[web] port JS code to Rust

egui_web/src/lib.rs

@@ -3,6 +3,73 @@
 
 pub mod webgl;
 
+// ----------------------------------------------------------------------------
+
+use std::sync::Arc;
+use wasm_bindgen::JsValue;
+
+pub struct State {
+    ctx: Arc<egui::Context>,
+    webgl_painter: webgl::Painter,
+    frame_times: egui::MovementTracker<f32>,
+    frame_start: Option<f64>,
+}
+
+impl State {
+    pub fn new(canvas_id: &str) -> Result<State, JsValue> {
+        let ctx = egui::Context::new();
+        load_memory(&ctx);
+        Ok(State {
+            ctx,
+            webgl_painter: webgl::Painter::new(canvas_id)?,
+            frame_times: egui::MovementTracker::new(1000, 1.0),
+            frame_start: None,
+        })
+    }
+
+    pub fn begin_frame(&mut self, raw_input: egui::RawInput) -> egui::Ui {
+        self.frame_start = Some(now_sec());
+        self.ctx.begin_frame(raw_input)
+    }
+
+    pub fn end_frame(&mut self) -> Result<egui::Output, JsValue> {
+        let frame_start = self
+            .frame_start
+            .take()
+            .expect("unmatched calls to begin_frame/end_frame");
+
+        let bg_color = egui::color::srgba(0, 0, 0, 0); // Use background css color.
+        let (output, batches) = self.ctx.end_frame();
+
+        let now = now_sec();
+        self.frame_times.add(now, (now - frame_start) as f32);
+
+        self.webgl_painter.paint_batches(
+            bg_color,
+            batches,
+            self.ctx.texture(),
+            self.ctx.pixels_per_point(),
+        )?;
+
+        save_memory(&self.ctx); // TODO: don't save every frame
+
+        Ok(output)
+    }
+
+    pub fn painter_debug_info(&self) -> String {
+        self.webgl_painter.debug_info()
+    }
+
+    /// excludes painting
+    pub fn cpu_usage(&self) -> f32 {
+        self.frame_times.average().unwrap_or_default()
+    }
+
+    pub fn fps(&self) -> f32 {
+        1.0 / self.frame_times.mean_time_interval().unwrap_or_default()
+    }
+}
+
 // ----------------------------------------------------------------------------
 // Helpers to hide some of the verbosity of web_sys
 
@@ -10,6 +77,14 @@ pub fn console_log(s: String) {
     web_sys::console::log_1(&s.into());
 }
 
+pub fn screen_size() -> Option<egui::Vec2> {
+    let window = web_sys::window()?;
+    Some(egui::Vec2::new(
+        window.inner_width().ok()?.as_f64()? as f32,
+        window.inner_height().ok()?.as_f64()? as f32,
+    ))
+}
+
 pub fn now_sec() -> f64 {
     web_sys::window()
         .expect("should have a Window")
@@ -19,6 +94,44 @@ pub fn now_sec() -> f64 {
         / 1000.0
 }
 
+pub fn seconds_since_midnight() -> f64 {
+    let d = js_sys::Date::new_0();
+    let seconds = (d.get_hours() * 60 + d.get_minutes()) * 60 + d.get_seconds();
+    return seconds as f64 + 1e-3 * (d.get_milliseconds() as f64);
+}
+
+pub fn pixels_per_point() -> f32 {
+    let pixels_per_point = web_sys::window().unwrap().device_pixel_ratio() as f32;
+    if pixels_per_point > 0.0 && pixels_per_point.is_finite() {
+        pixels_per_point
+    } else {
+        1.0
+    }
+}
+
+pub fn resize_to_screen_size(canvas_id: &str) -> Option<()> {
+    use wasm_bindgen::JsCast;
+    let document = web_sys::window()?.document()?;
+    let canvas = document.get_element_by_id(canvas_id)?;
+    let canvas: web_sys::HtmlCanvasElement =
+        canvas.dyn_into::<web_sys::HtmlCanvasElement>().ok()?;
+
+    let screen_size = screen_size()?;
+    let pixels_per_point = pixels_per_point();
+    canvas
+        .style()
+        .set_property("width", &format!("{}px", screen_size.x))
+        .ok()?;
+    canvas
+        .style()
+        .set_property("height", &format!("{}px", screen_size.y))
+        .ok()?;
+    canvas.set_width((screen_size.x * pixels_per_point).round() as u32);
+    canvas.set_height((screen_size.y * pixels_per_point).round() as u32);
+
+    Some(())
+}
+
 pub fn local_storage() -> Option<web_sys::Storage> {
     web_sys::window()?.local_storage().ok()?
 }
@@ -61,3 +174,47 @@ pub fn save_memory(ctx: &egui::Context) {
         }
     }
 }
+
+pub fn handle_output(output: &egui::Output) {
+    set_cursor_icon(output.cursor_icon);
+    if let Some(url) = &output.open_url {
+        open_url(url);
+    }
+}
+
+pub fn set_cursor_icon(cursor: egui::CursorIcon) -> Option<()> {
+    let document = web_sys::window()?.document()?;
+    document
+        .body()?
+        .style()
+        .set_property("cursor", cursor_web_name(cursor))
+        .ok()
+}
+
+fn cursor_web_name(cursor: egui::CursorIcon) -> &'static str {
+    use egui::CursorIcon::*;
+    match cursor {
+        Default => "default",
+        PointingHand => "pointer",
+        ResizeHorizontal => "ew-resize",
+        ResizeNeSw => "nesw-resize",
+        ResizeNwSe => "nwse-resize",
+        ResizeVertical => "ns-resize",
+        Text => "text",
+        // "no-drop"
+        // "not-allowed"
+        // default, help, pointer, progress, wait, cell, crosshair, text, alias, copy, move, grab, grabbing,
+    }
+}
+
+pub fn open_url(url: &str) -> Option<()> {
+    web_sys::window()?
+        .open_with_url_and_target(url, "_self")
+        .ok()?;
+    Some(())
+}
+
+/// e.g. "#fragment" part of "www.example.com/index.html#fragment"
+pub fn location_hash() -> Option<String> {
+    web_sys::window()?.location().hash().ok()
+}