wip: refactor into crates

crates/tek_core/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "tek_core"
+edition = "2021"
+version = "0.1.0"
+
+[dependencies]
+clap = { version = "4.5.4", features = [ "derive" ] }
+crossterm = "0.27"
+ratatui = { version = "0.26.3", features = [ "unstable-widget-ref", "underline-color" ] }
+backtrace = "0.3.72"
+microxdg = "0.1.2"
+toml = "0.8.12"
+better-panic = "0.3.0"
+midly = "0.5"

crates/tek_core/README.md

@@ -0,0 +1,38 @@
+# `tek_core`
+
+Core "utilities" module of Tek TUI DAW.
+
+## Exiting
+
+The `Exit` trait defines the API for exitable entities,
+such as the main app or the modal dialogs.
+
+## Rendering output
+
+The `Render` trait...
+
+The `render!` macro for implementing the `Render` trait...
+
+The `render_thread` function for starting the render thread...
+
+The various layout and rendering helpers...
+
+## Handling input
+
+The `Handle` trait...
+
+The `handle!` macro...
+
+The `input_thread` function...
+
+## Running an app
+
+The `Component` trait...
+
+The `run` function...
+
+## Module helpers
+
+The `submod!` macro...
+
+The `pubmod!` macro...

crates/tek_core/src/exit.rs

@@ -0,0 +1,20 @@
+pub trait Exit: Send {
+    fn exited (&self) -> bool;
+    fn exit (&mut self);
+    fn boxed (self) -> Box<dyn Exit> where Self: Sized + 'static {
+        Box::new(self)
+    }
+}
+
+#[macro_export] macro_rules! exit {
+    ($T:ty) => {
+        impl Exit for $T {
+            fn exited (&self) -> bool {
+                self.exited
+            }
+            fn exit (&mut self) {
+                self.exited = true
+            }
+        }
+    }
+}

crates/tek_core/src/handle.rs

@@ -0,0 +1,108 @@
+use crate::*;
+
+/// Spawn thread that listens for user input
+pub fn input_thread (
+    exited: &Arc<AtomicBool>,
+    device: &Arc<RwLock<impl Handle + Send + Sync + 'static>>
+) -> JoinHandle<()> {
+    let poll = Duration::from_millis(100);
+    let exited = exited.clone();
+    let device = device.clone();
+    spawn(move || loop {
+        // Exit if flag is set
+        if exited.fetch_and(true, Ordering::Relaxed) {
+            break
+        }
+        // Listen for events and send them to the main thread
+        if ::crossterm::event::poll(poll).is_ok() {
+            let event = ::crossterm::event::read().unwrap();
+            if let Event::Key(KeyEvent {
+                code: KeyCode::Char('c'), modifiers: KeyModifiers::CONTROL, ..
+            }) = event {
+                exited.store(true, Ordering::Relaxed);
+            } else if let Err(e) = device.write().unwrap().handle(&AppEvent::Input(event)) {
+                panic!("{e}")
+            }
+        }
+    })
+}
+
+/// Trait for things that handle input events.
+pub trait Handle {
+    /// Handle an input event.
+    /// Returns Ok(true) if the device handled the event.
+    /// This is the mechanism which allows nesting of components;.
+    fn handle (&mut self, _e: &AppEvent) -> Usually<bool> {
+        Ok(false)
+    }
+}
+
+/// Implement the `Handle` trait.
+#[macro_export] macro_rules! handle {
+    ($T:ty) => {
+        impl Handle for $T {}
+    };
+    ($T:ty |$self:ident, $e:ident|$block:expr) => {
+        impl Handle for $T {
+            fn handle (&mut $self, $e: &AppEvent) -> Usually<bool> {
+                $block
+            }
+        }
+    };
+    ($T:ty = $handle:path) => {
+        impl Handle for $T {
+            fn handle (&mut self, e: &AppEvent) -> Usually<bool> {
+                $handle(self, e)
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum AppEvent {
+    /// Terminal input
+    Input(::crossterm::event::Event),
+    /// Update values but not the whole form.
