wip: refactor(tui): 44 errors

tui/src/tui_impls.rs

@@ -0,0 +1,885 @@
+use crate::*;
+use ratatui::style::Stylize;
+use ratatui::{prelude::Position, style::Color::*};
+use crate::ratatui::prelude::Position;
+use unicode_width::{UnicodeWidthStr, UnicodeWidthChar};
+use ratatui::prelude::Position;
+use rand::{thread_rng, distributions::uniform::UniformSampler};
+
+impl Tui {
+    pub const fn fg     <T>    (color: Color, w: T) -> Foreground<Color, T> { Foreground(color, w) }
+    pub const fn bg     <T>    (color: Color, w: T) -> Background<Color, T> { Background(color, w) }
+    pub const fn fg_bg  <T>    (fg: Color, bg: Color, w: T) -> Background<Color, Foreground<Color, T>> { Background(bg, Foreground(fg, w)) }
+    pub const fn modify <T>    (enable: bool, modifier: Modifier, w: T) -> Modify<T> { Modify(enable, modifier, w) }
+    pub const fn bold   <T>    (enable: bool, w: T) -> Modify<T> { Self::modify(enable, Modifier::BOLD, w) }
+    pub const fn border <S, T> (enable: bool, style: S, w: T) -> Bordered<S, T> { Bordered(enable, style, w) }
+    pub const fn null     () -> Color { Color::Reset }
+    pub const fn g   (g: u8) -> Color { Color::Rgb(g, g, g) }
+    pub const fn red      () -> Color { Color::Rgb(255,0,  0) }
+    pub const fn orange   () -> Color { Color::Rgb(255,128,0) }
+    pub const fn yellow   () -> Color { Color::Rgb(255,255,0) }
+    pub const fn brown    () -> Color { Color::Rgb(128,255,0) }
+    pub const fn green    () -> Color { Color::Rgb(0,255,0) }
+    pub const fn electric () -> Color { Color::Rgb(0,255,128) }
+    //fn bg0  () -> Color { Color::Rgb(20, 20, 20) }
+    //fn bg   () -> Color { Color::Rgb(28, 35, 25) }
+    //fn border_bg () -> Color { Color::Rgb(40, 50, 30) }
+    //fn border_fg (f: bool) -> Color { if f { Self::bo1() } else { Self::bo2() } }
+    //fn title_fg (f: bool) -> Color { if f { Self::ti1() } else { Self::ti2() } }
+    //fn separator_fg (_: bool) -> Color { Color::Rgb(0, 0, 0) }
+    //fn mode_bg () -> Color { Color::Rgb(150, 160, 90) }
+    //fn mode_fg () -> Color { Color::Rgb(255, 255, 255) }
+    //fn status_bar_bg () -> Color { Color::Rgb(28, 35, 25) }
+    //fn bo1 () -> Color { Color::Rgb(100, 110, 40) }
+    //fn bo2 () -> Color { Color::Rgb(70, 80, 50) }
+    //fn ti1 () -> Color { Color::Rgb(150, 160, 90) }
+    //fn ti2 () -> Color { Color::Rgb(120, 130, 100) }
+    /// Construct a new TUI engine and wrap it for shared ownership.
+    pub fn new () -> Usually<Arc<RwLock<Self>>> {
+        let backend = CrosstermBackend::new(stdout());
+        let Size { width, height } = backend.size()?;
+        Ok(Arc::new(RwLock::new(Self {
+            exited:  Arc::new(AtomicBool::new(false)),
+            buffer:  Buffer::empty(Rect { x: 0, y: 0, width, height }),
+            area:    [0, 0, width, height],
+            backend,
+            perf: Default::default(),
+        })))
+    }
+    /// True if done
+    pub fn exited (&self) -> bool {
+        self.exited.fetch_and(true, Relaxed)
+    }
+    /// Prepare before run
+    pub fn setup (&mut self) -> Usually<()> {
+        let better_panic_handler = Settings::auto().verbosity(Verbosity::Full).create_panic_handler();
+        std::panic::set_hook(Box::new(move |info: &std::panic::PanicHookInfo|{
+            stdout().execute(LeaveAlternateScreen).unwrap();
+            CrosstermBackend::new(stdout()).show_cursor().unwrap();
+            disable_raw_mode().unwrap();
+            better_panic_handler(info);
+        }));
+        stdout().execute(EnterAlternateScreen)?;
+        self.backend.hide_cursor()?;
+        enable_raw_mode().map_err(Into::into)
+    }
+    /// Update the display buffer.
