feat(canvas): implement half block marker

examples/canvas.rs

@@ -1,28 +1,29 @@
 use std::{
-    error::Error,
-    io,
+    io::{self, stdout, Stdout},
     time::{Duration, Instant},
 };
 
 use crossterm::{
-    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
-    execute,
+    event::{self, Event, KeyCode},
     terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
+    ExecutableCommand,
 };
 use ratatui::{
     prelude::*,
     widgets::{canvas::*, *},
 };
 
+fn main() -> io::Result<()> {
+    App::run()
+}
+
 struct App {
     x: f64,
     y: f64,
-    ball: Rectangle,
+    ball: Circle,
     playground: Rect,
     vx: f64,
     vy: f64,
-    dir_x: bool,
-    dir_y: bool,
     tick_count: u64,
     marker: Marker,
 }
@@ -32,155 +33,166 @@ impl App {
         App {
             x: 0.0,
             y: 0.0,
-            ball: Rectangle {
-                x: 10.0,
-                y: 30.0,
-                width: 10.0,
-                height: 10.0,
+            ball: Circle {
+                x: 20.0,
+                y: 40.0,
+                radius: 10.0,
                 color: Color::Yellow,
             },
             playground: Rect::new(10, 10, 100, 100),
-            vx: 1.0,
-            vy: 1.0,
-            dir_x: true,
-            dir_y: true,
+            vx: 0.1,
+            vy: 0.1,
             tick_count: 0,
             marker: Marker::Dot,
         }
     }
 
+    pub fn run() -> io::Result<()> {
+        let mut terminal = init_terminal()?;
+        let mut app = App::new();
+        let mut last_tick = Instant::now();
+        let tick_rate = Duration::from_millis(16);
+        loop {
+            let _ = terminal.draw(|frame| app.ui(frame));
+            let timeout = tick_rate.saturating_sub(last_tick.elapsed());
+            if event::poll(timeout)? {
+                if let Event::Key(key) = event::read()? {
+                    match key.code {
+                        KeyCode::Char('q') => break,
+                        KeyCode::Down => app.y += 1.0,
+                        KeyCode::Up => app.y -= 1.0,
+                        KeyCode::Right => app.x += 1.0,
+                        KeyCode::Left => app.x -= 1.0,
+                        _ => {}
+                    }
+                }
+            }
+
+            if last_tick.elapsed() >= tick_rate {
+                app.on_tick();
+                last_tick = Instant::now();
+            }
+        }
+        restore_terminal()
+    }
+
     fn on_tick(&mut self) {
         self.tick_count += 1;
-        // only change marker every 4 ticks (1s) to avoid stroboscopic effect
-        if (self.tick_count % 4) == 0 {
+        // only change marker every 180 ticks (3s) to avoid stroboscopic effect
+        if (self.tick_count % 180) == 0 {
             self.marker = match self.marker {
-                Marker::Dot => Marker::Block,
-                Marker::Block => Marker::Bar,
-                Marker::Bar => Marker::Braille,
-                Marker::Braille => Marker::Dot,
+                Marker::Dot => Marker::Braille,
+                Marker::Braille => Marker::Block,
+                Marker::Block => Marker::HalfBlock,
+                Marker::HalfBlock => Marker::Bar,
+                Marker::Bar => Marker::Dot,
             };
         }
-        if self.ball.x < self.playground.left() as f64
-            || self.ball.x + self.ball.width > self.playground.right() as f64
+        // bounce the ball by flipping the velocity vector
+        let ball = &self.ball;
+        let playground = self.playground;
+        if ball.x - ball.radius < playground.left() as f64
+            || ball.x + ball.radius > playground.right() as f64
         {
-            self.dir_x = !self.dir_x;
+            self.vx = -self.vx;
         }
-        if self.ball.y < self.playground.top() as f64
-            || self.ball.y + self.ball.height > self.playground.bottom() as f64
+        if ball.y - ball.radius < playground.top() as f64
+            || ball.y + ball.radius > playground.bottom() as f64
         {
-            self.dir_y = !self.dir_y;
-        }
-
-        if self.dir_x {
-            self.ball.x += self.vx;
-        } else {
-            self.ball.x -= self.vx;
+            self.vy = -self.vy;
         }
 
