docs(examples): make custom widget example into a button (#539)

The widget also now supports mouse

examples/custom_widget.rs

@@ -1,27 +1,121 @@
-use std::{error::Error, io};
+use std::{error::Error, io, ops::ControlFlow, time::Duration};
 
 use crossterm::{
-    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
+    event::{
+        self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode, MouseButton, MouseEvent,
+        MouseEventKind,
+    },
     execute,
     terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
 };
 use ratatui::{prelude::*, widgets::*};
 
-#[derive(Default)]
-struct Label<'a> {
-    text: &'a str,
+/// A custom widget that renders a button with a label, theme and state.
+#[derive(Debug, Clone)]
+struct Button<'a> {
+    label: Line<'a>,
+    theme: Theme,
+    state: State,
 }
 
-impl<'a> Widget for Label<'a> {
-    fn render(self, area: Rect, buf: &mut Buffer) {
-        buf.set_string(area.left(), area.top(), self.text, Style::default());
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum State {
+    Normal,
+    Selected,
+    Active,
+}
+
+#[derive(Debug, Clone, Copy)]
+struct Theme {
+    text: Color,
+    background: Color,
+    highlight: Color,
+    shadow: Color,
+}
+
+const BLUE: Theme = Theme {
+    text: Color::Rgb(16, 24, 48),
+    background: Color::Rgb(48, 72, 144),
+    highlight: Color::Rgb(64, 96, 192),
+    shadow: Color::Rgb(32, 48, 96),
+};
+
+const RED: Theme = Theme {
+    text: Color::Rgb(48, 16, 16),
+    background: Color::Rgb(144, 48, 48),
+    highlight: Color::Rgb(192, 64, 64),
+    shadow: Color::Rgb(96, 32, 32),
+};
+
+const GREEN: Theme = Theme {
+    text: Color::Rgb(16, 48, 16),
+    background: Color::Rgb(48, 144, 48),
+    highlight: Color::Rgb(64, 192, 64),
+    shadow: Color::Rgb(32, 96, 32),
+};
+
+/// A button with a label that can be themed.
+impl<'a> Button<'a> {
+    pub fn new<T: Into<Line<'a>>>(label: T) -> Button<'a> {
+        Button {
+            label: label.into(),
+            theme: BLUE,
+            state: State::Normal,
+        }
+    }
+
+    pub fn theme(mut self, theme: Theme) -> Button<'a> {
+        self.theme = theme;
+        self
+    }
+
+    pub fn state(mut self, state: State) -> Button<'a> {
+        self.state = state;
+        self
     }
 }
 
-impl<'a> Label<'a> {
-    fn text(mut self, text: &'a str) -> Label<'a> {
-        self.text = text;
-        self
+impl<'a> Widget for Button<'a> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        let (background, text, shadow, highlight) = self.colors();
+        buf.set_style(area, Style::new().bg(background).fg(text));
+
+        // render top line if there's enough space
+        if area.height > 2 {
+            buf.set_string(
+                area.x,
+                area.y,
+                "▔".repeat(area.width as usize),
+                Style::new().fg(highlight).bg(background),
+            );
+        }
+        // render bottom line if there's enough space
+        if area.height > 1 {
+            buf.set_string(
+                area.x,
+                area.y + area.height - 1,
+                "▁".repeat(area.width as usize),
+                Style::new().fg(shadow).bg(background),
+            );
+        }
+        // render label centered
+        buf.set_line(
+            area.x + (area.width.saturating_sub(self.label.width() as u16)) / 2,
+            area.y + (area.height.saturating_sub(1)) / 2,
+            &self.label,
+            area.width,
+        );
+    }
+}
+
+impl Button<'_> {
+    fn colors(&self) -> (Color, Color, Color, Color) {
+        let theme = self.theme;
+        match self.state {
+            State::Normal => (theme.background, theme.text, theme.shadow, theme.highlight),
+            State::Selected => (theme.highlight, theme.text, theme.shadow, theme.highlight),
+            State::Active => (theme.background, theme.text, theme.highlight, theme.shadow),
+        }
     }
 }
 
