Don't paint until first animation frame

/ · May 16, 2023 · May 16, 2023 · May 16, 2023 · May 16, 2023 · May 16, 2023
commit 171dbd70ddbd84c5ad5c15fbf1fa4c0b1caace55
diff --git a/crates/eframe/src/web/events.rs b/crates/eframe/src/web/events.rs
@@ -1,30 +1,11 @@
 use super::*;
 
+// ------------------------------------------------------------------------
+
 /// Calls `request_animation_frame` to schedule repaint.
 ///
 /// It will only paint if needed, but will always call `request_animation_frame` immediately.
-pub fn paint_and_schedule(runner_ref: &WebRunner) -> Result<(), JsValue> {
-    fn paint_if_needed(runner: &mut AppRunner) -> Result<(), JsValue> {
-        if runner.needs_repaint.when_to_repaint() <= now_sec() {
-            runner.needs_repaint.clear();
-            let (repaint_after, clipped_primitives) = runner.logic();
-            runner.paint(&clipped_primitives)?;
-            runner
-                .needs_repaint
-                .repaint_after(repaint_after.as_secs_f64());
-            runner.auto_save_if_needed();
-        }
-        Ok(())
-    }
-
-    fn request_animation_frame(runner_ref: WebRunner) -> Result<(), JsValue> {
-        let window = web_sys::window().unwrap();
-        let closure = Closure::once(move || paint_and_schedule(&runner_ref));
-        window.request_animation_frame(closure.as_ref().unchecked_ref())?;
-        closure.forget(); // We must forget it, or else the callback is canceled on drop
-        Ok(())
-    }
-
+fn paint_and_schedule(runner_ref: &WebRunner) -> Result<(), JsValue> {
     // Only paint and schedule if there has been no panic
     if let Some(mut runner_lock) = runner_ref.try_lock() {
         paint_if_needed(&mut runner_lock)?;
@@ -35,6 +16,29 @@ pub fn paint_and_schedule(runner_ref: &WebRunner) -> Result<(), JsValue> {
     Ok(())
 }
 
+fn paint_if_needed(runner: &mut AppRunner) -> Result<(), JsValue> {
+    if runner.needs_repaint.when_to_repaint() <= now_sec() {
+        runner.needs_repaint.clear();
+        let (repaint_after, clipped_primitives) = runner.logic();
+        runner.paint(&clipped_primitives)?;
+        runner
+            .needs_repaint
+            .repaint_after(repaint_after.as_secs_f64());
+        runner.auto_save_if_needed();
+    }
+    Ok(())
+}
+
+pub fn request_animation_frame(runner_ref: WebRunner) -> Result<(), JsValue> {
+    let window = web_sys::window().unwrap();
+    let closure = Closure::once(move || paint_and_schedule(&runner_ref));
+    window.request_animation_frame(closure.as_ref().unchecked_ref())?;
+    closure.forget(); // We must forget it, or else the callback is canceled on drop
+    Ok(())
+}
+
+// ------------------------------------------------------------------------
+
 pub fn install_document_events(runner_ref: &WebRunner) -> Result<(), JsValue> {
     let document = web_sys::window().unwrap().document().unwrap();
 

diff --git a/crates/eframe/src/web/web_runner.rs b/crates/eframe/src/web/web_runner.rs
@@ -62,16 +62,17 @@ impl WebRunner {
         runner.warm_up();
         self.runner.replace(Some(runner));
 
-        // Install events:
         {
             events::install_canvas_events(self)?;
             events::install_document_events(self)?;
             events::install_window_events(self)?;
             super::text_agent::install_text_agent(self)?;
+
             if follow_system_theme {
                 events::install_color_scheme_change_event(self)?;
             }
-            events::paint_and_schedule(self)?;
+
+            events::request_animation_frame(self.clone())?;
         }
 
         Ok(())