Bug 1794956 - TransferToImageBitmap should reset bitmap but not state. r=gfx-reviewers,lsalzman

s/Reset/ResetBitmap/ and implement for WebGL and WebGPU.

Differential Revision: https://phabricator.services.mozilla.com/D159346

dom/canvas/CanvasRenderingContext2D.cpp

@@ -1073,7 +1073,7 @@ CanvasRenderingContext2D::CanvasRenderingContext2D(
 CanvasRenderingContext2D::~CanvasRenderingContext2D() {
   RemovePostRefreshObserver();
   RemoveShutdownObserver();
-  Reset();
+  ResetBitmap();
 
   sNumLivingContexts.set(sNumLivingContexts.get() - 1);
   if (sNumLivingContexts.get() == 0 && sErrorTarget.get()) {
@@ -1117,7 +1117,7 @@ bool CanvasRenderingContext2D::ParseColor(const nsACString& aString,
   return true;
 }
 
-nsresult CanvasRenderingContext2D::Reset() {
+void CanvasRenderingContext2D::ResetBitmap() {
   if (mCanvasElement) {
     mCanvasElement->InvalidateCanvas();
   }
@@ -1138,8 +1138,6 @@ nsresult CanvasRenderingContext2D::Reset() {
   mIsEntireFrameInvalid = false;
   mPredictManyRedrawCalls = false;
   mFrameCaptureState = FrameCaptureState::CLEAN;
-
-  return NS_OK;
 }
 
 void CanvasRenderingContext2D::OnShutdown() {
@@ -1147,7 +1145,7 @@ void CanvasRenderingContext2D::OnShutdown() {
 
   RefPtr<PersistentBufferProvider> provider = mBufferProvider;
 
-  Reset();
+  ResetBitmap();
 
   if (provider) {
     provider->OnShutdown();
@@ -1652,7 +1650,7 @@ void CanvasRenderingContext2D::RemoveAssociatedMemory() {
 }
 
 void CanvasRenderingContext2D::ClearTarget(int32_t aWidth, int32_t aHeight) {
-  Reset();
+  ResetBitmap();
 
   mResetLayer = true;
 

dom/canvas/CanvasRenderingContext2D.h

@@ -445,7 +445,7 @@ class CanvasRenderingContext2D : public nsICanvasRenderingContextInternal,
 
   virtual void SetOpaqueValueFromOpaqueAttr(bool aOpaqueAttrValue) override;
   bool GetIsOpaque() override { return mOpaque; }
-  NS_IMETHOD Reset() override;
+  void ResetBitmap() override;
 
   bool UpdateWebRenderCanvasData(nsDisplayListBuilder* aBuilder,
                                  WebRenderCanvasData* aCanvasData) override;

dom/canvas/ClientWebGLContext.cpp

@@ -685,6 +685,11 @@ ClientWebGLContext::SetDimensions(const int32_t signedWidth,
   return NS_OK;
 }
 
+void ClientWebGLContext::ResetBitmap() {
+  const auto size = DrawingBufferSize();
+  Run<RPROC(Resize)>(size);  // No-change resize still clears/resets everything.
+}
+
 static bool IsWebglOutOfProcessEnabled() {
   if (StaticPrefs::webgl_out_of_process_force()) {
     return true;

dom/canvas/ClientWebGLContext.h

@@ -962,10 +962,7 @@ class ClientWebGLContext final : public nsICanvasRenderingContextInternal,
     return NS_ERROR_NOT_IMPLEMENTED;
   }
 
-  NS_IMETHOD Reset() override {
-    /* (InitializeWithSurface) */
-    return NS_ERROR_NOT_IMPLEMENTED;
-  }
+  void ResetBitmap() override;
 