-        if self.dir_y {
-            self.ball.y += self.vy;
-        } else {
-            self.ball.y -= self.vy
-        }
+        self.ball.x += self.vx;
+        self.ball.y += self.vy;
     }
-}
 
-fn main() -> Result<(), Box<dyn Error>> {
-    // setup terminal
-    enable_raw_mode()?;
-    let mut stdout = io::stdout();
-    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
-    let backend = CrosstermBackend::new(stdout);
-    let mut terminal = Terminal::new(backend)?;
+    fn ui(&self, frame: &mut Frame) {
+        let main_layout = Layout::default()
+            .direction(Direction::Horizontal)
+            .constraints([Constraint::Percentage(50), Constraint::Percentage(50)].as_ref())
+            .split(frame.size());
 
-    // create app and run it
-    let tick_rate = Duration::from_millis(250);
-    let app = App::new();
-    let res = run_app(&mut terminal, app, tick_rate);
+        let right_layout = Layout::default()
+            .direction(Direction::Vertical)
+            .constraints([Constraint::Percentage(50), Constraint::Percentage(50)].as_ref())
+            .split(main_layout[1]);
 
-    // restore terminal
-    disable_raw_mode()?;
-    execute!(
-        terminal.backend_mut(),
-        LeaveAlternateScreen,
-        DisableMouseCapture
-    )?;
-    terminal.show_cursor()?;
-
-    if let Err(err) = res {
-        println!("{err:?}");
+        frame.render_widget(self.map_canvas(), main_layout[0]);
+        frame.render_widget(self.pong_canvas(), right_layout[0]);
+        frame.render_widget(self.boxes_canvas(right_layout[1]), right_layout[1]);
     }
 
-    Ok(())
-}
+    fn map_canvas(&self) -> impl Widget + '_ {
+        Canvas::default()
+            .block(Block::default().borders(Borders::ALL).title("World"))
+            .marker(self.marker)
+            .paint(|ctx| {
+                ctx.draw(&Map {
+                    color: Color::Green,
+                    resolution: MapResolution::High,
+                });
+                ctx.print(self.x, -self.y, "You are here".yellow());
+            })
+            .x_bounds([-180.0, 180.0])
+            .y_bounds([-90.0, 90.0])
+    }
 
-fn run_app<B: Backend>(
-    terminal: &mut Terminal<B>,
-    mut app: App,
-    tick_rate: Duration,
-) -> io::Result<()> {
-    let mut last_tick = Instant::now();
-    loop {
-        terminal.draw(|f| ui(f, &app))?;
-
-        let timeout = tick_rate
-            .checked_sub(last_tick.elapsed())
-            .unwrap_or_else(|| Duration::from_secs(0));
-        if event::poll(timeout)? {
-            if let Event::Key(key) = event::read()? {
-                match key.code {
-                    KeyCode::Char('q') => {
-                        return Ok(());
-                    }
-                    KeyCode::Down => {
-                        app.y += 1.0;
-                    }
-                    KeyCode::Up => {
-                        app.y -= 1.0;
-                    }
-                    KeyCode::Right => {
-                        app.x += 1.0;
+    fn pong_canvas(&self) -> impl Widget + '_ {
+        Canvas::default()
+            .block(Block::default().borders(Borders::ALL).title("Pong"))
+            .marker(self.marker)
+            .paint(|ctx| {
+                ctx.draw(&self.ball);
+            })
+            .x_bounds([10.0, 110.0])
+            .y_bounds([10.0, 110.0])
+    }
+
+    fn boxes_canvas(&self, area: Rect) -> impl Widget {
+        let (left, right, bottom, top) =
+            (0.0, area.width as f64, 0.0, area.height as f64 * 2.0 - 4.0);
+        Canvas::default()
+            .block(Block::default().borders(Borders::ALL).title("Rects"))
+            .marker(self.marker)
+            .x_bounds([left, right])
+            .y_bounds([bottom, top])
+            .paint(|ctx| {
+                for i in 0..=11 {
+                    ctx.draw(&Rectangle {
+                        x: (i * i + 3 * i) as f64 / 2.0 + 2.0,
+                        y: 2.0,
+                        width: i as f64,
+                        height: i as f64,
+                        color: Color::Red,
+                    });
+                    ctx.draw(&Rectangle {
+                        x: (i * i + 3 * i) as f64 / 2.0 + 2.0,
+                        y: 21.0,
+                        width: i as f64,
+                        height: i as f64,
+                        color: Color::Blue,
+                    });
+                }
+                for i in 0..100 {
+                    if i % 10 != 0 {
+                        ctx.print(i as f64 + 1.0, 0.0, format!("{i}", i = i % 10));
                     }
-                    KeyCode::Left => {
-                        app.x -= 1.0;
+                    if i % 2 == 0 && i % 10 != 0 {
+                        ctx.print(0.0, i as f64, format!("{i}", i = i % 10));
                     }
-                    _ => {}
                 }
-            }
-        }
-
-        if last_tick.elapsed() >= tick_rate {
-            app.on_tick();
-            last_tick = Instant::now();
-        }
+            })
     }
 }
 