+    pub fn flip (&mut self, mut buffer: Buffer, size: ratatui::prelude::Rect) -> Buffer {
+        if self.buffer.area != size {
+            self.backend.clear_region(ClearType::All).unwrap();
+            self.buffer.resize(size);
+            self.buffer.reset();
+        }
+        let updates = self.buffer.diff(&buffer);
+        self.backend.draw(updates.into_iter()).expect("failed to render");
+        self.backend.flush().expect("failed to flush output buffer");
+        std::mem::swap(&mut self.buffer, &mut buffer);
+        buffer.reset();
+        buffer
+    }
+    /// Clean up after run
+    pub fn teardown (&mut self) -> Usually<()> {
+        stdout().execute(LeaveAlternateScreen)?;
+        self.backend.show_cursor()?;
+        disable_raw_mode().map_err(Into::into)
+    }
+}
+
+impl<T: TuiWidget + Send + Sync + 'static> TuiRun<T> for Arc<RwLock<Tui>> {
+    fn run (&self, state: &Arc<RwLock<T>>) -> Usually<()> {
+        let _input_thread = TuiIn::run_input(self, state, Duration::from_millis(100));
+        self.write().unwrap().setup()?;
+        let render_thread = TuiOut::run_output(self, state, Duration::from_millis(10))?;
+        match render_thread.join() {
+            Ok(result) => {
+                self.write().unwrap().teardown()?;
+                println!("\n\rRan successfully: {result:?}\n\r");
+            },
+            Err(error) => {
+                self.write().unwrap().teardown()?;
+                panic!("\n\rDraw thread failed: error={error:?}.\n\r")
+            },
+        }
+        Ok(())
+    }
+}
+
+impl Ord for TuiEvent {
+    fn cmp (&self, other: &Self) -> std::cmp::Ordering {
+        self.partial_cmp(other)
+            .unwrap_or_else(||format!("{:?}", self).cmp(&format!("{other:?}"))) // FIXME perf
+    }
+}
+
+impl TuiEvent {
+    pub fn from_crossterm (event: Event) -> Self {
+        Self(event)
+    }
+    #[cfg(feature = "dsl")]
+    pub fn from_dsl (dsl: impl Language) -> Perhaps<Self> {
+        Ok(TuiKey::from_dsl(dsl)?.to_crossterm().map(Self))
+    }
+}
+
+impl TuiKey {
+    const SPLIT: char = '/';
+    #[cfg(feature = "dsl")]
+    pub fn from_dsl (dsl: impl Language) -> Usually<Self> {
+        if let Some(word) = dsl.word()? {
+            let word = word.trim();
+            Ok(if word == ":char" {
+                Self(None, KeyModifiers::NONE)
+            } else if word.chars().nth(0) == Some('@') {
+                let mut key       = None;
+                let mut modifiers = KeyModifiers::NONE;
+                let mut tokens    = word[1..].split(Self::SPLIT).peekable();
+                while let Some(token) = tokens.next() {
+                    if tokens.peek().is_some() {
+                        match token {
+                            "ctrl"  | "Ctrl"  | "c" | "C" => modifiers |= KeyModifiers::CONTROL,
+                            "alt"   | "Alt"   | "m" | "M" => modifiers |= KeyModifiers::ALT,
+                            "shift" | "Shift" | "s" | "S" => {
+                                modifiers |= KeyModifiers::SHIFT;
+                                // + TODO normalize character case, BackTab, etc.
+                            },
+                            _ => panic!("unknown modifier {token}"),
+                        }
+                    } else {
+                        key = if token.len() == 1 {
+                            Some(KeyCode::Char(token.chars().next().unwrap()))
+                        } else {
+                            Some(named_key(token).unwrap_or_else(||panic!("unknown character {token}")))
+                        }
+                    }
+                }
+                Self(key, modifiers)
+            } else {
+                return Err(format!("TuiKey: unexpected: {word}").into())
+            })
+        } else {
+            return Err(format!("TuiKey: unspecified").into())
+        }
+    }
+    pub fn to_crossterm (&self) -> Option<Event> {
+        self.0.map(|code|Event::Key(KeyEvent {
+            code,
+            modifiers: self.1,
+            kind:  KeyEventKind::Press,
+            state: KeyEventState::NONE,
+        }))
+    }
+}
+
+pub fn buffer_update (buf: &mut Buffer, area: XY<u16>, callback: &impl Fn(&mut Cell, u16, u16)) {
+    for row in 0..area.h() {
+        let y = area.y() + row;
+        for col in 0..area.w() {
+            let x = area.x() + col;
+            if x < buf.area.width && y < buf.area.height {
+                if let Some(cell) = buf.cell_mut(ratatui::prelude::Position { x, y }) {
+                    callback(cell, col, row);
+                }
+            }
+        }
+    }
+}
+
+impl_debug!(BigBuffer |self, f| {
+    write!(f, "[BB {}x{} ({})]", self.width, self.height, self.content.len())
+});
+
+impl BigBuffer {
+    pub fn new (width: usize, height: usize) -> Self {
+        Self { width, height, content: vec![Cell::default(); width*height] }
+    }
+    pub fn get (&self, x: usize, y: usize) -> Option<&Cell> {
+        let i = self.index_of(x, y);
+        self.content.get(i)
+    }
+    pub fn get_mut (&mut self, x: usize, y: usize) -> Option<&mut Cell> {
+        let i = self.index_of(x, y);
+        self.content.get_mut(i)
+    }
+    pub fn index_of (&self, x: usize, y: usize) -> usize {
+        y * self.width + x
+    }
+}
+
+from!(BigBuffer: |size:(usize, usize)| Self::new(size.0, size.1));
+impl Input for TuiIn {
+    type Event   = TuiEvent;
+    type Handled = bool;
+    fn event   (&self) -> &TuiEvent { &self.event }
+    fn is_done (&self) -> bool { self.exited.fetch_and(true, Relaxed) }
+    fn done    (&self) { self.exited.store(true, Relaxed); }
+}
+impl TuiIn {
+    /// Spawn the input thread.
