_split_by_height() {
+        let target = Rect {
+            x: 2,
+            y: 2,
+            width: 10,
+            height: 10,
+        };
+
+        let chunks = Layout::default()
+            .direction(Direction::Vertical)
+            .constraints(
+                [
+                    Constraint::Percentage(10),
+                    Constraint::Max(5),
+                    Constraint::Min(1),
+                ]
+                .as_ref(),
+            )
+            .split(target);
+
+        assert_eq!(target.height, chunks.iter().map(|r| r.height).sum::<u16>());
+        chunks.windows(2).for_each(|w| assert!(w[0].y <= w[1].y));
+    }
+
+    #[test]
+    fn test_rect_size_truncation() {
+        for width in 256u16..300u16 {
+            for height in 256u16..300u16 {
+                let rect = Rect::new(0, 0, width, height);
+                rect.area(); // Should not panic.
+                assert!(rect.width < width || rect.height < height);
+                // The target dimensions are rounded down so the math will not be too precise
+                // but let's make sure the ratios don't diverge crazily.
+                assert!(
+                    (f64::from(rect.width) / f64::from(rect.height)
+                        - f64::from(width) / f64::from(height))
+                    .abs()
+                        < 1.0
+                );
+            }
+        }
+
+        // One dimension below 255, one above. Area above max u16.
+        let width = 900;
+        let height = 100;
+        let rect = Rect::new(0, 0, width, height);
+        assert_ne!(rect.width, 900);
+        assert_ne!(rect.height, 100);
+        assert!(rect.width < width || rect.height < height);
+    }
+
+    #[test]
+    fn test_rect_size_preservation() {
+        for width in 0..256u16 {
+            for height in 0..256u16 {
+                let rect = Rect::new(0, 0, width, height);
+                rect.area(); // Should not panic.
+                assert_eq!(rect.width, width);
+                assert_eq!(rect.height, height);
+            }
+        }
+
+        // One dimension below 255, one above. Area below max u16.
+        let rect = Rect::new(0, 0, 300, 100);
+        assert_eq!(rect.width, 300);
+        assert_eq!(rect.height, 100);
+    }
+}
diff --git a/src/tui/mod.rs b/src/tui/mod.rs
new file mode 100644
index 00000000..29fe84cd
--- /dev/null
+++ b/src/tui/mod.rs
@@ -0,0 +1,20 @@
+//! Fork of `tui-rs`
+#![allow(
+    clippy::module_name_repetitions,
+    clippy::bool_to_int_with_if,
+    clippy::similar_names,
+    clippy::cast_possible_truncation,
+    clippy::cast_sign_loss,
+    dead_code
+)]
+
+pub mod backend;
+pub mod buffer;
+pub mod layout;
+pub mod style;
+pub mod symbols;
+pub mod terminal;
+pub mod text;
+pub mod widgets;
+
+pub use self::terminal::{Frame, Terminal, TerminalOptions, Viewport};
diff --git a/src/tui/style.rs b/src/tui/style.rs
new file mode 100644
index 00000000..4aa19d4a
--- /dev/null
+++ b/src/tui/style.rs
@@ -0,0 +1,278 @@
+//! `style` contains the primitives used to control how your user interface will look.
+
+use bitflags::bitflags;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Color {
+    Reset,
+    Black,
+    Red,
+    Green,
+    Yellow,
+    Blue,
+    Magenta,
+    Cyan,
+    Gray,
+    DarkGray,
+    LightRed,
+    LightGreen,
+    LightYellow,
+    LightBlue,
+    LightMagenta,
+    LightCyan,
+    White,
+    Rgb(u8, u8, u8),
+    Indexed(u8),
+}
+
+bitflags! {
+    /// Modifier changes the way a piece of text is displayed.
+    ///
+    /// They are bitflags so they can easily be composed.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::style::Modifier;
+    ///
+    /// let m = Modifier::BOLD | Modifier::ITALIC;
+    /// ```
+    pub struct Modifier: u16 {
+        const BOLD              = 0b0000_0000_0001;
+        const DIM               = 0b0000_0000_0010;
+        const ITALIC            = 0b0000_0000_0100;
+        const UNDERLINED        = 0b0000_0000_1000;
+        const SLOW_BLINK        = 0b0000_0001_0000;
+        const RAPID_BLINK       = 0b0000_0010_0000;
+        const REVERSED          = 0b0000_0100_0000;
+        const HIDDEN            = 0b0000_1000_0000;
+        const CROSSED_OUT       = 0b0001_0000_0000;
+    }
+}
+
+/// Style let you control the main characteristics of the displayed elements.
+///
+/// ```rust
+/// # use tui::style::{Color, Modifier, Style};
+/// Style::default()
+///     .fg(Color::Black)
+///     .bg(Color::Green)
+///     .add_modifier(Modifier::ITALIC | Modifier::BOLD);
+/// ```
+///
+/// It represents an incremental change. If you apply the styles S1, S2, S3 to a cell of the
+/// terminal buffer, the style of this cell will be the result of the merge of S1, S2 and S3, not
+/// just S3.
+///
+/// ```rust
+/// # use tui::style::{Color, Modifier, Style};
+/// # use tui::buffer::Buffer;
+/// # use tui::layout::Rect;
+/// let styles = [
+///     Style::default().fg(Color::Blue).add_modifier(Modifier::BOLD | Modifier::ITALIC),
+///     Style::default().bg(Color::Red),
+///     Style::default().fg(Color::Yellow).remove_modifier(Modifier::ITALIC),
+/// ];
+/// let mut buffer = Buffer::empty(Rect::new(0, 0, 1, 1));
+/// for style in &styles {
+///   buffer.get_mut(0, 0).set_style(*style);
+/// }
+/// assert_eq!(
+///     Style {
+///         fg: Some(Color::Yellow),
+///         bg: Some(Color::Red),
+///         add_modifier: Modifier::BOLD,
+///         sub_modifier: Modifier::empty(),
+///     },
+///     buffer.get(0, 0).style(),
+/// );
+/// ```
+///
+/// The default implementation returns a `Style` that does not modify anything. If you wish to
+/// reset all properties until that point use [`Style::reset`].
+///
+/// ```
+/// # use tui::style::{Color, Modifier, Style};
+/// # use tui::buffer::Buffer;
+/// # use tui::layout::Rect;
+/// let styles = [
+///     Style::default().fg(Color::Blue).add_modifier(Modifier::BOLD | Modifier::ITALIC),
+///     Style::reset().fg(Color::Yellow),
+/// ];
+/// let mut buffer = Buffer::empty(Rect::new(0, 0, 1, 1));
+/// for style in &styles {
+///   buffer.get_mut(0, 0).set_style(*style);
+/// }
+/// assert_eq!(
+///     Style {
+///         fg: Some(Color::Yellow),
+///         bg: Some(Color::Reset),
+///         add_modifier: Modifier::empty(),
+///         sub_modifier: Modifier::empty(),
+///     },
+///     buffer.get(0, 0).style(),
+/// );
+/// ```
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Style {
+    pub fg: Option<Color>,
+    pub bg: Option<Color>,
+    pub add_modifier: Modifier,
+    pub sub_modifier: Modifier,
+}
+
+impl Default for Style {
+    fn default() -> Style {
+        Style {
+            fg: None,
+            bg: None,
+            add_modifier: Modifier::empty(),
+            sub_modifier: Modifier::empty(),
+        }
+    }
+}
+
+impl Style {
+    /// Returns a `Style` resetting all properties.
+    pub fn reset() -> Style {
+        Style {
+            fg: Some(Color::Reset),
+            bg: Some(Color::Reset),
+            add_modifier: Modifier::empty(),
+            sub_modifier: Modifier::all(),
+        }
+    }
+
+    /// Changes the foreground color.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::style::{Color, Style};
+    /// let style = Style::default().fg(Color::Blue);
+    /// let diff = Style::default().fg(Color::Red);
+    /// assert_eq!(style.patch(diff), Style::default().fg(Color::Red));
+    /// ```
+    pub fn fg(mut self, color: Color) -> Style {
+        self.fg = Some(color);
+        self
+    }
+
+    /// Changes the background color.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::style::{Color, Style};
+    /// let style = Style::default().bg(Color::Blue);
+    /// let diff = Style::default().bg(Color::Red);
+    /// assert_eq!(style.patch(diff), Style::default().bg(Color::Red));
+    /// ```
+    pub fn bg(mut self, color: Color) -> Style {
+        self.bg = Some(color);
+        self
+    }
+
+    /// Changes the text emphasis.
+    ///
+    /// When applied, it adds the given modifier to the `Style` modifiers.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style = Style::default().add_modifier(Modifier::BOLD);
+    /// let diff = Style::default().add_modifier(Modifier::ITALIC);
+    /// let patched = style.patch(diff);
+    /// assert_eq!(patched.add_modifier, Modifier::BOLD | Modifier::ITALIC);
+    /// assert_eq!(patched.sub_modifier, Modifier::empty());
+    /// ```
+    pub fn add_modifier(mut self, modifier: Modifier) -> Style {
+        self.sub_modifier.remove(modifier);
+        self.add_modifier.insert(modifier);
+        self
+    }
+
+    /// Changes the text emphasis.
+    ///
+    /// When applied, it removes the given modifier from the `Style` modifiers.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style = Style::default().add_modifier(Modifier::BOLD | Modifier::ITALIC);
+    /// let diff = Style::default().remove_modifier(Modifier::ITALIC);
+    /// let patched = style.patch(diff);
+    /// assert_eq!(patched.add_modifier, Modifier::BOLD);
+    /// assert_eq!(patched.sub_modifier, Modifier::ITALIC);
+    /// ```
+    pub fn remove_modifier(mut self, modifier: Modifier) -> Style {
+        self.add_modifier.remove(modifier);
+        self.sub_modifier.insert(modifier);
+        self
+    }
+
+    /// Results in a combined style that is equivalent to applying the two individual styles to
+    /// a style one after the other.