+    Update,
+    /// Update the whole form.
+    Redraw,
+    /// Device gains focus
+    Focus,
+    /// Device loses focus
+    Blur,
+    // /// JACK notification
+    // Jack(JackEvent)
+}
+
+pub type KeyHandler<T> = &'static dyn Fn(&mut T)->Usually<bool>;
+
+pub type KeyBinding<T> = (
+    KeyCode, KeyModifiers, &'static str, &'static str, KeyHandler<T>
+);
+
+pub type KeyMap<T> = [KeyBinding<T>];
+
+pub fn handle_keymap <T> (
+    state: &mut T, event: &AppEvent, keymap: &KeyMap<T>,
+) -> Usually<bool> {
+    match event {
+        AppEvent::Input(crossterm::event::Event::Key(event)) => {
+            for (code, modifiers, _, _, command) in keymap.iter() {
+                if *code == event.code && modifiers.bits() == event.modifiers.bits() {
+                    return command(state)
+                }
+            }
+        },
+        _ => {}
+    };
+    Ok(false)
+}
+
+/// Define a keymap
+#[macro_export] macro_rules! keymap {
+    ($T:ty { $([$k:ident $(($char:literal))?, $m:ident, $n: literal, $d: literal, $f: expr]),* $(,)? }) => {
+        &[
+            $((KeyCode::$k $(($char))?, KeyModifiers::$m, $n, $d, &$f as KeyHandler<$T>)),*
+        ] as &'static [KeyBinding<$T>]
+    }
+}

crates/tek_core/src/lib.rs

@@ -0,0 +1,90 @@
+pub use ratatui;
+pub use crossterm;
+pub use midly;
+
+pub(crate) use std::error::Error;
+pub(crate) use std::io::{stdout};
+pub(crate) use std::thread::{spawn, JoinHandle};
+pub(crate) use std::time::Duration;
+pub(crate) use std::sync::atomic::{Ordering, AtomicBool};
+pub(crate) use std::sync::{Arc, Mutex, RwLock};
+//, LockResult, RwLockReadGuard, RwLockWriteGuard};
+//pub(crate) use std::path::PathBuf;
+//pub(crate) use std::fs::read_dir;
+//pub(crate) use std::ffi::OsString;
+
+// Non-stdlib dependencies:
+//pub(crate) use microxdg::XdgApp;
+//pub(crate) use midly::{MidiMessage, live::LiveEvent, num::u7};
+pub(crate) use crossterm::{ExecutableCommand};
+pub(crate) use crossterm::event::{Event, KeyEvent, KeyCode, KeyModifiers};
+use better_panic::{Settings, Verbosity};
+use crossterm::terminal::{
+    EnterAlternateScreen, LeaveAlternateScreen,
+    enable_raw_mode, disable_raw_mode
+};
+
+/// Define and reexport submodules.
+#[macro_export] macro_rules! submod {
+    ($($name:ident)*) => { $(mod $name; pub use self::$name::*;)* };
+}
+
+/// Define and reexport public modules.
+#[macro_export] macro_rules! pubmod {
+    ($($name:ident)*) => { $(pub mod $name;)* };
+}
+
+submod! {
+    exit render handle
+}
+
+/// Standard result type.
+pub type Usually<T> = Result<T, Box<dyn Error>>;
+
+/// A UI component.
+pub trait Component: Render + Handle + Sync {
+    /// Perform type erasure for collecting heterogeneous components.
+    fn boxed (self) -> Box<dyn Component> where Self: Sized + 'static {
+        Box::new(self)
+    }
+}
+
+/// Anything that implements `Render` + `Handle` can be used as a UI component.
+impl<T: Render + Handle + Sync> Component for T {}
+
+/// Run the main loop.
