canvas: Add OffscreenCanvas 'transferToImageBitmap' method (#37880)

Follow the HTML speficication and add missing 'transferToImageBitmap'
method to OffscreenCanvas interface.

https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-transfertoimagebitmap

Testing: Improvements in the following tests
- html/canvas/offscreen/compositing/2d.composite.grid*
- html/canvas/offscreen/fill-and-stroke-styles/2d.gradient*
- html/canvas/offscreen/manual/the-offscreen-canvas/offscreencanvas*
- html/canvas/offscreen/reset/2d.reset*
- html/canvas/offscreen/text/2d.text*

Fixes (partially): #34111

Signed-off-by: Andrei Volykhin <andrei.volykhin@gmail.com>

components/script/dom/canvasrenderingcontext2d.rs

@@ -153,6 +153,10 @@ impl CanvasContext for CanvasRenderingContext2D {
         self.set_canvas_bitmap_dimensions(self.size().cast())
     }
 
+    fn reset_bitmap(&self) {
+        self.canvas_state.reset_bitmap()
+    }
+
     fn get_image_data(&self) -> Option<Snapshot> {
         if !self.canvas_state.is_paintable() {
             return None;

components/script/dom/offscreencanvas.rs

@@ -27,6 +27,7 @@ use crate::dom::blob::Blob;
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlcanvaselement::HTMLCanvasElement;
+use crate::dom::imagebitmap::ImageBitmap;
 use crate::dom::offscreencanvasrenderingcontext2d::OffscreenCanvasRenderingContext2D;
 use crate::dom::promise::Promise;
 use crate::realms::{AlreadyInRealm, InRealm};
@@ -214,6 +215,40 @@ impl OffscreenCanvasMethods<crate::DomTypeHolder> for OffscreenCanvas {
         }
     }
 
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-transfertoimagebitmap>
+    fn TransferToImageBitmap(&self, can_gc: CanGc) -> Fallible<DomRoot<ImageBitmap>> {
+        // TODO Step 1. If the value of this OffscreenCanvas object's
+        // [[Detached]] internal slot is set to true, then throw an
+        // "InvalidStateError" DOMException.
+
+        // Step 2. If this OffscreenCanvas object's context mode is set to none,
+        // then throw an "InvalidStateError" DOMException.
+        if self.context.borrow().is_none() {
+            return Err(Error::InvalidState);
+        }
+
+        // Step 3. Let image be a newly created ImageBitmap object that
+        // references the same underlying bitmap data as this OffscreenCanvas
+        // object's bitmap.
+        let Some(snapshot) = self.get_image_data() else {
+            return Err(Error::InvalidState);
+        };
+
+        let image_bitmap = ImageBitmap::new(&self.global(), snapshot, can_gc);
+        image_bitmap.set_origin_clean(self.origin_is_clean());
+
+        // Step 4. Set this OffscreenCanvas object's bitmap to reference a newly
+        // created bitmap of the same dimensions and color space as the previous
+        // bitmap, and with its pixels initialized to transparent black, or
+        // opaque black if the rendering context's alpha is false.
+        if let Some(canvas_context) = self.context() {
+            canvas_context.reset_bitmap();
+        }
+
+        // Step 5. Return image.
+        Ok(image_bitmap)
+    }
+
     /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-converttoblob>
     fn ConvertToBlob(&self, options: &ImageEncodeOptions, can_gc: CanGc) -> Rc<Promise> {
         // Step 5. Let result be a new promise object.

components/script/dom/offscreencanvasrenderingcontext2d.rs

@@ -84,6 +84,10 @@ impl CanvasContext for OffscreenCanvasRenderingContext2D {
         self.context.resize()
     }
 
+    fn reset_bitmap(&self) {
+        self.context.reset_bitmap()
+    }
+
     fn get_image_data(&self) -> Option<Snapshot> {
         self.context.get_image_data()
     }

components/script/dom/webgl2renderingcontext.rs

@@ -916,6 +916,10 @@ impl CanvasContext for WebGL2RenderingContext {
         self.base.resize();
     }
 
+    fn reset_bitmap(&self) {
+        self.base.reset_bitmap();
+    }
+
     fn get_image_data(&self) -> Option<Snapshot> {
         self.base.get_image_data()
     }

components/script/dom/webglrenderingcontext.rs

@@ -1974,6 +1974,10 @@ impl CanvasContext for WebGLRenderingContext {
         }
     }
 
+    fn reset_bitmap(&self) {
+        warn!("The WebGLRenderingContext 'reset_bitmap' is not implemented yet");
+    }
+
     // Used by HTMLCanvasElement.toDataURL
     //
     // This emits errors quite liberally, but the spec says that this operation

components/script/dom/webgpu/gpucanvascontext.rs

@@ -276,6 +276,10 @@ impl CanvasContext for GPUCanvasContext {
         }
     }
 
+    fn reset_bitmap(&self) {
+        warn!("The GPUCanvasContext 'reset_bitmap' is not implemented yet");
+    }
+
     /// <https://gpuweb.github.io/gpuweb/#ref-for-abstract-opdef-get-a-copy-of-the-image-contents-of-a-context%E2%91%A5>
     fn get_image_data(&self) -> Option<Snapshot> {
         // 1. Return a copy of the image contents of context.