+    pub fn run_input <T: Handle<TuiIn> + Send + Sync + 'static> (
+        engine: &Arc<RwLock<Tui>>,
+        state:  &Arc<RwLock<T>>,
+        timer:  Duration
+    ) -> JoinHandle<()> {
+        let exited = engine.read().unwrap().exited.clone();
+        let state  = state.clone();
+        spawn(move || loop {
+            if exited.fetch_and(true, Relaxed) {
+                break
+            }
+            if poll(timer).is_ok() {
+                let event = read().unwrap();
+                match event {
+                    Event::Key(KeyEvent {
+                        code:      KeyCode::Char('c'),
+                        modifiers: KeyModifiers::CONTROL,
+                        kind:      KeyEventKind::Press,
+                        state:     KeyEventState::NONE
+                    }) => {
+                        exited.store(true, Relaxed);
+                    },
+                    _ => {
+                        let exited = exited.clone();
+                        let event  = TuiEvent::from_crossterm(event);
+                        if let Err(e) = state.write().unwrap().handle(&TuiIn { exited, event }) {
+                            panic!("{e}")
+                        }
+                    }
+                }
+            }
+        })
+    }
+}
+
+pub trait HasPerf {
+    fn perf (&self) -> &PerfModel;
+}
+
+impl Default for PerfModel {
+    fn default () -> Self {
+        Self {
+            enabled: true,
+            clock:   quanta::Clock::new(),
+            used:    Default::default(),
+            window:  Default::default(),
+        }
+    }
+}
+
+impl PerfModel {
+    pub fn get_t0 (&self) -> Option<u64> {
+        if self.enabled {
+            Some(self.clock.raw())
+        } else {
+            None
+        }
+    }
+    pub fn get_t1 (&self, t0: Option<u64>) -> Option<std::time::Duration> {
+        if let Some(t0) = t0 {
+            if self.enabled {
+                Some(self.clock.delta(t0, self.clock.raw()))
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
+    pub fn update (&self, t0: Option<u64>, microseconds: f64) {
+        if let Some(t0) = t0 {
+            let t1 = self.clock.raw();
+            self.used.store(self.clock.delta_as_nanos(t0, t1) as f64, Relaxed);
+            self.window.store(microseconds, Relaxed,);
+        }
+    }
+    pub fn percentage (&self) -> Option<f64> {
+        let window = self.window.load(Relaxed) * 1000.0;
+        if window > 0.0 {
+            let used = self.used.load(Relaxed);
+            Some(100.0 * used / window)
+        } else {
+            None
+        }
+    }
+}
+
+from!(ItemColor: |okhsl: Okhsl<f32>|Self { okhsl, rgb: okhsl_to_rgb(okhsl) });
+from!(ItemColor: |rgb: Color|Self { rgb, okhsl: rgb_to_okhsl(rgb) });
+pub fn okhsl_to_rgb (color: Okhsl<f32>) -> Color {
+    let Srgb { red, green, blue, .. }: Srgb<f32> = Srgb::from_color_unclamped(color);
+    Color::Rgb((red   * 255.0) as u8, (green * 255.0) as u8, (blue  * 255.0) as u8,)
+}
+pub fn rgb_to_okhsl (color: Color) -> Okhsl<f32> {
+    if let Color::Rgb(r, g, b) = color {
+        Okhsl::from_color(Srgb::new(r as f32 / 255.0, g as f32 / 255.0, b as f32 / 255.0))
+    } else {
+        unreachable!("only Color::Rgb is supported")
+    }
+}
+
+// A single color within item theme parameters, in OKHSL and RGB representations.