+pub fn run <T> (state: Arc<RwLock<T>>) -> Usually<Arc<RwLock<T>>>
+    where T: Render + Handle + Send + Sync + Sized + 'static
+{
+    let exited = Arc::new(AtomicBool::new(false));
+    let _input_thread = input_thread(&exited, &state);
+    terminal_setup()?;
+    panic_hook_setup();
+    let main_thread = render_thread(&exited, &state)?;
+    main_thread.join().expect("main thread failed");
+    terminal_teardown()?;
+    Ok(state)
+}
+
+/// Set up panic hook
+pub fn panic_hook_setup () {
+    let better_panic_handler = Settings::auto().verbosity(Verbosity::Full).create_panic_handler();
+    std::panic::set_hook(Box::new(move |info: &std::panic::PanicInfo|{
+        stdout().execute(LeaveAlternateScreen).unwrap();
+        disable_raw_mode().unwrap();
+        better_panic_handler(info);
+    }));
+}
+
+/// Set up terminal
+pub fn terminal_setup () -> Usually<()> {
+    stdout().execute(EnterAlternateScreen)?;
+    enable_raw_mode()?;
+    Ok(())
+}
+/// Cleanup
+pub fn terminal_teardown () -> Usually<()> {
+    stdout().execute(LeaveAlternateScreen)?;
+    disable_raw_mode()?;
+    Ok(())
+}

crates/tek_core/src/render.rs

@@ -0,0 +1,592 @@
+//! Rendering of application to display.
+
+use crate::*;
+pub(crate) use ratatui::prelude::CrosstermBackend;
+pub(crate) use ratatui::style::{Stylize, Style, Color};
+pub(crate) use ratatui::layout::Rect;
+pub(crate) use ratatui::buffer::{Buffer, Cell};
+use ratatui::widgets::WidgetRef;
+
+/// Main thread render loop
+pub fn render_thread (
+    exited: &Arc<AtomicBool>,
+    device: &Arc<RwLock<impl Render + Send + Sync + 'static>>
+) -> Usually<JoinHandle<()>> {
+    let exited = exited.clone();
+    let device = device.clone();
+    let mut terminal = ratatui::Terminal::new(CrosstermBackend::new(stdout()))?;
+    let sleep = Duration::from_millis(20);
+    Ok(spawn(move || loop {
+
+        if let Ok(device) = device.try_read() {
+            terminal.draw(|frame|{
+                let area   = frame.size();
+                let buffer = frame.buffer_mut();
+                device
+                    .render(buffer, area)
+                    .expect("Failed to render content");
+            })
+                .expect("Failed to render frame");
+        }
+
+        if exited.fetch_and(true, Ordering::Relaxed) {
+            break
+        }
+        std::thread::sleep(sleep);
+    }))
+}
+
+pub fn make_dim (buf: &mut Buffer) {
+    for cell in buf.content.iter_mut() {
+        cell.bg = ratatui::style::Color::Rgb(30,30,30);
+        cell.fg = ratatui::style::Color::Rgb(100,100,100);
+        cell.modifier = ratatui::style::Modifier::DIM;
+    }
+}
+
+pub fn center_box (area: Rect, w: u16, h: u16) -> Rect {
+    let width  = w.min(area.width * 3 / 5);
+    let height = h.min(area.width * 3 / 5);
+    let x = area.x + (area.width  - width)  / 2;
+    let y = area.y + (area.height - height) / 2;
+    Rect { x, y, width, height }
+}
+
+pub fn buffer_update (
+    buf: &mut Buffer, area: Rect, callback: &impl Fn(&mut Cell, u16, u16)
+) {
+    for row in 0..area.height {
+        let y = area.y + row;
+        for col in 0..area.width {
+            let x = area.x + col;
+            if x < buf.area.width && y < buf.area.height {
+                callback(buf.get_mut(x, y), col, row);
+            }
+        }
+    }
+}
+
+pub fn fill_fg (buf: &mut Buffer, area: Rect, color: Color) {
+    buffer_update(buf, area, &|cell,_,_|{cell.set_fg(color);})
+}
+
+pub fn fill_bg (buf: &mut Buffer, area: Rect, color: Color) {
+    buffer_update(buf, area, &|cell,_,_|{cell.set_bg(color);})
+}
+
+pub fn to_fill_bg (color: Color) -> impl Render {
+    move |buf: &mut Buffer, area: Rect|{
+        fill_bg(buf, area, color);
+        Ok(area)
+    }
+}
+
+pub fn fill_char (buf: &mut Buffer, area: Rect, c: char) {
+    buffer_update(buf, area, &|cell,_,_|{cell.set_char(c);})
+}
+
+pub fn half_block (lower: bool, upper: bool) -> Option<char> {
+    match (lower, upper) {
+        (true, true)  => Some('█'),
+        (true, false) => Some('▄'),
+        (false, true) => Some('▀'),
+        _ => None
+    }
+}
+
+pub trait Blit {
+    // Render something to X, Y coordinates in a buffer, ignoring width/height.
