wezterm/termwiz/examples/widgets_nested.rs

//! This example shows how to make an app that uses parent/child widgets
#[cfg(feature = "widgets")]
mod inner {
    use anyhow::Error;
    use termwiz::caps::Capabilities;
    use termwiz::cell::AttributeChange;
    use termwiz::color::{AnsiColor, ColorAttribute, RgbColor};
    use termwiz::input::*;
    use termwiz::surface::Change;
    use termwiz::terminal::buffered::BufferedTerminal;
    use termwiz::terminal::{new_terminal, Terminal};
    use termwiz::widgets::layout::{ChildOrientation, VerticalAlignment};
    use termwiz::widgets::*;

    /// This is the main container widget for the app
    struct MainScreen {}

    impl MainScreen {
        pub fn new() -> Self {
            Self {}
        }
    }

    impl Widget for MainScreen {
        fn render(&mut self, _args: &mut RenderArgs) {}

        fn get_size_constraints(&self) -> layout::Constraints {
            // Switch from default horizontal layout to vertical layout
            let mut c = layout::Constraints::default();
            c.child_orientation = ChildOrientation::Vertical;
            c
        }
    }

    /// This is the main text input area for the app
    struct TextInput<'a> {
        /// Holds the input text that we wish the widget to display
        text: &'a mut String,
    }

    impl<'a> TextInput<'a> {
        /// Initialize the widget with the input text
        pub fn new(text: &'a mut String) -> Self {
            Self { text }
        }
    }

    impl<'a> Widget for TextInput<'a> {
        fn process_event(&mut self, event: &WidgetEvent, _args: &mut UpdateArgs) -> bool {
            match event {
                WidgetEvent::Input(InputEvent::Key(KeyEvent {
                    key: KeyCode::Char(c),
                    ..
                })) => self.text.push(*c),
                WidgetEvent::Input(InputEvent::Key(KeyEvent {
                    key: KeyCode::Enter,
                    ..
                })) => {
                    self.text.push_str("\r\n");
                }
                WidgetEvent::Input(InputEvent::Paste(s)) => {
                    self.text.push_str(&s);
                }
                _ => {}
            }

            true // handled it all
        }

        /// Draw ourselves into the surface provided by RenderArgs
        fn render(&mut self, args: &mut RenderArgs) {
            args.surface.add_change(Change::ClearScreen(
                ColorAttribute::TrueColorWithPaletteFallback(
                    RgbColor::new(0x31, 0x1B, 0x92),
                    AnsiColor::Black.into(),
                ),
            ));
            args.surface
                .add_change(Change::Attribute(AttributeChange::Foreground(
                    ColorAttribute::TrueColorWithPaletteFallback(
                        RgbColor::new(0xB3, 0x88, 0xFF),
                        AnsiColor::Purple.into(),
                    ),
                )));
            args.surface.add_change(self.text.clone());

            // Place the cursor at the end of the text.
            // A more advanced text editing widget would manage the
            // cursor position differently.
            *args.cursor = CursorShapeAndPosition {
                coords: args.surface.cursor_position().into(),
                shape: termwiz::surface::CursorShape::SteadyBar,
                ..Default::default()
            };
        }

        fn get_size_constraints(&self) -> layout::Constraints {
            let mut c = layout::Constraints::default();
            c.set_valign(VerticalAlignment::Top);
            c
        }
    }

    // This is a little status line widget that we render at the bottom
    struct StatusLine {}

    impl StatusLine {
        pub fn new() -> Self {
            Self {}
        }
    }

    impl Widget for StatusLine {
        /// Draw ourselves into the surface provided by RenderArgs
        fn render(&mut self, args: &mut RenderArgs) {
            let dims = args.surface.dimensions();
            args.surface
                .add_change(Change::ClearScreen(AnsiColor::Grey.into()));
            args.surface
                .add_change(format!("🤷 status surface size is {:?}", dims));
        }

        fn get_size_constraints(&self) -> layout::Constraints {
            let mut c = layout::Constraints::default();
            c.set_fixed_height(1);
            c.set_valign(VerticalAlignment::Bottom);
            c
        }
    }

    pub fn run() -> Result<(), Error> {
        // Start with an empty string; typing into the app will
        // update this string.
        let mut typed_text = String::new();

        {
            // Create a terminal and put it into full screen raw mode
            let caps = Capabilities::new_from_env()?;
            let mut buf = BufferedTerminal::new(new_terminal(caps)?)?;
            buf.terminal().set_raw_mode()?;

            // Set up the UI
            let mut ui = Ui::new();

            let root_id = ui.set_root(MainScreen::new());
            let buffer_id = ui.add_child(root_id, TextInput::new(&mut typed_text));
            ui.add_child(root_id, StatusLine::new());

            ui.set_focus(buffer_id);

            loop {
                ui.process_event_queue()?;

                // After updating and processing all of the widgets, compose them
                // and render them to the screen.
                if ui.render_to_screen(&mut buf)? {
                    // We have more events to process immediately; don't block waiting
                    // for input below, but jump to the top of the loop to re-run the
                    // updates.
                    continue;
                }
                // Compute an optimized delta to apply to the terminal and display it
                buf.flush()?;

                // Wait for user input
                match buf.terminal().poll_input(None) {
                    Ok(Some(InputEvent::Resized { rows, cols })) => {
                        // FIXME: this is working around a bug where we don't realize
                        // that we should redraw everything on resize in BufferedTerminal.
                        buf.add_change(Change::ClearScreen(Default::default()));
                        buf.resize(cols, rows);
                    }
                    Ok(Some(input)) => match input {
                        InputEvent::Key(KeyEvent {
                            key: KeyCode::Escape,
                            ..
                        }) => {
                            // Quit the app when escape is pressed
                            break;
                        }
                        input @ _ => {
                            // Feed input into the Ui
                            ui.queue_event(WidgetEvent::Input(input));
                        }
                    },
                    Ok(None) => {}
                    Err(e) => {
                        print!("{:?}\r\n", e);
                        break;
                    }
                }
            }
        }

        // After we've stopped the full screen raw terminal,
        // print out the final edited value of the input text.
        println!("The text you entered: {}", typed_text);

        Ok(())
    }
}

#[cfg(not(feature = "widgets"))]
mod inner {
    pub fn run() -> anyhow::Result<()> {
        println!("recompile with --features widgets");
        Ok(())
    }
}

fn main() -> anyhow::Result<()> {
    inner::run()
}