-fn ui(f: &mut Frame, app: &App) {
-    let chunks = Layout::default()
-        .direction(Direction::Horizontal)
-        .constraints([Constraint::Percentage(50), Constraint::Percentage(50)].as_ref())
-        .split(f.size());
-    let canvas = Canvas::default()
-        .block(Block::default().borders(Borders::ALL).title("World"))
-        .marker(app.marker)
-        .paint(|ctx| {
-            ctx.draw(&Map {
-                color: Color::White,
-                resolution: MapResolution::High,
-            });
-            ctx.print(app.x, -app.y, "You are here".yellow());
-        })
-        .x_bounds([-180.0, 180.0])
-        .y_bounds([-90.0, 90.0]);
-    f.render_widget(canvas, chunks[0]);
-    let canvas = Canvas::default()
-        .block(Block::default().borders(Borders::ALL).title("Pong"))
-        .marker(app.marker)
-        .paint(|ctx| {
-            ctx.draw(&app.ball);
-        })
-        .x_bounds([10.0, 110.0])
-        .y_bounds([10.0, 110.0]);
-    f.render_widget(canvas, chunks[1]);
+fn init_terminal() -> io::Result<Terminal<CrosstermBackend<Stdout>>> {
+    enable_raw_mode()?;
+    stdout().execute(EnterAlternateScreen)?;
+    Terminal::new(CrosstermBackend::new(stdout()))
+}
+
+fn restore_terminal() -> io::Result<()> {
+    disable_raw_mode()?;
+    stdout().execute(LeaveAlternateScreen)?;
+    Ok(())
 }

examples/canvas.tape

@@ -2,11 +2,12 @@
 # To run this script, install vhs and run `vhs ./examples/canvas.tape`
 Output "target/canvas.gif"
 Set Theme "OceanicMaterial"
+Set FontSize 12
 Set Width 1200
 Set Height 800
 Hide
 Type "cargo run --example=canvas --features=crossterm"
 Enter
 Sleep 1s
 Show
-Sleep 5s
+Sleep 30s

src/symbols.rs

@@ -54,6 +54,12 @@ pub mod block {
     };
 }
 
+pub mod half_block {
+    pub const UPPER: char = '▀';
+    pub const LOWER: char = '▄';
+    pub const FULL: char = '█';
+}
+
 pub mod bar {
     pub const FULL: &str = "█";
     pub const SEVEN_EIGHTHS: &str = "▇";
@@ -408,6 +414,10 @@ pub enum Marker {
     /// Braille Patterns. If your terminal does not support this, you will see unicode replacement
     /// characters (�) instead of Braille dots.
     Braille,
+    /// Use the unicode block and half block characters ("█", "▄", and "▀") to represent points in
+    /// a grid that is double the resolution of the terminal. Because each terminal cell is
+    /// generally about twice as tall as it is wide, this allows for a square grid of pixels.
+    HalfBlock,
 }
 
 pub mod scrollbar {