+    fn blit (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect>;
+}
+
+impl<T: AsRef<str>> Blit for T {
+    fn blit (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect> {
+        if x < buf.area.width && y < buf.area.height {
+            buf.set_string(x, y, self.as_ref(), style.unwrap_or(Style::default()));
+        }
+        Ok(Rect { x, y, width: self.as_ref().len() as u16, height: 1 })
+    }
+}
+
+/// Trait for things that render to the display.
+pub trait Render: Send {
+    // Render something to an area of the buffer.
+    // Returns area used by component.
+    // This is insufficient but for the most basic dynamic layout algorithms.
+    fn render (&self, _b: &mut Buffer, _a: Rect) -> Usually<Rect> {
+        Ok(Rect { x: 0, y: 0, width: 0, height: 0 })
+    }
+}
+
+/// Implement the `Render` trait.
+#[macro_export] macro_rules! render {
+    ($T:ty) => {
+        impl Render for $T {}
+    };
+    ($T:ty |$self:ident, $buf:ident, $area:ident|$block:expr) => {
+        impl Render for $T {
+            fn render (&$self, $buf: &mut Buffer, $area: Rect) -> Usually<Rect> {
+                $block
+            }
+        }
+    };
+    ($T:ty = $render:path) => {
+        impl Render for $T {
+            fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+                $render(self, buf, area)
+            }
+        }
+    }
+}
+
+impl Render for () {
+    fn render (&self, _: &mut Buffer, a: Rect) -> Usually<Rect> {
+        Ok(Rect { x: a.x, y: a.y, width: 0, height: 0 })
+    }
+}
+
+impl<T: Fn(&mut Buffer, Rect) -> Usually<Rect> + Send> Render for T {
+    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
+        (*self)(b, a)
+    }
+}
+
+impl<T: Render> Render for Arc<Mutex<T>> {
+    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
+        self.lock().unwrap().render(b, a)
+    }
+}
+
+impl<T: Render + Sync> Render for Arc<RwLock<T>> {
+    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
+        self.read().unwrap().render(b, a)
+    }
+}
+
+impl WidgetRef for &dyn Render {
+    fn render_ref (&self, area: Rect, buf: &mut Buffer) {
+        Render::render(*self, buf, area).expect("Failed to render device.");
+    }
+}
+
+impl WidgetRef for dyn Render {
+    fn render_ref (&self, area: Rect, buf: &mut Buffer) {
+        Render::render(self, buf, area).expect("Failed to render device.");
+    }
+}
+
+#[derive(Default)]
+pub struct BigBuffer {
+    pub width:   usize,
+    pub height:  usize,
+    pub content: Vec<Cell>
+}
+
+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
+    }
+}
+
+pub struct Layered<'a, const N: usize>(pub [&'a (dyn Render + Sync); N]);
+
+impl<'a, const N: usize> Render for Layered<'a, N> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        for layer in self.0.iter() {
+            layer.render(buf, area)?;
+        }
+        Ok(area)
+    }
+}
+
+pub struct If<'a>(pub bool, pub &'a (dyn Render + Sync));
+
+impl<'a> Render for If<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        match self.0 {
+            true  => self.1 as &dyn Render,
+            false => &() as &dyn Render
+        }.render(buf, area)
+    }
+}
+
+pub struct IfElse<'a>(pub bool, pub &'a (dyn Render + Sync), pub &'a (dyn Render + Sync));
+
+impl<'a> Render for IfElse<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        match self.0 {
+            true  => self.1 as &dyn Render,
+            false => &() as &dyn Render
