docs(examples): add animation and FPS counter to colors_rgb (#583)

Cargo.toml

@@ -48,11 +48,12 @@ better-panic = "0.3.0"
 cargo-husky = { version = "1.5.0", default-features = false, features = [
   "user-hooks",
 ] }
+color-eyre = "0.6.2"
 criterion = { version = "0.5.1", features = ["html_reports"] }
 fakeit = "1.1"
-rand = "0.8.5"
 palette = "0.7.3"
 pretty_assertions = "1.4.0"
+rand = "0.8.5"
 
 [features]
 #! The crate provides a set of optional features that can be enabled in your `cargo.toml` file.

examples/README.md

@@ -117,7 +117,10 @@ two square-ish pixels in the space of a single rectangular terminal cell.
 cargo run --example=colors_rgb --features=crossterm
 ```
 
-![Colors RGB][colors_rgb.png]
+Note: VHs renders full screen animations poorly, so this is a screen capture rather than the output
+of the VHS tape.
+
+<https://github.com/ratatui-org/ratatui/assets/381361/485e775a-e0b5-4133-899b-1e8aeb56e774>
 
 ## Custom Widget
 
@@ -308,7 +311,6 @@ examples/generate.bash
 [canvas.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/canvas.gif?raw=true
 [chart.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/chart.gif?raw=true
 [colors.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/colors.gif?raw=true
-[colors_rgb.png]: https://github.com/ratatui-org/ratatui/blob/images/examples/colors_rgb.png?raw=true
 [custom_widget.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/custom_widget.gif?raw=true
 [demo.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/demo.gif?raw=true
 [demo2.gif]: https://github.com/ratatui-org/ratatui/blob/images/examples/demo2.gif?raw=true

examples/colors_rgb.rs

@@ -2,63 +2,85 @@
 ///
 /// Requires a terminal that supports 24-bit color (true color) and unicode.
 use std::{
-    error::Error,
-    io::{stdout, Stdout},
-    rc::Rc,
-    time::Duration,
+    io::stdout,
+    time::{Duration, Instant},
 };
 
+use color_eyre::config::HookBuilder;
 use crossterm::{
     event::{self, Event, KeyCode, KeyEventKind},
     terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
     ExecutableCommand,
 };
-use palette::{
-    convert::{FromColorUnclamped, IntoColorUnclamped},
-    Okhsv, Srgb,
-};
+use palette::{convert::FromColorUnclamped, Okhsv, Srgb};
 use ratatui::{prelude::*, widgets::*};
 
-type Result<T> = std::result::Result<T, Box<dyn Error>>;
-
-fn main() -> Result<()> {
-    install_panic_hook();
-    App::new()?.run()
+fn main() -> color_eyre::Result<()> {
+    App::run()
 }
 
+#[derive(Debug, Default)]
 struct App {
-    terminal: Terminal<CrosstermBackend<Stdout>>,
     should_quit: bool,
+    // a 2d vec of the colors to render, calculated when the size changes as this is expensive
+    // to calculate every frame
+    colors: Vec<Vec<Color>>,
+    last_size: Rect,
+    fps: Fps,
+    frame_count: usize,
+}
+
+#[derive(Debug)]
+struct Fps {
+    frame_count: usize,
+    last_instant: Instant,
+    fps: Option<f32>,
+}
+
+struct AppWidget<'a> {
+    title: Paragraph<'a>,
+    fps_widget: FpsWidget<'a>,
+    rgb_colors_widget: RgbColorsWidget<'a>,
+}
+
+struct FpsWidget<'a> {
+    fps: &'a Fps,
+}
+
+struct RgbColorsWidget<'a> {
+    /// The colors to render - should be double the height of the area
+    colors: &'a Vec<Vec<Color>>,
+    /// the number of elapsed frames that have passed - used to animate the colors
+    frame_count: usize,
 }
 
 impl App {
-    pub fn new() -> Result<Self> {
-        Ok(Self {
-            terminal: Terminal::new(CrosstermBackend::new(stdout()))?,
-            should_quit: false,
-        })
-    }
+    pub fn run() -> color_eyre::Result<()> {
+        install_panic_hook()?;
 
-    pub fn run(mut self) -> Result<()> {
-        init_terminal()?;
-        self.terminal.clear()?;
-        while !self.should_quit {
-            self.draw()?;
-            self.handle_events()?;
+        let mut terminal = init_terminal()?;
+        let mut app = Self::default();
+
+        while !app.should_quit {
+            app.tick();
+            terminal.draw(|frame| {
+                let size = frame.size();
+                app.setup_colors(size);
+                frame.render_widget(AppWidget::new(&app), size);
+            })?;
