16 bpp video stream capture, render and createImageBitmap(video) using (CPU) shared memory buffers

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index b93c275adfe6684bfb9dd6717913b9eda890da21..c4eb4c5b83b0b000bc3c934d0f0b6ea0c510582a 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -501,6 +501,28 @@ class ScopedFramebufferRestorer {
   Member<WebGLRenderingContextBase> m_context;
 };
 
+class ScopedUnpackParametersResetRestore {
+  STACK_ALLOCATED();
+
+ public:
+  explicit ScopedUnpackParametersResetRestore(
+      WebGLRenderingContextBase* context,
+      bool enabled = true)
+      : m_context(context), m_enabled(enabled) {
+    if (enabled)
+      m_context->resetUnpackParameters();
+  }
+
+  ~ScopedUnpackParametersResetRestore() {
+    if (m_enabled)
+      m_context->restoreUnpackParameters();
+  }
+
+ private:
+  Member<WebGLRenderingContextBase> m_context;
+  bool m_enabled;
+};
+
 static void formatWebGLStatusString(const StringView& glInfo,
                                     const StringView& infoString,
                                     StringBuilder& builder) {
@@ -4344,7 +4366,7 @@ void WebGLRenderingContextBase::texImageImpl(
     }
   }
 
-  resetUnpackParameters();
+  ScopedUnpackParametersResetRestore temporaryResetUnpack(this);
   if (functionID == TexImage2D) {
     texImage2DBase(target, level, internalformat, imageExtractor.imageWidth(),
                    imageExtractor.imageHeight(), 0, format, type,
@@ -4361,7 +4383,6 @@ void WebGLRenderingContextBase::texImageImpl(
                                imageExtractor.imageHeight(), 1, format, type,
                                needConversion ? data.data() : imagePixelData);
   }
-  restoreUnpackParameters();
 }
 
 bool WebGLRenderingContextBase::validateTexFunc(
@@ -4547,16 +4568,14 @@ void WebGLRenderingContextBase::texImageHelperDOMArrayBufferView(
     return;
   }
 
-  if (changeUnpackAlignment)
-    resetUnpackParameters();
+  ScopedUnpackParametersResetRestore temporaryResetUnpack(
+      this, changeUnpackAlignment);
   if (functionID == TexImage2D)
     texImage2DBase(target, level, internalformat, width, height, border, format,
                    type, data);
   else if (functionID == TexSubImage2D)
     contextGL()->TexSubImage2D(target, level, xoffset, yoffset, width, height,
                                format, type, data);
-  if (changeUnpackAlignment)
-    restoreUnpackParameters();
 }
 
 void WebGLRenderingContextBase::texImage2D(GLenum target,
@@ -4630,7 +4649,7 @@ void WebGLRenderingContextBase::texImageHelperImageData(
       return;
     }
   }
-  resetUnpackParameters();
+  ScopedUnpackParametersResetRestore temporaryResetUnpack(this);
   if (functionID == TexImage2D) {
     texImage2DBase(target, level, internalformat, pixels->width(),
                    pixels->height(), border, format, type,
@@ -4646,7 +4665,6 @@ void WebGLRenderingContextBase::texImageHelperImageData(
         pixels->height(), depth, format, type,
         needConversion ? data.data() : pixels->data()->data());
   }
-  restoreUnpackParameters();
 }
 
 void WebGLRenderingContextBase::texImage2D(GLenum target,
@@ -4957,45 +4975,58 @@ void WebGLRenderingContextBase::texImageHelperHTMLVideoElement(
                        yoffset, zoffset))
     return;
 
-  if (functionID == TexImage2D) {
+  const bool useCopyTextureChromium =
+      functionID == TexImage2D && GL_TEXTURE_2D == target &&
+      Extensions3DUtil::canUseCopyTextureCHROMIUM(target, internalformat, type,
+                                                  level);
+  if (useCopyTextureChromium) {
     // Go through the fast path doing a GPU-GPU textures copy without a readback
-    // to system memory if possible.  Otherwise, it will fall back to the normal
-    // SW path.
-    if (GL_TEXTURE_2D == target) {
-      if (Extensions3DUtil::canUseCopyTextureCHROMIUM(target, internalformat,
-                                                      type, level) &&
-          video->copyVideoTextureToPlatformTexture(
-              contextGL(), texture->object(), internalformat, type,
-              m_unpackPremultiplyAlpha, m_unpackFlipY)) {
-        return;
-      }
+    // to system memory if possible.
+    // Otherwise, it will fall back to the normal SW path.
+    if (video->copyVideoTextureToPlatformTexture(
+            contextGL(), texture->object(), internalformat, type,
+            m_unpackPremultiplyAlpha, m_unpackFlipY)) {
+      return;
+    }
+  }
 
