Desktop: Implement GPU accelerated offscreen rendering and improve rendering efficency (#3056)

* WIP accelerade offscreen canvas implementation

* Implement vulkan dmabuf import

* Add fps printing

* Add feature gates

* Forgot to add file

* Experimental windows support

* Cast ptr to isize

* Remove testing chrome://flags url

* Experimental macos support for texture import

* Cleanup code and improve latency / frame pacing

* Add path for importing textures on windows through dx12

* Update doc comment

* Import textures through metal on macos

* Review cleanup

---------

Co-authored-by: Timon Schelling <me@timon.zip>

desktop/src/cef/internal/render_handler.rs

@@ -9,6 +9,7 @@ pub(crate) struct RenderHandlerImpl<H: CefEventHandler> {
 	object: *mut RcImpl<_cef_render_handler_t, Self>,
 	event_handler: H,
 }
+
 impl<H: CefEventHandler> RenderHandlerImpl<H> {
 	pub(crate) fn new(event_handler: H) -> Self {
 		Self {
@@ -47,6 +48,23 @@ impl<H: CefEventHandler> ImplRenderHandler for RenderHandlerImpl<H> {
 		self.event_handler.draw(frame_buffer)
 	}
 
+	#[cfg(feature = "accelerated_paint")]
+	fn on_accelerated_paint(&self, _browser: Option<&mut Browser>, type_: PaintElementType, _dirty_rect_count: usize, _dirty_rects: Option<&Rect>, info: Option<&cef::AcceleratedPaintInfo>) {
+		use crate::cef::texture_import::shared_texture_handle::SharedTextureHandle;
+
+		if type_ != PaintElementType::default() {
+			return;
+		}
+
+		let shared_handle = SharedTextureHandle::new(info.unwrap());
+		if let SharedTextureHandle::Unsupported = shared_handle {
+			tracing::error!("Platform does not support accelerated painting");
+			return;
+		}
+
+		self.event_handler.draw_gpu(shared_handle);
+	}
+
 	fn get_raw(&self) -> *mut _cef_render_handler_t {
 		self.object.cast()
 	}