OffscreenCanvas.transferToImageBuffer() does not clear WebGL drawing …

…buffer correctly https://bugs.webkit.org/show_bug.cgi?id=272960 rdar://126738038 Reviewed by Matt Woodrow. OffscreenCanvas.transferToImageBuffer() should cause compositing steps similar to the case of preserveDrawingBuffer=false drawing buffer is displayed: - color buffer, depth, stencil is cleared Previous clear implementation would use WebGL context state, which would not necceassarily clear the correct framebuffer in a correct way. * Source/WebCore/html/OffscreenCanvas.cpp: (WebCore::OffscreenCanvas::transferToImageBitmap): * Source/WebCore/html/canvas/WebGLDefaultFramebuffer.cpp: (WebCore::WebGLDefaultFramebuffer::markAllBuffersDirty): * Source/WebCore/html/canvas/WebGLDefaultFramebuffer.h: * Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp: (WebCore::WebGLRenderingContextBase::markBuffersDirtyForTransfer): * Source/WebCore/html/canvas/WebGLRenderingContextBase.h: Canonical link: https://commits.webkit.org/279434@main
WebKit · May 29, 2024 · c3988b9 · c3988b9
1 parent 14d2ee9
commit c3988b9
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Showing 6 changed files with 27 additions and 16 deletions.
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
@@ -1333,7 +1333,6 @@ http/tests/websocket/tests/hybi/imported/blink/permessage-deflate-split-frames.h
 http/tests/websocket/tests/hybi/imported/blink/permessage-deflate-unsolicited-negotiation-response.html [ Skip ]
 http/tests/websocket/tests/hybi/imported/blink/permessage-deflate-window-bits.html [ Skip ]
 
-http/wpt/offscreen-canvas/transferToImageBitmap-webgl.html [ ImageOnlyFailure Failure ]
 imported/w3c/web-platform-tests/html/canvas/offscreen/manual/the-offscreen-canvas/offscreencanvas.resize.html [ Failure Pass ]
 imported/w3c/web-platform-tests/html/canvas/offscreen/the-offscreen-canvas/size.large.html [ Skip ]
 

diff --git a/Source/WebCore/html/OffscreenCanvas.cpp b/Source/WebCore/html/OffscreenCanvas.cpp
@@ -356,19 +356,11 @@ ExceptionOr<RefPtr<ImageBitmap>> OffscreenCanvas::transferToImageBitmap()
         auto buffer = allocateImageBuffer();
         if (!buffer)
             return { RefPtr<ImageBitmap> { nullptr } };
-
+        if (webGLContext->compositingResultsNeedUpdating())
+            webGLContext->prepareForDisplay();
         RefPtr gc3d = webGLContext->graphicsContextGL();
-        gc3d->drawSurfaceBufferToImageBuffer(GraphicsContextGL::SurfaceBuffer::DrawingBuffer, *buffer);
-
-        // FIXME: The transfer algorithm requires that the canvas effectively
-        // creates a new backing store. Since we're not doing that yet, we
-        // need to erase what's there.
-
-        GCGLfloat clearColor[4] { };
-        gc3d->getFloatv(GraphicsContextGL::COLOR_CLEAR_VALUE, clearColor);
-        gc3d->clearColor(0, 0, 0, 0);
-        gc3d->clear(GraphicsContextGL::COLOR_BUFFER_BIT | GraphicsContextGL::DEPTH_BUFFER_BIT | GraphicsContextGL::STENCIL_BUFFER_BIT);
-        gc3d->clearColor(clearColor[0], clearColor[1], clearColor[2], clearColor[3]);
+        gc3d->drawSurfaceBufferToImageBuffer(GraphicsContextGL::SurfaceBuffer::DisplayBuffer, *buffer);
+        webGLContext->markDrawingBuffersDirtyAfterTransfer();
         return { ImageBitmap::create(buffer.releaseNonNull(), originClean()) };
     }
 #endif

diff --git a/Source/WebCore/html/canvas/WebGLDefaultFramebuffer.cpp b/Source/WebCore/html/canvas/WebGLDefaultFramebuffer.cpp
@@ -67,6 +67,15 @@ void WebGLDefaultFramebuffer::markAllUnpreservedBuffersDirty()
     m_dirtyBuffers = m_unpreservedBuffers;
 }
 