   UniquePtr<uint8_t[]> GetImageBuffer(int32_t* out_format) override;
   NS_IMETHOD GetInputStream(const char* mimeType,

dom/canvas/ImageBitmapRenderingContext.cpp

@@ -69,7 +69,7 @@ void ImageBitmapRenderingContext::TransferImageBitmap(
 
 void ImageBitmapRenderingContext::TransferFromImageBitmap(
     ImageBitmap* aImageBitmap) {
-  Reset();
+  ResetBitmap();
 
   if (aImageBitmap) {
     mImage = aImageBitmap->TransferAsImage();
@@ -216,15 +216,13 @@ void ImageBitmapRenderingContext::SetOpaqueValueFromOpaqueAttr(
 
 bool ImageBitmapRenderingContext::GetIsOpaque() { return false; }
 
-NS_IMETHODIMP
-ImageBitmapRenderingContext::Reset() {
+void ImageBitmapRenderingContext::ResetBitmap() {
   if (mCanvasElement) {
     mCanvasElement->InvalidateCanvas();
   }
 
   mImage = nullptr;
   mFrameCaptureState = FrameCaptureState::CLEAN;
-  return NS_OK;
 }
 
 bool ImageBitmapRenderingContext::UpdateWebRenderCanvasData(

dom/canvas/ImageBitmapRenderingContext.h

@@ -80,7 +80,7 @@ class ImageBitmapRenderingContext final
 
   virtual void SetOpaqueValueFromOpaqueAttr(bool aOpaqueAttrValue) override;
   virtual bool GetIsOpaque() override;
-  NS_IMETHOD Reset() override;
+  void ResetBitmap() override;
   virtual already_AddRefed<layers::Image> GetAsImage() override {
     return ClipToIntrinsicSize();
   }

dom/canvas/OffscreenCanvas.cpp

@@ -259,17 +259,12 @@ already_AddRefed<ImageBitmap> OffscreenCanvas::TransferToImageBitmap(
 
   RefPtr<ImageBitmap> result =
       ImageBitmap::CreateFromOffscreenCanvas(GetOwnerGlobal(), *this, aRv);
-  if (aRv.Failed()) {
+  if (!result) {
     return nullptr;
   }
 
-  if (result && mCurrentContext) {
-    // FIXME(aosmond): The spec is unclear about the state of the canvas after
-    // clearing. Does it expect to preserve the WebGL state, other than the
-    // buffer state? Once we have clarity, we should ensure we clear the WebGL
-    // canvas as desired.
-    mCurrentContext->Reset();
-    mCurrentContext->SetDimensions(result->Width(), result->Height());
+  if (mCurrentContext) {
+    mCurrentContext->ResetBitmap();
   }
   return result.forget();
 }

dom/canvas/nsICanvasRenderingContextInternal.h

@@ -142,9 +142,8 @@ class nsICanvasRenderingContextInternal : public nsISupports,
   // attributes.
   virtual bool GetIsOpaque() = 0;
 
-  // Invalidate this context and release any held resources, in preperation
-  // for possibly reinitializing with SetDimensions/InitializeWithSurface.
-  NS_IMETHOD Reset() = 0;
+  // Clear and/or release backing bitmaps, such as for transferToImageBitmap.
+  virtual void ResetBitmap() = 0;
 
   virtual already_AddRefed<mozilla::layers::Image> GetAsImage() {
     return nullptr;

dom/html/HTMLCanvasElement.cpp

@@ -1339,7 +1339,7 @@ void HTMLCanvasElement::OnMemoryPressure() {
 
 void HTMLCanvasElement::OnDeviceReset() {
   if (!mOffscreenCanvas && mCurrentContext) {
-    mCurrentContext->Reset();
+    mCurrentContext->ResetBitmap();
   }
 }
 

dom/webgpu/CanvasContext.h

@@ -65,7 +65,9 @@ class CanvasContext final : public nsICanvasRenderingContextInternal,
 
   void SetOpaqueValueFromOpaqueAttr(bool aOpaqueAttrValue) override {}
   bool GetIsOpaque() override { return true; }
-  NS_IMETHOD Reset() override { return NS_OK; }
+
+  void ResetBitmap() override { Unconfigure(); }
+
   void MarkContextClean() override {}
 
   NS_IMETHOD Redraw(const gfxRect& aDirty) override { return NS_OK; }