@@ -53,19 +147,122 @@ fn main() -> Result<(), Box<dyn Error>> {
 }
 
 fn run_app<B: Backend>(terminal: &mut Terminal<B>) -> io::Result<()> {
+    let mut selected_button: usize = 0;
+    let button_states = &mut [State::Selected, State::Normal, State::Normal];
     loop {
-        terminal.draw(ui)?;
-
-        if let Event::Key(key) = event::read()? {
-            if let KeyCode::Char('q') = key.code {
-                return Ok(());
+        terminal.draw(|frame| ui(frame, button_states))?;
+        if !event::poll(Duration::from_millis(100))? {
+            continue;
+        }
+        match event::read()? {
+            Event::Key(key) => {
+                if key.kind != event::KeyEventKind::Press {
+                    continue;
+                }
+                if handle_key_event(key, button_states, &mut selected_button).is_break() {
+                    break;
+                }
             }
+            Event::Mouse(mouse) => handle_mouse_event(mouse, button_states, &mut selected_button),
+            _ => (),
         }
     }
+    Ok(())
 }
 
-fn ui(f: &mut Frame) {
-    let size = f.size();
-    let label = Label::default().text("Test");
-    f.render_widget(label, size);
+fn ui(frame: &mut Frame, states: &[State; 3]) {
+    let layout = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints(vec![
+            Constraint::Length(1),
+            Constraint::Max(3),
+            Constraint::Length(1),
+            Constraint::Min(0), // ignore remaining space
+        ])
+        .split(frame.size());
+    frame.render_widget(
+        Paragraph::new("Custom Widget Example (mouse enabled)"),
+        layout[0],
+    );
+    render_buttons(frame, layout[1], states);
+    frame.render_widget(
+        Paragraph::new("←/→: select, Space: toggle, q: quit"),
+        layout[2],
+    );
+}
+
+fn render_buttons(frame: &mut Frame<'_>, area: Rect, states: &[State; 3]) {
+    let layout = Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints(vec![
+            Constraint::Length(15),
+            Constraint::Length(15),
+            Constraint::Length(15),
+            Constraint::Min(0), // ignore remaining space
+        ])
+        .split(area);
+    frame.render_widget(Button::new("Red").theme(RED).state(states[0]), layout[0]);
+    frame.render_widget(
+        Button::new("Green").theme(GREEN).state(states[1]),
+        layout[1],
+    );
+    frame.render_widget(Button::new("Blue").theme(BLUE).state(states[2]), layout[2]);
+}
+
+fn handle_key_event(
+    key: event::KeyEvent,
+    button_states: &mut [State; 3],
+    selected_button: &mut usize,
+) -> ControlFlow<()> {
+    match key.code {
+        KeyCode::Char('q') => return ControlFlow::Break(()),
+        KeyCode::Left => {
+            button_states[*selected_button] = State::Normal;
+            *selected_button = selected_button.saturating_sub(1);
+            button_states[*selected_button] = State::Selected;
+        }
+        KeyCode::Right => {
+            button_states[*selected_button] = State::Normal;
+            *selected_button = selected_button.saturating_add(1).min(2);
+            button_states[*selected_button] = State::Selected;
+        }
+        KeyCode::Char(' ') => {
+            if button_states[*selected_button] == State::Active {
+                button_states[*selected_button] = State::Normal;
+            } else {
+                button_states[*selected_button] = State::Active;
+            }
+        }
+        _ => (),
+    }
+    ControlFlow::Continue(())
+}
+
+fn handle_mouse_event(
+    mouse: MouseEvent,
+    button_states: &mut [State; 3],
+    selected_button: &mut usize,
+) {
+    match mouse.kind {
+        MouseEventKind::Moved => {
+            let old_selected_button = *selected_button;
+            *selected_button = match mouse.column {
+                x if x < 15 => 0,
+                x if x < 30 => 1,
+                _ => 2,
+            };
+            if old_selected_button != *selected_button {
+                button_states[old_selected_button] = State::Normal;
+                button_states[*selected_button] = State::Selected;
+            }
+        }
+        MouseEventKind::Down(MouseButton::Left) => {
+            if button_states[*selected_button] == State::Active {
+                button_states[*selected_button] = State::Normal;
+            } else {
+                button_states[*selected_button] = State::Active;
+            }
+        }
+        _ => (),
+    }
 }

examples/custom_widget.tape

@@ -2,11 +2,20 @@
 # To run this script, install vhs and run `vhs ./examples/custom_widget.tape`
 Output "target/custom_widget.gif"
 Set Theme "OceanicMaterial"
-Set Width 1200
-Set Height 200
+Set Width 760
+Set Height 260
 Hide
 Type "cargo run --example=custom_widget --features=crossterm"
 Enter
-Sleep 1s
+Sleep 2s
 Show
-Sleep 5s
+Sleep 1s
+Set TypingSpeed 0.7s
+Right
+Right
+Space
+Space
+Left
+Space
+Left
+Space