+void WebGLDefaultFramebuffer::markAllBuffersDirty()
+{
+    m_dirtyBuffers |= GraphicsContextGL::COLOR_BUFFER_BIT;
+    if (m_hasStencil)
+        m_dirtyBuffers |= GraphicsContextGL::STENCIL_BUFFER_BIT;
+    if (m_hasDepth)
+        m_dirtyBuffers |= GraphicsContextGL::DEPTH_BUFFER_BIT;
+}
+
 }
 
 #endif
diff --git a/Source/WebCore/html/canvas/WebGLDefaultFramebuffer.h b/Source/WebCore/html/canvas/WebGLDefaultFramebuffer.h
@@ -46,6 +46,7 @@ class WebGLDefaultFramebuffer {
     GCGLbitfield dirtyBuffers() const { return m_dirtyBuffers; }
     void markBuffersClear(GCGLbitfield clearBuffers);
     void markAllUnpreservedBuffersDirty();
+    void markAllBuffersDirty();
 
 private:
     WebGLDefaultFramebuffer(WebGLRenderingContextBase&);

diff --git a/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp b/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp
@@ -810,6 +810,14 @@ RefPtr<VideoFrame> WebGLRenderingContextBase::surfaceBufferToVideoFrame(SurfaceB
 }
 #endif
 
+void WebGLRenderingContextBase::markDrawingBuffersDirtyAfterTransfer()
+{
+    // Any draw or read sees cleared drawing buffer.
+    m_defaultFramebuffer->markAllBuffersDirty();
+    // Next transfer uses the cleared drawing buffer.
+    m_compositingResultsNeedUpdating = true;
+}
+
 WebGLTexture::TextureExtensionFlag WebGLRenderingContextBase::textureExtensionFlags() const
 {
     return static_cast<WebGLTexture::TextureExtensionFlag>((m_oesTextureFloatLinear ? WebGLTexture::TextureExtensionFloatLinearEnabled : 0) | (m_oesTextureHalfFloatLinear ? WebGLTexture::TextureExtensionHalfFloatLinearEnabled : 0));
@@ -5682,6 +5690,7 @@ void WebGLRenderingContextBase::prepareForDisplay()
         return;
     ASSERT(m_compositingResultsNeedUpdating);
 
+    clearIfComposited(CallerTypeOther);
     m_context->prepareForDisplay();
     m_defaultFramebuffer->markAllUnpreservedBuffersDirty();
 

diff --git a/Source/WebCore/html/canvas/WebGLRenderingContextBase.h b/Source/WebCore/html/canvas/WebGLRenderingContextBase.h
@@ -445,6 +445,7 @@ class WebGLRenderingContextBase : public GraphicsContextGL::Client, public GPUBa
 #if ENABLE(MEDIA_STREAM) || ENABLE(WEB_CODECS)
     RefPtr<VideoFrame> surfaceBufferToVideoFrame(SurfaceBuffer);
 #endif
+    void markDrawingBuffersDirtyAfterTransfer();
 
     void removeSharedObject(WebGLObject&);
     void removeContextObject(WebGLObject&);
@@ -486,6 +487,9 @@ class WebGLRenderingContextBase : public GraphicsContextGL::Client, public GPUBa
     const PixelStoreParameters& unpackPixelStoreParameters() const { return m_unpackParameters; };
 
     WeakPtr<WebGLRenderingContextBase> createRefForContextObject();
+
+    bool compositingResultsNeedUpdating() const final { return m_compositingResultsNeedUpdating; }
+    void prepareForDisplay() final;
 protected:
     WebGLRenderingContextBase(CanvasBase&, WebGLContextAttributes&&);
 
@@ -590,10 +594,7 @@ class WebGLRenderingContextBase : public GraphicsContextGL::Client, public GPUBa
     void loseExtensions(LostContextMode);
 
     virtual void uncacheDeletedBuffer(const AbstractLocker&, WebGLBuffer*);
-
-    bool compositingResultsNeedUpdating() const final { return m_compositingResultsNeedUpdating; }
     bool needsPreparationForDisplay() const final { return true; }
-    void prepareForDisplay() final;
     void updateActiveOrdinal();
 
     struct ContextLostState {