+    ///
+    /// ## Examples
+    /// ```
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style_1 = Style::default().fg(Color::Yellow);
+    /// let style_2 = Style::default().bg(Color::Red);
+    /// let combined = style_1.patch(style_2);
+    /// assert_eq!(
+    ///     Style::default().patch(style_1).patch(style_2),
+    ///     Style::default().patch(combined));
+    /// ```
+    pub fn patch(mut self, other: Style) -> Style {
+        self.fg = other.fg.or(self.fg);
+        self.bg = other.bg.or(self.bg);
+
+        self.add_modifier.remove(other.sub_modifier);
+        self.add_modifier.insert(other.add_modifier);
+        self.sub_modifier.remove(other.add_modifier);
+        self.sub_modifier.insert(other.sub_modifier);
+
+        self
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn styles() -> Vec<Style> {
+        vec![
+            Style::default(),
+            Style::default().fg(Color::Yellow),
+            Style::default().bg(Color::Yellow),
+            Style::default().add_modifier(Modifier::BOLD),
+            Style::default().remove_modifier(Modifier::BOLD),
+            Style::default().add_modifier(Modifier::ITALIC),
+            Style::default().remove_modifier(Modifier::ITALIC),
+            Style::default().add_modifier(Modifier::ITALIC | Modifier::BOLD),
+            Style::default().remove_modifier(Modifier::ITALIC | Modifier::BOLD),
+        ]
+    }
+
+    #[test]
+    fn combined_patch_gives_same_result_as_individual_patch() {
+        let styles = styles();
+        for &a in &styles {
+            for &b in &styles {
+                for &c in &styles {
+                    for &d in &styles {
+                        let combined = a.patch(b.patch(c.patch(d)));
+
+                        assert_eq!(
+                            Style::default().patch(a).patch(b).patch(c).patch(d),
+                            Style::default().patch(combined)
+                        );
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/src/tui/symbols.rs b/src/tui/symbols.rs
new file mode 100644
index 00000000..040e77f6
--- /dev/null
+++ b/src/tui/symbols.rs
@@ -0,0 +1,233 @@
+pub mod block {
+    pub const FULL: &str = "█";
+    pub const SEVEN_EIGHTHS: &str = "▉";
+    pub const THREE_QUARTERS: &str = "▊";
+    pub const FIVE_EIGHTHS: &str = "▋";
+    pub const HALF: &str = "▌";
+    pub const THREE_EIGHTHS: &str = "▍";
+    pub const ONE_QUARTER: &str = "▎";
+    pub const ONE_EIGHTH: &str = "▏";
+
+    #[derive(Debug, Clone)]
+    pub struct Set {
+        pub full: &'static str,
+        pub seven_eighths: &'static str,
+        pub three_quarters: &'static str,
+        pub five_eighths: &'static str,
+        pub half: &'static str,
+        pub three_eighths: &'static str,
+        pub one_quarter: &'static str,
+        pub one_eighth: &'static str,
+        pub empty: &'static str,
+    }
+
+    pub const THREE_LEVELS: Set = Set {
+        full: FULL,
+        seven_eighths: FULL,
+        three_quarters: HALF,
+        five_eighths: HALF,
+        half: HALF,
+        three_eighths: HALF,
+        one_quarter: HALF,
+        one_eighth: " ",
+        empty: " ",
+    };
+
+    pub const NINE_LEVELS: Set = Set {
+        full: FULL,
+        seven_eighths: SEVEN_EIGHTHS,
+        three_quarters: THREE_QUARTERS,
+        five_eighths: FIVE_EIGHTHS,
+        half: HALF,
+        three_eighths: THREE_EIGHTHS,
+        one_quarter: ONE_QUARTER,
+        one_eighth: ONE_EIGHTH,
+        empty: " ",
+    };
+}
+
+pub mod bar {
+    pub const FULL: &str = "█";
+    pub const SEVEN_EIGHTHS: &str = "▇";
+    pub const THREE_QUARTERS: &str = "▆";
+    pub const FIVE_EIGHTHS: &str = "▅";
+    pub const HALF: &str = "▄";
+    pub const THREE_EIGHTHS: &str = "▃";
+    pub const ONE_QUARTER: &str = "▂";
+    pub const ONE_EIGHTH: &str = "▁";
+
+    #[derive(Debug, Clone)]
+    pub struct Set {
+        pub full: &'static str,
+        pub seven_eighths: &'static str,
+        pub three_quarters: &'static str,
+        pub five_eighths: &'static str,
+        pub half: &'static str,
+        pub three_eighths: &'static str,
+        pub one_quarter: &'static str,
+        pub one_eighth: &'static str,
+        pub empty: &'static str,
+    }
+
+    pub const THREE_LEVELS: Set = Set {
+        full: FULL,
+        seven_eighths: FULL,
+        three_quarters: HALF,
+        five_eighths: HALF,
+        half: HALF,
+        three_eighths: HALF,
+        one_quarter: HALF,
+        one_eighth: " ",
+        empty: " ",
+    };
+
+    pub const NINE_LEVELS: Set = Set {
+        full: FULL,
+        seven_eighths: SEVEN_EIGHTHS,
+        three_quarters: THREE_QUARTERS,
+        five_eighths: FIVE_EIGHTHS,
+        half: HALF,
+        three_eighths: THREE_EIGHTHS,
+        one_quarter: ONE_QUARTER,
+        one_eighth: ONE_EIGHTH,
+        empty: " ",
+    };
+}
+
+pub mod line {
+    pub const VERTICAL: &str = "│";
+    pub const DOUBLE_VERTICAL: &str = "║";
+    pub const THICK_VERTICAL: &str = "┃";
+
+    pub const HORIZONTAL: &str = "─";
+    pub const DOUBLE_HORIZONTAL: &str = "═";
+    pub const THICK_HORIZONTAL: &str = "━";
+
+    pub const TOP_RIGHT: &str = "┐";
+    pub const ROUNDED_TOP_RIGHT: &str = "╮";
+    pub const DOUBLE_TOP_RIGHT: &str = "╗";
+    pub const THICK_TOP_RIGHT: &str = "┓";
+
+    pub const TOP_LEFT: &str = "┌";
+    pub const ROUNDED_TOP_LEFT: &str = "╭";
+    pub const DOUBLE_TOP_LEFT: &str = "╔";
+    pub const THICK_TOP_LEFT: &str = "┏";
+
+    pub const BOTTOM_RIGHT: &str = "┘";
+    pub const ROUNDED_BOTTOM_RIGHT: &str = "╯";
+    pub const DOUBLE_BOTTOM_RIGHT: &str = "╝";
+    pub const THICK_BOTTOM_RIGHT: &str = "┛";
+
+    pub const BOTTOM_LEFT: &str = "└";
+    pub const ROUNDED_BOTTOM_LEFT: &str = "╰";
+    pub const DOUBLE_BOTTOM_LEFT: &str = "╚";
+    pub const THICK_BOTTOM_LEFT: &str = "┗";
+
+    pub const VERTICAL_LEFT: &str = "┤";
+    pub const DOUBLE_VERTICAL_LEFT: &str = "╣";
+    pub const THICK_VERTICAL_LEFT: &str = "┫";
+
+    pub const VERTICAL_RIGHT: &str = "├";
+    pub const DOUBLE_VERTICAL_RIGHT: &str = "╠";
+    pub const THICK_VERTICAL_RIGHT: &str = "┣";
+
+    pub const HORIZONTAL_DOWN: &str = "┬";
+    pub const DOUBLE_HORIZONTAL_DOWN: &str = "╦";
+    pub const THICK_HORIZONTAL_DOWN: &str = "┳";
+
+    pub const HORIZONTAL_UP: &str = "┴";
+    pub const DOUBLE_HORIZONTAL_UP: &str = "╩";
+    pub const THICK_HORIZONTAL_UP: &str = "┻";
+
+    pub const CROSS: &str = "┼";
+    pub const DOUBLE_CROSS: &str = "╬";
+    pub const THICK_CROSS: &str = "╋";
+
+    #[derive(Debug, Clone)]
+    pub struct Set {
+        pub vertical: &'static str,
+        pub horizontal: &'static str,
+        pub top_right: &'static str,
+        pub top_left: &'static str,
+        pub bottom_right: &'static str,
+        pub bottom_left: &'static str,
+        pub vertical_left: &'static str,
+        pub vertical_right: &'static str,
+        pub horizontal_down: &'static str,
+        pub horizontal_up: &'static str,
+        pub cross: &'static str,
+    }
+
+    pub const NORMAL: Set = Set {
+        vertical: VERTICAL,
+        horizontal: HORIZONTAL,
+        top_right: TOP_RIGHT,
+        top_left: TOP_LEFT,
+        bottom_right: BOTTOM_RIGHT,
+        bottom_left: BOTTOM_LEFT,
+        vertical_left: VERTICAL_LEFT,
+        vertical_right: VERTICAL_RIGHT,
+        horizontal_down: HORIZONTAL_DOWN,
+        horizontal_up: HORIZONTAL_UP,
+        cross: CROSS,
+    };
+
+    pub const ROUNDED: Set = Set {
+        top_right: ROUNDED_TOP_RIGHT,
+        top_left: ROUNDED_TOP_LEFT,
+        bottom_right: ROUNDED_BOTTOM_RIGHT,
+        bottom_left: ROUNDED_BOTTOM_LEFT,
+        ..NORMAL
+    };
+
+    pub const DOUBLE: Set = Set {
+        vertical: DOUBLE_VERTICAL,
+        horizontal: DOUBLE_HORIZONTAL,
+        top_right: DOUBLE_TOP_RIGHT,
+        top_left: DOUBLE_TOP_LEFT,
+        bottom_right: DOUBLE_BOTTOM_RIGHT,
+        bottom_left: DOUBLE_BOTTOM_LEFT,
+        vertical_left: DOUBLE_VERTICAL_LEFT,
+        vertical_right: DOUBLE_VERTICAL_RIGHT,
+        horizontal_down: DOUBLE_HORIZONTAL_DOWN,
+        horizontal_up: DOUBLE_HORIZONTAL_UP,
+        cross: DOUBLE_CROSS,
+    };
+
+    pub const THICK: Set = Set {
+        vertical: THICK_VERTICAL,
+        horizontal: THICK_HORIZONTAL,
+        top_right: THICK_TOP_RIGHT,
+        top_left: THICK_TOP_LEFT,
+        bottom_right: THICK_BOTTOM_RIGHT,
+        bottom_left: THICK_BOTTOM_LEFT,
+        vertical_left: THICK_VERTICAL_LEFT,
+        vertical_right: THICK_VERTICAL_RIGHT,
+        horizontal_down: THICK_HORIZONTAL_DOWN,
+        horizontal_up: THICK_HORIZONTAL_UP,
+        cross: THICK_CROSS,
+    };
+}
+
+pub const DOT: &str = "•";
+
+pub mod braille {
+    pub const BLANK: u16 = 0x2800;
+    pub const DOTS: [[u16; 2]; 4] = [
+        [0x0001, 0x0008],
+        [0x0002, 0x0010],
+        [0x0004, 0x0020],
+        [0x0040, 0x0080],
+    ];
+}
+
+/// Marker to use when plotting data points
+#[derive(Debug, Clone, Copy)]
+pub enum Marker {
+    /// One point per cell in shape of dot
+    Dot,
+    /// One point per cell in shape of a block
+    Block,
+    /// Up to 8 points per cell
+    Braille,
+}
diff --git a/src/tui/terminal.rs b/src/tui/terminal.rs
new file mode 100644
index 00000000..e64690e9
--- /dev/null
+++ b/src/tui/terminal.rs
@@ -0,0 +1,321 @@
+use crate::tui::{
+    backend::Backend,
+    buffer::Buffer,
+    layout::Rect,
+    widgets::{StatefulWidget, Widget},
+};
+use std::io;
+
+#[derive(Debug, Clone, PartialEq)]
+/// UNSTABLE
+enum ResizeBehavior {
+    Fixed,
+    Auto,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+/// UNSTABLE
+pub struct Viewport {
+    area: Rect,
+    resize_behavior: ResizeBehavior,
+}
+
+impl Viewport {
+    /// UNSTABLE
+    pub fn fixed(area: Rect) -> Viewport {
+        Viewport {
+            area,
+            resize_behavior: ResizeBehavior::Fixed,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+/// Options to pass to [`Terminal::with_options`]
+pub struct TerminalOptions {
+    /// Viewport used to draw to the terminal
+    pub viewport: Viewport,
+}
+
+/// Interface to the terminal backed by Termion
+#[derive(Debug)]
+pub struct Terminal<B>
+where
+    B: Backend,
+{
+    backend: B,
+    /// Holds the results of the current and previous draw calls. The two are compared at the end
+    /// of each draw pass to output the necessary updates to the terminal
+    buffers: [Buffer; 2],
+    /// Index of the current buffer in the previous array
+    current: usize,
+    /// Whether the cursor is currently hidden
+    hidden_cursor: bool,
+    /// Viewport
+    viewport: Viewport,
+}
+
+/// Represents a consistent terminal interface for rendering.