+        }.render(buf, area)
+    }
+}
+
+#[derive(Copy, Clone)]
+pub enum Direction { Down, Right }
+
+impl Direction {
+    pub fn split <'a, const N: usize> (&self, items: [&'a (dyn Render + Sync);N]) -> Split<'a, N> {
+        Split(*self, items)
+    }
+    pub fn split_focus <'a> (&self, index: usize, items: Renderables<'a>, style: Style) -> SplitFocus<'a> {
+        SplitFocus(*self, index, items, style)
+    }
+    pub fn is_down (&self) -> bool {
+        match self { Self::Down => true, _ => false }
+    }
+    pub fn is_right (&self) -> bool {
+        match self { Self::Right => true, _ => false }
+    }
+}
+
+pub struct Split<'a, const N: usize>(
+    pub Direction, pub [&'a (dyn Render + Sync);N]
+);
+
+impl<'a, const N: usize> Split<'a, N> {
+    pub fn down (items: [&'a (dyn Render + Sync);N]) -> Self {
+        Self(Direction::Down, items)
+    }
+    pub fn right (items: [&'a (dyn Render + Sync);N]) -> Self {
+        Self(Direction::Right, items)
+    }
+    pub fn render_areas (&self, buf: &mut Buffer, area: Rect) -> Usually<(Rect, Vec<Rect>)> {
+        let Rect { mut x, mut y, mut width, mut height } = area;
+        let mut areas = vec![];
+        for item in self.1 {
+            if width == 0 || height == 0 {
+                break
+            }
+            let result = item.render(buf, Rect { x, y, width, height })?;
+            match self.0 {
+                Direction::Down => {
+                    y = y + result.height;
+                    height = height.saturating_sub(result.height);
+                },
+                Direction::Right => {
+                    x = x + result.width;
+                    width = width.saturating_sub(result.width);
+                },
+            };
+            areas.push(area);
+        }
+        Ok((area, areas))
+    }
+}
+
+impl<'a, const N: usize> Render for Split<'a, N> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        Ok(self.render_areas(buf, area)?.0)
+    }
+}
+
+type Renderables<'a> = &'a [&'a dyn Component];
+
+pub struct SplitFocus<'a>(pub Direction, pub usize, pub Renderables<'a>, pub Style);
+
+impl<'a> SplitFocus<'a> {
+    pub fn render_areas (&self, buf: &mut Buffer, area: Rect) -> Usually<(Rect, Vec<Rect>)> {
+        let Rect { mut x, mut y, mut width, mut height } = area;
+        let mut areas = vec![];
+        for item in self.2.iter() {
+            if width == 0 || height == 0 {
+                break
+            }
+            let result = item.render(buf, Rect { x, y, width, height })?;
+            areas.push(result);
+            match self.0 {
+                Direction::Down => {
+                    y = y + result.height;
+                    height = height.saturating_sub(result.height);
+                },
+                Direction::Right => {
+                    x = x + result.width;
+                    width = width.saturating_sub(result.width);
+                },
+            }
+            Lozenge(self.3).draw(buf, result)?;
+        }
+        Ok((area, areas))
+    }
+}
+
+impl<'a> Render for SplitFocus<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        Ok(self.render_areas(buf, area)?.0)
+    }
+}
+
+pub trait Theme {
+    const BG0:    Color;
+    const BG1:    Color;
+    const BG2:    Color;
+    const BG3:    Color;
+    const BG4:    Color;
+    const RED:    Color;
+    const YELLOW: Color;
+    const GREEN:  Color;
+
+    const PLAYING: Color;
+    const SEPARATOR: Color;