+impl ItemColor {
+    pub const fn from_rgb (rgb: Color) -> Self {
+        Self { rgb, okhsl: Okhsl::new_const(OklabHue::new(0.0), 0.0, 0.0) }
+    }
+    pub const fn from_okhsl (okhsl: Okhsl<f32>) -> Self {
+        Self { rgb: Color::Rgb(0, 0, 0), okhsl }
+    }
+    pub fn random () -> Self {
+        let mut rng = thread_rng();
+        let lo = Okhsl::new(-180.0, 0.01, 0.25);
+        let hi = Okhsl::new( 180.0, 0.9,  0.5);
+        UniformOkhsl::new(lo, hi).sample(&mut rng).into()
+    }
+    pub fn random_dark () -> Self {
+        let mut rng = thread_rng();
+        let lo = Okhsl::new(-180.0, 0.025, 0.075);
+        let hi = Okhsl::new( 180.0, 0.5,   0.150);
+        UniformOkhsl::new(lo, hi).sample(&mut rng).into()
+    }
+    pub fn random_near (color: Self, distance: f32) -> Self {
+        color.mix(Self::random(), distance)
+    }
+    pub fn mix (&self, other: Self, distance: f32) -> Self {
+        if distance > 1.0 { panic!("color mixing takes distance between 0.0 and 1.0"); }
+        self.okhsl.mix(other.okhsl, distance).into()
+    }
+}
+
+
+from!(ItemTheme: |base: Color|    Self::from_tui_color(base));
+from!(ItemTheme: |base: ItemColor|Self::from_item_color(base));
+impl ItemTheme {
+    pub const G: [Self;256] = {
+        let mut builder = konst::array::ArrayBuilder::new();
+        while !builder.is_full() {
+            let index    = builder.len() as u8;
+            let light    = (index as f64 * 1.15) as u8;
+            let lighter  = (index as f64 * 1.7) as u8;
+            let lightest = (index as f64 * 1.85) as u8;
+            let dark     = (index as f64 * 0.9) as u8;
+            let darker   = (index as f64 * 0.6) as u8;
+            let darkest  = (index as f64 * 0.3) as u8;
+            builder.push(ItemTheme {
+                base:     ItemColor::from_rgb(Color::Rgb(index,    index,    index     )),
+                light:    ItemColor::from_rgb(Color::Rgb(light,    light,    light,    )),
+                lighter:  ItemColor::from_rgb(Color::Rgb(lighter,  lighter,  lighter,  )),
+                lightest: ItemColor::from_rgb(Color::Rgb(lightest, lightest, lightest, )),
+                dark:     ItemColor::from_rgb(Color::Rgb(dark,     dark,     dark,     )),
+                darker:   ItemColor::from_rgb(Color::Rgb(darker,   darker,   darker,   )),
+                darkest:  ItemColor::from_rgb(Color::Rgb(darkest,  darkest,  darkest,  )),
+            });
+        }
+        builder.build()
+    };
+    pub fn random () -> Self { ItemColor::random().into() }
+    pub fn random_near (color: Self, distance: f32) -> Self {
+        color.base.mix(ItemColor::random(), distance).into()
+    }
+    pub const G00: Self = {
+        let color: ItemColor = ItemColor {
+            okhsl: Okhsl { hue: OklabHue::new(0.0), lightness: 0.0, saturation: 0.0 },
+            rgb: Color::Rgb(0, 0, 0)
+        };
+        Self {
+            base:     color,
+            light:    color,
+            lighter:  color,
+            lightest: color,
+            dark:     color,
+            darker:   color,
+            darkest:  color,
+        }
+    };
+    pub fn from_tui_color (base: Color) -> Self {
+        Self::from_item_color(ItemColor::from_rgb(base))
+    }
+    pub fn from_item_color (base: ItemColor) -> Self {
+        let mut light      = base.okhsl;
+        light.lightness    = (light.lightness    * 1.3).min(1.0);
+        let mut lighter    = light;
+        lighter.lightness  = (lighter.lightness  * 1.3).min(1.0);
+        let mut lightest   = base.okhsl;
+        lightest.lightness = 0.95;
+        let mut dark       = base.okhsl;
+        dark.lightness     = (dark.lightness     * 0.75).max(0.0);
+        dark.saturation    = (dark.saturation    * 0.75).max(0.0);
+        let mut darker     = dark;
+        darker.lightness   = (darker.lightness   * 0.66).max(0.0);
+        darker.saturation  = (darker.saturation  * 0.66).max(0.0);
+        let mut darkest    = darker;