+pub struct Frame<'a, B: 'a + Backend> {
+    terminal: &'a mut Terminal<B>,
+
+    /// Where should the cursor be after drawing this frame?
+    ///
+    /// If `None`, the cursor is hidden and its position is controlled by the backend. If `Some((x,
+    /// y))`, the cursor is shown and placed at `(x, y)` after the call to `Terminal::draw()`.
+    cursor_position: Option<(u16, u16)>,
+}
+
+impl<'a, B> Frame<'a, B>
+where
+    B: Backend,
+{
+    /// Terminal size, guaranteed not to change when rendering.
+    pub fn size(&self) -> Rect {
+        self.terminal.viewport.area
+    }
+
+    /// Render a [`Widget`] to the current buffer using [`Widget::render`].
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use tui::Terminal;
+    /// # use tui::backend::TestBackend;
+    /// # use tui::layout::Rect;
+    /// # use tui::widgets::Block;
+    /// # let backend = TestBackend::new(5, 5);
+    /// # let mut terminal = Terminal::new(backend).unwrap();
+    /// let block = Block::default();
+    /// let area = Rect::new(0, 0, 5, 5);
+    /// let mut frame = terminal.get_frame();
+    /// frame.render_widget(block, area);
+    /// ```
+    pub fn render_widget<W>(&mut self, widget: W, area: Rect)
+    where
+        W: Widget,
+    {
+        widget.render(area, self.terminal.current_buffer_mut());
+    }
+
+    /// Render a [`StatefulWidget`] to the current buffer using [`StatefulWidget::render`].
+    ///
+    /// The last argument should be an instance of the [`StatefulWidget::State`] associated to the
+    /// given [`StatefulWidget`].
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use tui::Terminal;
+    /// # use tui::backend::TestBackend;
+    /// # use tui::layout::Rect;
+    /// # use tui::widgets::{List, ListItem, ListState};
+    /// # let backend = TestBackend::new(5, 5);
+    /// # let mut terminal = Terminal::new(backend).unwrap();
+    /// let mut state = ListState::default();
+    /// state.select(Some(1));
+    /// let items = vec![
+    ///     ListItem::new("Item 1"),
+    ///     ListItem::new("Item 2"),
+    /// ];
+    /// let list = List::new(items);
+    /// let area = Rect::new(0, 0, 5, 5);
+    /// let mut frame = terminal.get_frame();
+    /// frame.render_stateful_widget(list, area, &mut state);
+    /// ```
+    pub fn render_stateful_widget<W>(&mut self, widget: W, area: Rect, state: &mut W::State)
+    where
+        W: StatefulWidget,
+    {
+        widget.render(area, self.terminal.current_buffer_mut(), state);
+    }
+
+    /// After drawing this frame, make the cursor visible and put it at the specified (x, y)
+    /// coordinates. If this method is not called, the cursor will be hidden.
+    ///
+    /// Note that this will interfere with calls to `Terminal::hide_cursor()`,
+    /// `Terminal::show_cursor()`, and `Terminal::set_cursor()`. Pick one of the APIs and stick
+    /// with it.
+    pub fn set_cursor(&mut self, x: u16, y: u16) {
+        self.cursor_position = Some((x, y));
+    }
+}
+
+/// `CompletedFrame` represents the state of the terminal after all changes performed in the last
+/// [`Terminal::draw`] call have been applied. Therefore, it is only valid until the next call to
+/// [`Terminal::draw`].
+pub struct CompletedFrame<'a> {
+    pub buffer: &'a Buffer,
+    pub area: Rect,
+}
+
+impl<B> Drop for Terminal<B>
+where
+    B: Backend,
+{
+    fn drop(&mut self) {
+        // Attempt to restore the cursor state
+        if self.hidden_cursor {
+            if let Err(err) = self.show_cursor() {
+                eprintln!("Failed to show the cursor: {err}");
+            }
+        }
+    }
+}
+
+impl<B> Terminal<B>
+where
+    B: Backend,
+{
+    /// Wrapper around Terminal initialization. Each buffer is initialized with a blank string and
+    /// default colors for the foreground and the background
+    pub fn new(backend: B) -> io::Result<Terminal<B>> {
+        let size = backend.size()?;
+        Ok(Terminal::with_options(
+            backend,
+            TerminalOptions {
+                viewport: Viewport {
+                    area: size,
+                    resize_behavior: ResizeBehavior::Auto,
+                },
+            },
+        ))
+    }
+
+    /// UNSTABLE
+    pub fn with_options(backend: B, options: TerminalOptions) -> Terminal<B> {
+        Terminal {
+            backend,
+            buffers: [
+                Buffer::empty(options.viewport.area),
+                Buffer::empty(options.viewport.area),
+            ],
+            current: 0,
+            hidden_cursor: false,
+            viewport: options.viewport,
+        }
+    }
+
+    /// Get a Frame object which provides a consistent view into the terminal state for rendering.
+    pub fn get_frame(&mut self) -> Frame<B> {
+        Frame {
+            terminal: self,
+            cursor_position: None,
+        }
+    }
+
+    pub fn current_buffer_mut(&mut self) -> &mut Buffer {
+        &mut self.buffers[self.current]
+    }
+
+    pub fn backend(&self) -> &B {
+        &self.backend
+    }
+
+    pub fn backend_mut(&mut self) -> &mut B {
+        &mut self.backend
+    }
+
+    /// Obtains a difference between the previous and the current buffer and passes it to the
+    /// current backend for drawing.
+    pub fn flush(&mut self) -> io::Result<()> {
+        let previous_buffer = &self.buffers[1 - self.current];
+        let current_buffer = &self.buffers[self.current];
+        let updates = previous_buffer.diff(current_buffer);
+        self.backend.draw(updates.into_iter())
+    }
+
+    /// Updates the Terminal so that internal buffers match the requested size. Requested size will
+    /// be saved so the size can remain consistent when rendering.
+    /// This leads to a full clear of the screen.
+    pub fn resize(&mut self, area: Rect) -> io::Result<()> {
+        self.buffers[self.current].resize(area);
+        self.buffers[1 - self.current].resize(area);
+        self.viewport.area = area;
+        self.clear()
+    }
+
+    /// Queries the backend for size and resizes if it doesn't match the previous size.
+    pub fn autoresize(&mut self) -> io::Result<()> {
+        if self.viewport.resize_behavior == ResizeBehavior::Auto {
+            let size = self.size()?;
+            if size != self.viewport.area {
+                self.resize(size)?;
+            }
+        };
+        Ok(())
+    }
+
+    /// Synchronizes terminal size, calls the rendering closure, flushes the current internal state
+    /// and prepares for the next draw call.
+    pub fn draw<F>(&mut self, f: F) -> io::Result<CompletedFrame>
+    where
+        F: FnOnce(&mut Frame<B>),
+    {
+        // Autoresize - otherwise we get glitches if shrinking or potential desync between widgets
+        // and the terminal (if growing), which may OOB.
+        self.autoresize()?;
+
+        let mut frame = self.get_frame();
+        f(&mut frame);
+        // We can't change the cursor position right away because we have to flush the frame to
+        // stdout first. But we also can't keep the frame around, since it holds a &mut to
+        // Terminal. Thus, we're taking the important data out of the Frame and dropping it.
+        let cursor_position = frame.cursor_position;
+
+        // Draw to stdout
+        self.flush()?;
+
+        match cursor_position {
+            None => self.hide_cursor()?,
+            Some((x, y)) => {
+                self.show_cursor()?;
+                self.set_cursor(x, y)?;
+            }
+        }
+
+        // Swap buffers
+        self.buffers[1 - self.current].reset();
+        self.current = 1 - self.current;
+
+        // Flush
+        self.backend.flush()?;
+        Ok(CompletedFrame {
+            buffer: &self.buffers[1 - self.current],
+            area: self.viewport.area,
+        })
+    }
+
+    pub fn hide_cursor(&mut self) -> io::Result<()> {
+        self.backend.hide_cursor()?;
+        self.hidden_cursor = true;
+        Ok(())
+    }
+
+    pub fn show_cursor(&mut self) -> io::Result<()> {
+        self.backend.show_cursor()?;
+        self.hidden_cursor = false;
+        Ok(())
+    }
+
+    pub fn get_cursor(&mut self) -> io::Result<(u16, u16)> {
+        self.backend.get_cursor()
+    }
+
+    pub fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()> {
+        self.backend.set_cursor(x, y)
+    }
+
+    /// Clear the terminal and force a full redraw on the next draw call.
+    pub fn clear(&mut self) -> io::Result<()> {
+        self.backend.clear()?;
+        // Reset the back buffer to make sure the next update will redraw everything.
+        self.buffers[1 - self.current].reset();
+        Ok(())
+    }
+
+    /// Queries the real size of the backend.
+    pub fn size(&self) -> io::Result<Rect> {
+        self.backend.size()
+    }
+}
diff --git a/src/tui/text.rs b/src/tui/text.rs
new file mode 100644
index 00000000..e8a5aa73
--- /dev/null
+++ b/src/tui/text.rs
@@ -0,0 +1,428 @@
+//! Primitives for styled text.
+//!
+//! A terminal UI is at its root a lot of strings. In order to make it accessible and stylish,
+//! those strings may be associated to a set of styles. `tui` has three ways to represent them:
+//! - A single line string where all graphemes have the same style is represented by a [`Span`].
+//! - A single line string where each grapheme may have its own style is represented by [`Spans`].
+//! - A multiple line string where each grapheme may have its own style is represented by a
+//! [`Text`].
