fix(canvas)!: use full block for Marker::Block (#133)

Cargo.toml

@@ -35,6 +35,7 @@ serde = { version = "1", optional = true, features = ["derive"]}
 [dev-dependencies]
 rand = "0.8"
 argh = "0.1"
+indoc = "2.0"
 
 [[example]]
 name = "barchart"

examples/canvas.rs

@@ -7,6 +7,7 @@ use ratatui::{
     backend::{Backend, CrosstermBackend},
     layout::{Constraint, Direction, Layout, Rect},
     style::{Color, Style},
+    symbols::Marker,
     text::Span,
     widgets::{
         canvas::{Canvas, Map, MapResolution, Rectangle},
@@ -29,6 +30,8 @@ struct App {
     vy: f64,
     dir_x: bool,
     dir_y: bool,
+    tick_count: u64,
+    marker: Marker,
 }
 
 impl App {
@@ -48,10 +51,22 @@ impl App {
             vy: 1.0,
             dir_x: true,
             dir_y: true,
+            tick_count: 0,
+            marker: Marker::Dot,
         }
     }
 
     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 {
+            self.marker = match self.marker {
+                Marker::Dot => Marker::Block,
+                Marker::Block => Marker::Bar,
+                Marker::Bar => Marker::Braille,
+                Marker::Braille => Marker::Dot,
+            };
+        }
         if self.ball.x < self.playground.left() as f64
             || self.ball.x + self.ball.width > self.playground.right() as f64
         {
@@ -155,6 +170,7 @@ fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
         .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,
@@ -171,6 +187,7 @@ fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
     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);
         })

src/symbols.rs

@@ -228,6 +228,8 @@ pub enum Marker {
     Dot,
     /// One point per cell in shape of a block
     Block,
+    /// One point per cell in the shape of a bar
+    Bar,
     /// Up to 8 points per cell
     Braille,
 }

src/widgets/canvas/mod.rs

@@ -260,9 +260,13 @@ impl<'a> Context<'a> {
         y_bounds: [f64; 2],
         marker: symbols::Marker,
     ) -> Context<'a> {
+        let dot = symbols::DOT.chars().next().unwrap();
+        let block = symbols::block::FULL.chars().next().unwrap();
+        let bar = symbols::bar::HALF.chars().next().unwrap();
         let grid: Box<dyn Grid> = match marker {
-            symbols::Marker::Dot => Box::new(CharGrid::new(width, height, '•')),
-            symbols::Marker::Block => Box::new(CharGrid::new(width, height, '▄')),
+            symbols::Marker::Dot => Box::new(CharGrid::new(width, height, dot)),
+            symbols::Marker::Block => Box::new(CharGrid::new(width, height, block)),
+            symbols::Marker::Bar => Box::new(CharGrid::new(width, height, bar)),
             symbols::Marker::Braille => Box::new(BrailleGrid::new(width, height)),
         };
         Context {
@@ -508,3 +512,103 @@ where
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{buffer::Cell, symbols::Marker};
+    use indoc::indoc;
+
+    // helper to test the canvas checks that drawing a vertical and horizontal line
+    // results in the expected output
+    fn test_marker(marker: Marker, expected: &str) {
+        let area = Rect::new(0, 0, 5, 5);
+        let mut cell = Cell::default();
+        cell.set_char('x');
+        let mut buf = Buffer::filled(area, &cell);
+        let horizontal_line = Line {
+            x1: 0.0,
+            y1: 0.0,
+            x2: 10.0,
+            y2: 0.0,
+            color: Color::Reset,
+        };
+        let vertical_line = Line {
+            x1: 0.0,
+            y1: 0.0,
+            x2: 0.0,
+            y2: 10.0,
+            color: Color::Reset,
+        };
+        Canvas::default()
+            .marker(marker)
+            .paint(|ctx| {
+                ctx.draw(&vertical_line);
+                ctx.draw(&horizontal_line);
+            })
+            .x_bounds([0.0, 10.0])
+            .y_bounds([0.0, 10.0])
+            .render(area, &mut buf);
+        assert_eq!(buf, Buffer::with_lines(expected.lines().collect()));
+    }
+
+    #[test]
+    fn test_bar_marker() {
+        test_marker(
+            Marker::Bar,
+            indoc!(
+                "
+                ▄xxxx
+                ▄xxxx
+                ▄xxxx
+                ▄xxxx
+                ▄▄▄▄▄"
+            ),
+        );
+    }
+
+    #[test]
+    fn test_block_marker() {
+        test_marker(
+            Marker::Block,
+            indoc!(
+                "
+                █xxxx
+                █xxxx
+                █xxxx
+                █xxxx
+                █████"
+            ),
+        );
+    }
+
+    #[test]
+    fn test_braille_marker() {
+        test_marker(
+            Marker::Braille,
+            indoc!(
+                "
+                ⡇xxxx
+                ⡇xxxx
+                ⡇xxxx
+                ⡇xxxx
+                ⣇⣀⣀⣀⣀"
+            ),
+        );
+    }
+
+    #[test]
+    fn test_dot_marker() {
+        test_marker(
+            Marker::Dot,
+            indoc!(
+                "
+                •xxxx
+                •xxxx
+                •xxxx
+                •xxxx
+                •••••"
+            ),
+        );
+    }
+}