+        darkest.lightness  = 0.1;
+        darkest.saturation = (darkest.saturation * 0.50).max(0.0);
+        Self {
+            base,
+            light:    light.into(),
+            lighter:  lighter.into(),
+            lightest: lightest.into(),
+            dark:     dark.into(),
+            darker:   darker.into(),
+            darkest:  darkest.into(),
+        }
+    }
+}
+
+impl Draw<TuiOut> for u64 {
+    fn draw (&self, _to: &mut TuiOut) {
+        todo!()
+    }
+}
+
+impl Draw<TuiOut> for f64 {
+    fn draw (&self, _to: &mut TuiOut) {
+        todo!()
+    }
+}
+
+impl<T> Phat<T> {
+    pub const LO: &'static str = "▄";
+    pub const HI: &'static str = "▀";
+    /// A phat line
+    pub fn lo (fg: Color, bg: Color) -> impl Content<TuiOut> { Fixed::Y(1, Tui::fg_bg(fg, bg, RepeatH(Self::LO))) }
+    /// A phat line
+    pub fn hi (fg: Color, bg: Color) -> impl Content<TuiOut> { Fixed::Y(1, Tui::fg_bg(fg, bg, RepeatH(Self::HI))) }
+}
+
+impl<T: Content<TuiOut>> HasContent<TuiOut> for Phat<T> {
+    fn content (&self) -> impl Content<TuiOut> {
+        let [fg, bg, hi, lo] = self.colors;
+        let top = Fixed::Y(1, Self::lo(bg, hi));
+        let low = Fixed::Y(1, Self::hi(bg, lo));
+        let content = Tui::fg_bg(fg, bg, &self.content);
+        Min::XY(self.width, self.height, Bsp::s(top, Bsp::n(low, Fill::XY(content))))
+    }
+}
+
+impl Draw<TuiOut> for Repeat<'_> {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x, y, w, h] = to.area().xywh();
+        let a = self.0.len();
+        for (_v, y) in (y..y+h).enumerate() {
+            for (u, x) in (x..x+w).enumerate() {
+                if let Some(cell) = to.buffer.cell_mut(Position::from((x, y))) {
+                    let u = u % a;
+                    cell.set_symbol(&self.0[u..u+1]);
+                }
+            }
+        }
+    }
+}
+
+impl Layout<TuiOut> for RepeatV<'_> {}
+impl Draw<TuiOut> for RepeatV<'_> {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x, y, _w, h] = to.area().xywh();
+        for y in y..y+h {
+            if let Some(cell) = to.buffer.cell_mut(Position::from((x, y))) {
+                cell.set_symbol(&self.0);
+            }
+        }
+    }
+}
+
+impl Layout<TuiOut> for RepeatH<'_> {}
+impl Draw<TuiOut> for RepeatH<'_> {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x, y, w, _h] = to.area().xywh();
+        for x in x..x+w {
+            if let Some(cell) = to.buffer.cell_mut(Position::from((x, y))) {
+                cell.set_symbol(&self.0);
+            }
+        }
+    }
+}
+
+impl ScrollbarV {
+    const ICON_DEC: &[char] = &['▲'];
+    const ICON_INC: &[char] = &['▼'];
+}
+
+impl ScrollbarH {
+    const ICON_DEC: &[char] = &[' ', '🞀', ' '];
+    const ICON_INC: &[char] = &[' ', '🞂', ' '];
+}
+
+impl Draw<TuiOut> for ScrollbarV {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x, y1, _w, h] = to.area().xywh();
+        let y2 = y1 + h;
+        for (i, y) in (y1..=y2).enumerate() {
+            if let Some(cell) = to.buffer.cell_mut(Position::from((x, y))) {
+                if (i as usize) < (Self::ICON_DEC.len()) {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Rgb(0, 0, 0));
+                    cell.set_char(Self::ICON_DEC[i as usize]);
+                } else if (i as usize) > (h as usize - Self::ICON_INC.len()) {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Rgb(0, 0, 0));
+                    cell.set_char(Self::ICON_INC[h as usize - i]);
+                } else if false {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Reset);
+                    cell.set_char('‖'); // ━
+                } else {
+                    cell.set_fg(Rgb(0, 0, 0));
+                    cell.set_bg(Reset);
+                    cell.set_char('╎'); // ━
+                }
+            }
+        }
+    }
+}
+
+impl Draw<TuiOut> for ScrollbarH {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x1, y, w, _h] = to.area().xywh();
+        let x2 = x1 + w;