+//!
+//! These types form a hierarchy: [`Spans`] is a collection of [`Span`] and each line of [`Text`]
+//! is a [`Spans`].
+//!
+//! Keep it mind that a lot of widgets will use those types to advertise what kind of string is
+//! supported for their properties. Moreover, `tui` provides convenient `From` implementations so
+//! that you can start by using simple `String` or `&str` and then promote them to the previous
+//! primitives when you need additional styling capabilities.
+//!
+//! For example, for the [`crate::widgets::Block`] widget, all the following calls are valid to set
+//! its `title` property (which is a [`Spans`] under the hood):
+//!
+//! ```rust
+//! # use tui::widgets::Block;
+//! # use tui::text::{Span, Spans};
+//! # use tui::style::{Color, Style};
+//! // A simple string with no styling.
+//! // Converted to Spans(vec![
+//! //   Span { content: Cow::Borrowed("My title"), style: Style { .. } }
+//! // ])
+//! let block = Block::default().title("My title");
+//!
+//! // A simple string with a unique style.
+//! // Converted to Spans(vec![
+//! //   Span { content: Cow::Borrowed("My title"), style: Style { fg: Some(Color::Yellow), .. }
+//! // ])
+//! let block = Block::default().title(
+//!     Span::styled("My title", Style::default().fg(Color::Yellow))
+//! );
+//!
+//! // A string with multiple styles.
+//! // Converted to Spans(vec![
+//! //   Span { content: Cow::Borrowed("My"), style: Style { fg: Some(Color::Yellow), .. } },
+//! //   Span { content: Cow::Borrowed(" title"), .. }
+//! // ])
+//! let block = Block::default().title(vec![
+//!     Span::styled("My", Style::default().fg(Color::Yellow)),
+//!     Span::raw(" title"),
+//! ]);
+//! ```
+use crate::tui::style::Style;
+use std::borrow::Cow;
+use unicode_segmentation::UnicodeSegmentation;
+use unicode_width::UnicodeWidthStr;
+
+/// A grapheme associated to a style.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct StyledGrapheme<'a> {
+    pub symbol: &'a str,
+    pub style: Style,
+}
+
+/// A string where all graphemes have the same style.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Span<'a> {
+    pub content: Cow<'a, str>,
+    pub style: Style,
+}
+
+impl<'a> Span<'a> {
+    /// Create a span with no style.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::text::Span;
+    /// Span::raw("My text");
+    /// Span::raw(String::from("My text"));
+    /// ```
+    pub fn raw<T>(content: T) -> Span<'a>
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        Span {
+            content: content.into(),
+            style: Style::default(),
+        }
+    }
+
+    /// Create a span with a style.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use tui::text::Span;
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style = Style::default().fg(Color::Yellow).add_modifier(Modifier::ITALIC);
+    /// Span::styled("My text", style);
+    /// Span::styled(String::from("My text"), style);
+    /// ```
+    pub fn styled<T>(content: T, style: Style) -> Span<'a>
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        Span {
+            content: content.into(),
+            style,
+        }
+    }
+
+    /// Returns the width of the content held by this span.
+    pub fn width(&self) -> usize {
+        self.content.width()
+    }
+
+    /// Returns an iterator over the graphemes held by this span.
+    ///
+    /// `base_style` is the [`Style`] that will be patched with each grapheme [`Style`] to get
+    /// the resulting [`Style`].
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::text::{Span, StyledGrapheme};
+    /// # use tui::style::{Color, Modifier, Style};
+    /// # use std::iter::Iterator;
+    /// let style = Style::default().fg(Color::Yellow);
+    /// let span = Span::styled("Text", style);
+    /// let style = Style::default().fg(Color::Green).bg(Color::Black);
+    /// let styled_graphemes = span.styled_graphemes(style);
+    /// assert_eq!(
+    ///     vec![
+    ///         StyledGrapheme {
+    ///             symbol: "T",
+    ///             style: Style {
+    ///                 fg: Some(Color::Yellow),
+    ///                 bg: Some(Color::Black),
+    ///                 add_modifier: Modifier::empty(),
+    ///                 sub_modifier: Modifier::empty(),
+    ///             },
+    ///         },
+    ///         StyledGrapheme {
+    ///             symbol: "e",
+    ///             style: Style {
+    ///                 fg: Some(Color::Yellow),
+    ///                 bg: Some(Color::Black),
+    ///                 add_modifier: Modifier::empty(),
+    ///                 sub_modifier: Modifier::empty(),
+    ///             },
+    ///         },
+    ///         StyledGrapheme {
+    ///             symbol: "x",
+    ///             style: Style {
+    ///                 fg: Some(Color::Yellow),
+    ///                 bg: Some(Color::Black),
+    ///                 add_modifier: Modifier::empty(),
+    ///                 sub_modifier: Modifier::empty(),
+    ///             },
+    ///         },
+    ///         StyledGrapheme {
+    ///             symbol: "t",
+    ///             style: Style {
+    ///                 fg: Some(Color::Yellow),
+    ///                 bg: Some(Color::Black),
+    ///                 add_modifier: Modifier::empty(),
+    ///                 sub_modifier: Modifier::empty(),
+    ///             },
+    ///         },
+    ///     ],
+    ///     styled_graphemes.collect::<Vec<StyledGrapheme>>()
+    /// );
+    /// ```
+    pub fn styled_graphemes(
+        &'a self,
+        base_style: Style,
+    ) -> impl Iterator<Item = StyledGrapheme<'a>> {
+        UnicodeSegmentation::graphemes(self.content.as_ref(), true)
+            .map(move |g| StyledGrapheme {
+                symbol: g,
+                style: base_style.patch(self.style),
+            })
+            .filter(|s| s.symbol != "\n")
+    }
+}
+
+impl<'a> From<String> for Span<'a> {
+    fn from(s: String) -> Span<'a> {
+        Span::raw(s)
+    }
+}
+
+impl<'a> From<&'a str> for Span<'a> {
+    fn from(s: &'a str) -> Span<'a> {
+        Span::raw(s)
+    }
+}
+
+/// A string composed of clusters of graphemes, each with their own style.
+#[derive(Debug, Clone, PartialEq, Default, Eq)]
+pub struct Spans<'a>(pub Vec<Span<'a>>);
+
+impl<'a> Spans<'a> {
+    /// Returns the width of the underlying string.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::text::{Span, Spans};
+    /// # use tui::style::{Color, Style};
+    /// let spans = Spans::from(vec![
+    ///     Span::styled("My", Style::default().fg(Color::Yellow)),
+    ///     Span::raw(" text"),
+    /// ]);
+    /// assert_eq!(7, spans.width());
+    /// ```
+    pub fn width(&self) -> usize {
+        self.0.iter().map(Span::width).sum()
+    }
+}
+
+impl<'a> From<String> for Spans<'a> {
+    fn from(s: String) -> Spans<'a> {
+        Spans(vec![Span::from(s)])
+    }
+}
+
+impl<'a> From<&'a str> for Spans<'a> {
+    fn from(s: &'a str) -> Spans<'a> {
+        Spans(vec![Span::from(s)])
+    }
+}
+
+impl<'a> From<Vec<Span<'a>>> for Spans<'a> {
+    fn from(spans: Vec<Span<'a>>) -> Spans<'a> {
+        Spans(spans)
+    }
+}
+
+impl<'a> From<Span<'a>> for Spans<'a> {
+    fn from(span: Span<'a>) -> Spans<'a> {
+        Spans(vec![span])
+    }
+}
+
+impl<'a> From<Spans<'a>> for String {
+    fn from(line: Spans<'a>) -> String {
+        line.0.iter().fold(String::new(), |mut acc, s| {
+            acc.push_str(s.content.as_ref());
+            acc
+        })
+    }
+}
+
+/// A string split over multiple lines where each line is composed of several clusters, each with
+/// their own style.
+///
+/// A [`Text`], like a [`Span`], can be constructed using one of the many `From` implementations
+/// or via the [`Text::raw`] and [`Text::styled`] methods. Helpfully, [`Text`] also implements
+/// [`core::iter::Extend`] which enables the concatenation of several [`Text`] blocks.
+///
+/// ```rust
+/// # use tui::text::Text;
+/// # use tui::style::{Color, Modifier, Style};
+/// let style = Style::default().fg(Color::Yellow).add_modifier(Modifier::ITALIC);
+///
+/// // An initial two lines of `Text` built from a `&str`
+/// let mut text = Text::from("The first line\nThe second line");
+/// assert_eq!(2, text.height());
+///
+/// // Adding two more unstyled lines
+/// text.extend(Text::raw("These are two\nmore lines!"));
+/// assert_eq!(4, text.height());
+///
+/// // Adding a final two styled lines
+/// text.extend(Text::styled("Some more lines\nnow with more style!", style));
+/// assert_eq!(6, text.height());
+/// ```
+#[derive(Debug, Clone, PartialEq, Default, Eq)]
+pub struct Text<'a> {
+    pub lines: Vec<Spans<'a>>,
+}
+
+impl<'a> Text<'a> {
+    /// Create some text (potentially multiple lines) with no style.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// # use tui::text::Text;
+    /// Text::raw("The first line\nThe second line");
+    /// Text::raw(String::from("The first line\nThe second line"));
+    /// ```
+    pub fn raw<T>(content: T) -> Text<'a>
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        Text {
+            lines: match content.into() {
+                Cow::Borrowed(s) => s.lines().map(Spans::from).collect(),
+                Cow::Owned(s) => s.lines().map(|l| Spans::from(l.to_owned())).collect(),
+            },
+        }
+    }
+
+    /// Create some text (potentially multiple lines) with a style.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use tui::text::Text;
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style = Style::default().fg(Color::Yellow).add_modifier(Modifier::ITALIC);
+    /// Text::styled("The first line\nThe second line", style);
+    /// Text::styled(String::from("The first line\nThe second line"), style);
+    /// ```
+    pub fn styled<T>(content: T, style: Style) -> Text<'a>
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        let mut text = Text::raw(content);
+        text.patch_style(style);
+        text
+    }
+
+    /// Returns the max width of all the lines.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// use tui::text::Text;
+    /// let text = Text::from("The first line\nThe second line");
+    /// assert_eq!(15, text.width());
+    /// ```
+    pub fn width(&self) -> usize {
+        self.lines
+            .iter()
+            .map(Spans::width)
+            .max()
+            .unwrap_or_default()
+    }
+
+    /// Returns the height.