-      // Try using an accelerated image buffer, this allows YUV conversion to be
-      // done on the GPU.
-      std::unique_ptr<ImageBufferSurface> surface =
-          wrapUnique(new AcceleratedImageBufferSurface(
-              IntSize(video->videoWidth(), video->videoHeight())));
-      if (surface->isValid()) {
-        std::unique_ptr<ImageBuffer> imageBuffer(
-            ImageBuffer::create(std::move(surface)));
-        if (imageBuffer) {
-          // The video element paints an RGBA frame into our surface here. By
-          // using an AcceleratedImageBufferSurface, we enable the
-          // WebMediaPlayer implementation to do any necessary color space
-          // conversion on the GPU (though it
-          // may still do a CPU conversion and upload the results).
-          video->paintCurrentFrame(
-              imageBuffer->canvas(),
-              IntRect(0, 0, video->videoWidth(), video->videoHeight()),
-              nullptr);
-
-          // This is a straight GPU-GPU copy, any necessary color space
-          // conversion was handled in the paintCurrentFrameInContext() call.
-          if (imageBuffer->copyToPlatformTexture(
-                  contextGL(), texture->object(), internalformat, type, level,
-                  m_unpackPremultiplyAlpha, m_unpackFlipY)) {
-            return;
-          }
+  {
+    // Try using optimized CPU-GPU path for some formats: e.g. Y16 and Y8. It
+    // leaves early for other formats or if frame is stored on GPU.
+    ScopedUnpackParametersResetRestore(
+        this, m_unpackFlipY || m_unpackPremultiplyAlpha);
+    if (video->texImageImpl(getTexImageFunctionName(functionID), target,
+                            contextGL(), level, internalformat, format, type,
+                            xoffset, yoffset, zoffset, m_unpackFlipY,
+                            m_unpackPremultiplyAlpha &&
+                                m_unpackColorspaceConversion == GL_NONE))
+      return;
+  }
+
+  if (useCopyTextureChromium) {
+    // Try using an accelerated image buffer, this allows YUV conversion to be
+    // done on the GPU.
+    std::unique_ptr<ImageBufferSurface> surface =
+        wrapUnique(new AcceleratedImageBufferSurface(
+            IntSize(video->videoWidth(), video->videoHeight())));
+    if (surface->isValid()) {
+      std::unique_ptr<ImageBuffer> imageBuffer(
+          ImageBuffer::create(std::move(surface)));
+      if (imageBuffer) {
+        // The video element paints an RGBA frame into our surface here.  By
+        // using an AcceleratedImageBufferSurface, we enable the WebMediaPlayer
+        // implementation to do any necessary color space conversion on the GPU
+        // (though it may still do a CPU conversion and upload the results).
+        video->paintCurrentFrame(
+            imageBuffer->canvas(),
+            IntRect(0, 0, video->videoWidth(), video->videoHeight()), nullptr);
+
+        // This is a straight GPU-GPU copy, any necessary color space conversion
+        // was handled in the paintCurrentFrameInContext() call.
+        if (imageBuffer->copyToPlatformTexture(
+                contextGL(), texture->object(), internalformat, type, level,
+                m_unpackPremultiplyAlpha, m_unpackFlipY)) {
+          return;
         }
       }
     }
@@ -5120,7 +5151,7 @@ void WebGLRenderingContextBase::texImageHelperImageBitmap(
       return;
     }
   }
-  resetUnpackParameters();
+  ScopedUnpackParametersResetRestore temporaryResetUnpack(this);
   if (functionID == TexImage2D) {
     texImage2DBase(target, level, internalformat, bitmap->width(),
                    bitmap->height(), 0, format, type,
@@ -5136,7 +5167,6 @@ void WebGLRenderingContextBase::texImageHelperImageBitmap(
                                type,
                                needConversion ? data.data() : pixelDataPtr);
   }
-  restoreUnpackParameters();
 }
 
 void WebGLRenderingContextBase::texImage2D(GLenum target,