+        for (i, x) in (x1..=x2).enumerate() {
+            if let Some(cell) = to.buffer.cell_mut(Position::from((x, y))) {
+                if i < (Self::ICON_DEC.len()) {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Rgb(0, 0, 0));
+                    cell.set_char(Self::ICON_DEC[i as usize]);
+                } else if i > (w as usize - Self::ICON_INC.len()) {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Rgb(0, 0, 0));
+                    cell.set_char(Self::ICON_INC[w as usize - i]);
+                } else if false {
+                    cell.set_fg(Rgb(255, 255, 255));
+                    cell.set_bg(Reset);
+                    cell.set_char('━');
+                } else {
+                    cell.set_fg(Rgb(0, 0, 0));
+                    cell.set_bg(Reset);
+                    cell.set_char('╌');
+                }
+            }
+        }
+    }
+}
+
+impl Draw<TuiOut> for &str {
+    fn draw (&self, to: &mut TuiOut) {
+        let [x, y, w, ..] = self.layout(to.area());
+        to.text(&self, x, y, w)
+    }
+}
+impl Draw<TuiOut> for String {
+    fn draw (&self, to: &mut TuiOut) {
+        self.as_str().draw(to)
+    }
+}
+impl Draw<TuiOut> for Arc<str> {
+    fn draw (&self, to: &mut TuiOut) { self.as_ref().draw(to) }
+}
+
+impl Layout<TuiOut> for &str {
+    fn layout (&self, to: XY<u16>) -> XY<u16> { to.center_xy([width_chars_max(to.w(), self), 1]) }
+}
+impl Layout<TuiOut> for String {
+    fn layout (&self, to: XY<u16>) -> XY<u16> {
+        self.as_str().layout(to)
+    }
+}
+impl Layout<TuiOut> for Arc<str> {
+    fn layout (&self, to: XY<u16>) -> XY<u16> {
+        self.as_ref().layout(to)
+    }
+}
+
+fn width_chars_max (max: u16, text: impl AsRef<str>) -> u16 {
+    let mut width: u16 = 0;
+    let mut chars = text.as_ref().chars();
+    while let Some(c) = chars.next() {
+        width += c.width().unwrap_or(0) as u16;
+        if width > max {
+            break
+        }
+    }
+    return width
+}
+
+/// Trim string with [unicode_width].
+pub fn trim_string (max_width: usize, input: impl AsRef<str>) -> String {
+    let input = input.as_ref();
+    let mut output = Vec::with_capacity(input.len());
+    let mut width: usize = 1;
+    let mut chars = input.chars();
+    while let Some(c) = chars.next() {
+        if width > max_width {
+            break
+        }
+        output.push(c);
+        width += c.width().unwrap_or(0);
+    }
+    return output.into_iter().collect()
+}
+
+
+impl<'a, T: AsRef<str>> TrimString<T> {
+    fn as_ref (&self) -> TrimStringRef<'_, T> { TrimStringRef(self.0, &self.1) }
+}
+impl<'a, T: AsRef<str>> Draw<TuiOut> for TrimString<T> {
+    fn draw (&self, to: &mut TuiOut) { Draw::draw(&self.as_ref(), to) }
+}
+impl<'a, T: AsRef<str>> Layout<TuiOut> for TrimString<T> {
+    fn layout (&self, to: XY<u16>) -> XY<u16> { Layout::layout(&self.as_ref(), to) }
+}
+
+impl<'a, T: AsRef<str>> Layout<TuiOut> for TrimStringRef<'a, T> {
+    fn layout (&self, to: XY<u16>) -> XY<u16> {
+        [to.x(), to.y(), to.w().min(self.0).min(self.1.as_ref().width() as u16), to.h()]
+    }
+}
+impl<T: AsRef<str>> Draw<TuiOut> for TrimStringRef<'_, T> {
+    fn draw (&self, target: &mut TuiOut) {
+        let area = target.area();
+        let mut width: u16 = 1;
+        let mut chars = self.1.as_ref().chars();
+        while let Some(c) = chars.next() {
+            if width > self.0 || width > area.w() {
+                break
+            }
+            if let Some(cell) = target.buffer.cell_mut(Position {
+                x: area.x() + width - 1,
+                y: area.y()
+            }) {
+                cell.set_char(c);
+            }
+            width += c.width().unwrap_or(0) as u16;
+        }
+    }
+}
+
+impl<
+    A: Content<TuiOut>,
+    B: Content<TuiOut>,
+    C: Content<TuiOut>,
+> HasContent<TuiOut> for Tryptich<A, B, C> {
+    fn content (&self) -> impl Content<TuiOut> {
+        let Self { top, h, left: (w_a, ref a), middle: (w_b, ref b), right: (w_c, ref c) } = *self;