+    ///
+    /// ## Examples
+    ///
+    /// ```rust
+    /// use tui::text::Text;
+    /// let text = Text::from("The first line\nThe second line");
+    /// assert_eq!(2, text.height());
+    /// ```
+    pub fn height(&self) -> usize {
+        self.lines.len()
+    }
+
+    /// Apply a new style to existing text.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use tui::text::Text;
+    /// # use tui::style::{Color, Modifier, Style};
+    /// let style = Style::default().fg(Color::Yellow).add_modifier(Modifier::ITALIC);
+    /// let mut raw_text = Text::raw("The first line\nThe second line");
+    /// let styled_text = Text::styled(String::from("The first line\nThe second line"), style);
+    /// assert_ne!(raw_text, styled_text);
+    ///
+    /// raw_text.patch_style(style);
+    /// assert_eq!(raw_text, styled_text);
+    /// ```
+    pub fn patch_style(&mut self, style: Style) {
+        for line in &mut self.lines {
+            for span in &mut line.0 {
+                span.style = span.style.patch(style);
+            }
+        }
+    }
+}
+
+impl<'a> From<String> for Text<'a> {
+    fn from(s: String) -> Text<'a> {
+        Text::raw(s)
+    }
+}
+
+impl<'a> From<&'a str> for Text<'a> {
+    fn from(s: &'a str) -> Text<'a> {
+        Text::raw(s)
+    }
+}
+
+impl<'a> From<Cow<'a, str>> for Text<'a> {
+    fn from(s: Cow<'a, str>) -> Text<'a> {
+        Text::raw(s)
+    }
+}
+
+impl<'a> From<Span<'a>> for Text<'a> {
+    fn from(span: Span<'a>) -> Text<'a> {
+        Text {
+            lines: vec![Spans::from(span)],
+        }
+    }
+}
+
+impl<'a> From<Spans<'a>> for Text<'a> {
+    fn from(spans: Spans<'a>) -> Text<'a> {
+        Text { lines: vec![spans] }
+    }
+}
+
+impl<'a> From<Vec<Spans<'a>>> for Text<'a> {
+    fn from(lines: Vec<Spans<'a>>) -> Text<'a> {
+        Text { lines }
+    }
+}
+
+impl<'a> IntoIterator for Text<'a> {
+    type Item = Spans<'a>;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.lines.into_iter()
+    }
+}
+
+impl<'a> Extend<Spans<'a>> for Text<'a> {
+    fn extend<T: IntoIterator<Item = Spans<'a>>>(&mut self, iter: T) {
+        self.lines.extend(iter);
+    }
+}
diff --git a/src/tui/widgets/block.rs b/src/tui/widgets/block.rs
new file mode 100644
index 00000000..eb59f9c3
--- /dev/null
+++ b/src/tui/widgets/block.rs
@@ -0,0 +1,562 @@
+use crate::tui::{
+    buffer::Buffer,
+    layout::{Alignment, Rect},
+    style::Style,
+    symbols::line,
+    text::Spans,
+    widgets::{Borders, Widget},
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BorderType {
+    Plain,
+    Rounded,
+    Double,
+    Thick,
+}
+
+impl BorderType {
+    pub fn line_symbols(border_type: BorderType) -> line::Set {
+        match border_type {
+            BorderType::Plain => line::NORMAL,
+            BorderType::Rounded => line::ROUNDED,
+            BorderType::Double => line::DOUBLE,
+            BorderType::Thick => line::THICK,
+        }
+    }
+}
+
+/// Base widget to be used with all upper level ones. It may be used to display a box border around
+/// the widget and/or add a title.
+///
+/// # Examples
+///
+/// ```
+/// # use tui::widgets::{Block, BorderType, Borders};
+/// # use tui::style::{Style, Color};
+/// Block::default()
+///     .title("Block")
+///     .borders(Borders::LEFT | Borders::RIGHT)
+///     .border_style(Style::default().fg(Color::White))
+///     .border_type(BorderType::Rounded)
+///     .style(Style::default().bg(Color::Black));
+/// ```
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Block<'a> {
+    /// Optional title place on the upper left of the block
+    title: Option<Spans<'a>>,
+    /// Title alignment. The default is top left of the block, but one can choose to place
+    /// title in the top middle, or top right of the block
+    title_alignment: Alignment,
+    /// Visible borders
+    borders: Borders,
+    /// Border style
+    border_style: Style,
+    /// Type of the border. The default is plain lines but one can choose to have rounded corners
+    /// or doubled lines instead.
+    border_type: BorderType,
+    /// Widget style
+    style: Style,
+}
+
+impl<'a> Default for Block<'a> {
+    fn default() -> Block<'a> {
+        Block {
+            title: None,
+            title_alignment: Alignment::Left,
+            borders: Borders::NONE,
+            border_style: Style::default(),
+            border_type: BorderType::Plain,
+            style: Style::default(),
+        }
+    }
+}
+
+impl<'a> Block<'a> {
+    pub fn title<T>(mut self, title: T) -> Block<'a>
+    where
+        T: Into<Spans<'a>>,
+    {
+        self.title = Some(title.into());
+        self
+    }
+
+    pub fn title_alignment(mut self, alignment: Alignment) -> Block<'a> {
+        self.title_alignment = alignment;
+        self
+    }
+
+    pub fn border_style(mut self, style: Style) -> Block<'a> {
+        self.border_style = style;
+        self
+    }
+
+    pub fn style(mut self, style: Style) -> Block<'a> {
+        self.style = style;
+        self
+    }
+
+    pub fn borders(mut self, flag: Borders) -> Block<'a> {
+        self.borders = flag;
+        self
+    }
+
+    pub fn border_type(mut self, border_type: BorderType) -> Block<'a> {
+        self.border_type = border_type;
+        self
+    }
+
+    /// Compute the inner area of a block based on its border visibility rules.
+    pub fn inner(&self, area: Rect) -> Rect {
+        let mut inner = area;
+        if self.borders.intersects(Borders::LEFT) {
+            inner.x = inner.x.saturating_add(1).min(inner.right());
+            inner.width = inner.width.saturating_sub(1);
+        }
+        if self.borders.intersects(Borders::TOP) || self.title.is_some() {
+            inner.y = inner.y.saturating_add(1).min(inner.bottom());
+            inner.height = inner.height.saturating_sub(1);
+        }
+        if self.borders.intersects(Borders::RIGHT) {
+            inner.width = inner.width.saturating_sub(1);
+        }
+        if self.borders.intersects(Borders::BOTTOM) {
+            inner.height = inner.height.saturating_sub(1);
+        }
+        inner
+    }
+}
+
+impl<'a> Widget for Block<'a> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        if area.area() == 0 {
+            return;
+        }
+        buf.set_style(area, self.style);
+        let symbols = BorderType::line_symbols(self.border_type);
+
+        // Sides
+        if self.borders.intersects(Borders::LEFT) {
+            for y in area.top()..area.bottom() {
+                buf.get_mut(area.left(), y)
+                    .set_symbol(symbols.vertical)
+                    .set_style(self.border_style);
+            }
+        }
+        if self.borders.intersects(Borders::TOP) {
+            for x in area.left()..area.right() {
+                buf.get_mut(x, area.top())
+                    .set_symbol(symbols.horizontal)
+                    .set_style(self.border_style);
+            }
+        }
+        if self.borders.intersects(Borders::RIGHT) {
+            let x = area.right() - 1;
+            for y in area.top()..area.bottom() {
+                buf.get_mut(x, y)
+                    .set_symbol(symbols.vertical)
+                    .set_style(self.border_style);
+            }
+        }
+        if self.borders.intersects(Borders::BOTTOM) {
+            let y = area.bottom() - 1;
+            for x in area.left()..area.right() {
+                buf.get_mut(x, y)
+                    .set_symbol(symbols.horizontal)
+                    .set_style(self.border_style);
+            }
+        }
+
+        // Corners
+        if self.borders.contains(Borders::RIGHT | Borders::BOTTOM) {
+            buf.get_mut(area.right() - 1, area.bottom() - 1)
+                .set_symbol(symbols.bottom_right)
+                .set_style(self.border_style);
+        }
+        if self.borders.contains(Borders::RIGHT | Borders::TOP) {
+            buf.get_mut(area.right() - 1, area.top())
+                .set_symbol(symbols.top_right)
+                .set_style(self.border_style);
+        }
+        if self.borders.contains(Borders::LEFT | Borders::BOTTOM) {
+            buf.get_mut(area.left(), area.bottom() - 1)
+                .set_symbol(symbols.bottom_left)
+                .set_style(self.border_style);
+        }
+        if self.borders.contains(Borders::LEFT | Borders::TOP) {
+            buf.get_mut(area.left(), area.top())
+                .set_symbol(symbols.top_left)
+                .set_style(self.border_style);
+        }
+
+        // Title
+        if let Some(title) = self.title {
+            let left_border_dx = if self.borders.intersects(Borders::LEFT) {
+                1
+            } else {
+                0
+            };
+
+            let right_border_dx = if self.borders.intersects(Borders::RIGHT) {
+                1
+            } else {
+                0
+            };
+
+            let title_area_width = area
+                .width
+                .saturating_sub(left_border_dx)
+                .saturating_sub(right_border_dx);
+
+            let title_dx = match self.title_alignment {
+                Alignment::Left => left_border_dx,
+                Alignment::Center => area.width.saturating_sub(title.width() as u16) / 2,
+                Alignment::Right => area
+                    .width
+                    .saturating_sub(title.width() as u16)
+                    .saturating_sub(right_border_dx),
+            };
+
+            let title_x = area.left() + title_dx;
+            let title_y = area.top();
+
+            buf.set_spans(title_x, title_y, &title, title_area_width);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tui::layout::Rect;
+
+    #[test]
+    #[allow(clippy::too_many_lines)]
+    fn inner_takes_into_account_the_borders() {
+        // No borders
+        assert_eq!(
+            Block::default().inner(Rect::default()),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 0
+            },
+            "no borders, width=0, height=0"
+        );
+        assert_eq!(
+            Block::default().inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            },
+            "no borders, width=1, height=1"
+        );
+
+        // Left border
+        assert_eq!(
+            Block::default().borders(Borders::LEFT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1
+            },
+            "left, width=0"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::LEFT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 1,
+                y: 0,
+                width: 0,
+                height: 1
+            },
+            "left, width=1"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::LEFT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 1
+            }),
+            Rect {
+                x: 1,
+                y: 0,
+                width: 1,
+                height: 1
+            },
+            "left, width=2"
+        );
+
+        // Top border
+        assert_eq!(
+            Block::default().borders(Borders::TOP).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 0
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 0
+            },
+            "top, height=0"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::TOP).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 1,
+                width: 1,
+                height: 0
+            },
+            "top, height=1"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::TOP).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 2
+            }),
+            Rect {
+                x: 0,
+                y: 1,
+                width: 1,
+                height: 1
+            },
+            "top, height=2"
+        );
+
+        // Right border
+        assert_eq!(
+            Block::default().borders(Borders::RIGHT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1
+            },
+            "right, width=0"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::RIGHT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1
+            },
+            "right, width=1"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::RIGHT).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            },
+            "right, width=2"
+        );
+
+        // Bottom border
+        assert_eq!(
+            Block::default().borders(Borders::BOTTOM).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 0
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 0
+            },
+            "bottom, height=0"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::BOTTOM).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 0
+            },
+            "bottom, height=1"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::BOTTOM).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 2
+            }),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            },
+            "bottom, height=2"
+        );
+
+        // All borders
+        assert_eq!(
+            Block::default()
+                .borders(Borders::ALL)
+                .inner(Rect::default()),
+            Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 0
+            },
+            "all borders, width=0, height=0"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::ALL).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 1,
+                height: 1
+            }),
+            Rect {
+                x: 1,
+                y: 1,
+                width: 0,
+                height: 0,
+            },
+            "all borders, width=1, height=1"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::ALL).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 2,
+            }),
+            Rect {
+                x: 1,
+                y: 1,
+                width: 0,
+                height: 0,
+            },
+            "all borders, width=2, height=2"
+        );
+        assert_eq!(
+            Block::default().borders(Borders::ALL).inner(Rect {
+                x: 0,
+                y: 0,
+                width: 3,
+                height: 3,
+            }),
+            Rect {
+                x: 1,
+                y: 1,
+                width: 1,
+                height: 1,
+            },
+            "all borders, width=3, height=3"
+        );
+    }
+
+    #[test]
+    fn inner_takes_into_account_the_title() {
+        assert_eq!(
+            Block::default().title("Test").inner(Rect {
+                x: 0,
+                y: 0,
+                width: 0,
+                height: 1,
+            }),
+            Rect {
+                x: 0,
+                y: 1,
+                width: 0,
+                height: 0,
+            },
+        );
+        assert_eq!(
+            Block::default()
+                .title("Test")
+                .title_alignment(Alignment::Center)
+                .inner(Rect {
+                    x: 0,
+                    y: 0,
+                    width: 0,
+                    height: 1,
+                }),
+            Rect {
+                x: 0,
+                y: 1,
+                width: 0,
+                height: 0,
+            },
+        );
+        assert_eq!(
+            Block::default()
+                .title("Test")
+                .title_alignment(Alignment::Right)
+                .inner(Rect {
+                    x: 0,
+                    y: 0,
+                    width: 0,
+                    height: 1,
+                }),
+            Rect {
+                x: 0,
+                y: 1,
+                width: 0,
+                height: 0,
+            },
+        );
+    }
+}
diff --git a/src/tui/widgets/mod.rs b/src/tui/widgets/mod.rs
new file mode 100644
index 00000000..635185e5
--- /dev/null
+++ b/src/tui/widgets/mod.rs
@@ -0,0 +1,159 @@
+//! `widgets` is a collection of types that implement [`Widget`] or [`StatefulWidget`] or both.
