interactive_winit_app.rs

// This example shows a bit more interaction with mouse input

use skulpin::skia_safe;
use skulpin::app::AppHandler;
use skulpin::app::AppError;
use skulpin::app::AppBuilder;
use skulpin::app::MouseButton;
use skulpin::app::VirtualKeyCode;
use skulpin::app::PhysicalPosition;
use skulpin::LogicalSize;
use skulpin::app::AppUpdateArgs;
use skulpin::app::AppDrawArgs;

use std::collections::VecDeque;

use skulpin::winit;
use winit::dpi::LogicalPosition;

fn main() {
    // Setup logging
    env_logger::Builder::from_default_env()
        .filter_level(log::LevelFilter::Debug)
        .init();

    let example_app = ExampleApp::new();

    AppBuilder::new()
        .inner_size(LogicalSize::new(900, 600))
        .run(example_app);
}

struct PreviousClick {
    position: PhysicalPosition<f64>,
    time: std::time::Instant,
}

impl PreviousClick {
    fn new(
        position: PhysicalPosition<f64>,
        time: std::time::Instant,
    ) -> Self {
        PreviousClick { position, time }
    }
}

struct ExampleApp {
    last_fps_text_change: Option<std::time::Instant>,
    fps_text: String,
    previous_clicks: VecDeque<PreviousClick>,
}

impl ExampleApp {
    pub fn new() -> Self {
        ExampleApp {
            last_fps_text_change: None,
            fps_text: "".to_string(),
            previous_clicks: VecDeque::new(),
        }
    }
}

impl AppHandler for ExampleApp {
    fn update(
        &mut self,
        update_args: AppUpdateArgs,
    ) {
        let time_state = update_args.time_state;
        let input_state = update_args.input_state;
        let app_control = update_args.app_control;

        let now = time_state.current_instant();

        //
        // Quit if user hits escape
        //
        if input_state.is_key_down(VirtualKeyCode::Escape) {
            app_control.enqueue_terminate_process();
        }

        //
        // Update FPS once a second
        //
        let update_text_string = match self.last_fps_text_change {
            Some(last_update_instant) => (now - last_update_instant).as_secs_f32() >= 1.0,
            None => true,
        };

        if update_text_string {
            let fps = time_state.updates_per_second();
            self.fps_text = format!("Fps: {:.1}", fps);
            self.last_fps_text_change = Some(now);
        }

        //
        // Pop old clicks from the previous_clicks list
        //
        while !self.previous_clicks.is_empty()
            && (now - self.previous_clicks[0].time).as_secs_f32() >= 1.0
        {
            self.previous_clicks.pop_front();
        }

        //
        // Push new clicks onto the previous_clicks list
        //
        if input_state.is_mouse_just_down(MouseButton::Left) {
            let previous_click = PreviousClick::new(input_state.mouse_position(), now);

            self.previous_clicks.push_back(previous_click);
        }
    }

    fn draw(
        &mut self,
        draw_args: AppDrawArgs,
    ) {
        let time_state = draw_args.time_state;
        let canvas = draw_args.canvas;
        let input_state = draw_args.input_state;

        let now = time_state.current_instant();

        // Generally would want to clear data every time we draw
        canvas.clear(skia_safe::Color::from_argb(0, 0, 0, 255));

        // Make a color to draw with
        let mut paint = skia_safe::Paint::new(skia_safe::Color4f::new(0.0, 1.0, 0.0, 1.0), None);
        paint.set_anti_alias(true);
        paint.set_style(skia_safe::paint::Style::Stroke);
        paint.set_stroke_width(2.0);

        //
        // Draw current mouse position.
        //
        let mouse_position: LogicalPosition<f64> = input_state
            .mouse_position()
            .to_logical(input_state.scale_factor());
        canvas.draw_circle(
            skia_safe::Point::new(mouse_position.x as f32, mouse_position.y as f32),
            15.0,
            &paint,
        );

        //
        // Draw previous mouse clicks
        //
        for previous_click in &self.previous_clicks {
            let age = now - previous_click.time;
            let age = age.as_secs_f32().min(1.0).max(0.0);

            // Make a color that fades out as the click is further in the past
            let mut paint =
                skia_safe::Paint::new(skia_safe::Color4f::new(0.0, 1.0 - age, 0.0, 1.0), None);
            paint.set_anti_alias(true);
            paint.set_style(skia_safe::paint::Style::Stroke);
            paint.set_stroke_width(3.0);

            let position: LogicalPosition<f64> = previous_click
                .position
                .to_logical(input_state.scale_factor());

            canvas.draw_circle(
                skia_safe::Point::new(position.x as f32, position.y as f32),
                25.0,
                &paint,
            );
        }

        //
        // If mouse is being dragged, draw a line to show the drag
        //
        if let Some(drag) = input_state.mouse_drag_in_progress(MouseButton::Left) {
            let begin_position: LogicalPosition<f32> =
                drag.begin_position.to_logical(input_state.scale_factor());
            let end_position: LogicalPosition<f32> =
                drag.end_position.to_logical(input_state.scale_factor());

            canvas.draw_line(
                skia_safe::Point::new(begin_position.x, begin_position.y),
                skia_safe::Point::new(end_position.x, end_position.y),
                &paint,
            );
        }

        //
        // Draw FPS text
        //
        let mut text_paint =
            skia_safe::Paint::new(skia_safe::Color4f::new(1.0, 1.0, 0.0, 1.0), None);
        text_paint.set_anti_alias(true);
        text_paint.set_style(skia_safe::paint::Style::StrokeAndFill);
        text_paint.set_stroke_width(1.0);

        let mut font = skia_safe::Font::default();
        font.set_size(20.0);
        canvas.draw_str(self.fps_text.clone(), (50, 50), &font, &text_paint);
        canvas.draw_str("Click and drag the mouse", (50, 80), &font, &text_paint);
        canvas.draw_str(
            format!("scale factor: {}", input_state.scale_factor()),
            (50, 110),
            &font,
            &text_paint,
        );
        let physical_mouse_position = input_state.mouse_position();
        let logical_mouse_position =
            physical_mouse_position.to_logical::<i32>(input_state.scale_factor());
        canvas.draw_str(
            format!(
                "mouse L: ({:.1} {:.1}) P: ({:.1} {:.1})",
                logical_mouse_position.x,
                logical_mouse_position.y,
                physical_mouse_position.x,
                physical_mouse_position.y
            ),
            (50, 140),
            &font,
            &text_paint,
        );
    }

    fn fatal_error(
        &mut self,
        error: &AppError,
    ) {
        println!("{}", error);
    }
}