+
+    fn bg_hier (focused: bool, entered: bool) -> Color {
+        if focused && entered {
+            Self::BG3
+        } else if focused {
+            Self::BG2
+        } else {
+            Self::BG1
+        }
+    }
+
+    fn bg_hi (focused: bool, entered: bool) -> Color {
+        if focused && entered {
+            Self::BG2
+        } else if focused {
+            Self::BG1
+        } else {
+            Self::BG0
+        }
+    }
+
+    fn bg_lo (focused: bool, entered: bool) -> Color {
+        if focused && entered {
+            Self::BG1
+        } else if focused {
+            Self::BG0
+        } else {
+            Color::Reset
+        }
+    }
+
+    fn style_hi (focused: bool, highlight: bool) -> Style {
+        if highlight && focused {
+            Style::default().yellow().not_dim()
+        }  else if highlight {
+            Style::default().yellow().dim()
+        } else {
+            Style::default()
+        }
+    }
+}
+
+pub struct Nord;
+
+impl Theme for Nord {
+    const BG0:    Color = Color::Rgb(41, 46, 57);
+    const BG1:    Color = Color::Rgb(46, 52, 64);
+    const BG2:    Color = Color::Rgb(59, 66, 82);
+    const BG3:    Color = Color::Rgb(67, 76, 94);
+    const BG4:    Color = Color::Rgb(76, 86, 106);
+    const RED:    Color = Color::Rgb(191, 97, 106);
+    const YELLOW: Color = Color::Rgb(235, 203, 139);
+    const GREEN:  Color = Color::Rgb(163, 190, 140);
+
+    const PLAYING:   Color = Color::Rgb(60, 100, 50);
+    const SEPARATOR: Color = Color::Rgb(0, 0, 0);
+}
+
+pub trait BorderStyle {
+    const NW: &'static str = "";
+    const N:  &'static str = "";
+    const NE: &'static str = "";
+    const E:  &'static str = "";
+    const SE: &'static str = "";
+    const S:  &'static str = "";
+    const SW: &'static str = "";
+    const W:  &'static str = "";
+
+    #[inline]
+    fn draw (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        self.draw_horizontal(buf, area, None)?;
+        self.draw_vertical(buf, area, None)?;
+        self.draw_corners(buf, area, None)?;
+        Ok(area)
+    }
+
+    #[inline]
+    fn draw_horizontal (&self, buf: &mut Buffer, area: Rect, style: Option<Style>) -> Usually<Rect> {
+        let style = style.or_else(||self.style_horizontal());
+        for x in area.x..(area.x+area.width).saturating_sub(1) {
+            self.draw_north(buf, x, area.y, style)?;
+            self.draw_south(buf, x, (area.y + area.height).saturating_sub(1), style)?;
+        }
+        Ok(area)
+    }
+    #[inline]
+    fn draw_north (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect> {
+        Self::N.blit(buf, x, y, style)
+    }
+    #[inline]
+    fn draw_south (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect> {
+        Self::S.blit(buf, x, y, style)
+    }
+
+    #[inline]
+    fn draw_vertical (&self, buf: &mut Buffer, area: Rect, style: Option<Style>) -> Usually<Rect> {
+        let style = style.or_else(||self.style_vertical());
+        for y in area.y..(area.y+area.height).saturating_sub(1) {
+            Self::W.blit(buf, area.x, y, style)?;
+            Self::E.blit(buf, area.x + area.width - 1, y, style)?;
+        }
+        Ok(area)
+    }
+
+    #[inline]
+    fn draw_corners (&self, buf: &mut Buffer, area: Rect, style: Option<Style>) -> Usually<Rect> {
+        let style = style.or_else(||self.style_corners());
+        Self::NW.blit(buf, area.x, area.y, style)?;