+        Fixed::Y(h, if top {
+            Bsp::a(
+                Fill::X(Align::n(Fixed::X(w_b, Align::x(Tui::bg(Color::Reset, b))))),
+                Bsp::a(
+                    Fill::X(Align::nw(Fixed::X(w_a, Tui::bg(Color::Reset, a)))),
+                    Fill::X(Align::ne(Fixed::X(w_c, Tui::bg(Color::Reset, c)))),
+                ),
+            )
+        } else {
+            Bsp::a(
+                Fill::XY(Align::c(Fixed::X(w_b, Align::x(Tui::bg(Color::Reset, b))))),
+                Bsp::a(
+                    Fill::XY(Align::w(Fixed::X(w_a, Tui::bg(Color::Reset, a)))),
+                    Fill::XY(Align::e(Fixed::X(w_c, Tui::bg(Color::Reset, c)))),
+                ),
+            )
+        })
+    }
+}
+
+impl<O: Out, T: Draw<O>> ErrorBoundary<O, T> {
+    pub fn new (content: Perhaps<T>) -> Self {
+        Self(Default::default(), content)
+    }
+}
+
+impl<T: Draw<TuiOut>> Draw<TuiOut> for ErrorBoundary<TuiOut, T> {
+    fn draw (&self, to: &mut TuiOut) {
+        match self.1.as_ref() {
+            Ok(Some(content)) => content.draw(to),
+            Ok(None) => to.blit(&"empty?", 0, 0, Some(Style::default().yellow())),
+            Err(e) => {
+                let err_fg = Color::Rgb(255,224,244);
+                let err_bg = Color::Rgb(96,24,24);
+                let title  = Bsp::e(Tui::bold(true, "oops. "), "rendering failed.");
+                let error  = Bsp::e("\"why?\" ", Tui::bold(true, format!("{e}")));
+                to.place(&Tui::fg_bg(err_fg, err_bg, Bsp::s(title, error)))
+            }
+        }
+    }
+}
+
+impl<S: BorderStyle, W: Content<TuiOut>> HasContent<TuiOut> for Bordered<S, W> {
+    fn content (&self) -> impl Content<TuiOut> {
+        Fill::XY(lay!( When::new(self.0, Border(self.0, self.1)), Pad::XY(1, 1, &self.2) ))
+    }
+}
+
+impl<S: BorderStyle> Draw<TuiOut> for Border<S> {
+    fn draw (&self, to: &mut TuiOut) {
+        let Border(enabled, style) = self;
+        if *enabled {
+            let area = to.area();
+            if area.w() > 0 && area.y() > 0 {
+                to.blit(&style.border_nw(), area.x(), area.y(), style.style());
+                to.blit(&style.border_ne(), area.x() + area.w() - 1, area.y(), style.style());
+                to.blit(&style.border_sw(), area.x(), area.y() + area.h() - 1, style.style());
+                to.blit(&style.border_se(), area.x() + area.w() - 1, area.y() + area.h() - 1, style.style());
+                for x in area.x()+1..area.x()+area.w()-1 {
+                    to.blit(&style.border_n(), x, area.y(), style.style());
+                    to.blit(&style.border_s(), x, area.y() + area.h() - 1, style.style());
+                }
+                for y in area.y()+1..area.y()+area.h()-1 {
+                    to.blit(&style.border_w(), area.x(), y, style.style());
+                    to.blit(&style.border_e(), area.x() + area.w() - 1, y, style.style());
+                }
+            }
+        }
+    }
+}
+
+impl<T: Content<TuiOut>> Draw<TuiOut> for Foreground<Color, T> {
+    fn draw (&self, to: &mut TuiOut) {
+        let area = self.layout(to.area());
+        to.fill_fg(area, self.0);
+        to.place_at(area, &self.1);
+    }
+}
+
+impl<T: Content<TuiOut>> Draw<TuiOut> for Background<Color, T> {
+    fn draw (&self, to: &mut TuiOut) {
+        let area = self.layout(to.area());
+        to.fill_bg(area, self.0);
+        to.place_at(area, &self.1);
+    }
+}
+
+impl<T: Content<TuiOut>> Layout<TuiOut> for Modify<T> {}
+
+impl<T: Content<TuiOut>> Draw<TuiOut> for Modify<T> {
+    fn draw (&self, to: &mut TuiOut) {
+        to.fill_mod(to.area(), self.0, self.1);
+        self.2.draw(to)
+    }
+}
+
+impl<T: Content<TuiOut>> Layout<TuiOut> for Styled<T> {}
+
+impl<T: Content<TuiOut>> Draw<TuiOut> for Styled<T> {
+    fn draw (&self, to: &mut TuiOut) {
+        to.place(&self.1);
+        // TODO write style over area
+    }
+}
+
+impl TuiOut {
+    /// Spawn the output thread.