+            app.handle_events()?;
         }
         restore_terminal()?;
         Ok(())
     }
 
-    fn draw(&mut self) -> Result<()> {
-        self.terminal.draw(|frame| {
-            frame.render_widget(RgbColors, frame.size());
-        })?;
-        Ok(())
+    fn tick(&mut self) {
+        self.frame_count += 1;
+        self.fps.tick();
     }
 
-    fn handle_events(&mut self) -> Result<()> {
-        if event::poll(Duration::from_millis(100))? {
+    fn handle_events(&mut self) -> color_eyre::Result<()> {
+        if event::poll(Duration::from_secs_f32(1.0 / 60.0))? {
             if let Event::Key(key) = event::read()? {
                 if key.kind == KeyEventKind::Press && key.code == KeyCode::Char('q') {
                     self.should_quit = true;
@@ -67,80 +89,140 @@ impl App {
         }
         Ok(())
     }
-}
 
-impl Drop for App {
-    fn drop(&mut self) {
-        let _ = restore_terminal();
+    fn setup_colors(&mut self, size: Rect) {
+        // only update the colors if the size has changed since the last time we rendered
+        if self.last_size.width == size.width && self.last_size.height == size.height {
+            return;
+        }
+        self.last_size = size;
+        let Rect { width, height, .. } = size;
+        // double the height because each screen row has two rows of half block pixels
+        let height = height * 2;
+        self.colors.clear();
+        for y in 0..height {
+            let mut row = Vec::new();
+            for x in 0..width {
+                let hue = x as f32 * 360.0 / width as f32;
+                let value = (height - y) as f32 / height as f32;
+                let saturation = Okhsv::max_saturation();
+                let color = Okhsv::new(hue, saturation, value);
+                let color = Srgb::<f32>::from_color_unclamped(color);
+                let color: Srgb<u8> = color.into_format();
+                let color = Color::Rgb(color.red, color.green, color.blue);
+                row.push(color);
+            }
+            self.colors.push(row);
+        }
     }
 }
 
-struct RgbColors;
+impl Fps {
+    fn tick(&mut self) {
+        self.frame_count += 1;
+        let elapsed = self.last_instant.elapsed();
+        // update the fps every second, but only if we've rendered at least 2 frames (to avoid
+        // noise in the fps calculation)
+        if elapsed > Duration::from_secs(1) && self.frame_count > 2 {
+            self.fps = Some(self.frame_count as f32 / elapsed.as_secs_f32());
+            self.frame_count = 0;
+            self.last_instant = Instant::now();
+        }
+    }
+}
 
-impl Widget for RgbColors {
+impl Default for Fps {
+    fn default() -> Self {
+        Self {
+            frame_count: 0,
+            last_instant: Instant::now(),
+            fps: None,
+        }
+    }
+}
+
+impl<'a> AppWidget<'a> {
+    fn new(app: &'a App) -> Self {
+        let title =
+            Paragraph::new("colors_rgb example. Press q to quit").alignment(Alignment::Center);
+        Self {
+            title,
+            fps_widget: FpsWidget { fps: &app.fps },
+            rgb_colors_widget: RgbColorsWidget {
+                colors: &app.colors,
+                frame_count: app.frame_count,
+            },
+        }
+    }
+}
+
+impl Widget for AppWidget<'_> {
     fn render(self, area: Rect, buf: &mut Buffer) {
-        let layout = Self::layout(area);
-        Self::render_title(layout[0], buf);
-        Self::render_colors(layout[1], buf);
-    }
-}
-
-impl RgbColors {
-    fn layout(area: Rect) -> Rc<[Rect]> {
-        Layout::default()
+        let main_layout = Layout::default()
             .direction(Direction::Vertical)
             .constraints([Constraint::Length(1), Constraint::Min(0)])
-            .split(area)
-    }
+            .split(area);
+        let title_layout = Layout::default()
+            .direction(Direction::Horizontal)
+            .constraints([Constraint::Min(0), Constraint::Length(8)])
+            .split(main_layout[0]);
 
-    fn render_title(area: Rect, buf: &mut Buffer) {
-        Paragraph::new("colors_rgb example. Press q to quit")
-            .dark_gray()
-            .alignment(Alignment::Center)
