perf(desktop): streamline continuous resize rendering

Author: 1jehuang

crates/jcode-desktop/src/canvas.rs

@@ -484,7 +484,11 @@ impl Canvas {
         self.primitive_vertices_cache.clear();
         self.primitive_frame_vertices.clear();
         self.primitive_caret_vertices.clear();
-        self.workspace_text_pane_cache.clear();
+        // Keep workspace pane entries across resizes. Their identity keys include
+        // the panel dimensions, so the next render refreshes any size-sensitive
+        // text and geometry while retaining the previous buffers for compatible
+        // layout buckets. Clearing here made every intermediate resize frame a
+        // cold render and dropped all glyph/vertex allocations.
         self.app_mode_transition.clear();
         self.app_mode_transition_vertices.clear();
         self.single_session_scroll_motion.clear();

crates/jcode-desktop/src/main.rs

@@ -560,27 +560,10 @@ async fn run() -> Result<()> {
                 WindowEvent::CloseRequested => target.exit(),
                 WindowEvent::Resized(size) => {
                     pending_resize = Some(size);
-                    forward_app_worker_input(
-                        &mut hot_reloader,
-                        DesktopInputEvent::Window(DesktopWindowEvent::Resized {
-                            width: size.width,
-                            height: size.height,
-                            scale_factor: window.scale_factor() as f32,
-                        }),
-                    );
                     window.request_redraw();
                 }
                 WindowEvent::ScaleFactorChanged { .. } => {
                     pending_resize = Some(window.inner_size());
-                    let size = window.inner_size();
-                    forward_app_worker_input(
-                        &mut hot_reloader,
-                        DesktopInputEvent::Window(DesktopWindowEvent::Resized {
-                            width: size.width,
-                            height: size.height,
-                            scale_factor: window.scale_factor() as f32,
-                        }),
-                    );
                     window.request_redraw();
                 }
                 WindowEvent::Focused(focused) => {
@@ -1229,6 +1212,18 @@ async fn run() -> Result<()> {
                     };
                     if let Some(size) = pending_resize.take() {
                         canvas.resize(size);
+                        // Winit may deliver many resize events between presented
+                        // frames. Forward only the newest dimensions so the app
+                        // worker does not rebuild and serialize a discarded scene
+                        // for every intermediate event.
+                        forward_app_worker_input(
+                            &mut hot_reloader,
+                            DesktopInputEvent::Window(DesktopWindowEvent::Resized {
+                                width: size.width,
+                                height: size.height,
+                                scale_factor: window.scale_factor() as f32,
+                            }),
+                        );
                     }
                     let window_size = window.inner_size();
                     if !desktop_surface_size_is_renderable(window_size) {