+        Self::NE.blit(buf, area.x + area.width - 1, area.y, style)?;
+        Self::SW.blit(buf, area.x, area.y + area.height - 1, style)?;
+        Self::SE.blit(buf, area.x + area.width - 1, area.y + area.height - 1, style)?;
+        Ok(area)
+    }
+
+    #[inline]
+    fn style (&self) -> Option<Style> {
+        None
+    }
+    #[inline]
+    fn style_horizontal (&self) -> Option<Style> {
+        self.style()
+    }
+    #[inline]
+    fn style_vertical (&self) -> Option<Style> {
+        self.style()
+    }
+    #[inline]
+    fn style_corners (&self) -> Option<Style> {
+        self.style()
+    }
+}
+
+macro_rules! border {
+    ($($T:ty {
+        $nw:literal $n:literal $ne:literal $w:literal $e:literal $sw:literal $s:literal $se:literal
+        $($x:tt)*
+    }),+) => {
+        $(impl BorderStyle for $T {
+            const NW: &'static str = $nw;
+            const N:  &'static str = $n;
+            const NE: &'static str = $ne;
+            const W:  &'static str = $w;
+            const E:  &'static str = $e;
+            const SW: &'static str = $sw;
+            const S:  &'static str = $s;
+            const SE: &'static str = $se;
+            $($x)*
+        })+
+    }
+}
+
+pub struct Lozenge(pub Style);
+pub struct LozengeV(pub Style);
+pub struct LozengeDotted(pub Style);
+pub struct Quarter(pub Style);
+pub struct QuarterV(pub Style);
+pub struct Chamfer(pub Style);
+pub struct Corners(pub Style);
+
+border! {
+    Lozenge {
+        "╭" "─" "╮"
+        "│"     "│"
+        "╰" "─" "╯"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    LozengeV {
+        "╭" "" "╮"
+        "│"    "│"
+        "╰" "" "╯"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    LozengeDotted {
+        "╭" "┅" "╮"
+        "┇"     "┇"
+        "╰" "┅" "╯"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    Quarter {
+        "▎" "▔" "🮇"
+        "▎"     "🮇"
+        "▎" "▁" "🮇"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    QuarterV {
+        "▎" "" "🮇"
+        "▎"    "🮇"
+        "▎" "" "🮇"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    Chamfer {
+        "🭂" "▔" "🭍"
+        "▎"     "🮇"
+        "🭓" "▁" "🭞"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    },
+    Corners {
+        "🬆" "" "🬊" // 🬴 🬸
+        ""     ""
+        "🬱" "" "🬵"
+        fn style (&self) -> Option<Style> {
+            Some(self.0)
+        }
+    }
+}
+
+macro_rules! impl_axis_common { ($A:ident $T:ty) => {
+    impl $A<$T> {
+        pub fn start_inc (&mut self) -> $T {
+            self.start = self.start + 1;
+            self.start
+        }
+        pub fn start_dec (&mut self) -> $T {
+            self.start = self.start.saturating_sub(1);
+            self.start
+        }
+        pub fn point_inc (&mut self) -> Option<$T> {
+            self.point = self.point.map(|p|p + 1);
+            self.point
+        }
+        pub fn point_dec (&mut self) -> Option<$T> {
+            self.point = self.point.map(|p|p.saturating_sub(1));
+            self.point
+        }
+    }
+} }
+
+pub struct FixedAxis<T> { pub start: T, pub point: Option<T> }
+impl_axis_common!(FixedAxis u16);
+impl_axis_common!(FixedAxis usize);
+
+pub struct ScaledAxis<T> { pub start: T, pub scale: T, pub point: Option<T> }
+impl_axis_common!(ScaledAxis u16);
+impl_axis_common!(ScaledAxis usize);
+impl<T: Copy> ScaledAxis<T> {
+    pub fn scale_mut (&mut self, cb: &impl Fn(T)->T) {
+        self.scale = cb(self.scale)
+    }
+}