Only rerender ui if it has changed

desktop/src/app.rs

@@ -245,6 +245,9 @@ impl App {
 				if let Some(render_state) = &mut self.render_state {
 					render_state.set_overlays_scene(scene);
 				}
+				if let Some(window) = &self.window {
+					window.request_redraw();
+				}
 			}
 			DesktopFrontendMessage::PersistenceWriteDocument { id, document } => {
 				self.persistent_data.write_document(id, document);
@@ -544,6 +547,7 @@ impl ApplicationHandler for App {
 						Err(RenderError::SurfaceError(e)) => tracing::error!("Render error: {:?}", e),
 					}
 					let _ = self.start_render_sender.try_send(());
+					// self.cef_context.schedule_frame();
 				}
 			}
 			WindowEvent::DragDropped { paths, .. } => {
@@ -612,7 +616,6 @@ impl ApplicationHandler for App {
 	fn about_to_wait(&mut self, event_loop: &dyn ActiveEventLoop) {
 		// Set a timeout in case we miss any cef schedule requests
 		let timeout = Instant::now() + Duration::from_millis(10);
-		let wait_until = timeout.min(self.cef_schedule.unwrap_or(timeout));
 		if let Some(schedule) = self.cef_schedule
 			&& schedule < Instant::now()
 		{
@@ -621,11 +624,9 @@ impl ApplicationHandler for App {
 			for _ in 0..CEF_MESSAGE_LOOP_MAX_ITERATIONS {
 				self.cef_context.work();
 			}
+		} else {
+			let wait_until = timeout.min(self.cef_schedule.unwrap_or(timeout));
+			event_loop.set_control_flow(ControlFlow::WaitUntil(wait_until));
 		}
-		if let Some(window) = &self.window.as_ref() {
-			window.request_redraw();
-		}
-
-		event_loop.set_control_flow(ControlFlow::WaitUntil(wait_until));
 	}
 }

desktop/src/render/state.rs

@@ -23,6 +23,7 @@ pub(crate) struct RenderState {
 	bind_group: Option<wgpu::BindGroup>,
 	#[derivative(Debug = "ignore")]
 	overlays_scene: Option<vello::Scene>,
+	surface_outdated: bool,
 }
 
 impl RenderState {
@@ -186,6 +187,7 @@ impl RenderState {
 			ui_texture: None,
 			bind_group: None,
 			overlays_scene: None,
+			surface_outdated: true,
 		}
 	}
 
@@ -196,6 +198,7 @@ impl RenderState {
 
 		self.desired_width = width;
 		self.desired_height = height;
+		self.surface_outdated = true;
 
 		if width > 0 && height > 0 && (self.config.width != width || self.config.height != height) {
 			self.config.width = width;
@@ -215,14 +218,17 @@ impl RenderState {
 	}
 
 	pub(crate) fn set_viewport_scale(&mut self, scale: [f32; 2]) {
+		self.surface_outdated = true;
 		self.viewport_scale = scale;
 	}
 
 	pub(crate) fn set_viewport_offset(&mut self, offset: [f32; 2]) {
+		self.surface_outdated = true;
 		self.viewport_offset = offset;
 	}
 
 	pub(crate) fn set_overlays_scene(&mut self, scene: vello::Scene) {
+		self.surface_outdated = true;
 		self.overlays_scene = Some(scene);
 	}
 
@@ -244,6 +250,9 @@ impl RenderState {
 	}
 
 	pub(crate) fn render(&mut self, window: &Window) -> Result<(), RenderError> {
+		if !self.surface_outdated {
+			return Ok(());
+		}
 		let ui_scale = if let Some(ui_texture) = &self.ui_texture
 			&& (self.desired_width != ui_texture.width() || self.desired_height != ui_texture.height())
 		{
@@ -305,11 +314,13 @@ impl RenderState {
 		if ui_scale.is_some() {
 			return Err(RenderError::OutdatedUITextureError);
 		}
+		self.surface_outdated = false;
 
 		Ok(())
 	}
 
 	fn update_bindgroup(&mut self) {
+		self.surface_outdated = true;
 		let viewport_texture_view = self.viewport_texture.as_ref().unwrap_or(&self.transparent_texture).create_view(&wgpu::TextureViewDescriptor::default());
 		let overlays_texture_view = self
 			.overlays_texture