+//!
+//! All widgets are implemented using the builder pattern and are consumable objects. They are not
+//! meant to be stored but used as *commands* to draw common figures in the UI.
+//!
+//! The available widgets are:
+//! - [`Block`]
+//! - [`Paragraph`]
+
+mod block;
+mod paragraph;
+mod reflow;
+
+pub use self::block::{Block, BorderType};
+pub use self::paragraph::{Paragraph, Wrap};
+
+use crate::tui::{buffer::Buffer, layout::Rect};
+use bitflags::bitflags;
+
+bitflags! {
+    /// Bitflags that can be composed to set the visible borders essentially on the block widget.
+    pub struct Borders: u32 {
+        /// Show no border (default)
+        const NONE  = 0b0000_0001;
+        /// Show the top border
+        const TOP   = 0b0000_0010;
+        /// Show the right border
+        const RIGHT = 0b0000_0100;
+        /// Show the bottom border
+        const BOTTOM = 0b000_1000;
+        /// Show the left border
+        const LEFT = 0b0001_0000;
+        /// Show all borders
+        const ALL = Self::TOP.bits | Self::RIGHT.bits | Self::BOTTOM.bits | Self::LEFT.bits;
+    }
+}
+
+/// Base requirements for a Widget
+pub trait Widget {
+    /// Draws the current state of the widget in the given buffer. That is the only method required
+    /// to implement a custom widget.
+    fn render(self, area: Rect, buf: &mut Buffer);
+}
+
+/// A `StatefulWidget` is a widget that can take advantage of some local state to remember things
+/// between two draw calls.
+///
+/// Most widgets can be drawn directly based on the input parameters. However, some features may
+/// require some kind of associated state to be implemented.
+///
+/// For example, the [`List`] widget can highlight the item currently selected. This can be
+/// translated in an offset, which is the number of elements to skip in order to have the selected
+/// item within the viewport currently allocated to this widget. The widget can therefore only
+/// provide the following behavior: whenever the selected item is out of the viewport scroll to a
+/// predefined position (making the selected item the last viewable item or the one in the middle
+/// for example). Nonetheless, if the widget has access to the last computed offset then it can
+/// implement a natural scrolling experience where the last offset is reused until the selected
+/// item is out of the viewport.
+///
+/// ## Examples
+///
+/// ```rust,no_run
+/// # use std::io;
+/// # use tui::Terminal;
+/// # use tui::backend::{Backend, TestBackend};
+/// # use tui::widgets::{Widget, List, ListItem, ListState};
+///
+/// // Let's say we have some events to display.
+/// struct Events {
+///     // `items` is the state managed by your application.
+///     items: Vec<String>,
+///     // `state` is the state that can be modified by the UI. It stores the index of the selected
+///     // item as well as the offset computed during the previous draw call (used to implement
+///     // natural scrolling).
+///     state: ListState
+/// }
+///
+/// impl Events {
+///     fn new(items: Vec<String>) -> Events {
+///         Events {
+///             items,
+///             state: ListState::default(),
+///         }
+///     }
+///
+///     pub fn set_items(&mut self, items: Vec<String>) {
+///         self.items = items;
+///         // We reset the state as the associated items have changed. This effectively reset
+///         // the selection as well as the stored offset.
+///         self.state = ListState::default();
+///     }
+///
+///     // Select the next item. This will not be reflected until the widget is drawn in the
+///     // `Terminal::draw` callback using `Frame::render_stateful_widget`.
+///     pub fn next(&mut self) {
+///         let i = match self.state.selected() {
+///             Some(i) => {
+///                 if i >= self.items.len() - 1 {
+///                     0
+///                 } else {
+///                     i + 1
+///                 }
+///             }
+///             None => 0,
+///         };
+///         self.state.select(Some(i));
+///     }
+///
+///     // Select the previous item. This will not be reflected until the widget is drawn in the
+///     // `Terminal::draw` callback using `Frame::render_stateful_widget`.
+///     pub fn previous(&mut self) {
+///         let i = match self.state.selected() {
+///             Some(i) => {
+///                 if i == 0 {
+///                     self.items.len() - 1
+///                 } else {
+///                     i - 1
+///                 }
+///             }
+///             None => 0,
+///         };
+///         self.state.select(Some(i));
+///     }
+///
+///     // Unselect the currently selected item if any. The implementation of `ListState` makes
+///     // sure that the stored offset is also reset.
+///     pub fn unselect(&mut self) {
+///         self.state.select(None);
+///     }
+/// }
+///
+/// # let backend = TestBackend::new(5, 5);
+/// # let mut terminal = Terminal::new(backend).unwrap();
+///
+/// let mut events = Events::new(vec![
+///     String::from("Item 1"),
+///     String::from("Item 2")
+/// ]);
+///
+/// loop {
+///     terminal.draw(|f| {
+///         // The items managed by the application are transformed to something
+///         // that is understood by tui.
+///         let items: Vec<ListItem>= events.items.iter().map(|i| ListItem::new(i.as_ref())).collect();
+///         // The `List` widget is then built with those items.
+///         let list = List::new(items);
+///         // Finally the widget is rendered using the associated state. `events.state` is
+///         // effectively the only thing that we will "remember" from this draw call.
+///         f.render_stateful_widget(list, f.size(), &mut events.state);
+///     });
+///
+///     // In response to some input events or an external http request or whatever:
+///     events.next();
+/// }
+/// ```
+pub trait StatefulWidget {
+    type State;
+    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State);
+}
diff --git a/src/tui/widgets/paragraph.rs b/src/tui/widgets/paragraph.rs
new file mode 100644
index 00000000..a5036148
--- /dev/null
+++ b/src/tui/widgets/paragraph.rs
@@ -0,0 +1,194 @@
+use crate::tui::{
+    buffer::Buffer,
+    layout::{Alignment, Rect},
+    style::Style,
+    text::{StyledGrapheme, Text},
+    widgets::{
+        reflow::{LineComposer, LineTruncator, WordWrapper},
+        Block, Widget,
+    },
+};
+use std::iter;
+use unicode_width::UnicodeWidthStr;
+
+fn get_line_offset(line_width: u16, text_area_width: u16, alignment: Alignment) -> u16 {
+    match alignment {
+        Alignment::Center => (text_area_width / 2).saturating_sub(line_width / 2),
+        Alignment::Right => text_area_width.saturating_sub(line_width),
+        Alignment::Left => 0,
+    }
+}
+
+/// A widget to display some text.
+///
+/// # Examples
+///
+/// ```
+/// # use tui::text::{Text, Spans, Span};
+/// # use tui::widgets::{Block, Borders, Paragraph, Wrap};
+/// # use tui::style::{Style, Color, Modifier};
+/// # use tui::layout::{Alignment};
+/// let text = vec![
+///     Spans::from(vec![
+///         Span::raw("First"),
+///         Span::styled("line",Style::default().add_modifier(Modifier::ITALIC)),
+///         Span::raw("."),
+///     ]),
+///     Spans::from(Span::styled("Second line", Style::default().fg(Color::Red))),
+/// ];
+/// Paragraph::new(text)
+///     .block(Block::default().title("Paragraph").borders(Borders::ALL))
+///     .style(Style::default().fg(Color::White).bg(Color::Black))
+///     .alignment(Alignment::Center)
+///     .wrap(Wrap { trim: true });
+/// ```
+#[derive(Debug, Clone)]
+pub struct Paragraph<'a> {
+    /// A block to wrap the widget in
+    block: Option<Block<'a>>,
+    /// Widget style
+    style: Style,
+    /// How to wrap the text
+    wrap: Option<Wrap>,
+    /// The text to display
+    text: Text<'a>,
+    /// Scroll
+    scroll: (u16, u16),
+    /// Alignment of the text
+    alignment: Alignment,
+}
+
+/// Describes how to wrap text across lines.