+    pub fn run_output <T: Draw<TuiOut> + Send + Sync + 'static> (
+        engine: &Arc<RwLock<Tui>>,
+        state:  &Arc<RwLock<T>>,
+        timer:  Duration
+    ) -> Result<JoinHandle<()>, std::io::Error> {
+        let exited = engine.read().unwrap().exited.clone();
+        let engine = engine.clone();
+        let state  = state.clone();
+        let Size { width, height } = engine.read().unwrap().backend.size().expect("get size failed");
+        let mut buffer = Buffer::empty(Rect { x: 0, y: 0, width, height });
+        std::thread::Builder::new()
+            .name("tui output thread".into())
+            .spawn(move || loop {
+                if exited.fetch_and(true, Relaxed) {
+                    break
+                }
+                let t0 = engine.read().unwrap().perf.get_t0();
+                let Size { width, height } = engine.read().unwrap().backend.size()
+                    .expect("get size failed");
+                if let Ok(state) = state.try_read() {
+                    let size = Rect { x: 0, y: 0, width, height };
+                    if buffer.area != size {
+                        engine.write().unwrap().backend.clear_region(ClearType::All).expect("clear failed");
+                        buffer.resize(size);
+                        buffer.reset();
+                    }
+                    let mut output = TuiOut { buffer, area: [0, 0, width, height] };
+                    state.draw(&mut output);
+                    buffer = engine.write().unwrap().flip(output.buffer, size);
+                }
+                let t1 = engine.read().unwrap().perf.get_t1(t0).unwrap();
+                buffer.set_string(0, 0, &format!("{:>3}.{:>3}ms", t1.as_millis(), t1.as_micros() % 1000), Style::default());
+                std::thread::sleep(timer);
+            })
+    }
+    #[inline]
+    pub fn with_rect (&mut self, area: XY<u16>) -> &mut Self {
+        self.area = area;
+        self
+    }
+    pub fn blit (
+        &mut self, text: &impl AsRef<str>, x: u16, y: u16, style: Option<Style>
+    ) {
+        let text  = text.as_ref();
+        let buf   = &mut self.buffer;
+        let style = style.unwrap_or(Style::default());
+        if x < buf.area.width && y < buf.area.height {
+            buf.set_string(x, y, text, style);
+        }
+    }
+    /// Write a line of text
+    ///
+    /// TODO: do a paragraph (handle newlines)
+    pub fn text (&mut self, text: &impl AsRef<str>, x0: u16, y: u16, max_width: u16) {
+        let text = text.as_ref();
+        let buf  = &mut self.buffer;
+        let mut string_width: u16 = 0;
+        for character in text.chars() {
+            let x = x0 + string_width;
+            let character_width = character.width().unwrap_or(0) as u16;
+            string_width += character_width;
+            if string_width > max_width {
+                break
+            }
+            if let Some(cell) = buf.cell_mut(ratatui::prelude::Position { x, y }) {
+                cell.set_char(character);
+            } else {
+                break
+            }
+        }
+    }
+    pub fn buffer_update (&mut self, area: XY<u16>, callback: &impl Fn(&mut Cell, u16, u16)) {
+        buffer_update(&mut self.buffer, area, callback);
+    }
+    pub fn fill_char (&mut self, area: XY<u16>, c: char) {
+        self.buffer_update(area, &|cell,_,_|{cell.set_char(c);})
+    }
+    pub fn fill_bg (&mut self, area: XY<u16>, color: Color) {
+        self.buffer_update(area, &|cell,_,_|{cell.set_bg(color);})
+    }
+    pub fn fill_fg (&mut self, area: XY<u16>, color: Color) {
+        self.buffer_update(area, &|cell,_,_|{cell.set_fg(color);})
+    }
+    pub fn fill_mod (&mut self, area: XY<u16>, on: bool, modifier: Modifier) {
+        if on {
+            self.buffer_update(area, &|cell,_,_|cell.modifier.insert(modifier))
+        } else {
+            self.buffer_update(area, &|cell,_,_|cell.modifier.remove(modifier))
+        }
+    }
+    pub fn fill_bold (&mut self, area: XY<u16>, on: bool) {
+        self.fill_mod(area, on, Modifier::BOLD)
+    }
+    pub fn fill_reversed (&mut self, area: XY<u16>, on: bool) {
+        self.fill_mod(area, on, Modifier::REVERSED)
+    }
+    pub fn fill_crossed_out (&mut self, area: XY<u16>, on: bool) {
+        self.fill_mod(area, on, Modifier::CROSSED_OUT)
+    }
+    pub fn fill_ul (&mut self, area: XY<u16>, color: Option<Color>) {
+        if let Some(color) = color {
+            self.buffer_update(area, &|cell,_,_|{
+                cell.modifier.insert(ratatui::prelude::Modifier::UNDERLINED);
+                cell.underline_color = color;
+            })
+        } else {
+            self.buffer_update(area, &|cell,_,_|{
+                cell.modifier.remove(ratatui::prelude::Modifier::UNDERLINED);
+            })
+        }
+    }
+    pub fn tint_all (&mut self, fg: Color, bg: Color, modifier: Modifier) {
+        for cell in self.buffer.content.iter_mut() {
+            cell.fg = fg;
+            cell.bg = bg;
+            cell.modifier = modifier;
+        }
+    }
+}