-            .render(area, buf);
+        self.title.render(title_layout[0], buf);
+        self.fps_widget.render(title_layout[1], buf);
+        self.rgb_colors_widget.render(main_layout[1], buf);
     }
+}
 
-    /// Render a colored grid of half block characters (`"▀"`) each with a different RGB color.
-    fn render_colors(area: Rect, buf: &mut Buffer) {
+impl Widget for RgbColorsWidget<'_> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        let colors = self.colors;
         for (xi, x) in (area.left()..area.right()).enumerate() {
+            // animate the colors by shifting the x index by the frame number
+            let xi = (xi + self.frame_count) % (area.width as usize);
             for (yi, y) in (area.top()..area.bottom()).enumerate() {
-                let hue = xi as f32 * 360.0 / area.width as f32;
-
-                let value_fg = (yi as f32) / (area.height as f32 - 0.5);
-                let fg = Okhsv::<f32>::new(hue, Okhsv::max_saturation(), value_fg);
-                let fg: Srgb = fg.into_color_unclamped();
-                let fg: Srgb<u8> = fg.into_format();
-                let fg = Color::Rgb(fg.red, fg.green, fg.blue);
-
-                let value_bg = (yi as f32 + 0.5) / (area.height as f32 - 0.5);
-                let bg = Okhsv::new(hue, Okhsv::max_saturation(), value_bg);
-                let bg = Srgb::<f32>::from_color_unclamped(bg);
-                let bg: Srgb<u8> = bg.into_format();
-                let bg = Color::Rgb(bg.red, bg.green, bg.blue);
-
+                let fg = colors[yi * 2][xi];
+                let bg = colors[yi * 2 + 1][xi];
                 buf.get_mut(x, y).set_char('▀').set_fg(fg).set_bg(bg);
             }
         }
     }
 }
 
-/// Install a panic hook that restores the terminal before panicking.
-fn install_panic_hook() {
-    better_panic::install();
-    let prev_hook = std::panic::take_hook();
-    std::panic::set_hook(Box::new(move |info| {
-        let _ = restore_terminal();
-        prev_hook(info);
-    }));
+impl<'a> Widget for FpsWidget<'a> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        if let Some(fps) = self.fps.fps {
+            let text = format!("{:.1} fps", fps);
+            Paragraph::new(text).render(area, buf);
+        }
+    }
 }
 
-fn init_terminal() -> Result<()> {
-    enable_raw_mode()?;
-    stdout().execute(EnterAlternateScreen)?;
+/// Install a panic hook that restores the terminal before panicking.
+fn install_panic_hook() -> color_eyre::Result<()> {
+    let (panic, error) = HookBuilder::default().into_hooks();
+    let panic = panic.into_panic_hook();
+    let error = error.into_eyre_hook();
+    color_eyre::eyre::set_hook(Box::new(move |e| {
+        let _ = restore_terminal();
+        error(e)
+    }))?;
+    std::panic::set_hook(Box::new(move |info| {
+        let _ = restore_terminal();
+        panic(info)
+    }));
     Ok(())
 }
 
-fn restore_terminal() -> Result<()> {
+fn init_terminal() -> color_eyre::Result<Terminal<impl Backend>> {
+    enable_raw_mode()?;
+    stdout().execute(EnterAlternateScreen)?;
+    let mut terminal = Terminal::new(CrosstermBackend::new(stdout()))?;
+    terminal.clear()?;
+    terminal.hide_cursor()?;
+    Ok(terminal)
+}
+
+fn restore_terminal() -> color_eyre::Result<()> {
     disable_raw_mode()?;
     stdout().execute(LeaveAlternateScreen)?;
     Ok(())

examples/colors_rgb.tape

@@ -1,13 +1,21 @@
 # This is a vhs script. See https://github.com/charmbracelet/vhs for more info.
 # To run this script, install vhs and run `vhs ./examples/colors_rgb.tape`
+
+# note that this script sometimes results in the gif having screen tearing
+# issues. I'm not sure why, but it's not a problem with the library.
 Output "target/colors_rgb.gif"
 Set Theme "Aardvark Blue"
 Set Width 1200
-Set Height 800
+Set Height 1200
+
+# unsure if these help the screen tearing issue, but they don't hurt
+Set Framerate 60
+Set CursorBlink false
+
 Hide
-Type "cargo run --example=colors_rgb --features=crossterm"
+Type "cargo run --example=colors_rgb --features=crossterm --release"
 Enter
 Sleep 2s
-Screenshot "target/colors_rgb.png"
+# Screenshot "target/colors_rgb.png"
 Show
-Sleep 1s
+Sleep 10s