+///
+/// ## Examples
+///
+/// ```
+/// # use tui::widgets::{Paragraph, Wrap};
+/// # use tui::text::Text;
+/// let bullet_points = Text::from(r#"Some indented points:
+///     - First thing goes here and is long so that it wraps
+///     - Here is another point that is long enough to wrap"#);
+///
+/// // With leading spaces trimmed (window width of 30 chars):
+/// Paragraph::new(bullet_points.clone()).wrap(Wrap { trim: true });
+/// // Some indented points:
+/// // - First thing goes here and is
+/// // long so that it wraps
+/// // - Here is another point that
+/// // is long enough to wrap
+///
+/// // But without trimming, indentation is preserved:
+/// Paragraph::new(bullet_points).wrap(Wrap { trim: false });
+/// // Some indented points:
+/// //     - First thing goes here
+/// // and is long so that it wraps
+/// //     - Here is another point
+/// // that is long enough to wrap
+/// ```
+#[derive(Debug, Clone, Copy)]
+pub struct Wrap {
+    /// Should leading whitespace be trimmed
+    pub trim: bool,
+}
+
+impl<'a> Paragraph<'a> {
+    pub fn new<T>(text: T) -> Paragraph<'a>
+    where
+        T: Into<Text<'a>>,
+    {
+        Paragraph {
+            block: None,
+            style: Style::default(),
+            wrap: None,
+            text: text.into(),
+            scroll: (0, 0),
+            alignment: Alignment::Left,
+        }
+    }
+
+    pub fn block(mut self, block: Block<'a>) -> Paragraph<'a> {
+        self.block = Some(block);
+        self
+    }
+
+    pub fn style(mut self, style: Style) -> Paragraph<'a> {
+        self.style = style;
+        self
+    }
+
+    pub fn wrap(mut self, wrap: Wrap) -> Paragraph<'a> {
+        self.wrap = Some(wrap);
+        self
+    }
+
+    pub fn scroll(mut self, offset: (u16, u16)) -> Paragraph<'a> {
+        self.scroll = offset;
+        self
+    }
+
+    pub fn alignment(mut self, alignment: Alignment) -> Paragraph<'a> {
+        self.alignment = alignment;
+        self
+    }
+}
+
+impl<'a> Widget for Paragraph<'a> {
+    fn render(mut self, area: Rect, buf: &mut Buffer) {
+        buf.set_style(area, self.style);
+        let text_area = self.block.take().map_or(area, |b| {
+            let inner_area = b.inner(area);
+            b.render(area, buf);
+            inner_area
+        });
+
+        if text_area.height < 1 {
+            return;
+        }
+
+        let style = self.style;
+        let mut styled = self.text.lines.iter().flat_map(|spans| {
+            spans
+                .0
+                .iter()
+                .flat_map(|span| span.styled_graphemes(style))
+                // Required given the way composers work but might be refactored out if we change
+                // composers to operate on lines instead of a stream of graphemes.
+                .chain(iter::once(StyledGrapheme {
+                    symbol: "\n",
+                    style: self.style,
+                }))
+        });
+
+        let mut line_composer: Box<dyn LineComposer> = if let Some(Wrap { trim }) = self.wrap {
+            Box::new(WordWrapper::new(&mut styled, text_area.width, trim))
+        } else {
+            let mut line_composer = Box::new(LineTruncator::new(&mut styled, text_area.width));
+            if self.alignment == Alignment::Left {
+                line_composer.set_horizontal_offset(self.scroll.1);
+            }
+            line_composer
+        };
+        let mut y = 0;
+        while let Some((current_line, current_line_width)) = line_composer.next_line() {
+            if y >= self.scroll.0 {
+                let mut x = get_line_offset(current_line_width, text_area.width, self.alignment);
+                for StyledGrapheme { symbol, style } in current_line {
+                    buf.get_mut(text_area.left() + x, text_area.top() + y - self.scroll.0)
+                        .set_symbol(if symbol.is_empty() {
+                            // If the symbol is empty, the last char which rendered last time will
+                            // leave on the line. It's a quick fix.
+                            " "
+                        } else {
+                            symbol
+                        })
+                        .set_style(*style);
+                    x += symbol.width() as u16;
+                }
+            }
+            y += 1;
+            if y >= text_area.height + self.scroll.0 {
+                break;
+            }
+        }
+    }
+}
diff --git a/src/tui/widgets/reflow.rs b/src/tui/widgets/reflow.rs
new file mode 100644
index 00000000..d174932b
--- /dev/null
+++ b/src/tui/widgets/reflow.rs
@@ -0,0 +1,537 @@
+use crate::tui::text::StyledGrapheme;
+use unicode_segmentation::UnicodeSegmentation;
+use unicode_width::UnicodeWidthStr;
+
+const NBSP: &str = "\u{00a0}";
+
+/// A state machine to pack styled symbols into lines.
+/// Cannot implement it as Iterator since it yields slices of the internal buffer (need streaming
+/// iterators for that).
+pub trait LineComposer<'a> {
+    fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)>;
+}
+
+/// A state machine that wraps lines on word boundaries.
+pub struct WordWrapper<'a, 'b> {
+    symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>,
+    max_line_width: u16,
+    current_line: Vec<StyledGrapheme<'a>>,
+    next_line: Vec<StyledGrapheme<'a>>,
+    /// Removes the leading whitespace from lines
+    trim: bool,
+}
+
+impl<'a, 'b> WordWrapper<'a, 'b> {
+    pub fn new(
+        symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>,
+        max_line_width: u16,
+        trim: bool,
+    ) -> WordWrapper<'a, 'b> {
+        WordWrapper {
+            symbols,
+            max_line_width,
+            current_line: vec![],
+            next_line: vec![],
+            trim,
+        }
+    }
+}
+
+impl<'a, 'b> LineComposer<'a> for WordWrapper<'a, 'b> {
+    fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)> {
+        if self.max_line_width == 0 {
+            return None;
+        }
+        std::mem::swap(&mut self.current_line, &mut self.next_line);
+        self.next_line.truncate(0);
+
+        let mut current_line_width = self
+            .current_line
+            .iter()
+            .map(|StyledGrapheme { symbol, .. }| symbol.width() as u16)
+            .sum();
+
+        let mut symbols_to_last_word_end: usize = 0;
+        let mut width_to_last_word_end: u16 = 0;
+        let mut prev_whitespace = false;
+        let mut symbols_exhausted = true;
+        for StyledGrapheme { symbol, style } in &mut self.symbols {
+            symbols_exhausted = false;
+            let symbol_whitespace = symbol.chars().all(&char::is_whitespace) && symbol != NBSP;
+
+            // Ignore characters wider that the total max width.
+            if symbol.width() as u16 > self.max_line_width
+                // Skip leading whitespace when trim is enabled.
+                || self.trim && symbol_whitespace && symbol != "\n" && current_line_width == 0
+            {
+                continue;
+            }
+
+            // Break on newline and discard it.
+            if symbol == "\n" {
+                if prev_whitespace {
+                    current_line_width = width_to_last_word_end;
+                    self.current_line.truncate(symbols_to_last_word_end);
+                }
+                break;
+            }
+
+            // Mark the previous symbol as word end.
+            if symbol_whitespace && !prev_whitespace {
+                symbols_to_last_word_end = self.current_line.len();
+                width_to_last_word_end = current_line_width;
+            }
+
+            self.current_line.push(StyledGrapheme { symbol, style });
+            current_line_width += symbol.width() as u16;
+
+            if current_line_width > self.max_line_width {
+                // If there was no word break in the text, wrap at the end of the line.
+                let (truncate_at, truncated_width) = if symbols_to_last_word_end == 0 {
+                    (self.current_line.len() - 1, self.max_line_width)
+                } else {
+                    (symbols_to_last_word_end, width_to_last_word_end)
+                };
+
+                // Push the remainder to the next line but strip leading whitespace:
+                {
+                    let remainder = &self.current_line[truncate_at..];
+                    if let Some(remainder_nonwhite) =
+                        remainder.iter().position(|StyledGrapheme { symbol, .. }| {
+                            !symbol.chars().all(&char::is_whitespace)
+                        })
+                    {
+                        self.next_line
+                            .extend_from_slice(&remainder[remainder_nonwhite..]);
+                    }
+                }
+                self.current_line.truncate(truncate_at);
+                current_line_width = truncated_width;
+                break;
+            }
+
+            prev_whitespace = symbol_whitespace;
+        }
+
+        // Even if the iterator is exhausted, pass the previous remainder.
+        if symbols_exhausted && self.current_line.is_empty() {
+            None
+        } else {
+            Some((&self.current_line[..], current_line_width))
+        }
+    }
+}
+
+/// A state machine that truncates overhanging lines.
+pub struct LineTruncator<'a, 'b> {
+    symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>,
+    max_line_width: u16,
+    current_line: Vec<StyledGrapheme<'a>>,
+    /// Record the offet to skip render
+    horizontal_offset: u16,
+}
+
+impl<'a, 'b> LineTruncator<'a, 'b> {
+    pub fn new(
+        symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>,
+        max_line_width: u16,
+    ) -> LineTruncator<'a, 'b> {
+        LineTruncator {
+            symbols,
+            max_line_width,
+            horizontal_offset: 0,
+            current_line: vec![],
+        }
+    }
+
+    pub fn set_horizontal_offset(&mut self, horizontal_offset: u16) {
+        self.horizontal_offset = horizontal_offset;
+    }
+}
+
+impl<'a, 'b> LineComposer<'a> for LineTruncator<'a, 'b> {
+    fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)> {
+        if self.max_line_width == 0 {
+            return None;
+        }
+
+        self.current_line.truncate(0);
+        let mut current_line_width = 0;
+
+        let mut skip_rest = false;
+        let mut symbols_exhausted = true;
+        let mut horizontal_offset = self.horizontal_offset as usize;
+        for StyledGrapheme { symbol, style } in &mut self.symbols {
+            symbols_exhausted = false;
+
+            // Ignore characters wider that the total max width.
+            if symbol.width() as u16 > self.max_line_width {
+                continue;
+            }
+
+            // Break on newline and discard it.
+            if symbol == "\n" {
+                break;
+            }
+
+            if current_line_width + symbol.width() as u16 > self.max_line_width {
+                // Exhaust the remainder of the line.
+                skip_rest = true;
+                break;
+            }
+
+            let symbol = if horizontal_offset == 0 {
+                symbol
+            } else {
+                let w = symbol.width();
+                if w > horizontal_offset {
+                    let t = trim_offset(symbol, horizontal_offset);
+                    horizontal_offset = 0;
+                    t
+                } else {
+                    horizontal_offset -= w;
+                    ""
+                }
+            };
+            current_line_width += symbol.width() as u16;
+            self.current_line.push(StyledGrapheme { symbol, style });
+        }
+
+        if skip_rest {
+            for StyledGrapheme { symbol, .. } in &mut self.symbols {
+                if symbol == "\n" {
+                    break;
+                }
+            }
+        }
+
+        if symbols_exhausted && self.current_line.is_empty() {
+            None
+        } else {
+            Some((&self.current_line[..], current_line_width))
+        }
+    }
+}
+
+/// This function will return a str slice which start at specified offset.
+/// As src is a unicode str, start offset has to be calculated with each character.
+fn trim_offset(src: &str, mut offset: usize) -> &str {
+    let mut start = 0;
+    for c in UnicodeSegmentation::graphemes(src, true) {
+        let w = c.width();
+        if w <= offset {
+            offset -= w;
+            start += c.len();
+        } else {
+            break;
+        }
+    }
+    &src[start..]
+}
+
+#[cfg(test)]
+mod test {
+    use crate::tui::style::Style;
+
+    use super::*;
+    use unicode_segmentation::UnicodeSegmentation;
+
+    #[derive(Clone, Copy)]
+    enum Composer {
+        WordWrapper { trim: bool },
+        LineTruncator,
+    }
+
+    fn run_composer(which: Composer, text: &str, text_area_width: u16) -> (Vec<String>, Vec<u16>) {
+        let style = Style::default();
+        let mut styled =
+            UnicodeSegmentation::graphemes(text, true).map(|g| StyledGrapheme { symbol: g, style });
+        let mut composer: Box<dyn LineComposer> = match which {
+            Composer::WordWrapper { trim } => {
+                Box::new(WordWrapper::new(&mut styled, text_area_width, trim))
+            }
+            Composer::LineTruncator => Box::new(LineTruncator::new(&mut styled, text_area_width)),
+        };
+        let mut lines = vec![];
+        let mut widths = vec![];
+        while let Some((styled, width)) = composer.next_line() {
+            let line = styled
+                .iter()
+                .map(|StyledGrapheme { symbol, .. }| *symbol)
+                .collect::<String>();
+            assert!(width <= text_area_width);
+            lines.push(line);
+            widths.push(width);
+        }
+        (lines, widths)
+    }
+
+    #[test]
+    fn line_composer_one_line() {
+        let width = 40;
+        for i in 1..width {
+            let text = "a".repeat(i);
+            let (word_wrapper, _) =
+                run_composer(Composer::WordWrapper { trim: true }, &text, width as u16);
+            let (line_truncator, _) = run_composer(Composer::LineTruncator, &text, width as u16);
+            let expected = vec![text];
+            assert_eq!(word_wrapper, expected);
+            assert_eq!(line_truncator, expected);
+        }
+    }
+
+    #[test]
+    fn line_composer_short_lines() {
+        let width = 20;
+        let text =
+            "abcdefg\nhijklmno\npabcdefg\nhijklmn\nopabcdefghijk\nlmnopabcd\n\n\nefghijklmno";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+
+        let wrapped: Vec<&str> = text.split('\n').collect();
+        assert_eq!(word_wrapper, wrapped);
+        assert_eq!(line_truncator, wrapped);
+    }
+
+    #[test]
+    fn line_composer_long_word() {
+        let width = 20;
+        let text = "abcdefghijklmnopabcdefghijklmnopabcdefghijklmnopabcdefghijklmno";
+        let (word_wrapper, _) =
+            run_composer(Composer::WordWrapper { trim: true }, text, width as u16);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width as u16);
+
+        let wrapped = vec![
+            &text[..width],
+            &text[width..width * 2],
+            &text[width * 2..width * 3],
+            &text[width * 3..],
+        ];
+        assert_eq!(
+            word_wrapper, wrapped,
+            "WordWrapper should detect the line cannot be broken on word boundary and \
+             break it at line width limit."
+        );
+        assert_eq!(line_truncator, vec![&text[..width]]);
+    }
+
+    #[test]
+    fn line_composer_long_sentence() {
+        let width = 20;
+        let text =
+            "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab c d e f g h i j k l m n o";
+        let text_multi_space =
+            "abcd efghij    klmnopabcd efgh     ijklmnopabcdefg hijkl mnopab c d e f g h i j k l \
+             m n o";
+        let (word_wrapper_single_space, _) =
+            run_composer(Composer::WordWrapper { trim: true }, text, width as u16);
+        let (word_wrapper_multi_space, _) = run_composer(
+            Composer::WordWrapper { trim: true },
+            text_multi_space,
+            width as u16,
+        );
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width as u16);
+
+        let word_wrapped = vec![
+            "abcd efghij",
+            "klmnopabcd efgh",
+            "ijklmnopabcdefg",
+            "hijkl mnopab c d e f",
+            "g h i j k l m n o",
+        ];
+        assert_eq!(word_wrapper_single_space, word_wrapped);
+        assert_eq!(word_wrapper_multi_space, word_wrapped);
+
+        assert_eq!(line_truncator, vec![&text[..width]]);
+    }
+
+    #[test]
+    fn line_composer_zero_width() {
+        let width = 0;
+        let text = "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab ";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+
+        let expected: Vec<&str> = Vec::new();
+        assert_eq!(word_wrapper, expected);
+        assert_eq!(line_truncator, expected);
+    }
+
+    #[test]
+    fn line_composer_max_line_width_of_1() {
+        let width = 1;
+        let text = "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab ";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+
+        let expected: Vec<&str> = UnicodeSegmentation::graphemes(text, true)
+            .filter(|g| g.chars().any(|c| !c.is_whitespace()))
+            .collect();
+        assert_eq!(word_wrapper, expected);
+        assert_eq!(line_truncator, vec!["a"]);
+    }
+
+    #[test]
+    fn line_composer_max_line_width_of_1_double_width_characters() {
+        let width = 1;
+        let text = "コンピュータ上で文字を扱う場合、典型的には文字\naaaによる通信を行う場合にその\
+                    両端点では、";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+        assert_eq!(word_wrapper, vec!["", "a", "a", "a"]);
+        assert_eq!(line_truncator, vec!["", "a"]);
+    }
+
+    /// Tests `WordWrapper` with words some of which exceed line length and some not.
+    #[test]
+    fn line_composer_word_wrapper_mixed_length() {
+        let width = 20;
+        let text = "abcd efghij klmnopabcdefghijklmnopabcdefghijkl mnopab cdefghi j klmno";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        assert_eq!(
+            word_wrapper,
+            vec![
+                "abcd efghij",
+                "klmnopabcdefghijklmn",
+                "opabcdefghijkl",
+                "mnopab cdefghi j",
+                "klmno",
+            ]
+        );
+    }
+
+    #[test]
+    fn line_composer_double_width_chars() {
+        let width = 20;
+        let text = "コンピュータ上で文字を扱う場合、典型的には文字による通信を行う場合にその両端点\
+                    では、";
+        let (word_wrapper, word_wrapper_width) =
+            run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+        assert_eq!(line_truncator, vec!["コンピュータ上で文字"]);
+        let wrapped = vec![
+            "コンピュータ上で文字",
+            "を扱う場合、典型的に",
+            "は文字による通信を行",
+            "う場合にその両端点で",
+            "は、",
+        ];
+        assert_eq!(word_wrapper, wrapped);
+        assert_eq!(word_wrapper_width, vec![width, width, width, width, 4]);
+    }
+
+    #[test]
+    fn line_composer_leading_whitespace_removal() {
+        let width = 20;
+        let text = "AAAAAAAAAAAAAAAAAAAA    AAA";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+        assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAAAAAAA", "AAA",]);
+        assert_eq!(line_truncator, vec!["AAAAAAAAAAAAAAAAAAAA"]);
+    }
+
+    /// Tests truncation of leading whitespace.
+    #[test]
+    fn line_composer_lots_of_spaces() {
+        let width = 20;
+        let text = "                                                                     ";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+        assert_eq!(word_wrapper, vec![""]);
+        assert_eq!(line_truncator, vec!["                    "]);
+    }
+
+    /// Tests an input starting with a letter, folowed by spaces - some of the behaviour is
+    /// incidental.
+    #[test]
+    fn line_composer_char_plus_lots_of_spaces() {
+        let width = 20;
+        let text = "a                                                                     ";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width);
+        // What's happening below is: the first line gets consumed, trailing spaces discarded,
+        // after 20 of which a word break occurs (probably shouldn't). The second line break
+        // discards all whitespace. The result should probably be vec!["a"] but it doesn't matter
+        // that much.
+        assert_eq!(word_wrapper, vec!["a", ""]);
+        assert_eq!(line_truncator, vec!["a                   "]);
+    }
+
+    #[test]
+    fn line_composer_word_wrapper_double_width_chars_mixed_with_spaces() {
+        let width = 20;
+        // Japanese seems not to use spaces but we should break on spaces anyway... We're using it
+        // to test double-width chars.
+        // You are more than welcome to add word boundary detection based of alterations of
+        // hiragana and katakana...
+        // This happens to also be a test case for mixed width because regular spaces are single width.
+        let text = "コンピュ ータ上で文字を扱う場合、 典型的には文 字による 通信を行 う場合にその両端点では、";
+        let (word_wrapper, word_wrapper_width) =
+            run_composer(Composer::WordWrapper { trim: true }, text, width);
+        assert_eq!(
+            word_wrapper,
+            vec![
+                "コンピュ",
+                "ータ上で文字を扱う場",
+                "合、 典型的には文",
+                "字による 通信を行",
+                "う場合にその両端点で",
+                "は、",
+            ]
+        );
+        // Odd-sized lines have a space in them.
+        assert_eq!(word_wrapper_width, vec![8, 20, 17, 17, 20, 4]);
+    }
+
+    /// Ensure words separated by nbsp are wrapped as if they were a single one.
+    #[test]
+    fn line_composer_word_wrapper_nbsp() {
+        let width = 20;
+        let text = "AAAAAAAAAAAAAAA AAAA\u{00a0}AAA";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAA", "AAAA\u{00a0}AAA",]);
+
+        // Ensure that if the character was a regular space, it would be wrapped differently.
+        let text_space = text.replace('\u{00a0}', " ");
+        let (word_wrapper_space, _) =
+            run_composer(Composer::WordWrapper { trim: true }, &text_space, width);
+        assert_eq!(word_wrapper_space, vec!["AAAAAAAAAAAAAAA AAAA", "AAA",]);
+    }
+
+    #[test]
+    fn line_composer_word_wrapper_preserve_indentation() {
+        let width = 20;
+        let text = "AAAAAAAAAAAAAAAAAAAA    AAA";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width);
+        assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAAAAAAA", "   AAA",]);
+    }
+
+    #[test]
+    fn line_composer_word_wrapper_preserve_indentation_with_wrap() {
+        let width = 10;
+        let text = "AAA AAA AAAAA AA AAAAAA\n B\n  C\n   D";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width);
+        assert_eq!(
+            word_wrapper,
+            vec!["AAA AAA", "AAAAA AA", "AAAAAA", " B", "  C", "   D"]
+        );
+    }
+
+    #[test]
+    fn line_composer_word_wrapper_preserve_indentation_lots_of_whitespace() {
+        let width = 10;
+        let text = "               4 Indent\n                 must wrap!";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width);
+        assert_eq!(
+            word_wrapper,
+            vec![
+                "          ",
+                "    4",
+                "Indent",
+                "          ",
+                "      must",
+                "wrap!"
+            ]
+        );
+    }
+}