Enable WebGL rendering into ImageCHROMIUM, backed by a scanout buffer to enable overlay suppor…

Source/platform/graphics/gpu/DrawingBuffer.cpp

Index: Source/platform/graphics/gpu/DrawingBuffer.cpp
diff --git a/Source/platform/graphics/gpu/DrawingBuffer.cpp b/Source/platform/graphics/gpu/DrawingBuffer.cpp
index 8927cd7eb2ea07757d87929eff452128fe81650e..0932e14b8ee9480ceffe54706a823d35a7ad9f87 100644
--- a/Source/platform/graphics/gpu/DrawingBuffer.cpp
+++ b/Source/platform/graphics/gpu/DrawingBuffer.cpp
@@ -147,6 +147,11 @@ DrawingBuffer::DrawingBuffer(PassOwnPtr<blink::WebGraphicsContext3D> context,
     , m_sampleCount(0)
     , m_packAlignment(4)
     , m_destructionInProgress(false)
+#ifdef ENABLE_WEBGL_IMAGE_CHROMIUM

[piman, 2014/05/09 19:34:14]

Why an ifdef? Should we, say, turn it on with a command-line flag?

+    , m_useImageChromium(true)
+#else
+    , m_useImageChromium(false)
+#endif
     , m_contextEvictionManager(contextEvictionManager)
 {
     // Used by browser tests to detect the use of a DrawingBuffer.
@@ -228,7 +233,8 @@ bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox,
 
     // No buffer available to recycle, create a new one.
     if (!frontColorBufferMailbox) {
-        unsigned newColorBuffer = createColorTexture(m_size);
+        unsigned newColorBuffer = createColorTexture();
+        allocateTextureMemory(newColorBuffer, m_size);
         // Bad things happened, abandon ship.
         if (!newColorBuffer)
             return false;
@@ -323,7 +329,7 @@ PassRefPtr<DrawingBuffer::MailboxInfo> DrawingBuffer::recycledMailbox()
 
     if (mailboxInfo->size != m_size) {
         m_context->bindTexture(GL_TEXTURE_2D, mailboxInfo->textureId);
-        texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, m_size.width(), m_size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
+        allocateTextureMemory(mailboxInfo->textureId, m_size);
         mailboxInfo->size = m_size;
     }
 
@@ -346,6 +352,9 @@ void DrawingBuffer::deleteMailbox(const blink::WebExternalTextureMailbox& mailbo
         if (nameEquals(m_textureMailboxes[i]->mailbox, mailbox)) {
             if (mailbox.syncPoint)
                 m_context->waitSyncPoint(mailbox.syncPoint);
+            if (m_useImageChromium)
+                deleteChromiumImageForTexture(m_textureMailboxes[i]->textureId);
+
             m_context->deleteTexture(m_textureMailboxes[i]->textureId);
             m_textureMailboxes.remove(i);
             return;
@@ -530,7 +539,8 @@ void DrawingBuffer::paintCompositedResultsToCanvas(ImageBuffer* imageBuffer)
     // We have to make a copy of it here and bind that copy instead.
     // FIXME: That's not true any more, provided we don't change texture
     // parameters.
-    unsigned sourceTexture = createColorTexture(m_size);
+    unsigned sourceTexture = createColorTexture();
+    texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, m_size.width(), m_size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
     m_context->copyTextureCHROMIUM(GL_TEXTURE_2D, m_frontColorBuffer, sourceTexture, 0, GL_RGBA, GL_UNSIGNED_BYTE);
 
     // Since we're using the same context as WebGL, we have to restore any state we change (in this case, just the framebuffer binding).
@@ -588,8 +598,12 @@ void DrawingBuffer::beginDestruction()
     if (m_stencilBuffer)
         m_context->deleteRenderbuffer(m_stencilBuffer);
 
-    if (m_colorBuffer)
+    if (m_colorBuffer) {
+        if (m_useImageChromium)
+            deleteChromiumImageForTexture(m_colorBuffer);
+
         m_context->deleteTexture(m_colorBuffer);
+    }
 
     setSize(IntSize());
 
@@ -607,7 +621,7 @@ void DrawingBuffer::beginDestruction()
         GraphicsLayer::unregisterContentsLayer(m_layer->layer());
 }
 
-unsigned DrawingBuffer::createColorTexture(const IntSize& size)
+unsigned DrawingBuffer::createColorTexture()
 {
     unsigned offscreenColorTexture = m_context->createTexture();
     if (!offscreenColorTexture)
@@ -618,8 +632,6 @@ unsigned DrawingBuffer::createColorTexture(const IntSize& size)
     m_context->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     m_context->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     m_context->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-    if (!size.isEmpty())
-        texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
 
     return offscreenColorTexture;
 }
@@ -641,7 +653,7 @@ bool DrawingBuffer::resizeFramebuffer(const IntSize& size)
 
     m_context->bindTexture(GL_TEXTURE_2D, m_colorBuffer);
 
-    texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
+    allocateTextureMemory(m_colorBuffer, m_size);
 
     if (m_multisampleMode == ImplicitResolve)
         m_context->framebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer, 0, m_sampleCount);
@@ -1020,4 +1032,31 @@ void DrawingBuffer::texImage2DResourceSafe(GLenum target, GLint level, GLenum in
     m_context->texImage2D(target, level, internalformat, width, height, border, format, type, 0);
 }
 
+void DrawingBuffer::allocateTextureMemory(Platform3DObject textureId, const IntSize& size)
+{
+    if (m_useImageChromium) {
+        deleteChromiumImageForTexture(textureId);
+
+        blink::WGC3Duint newImage = m_context->createImageCHROMIUM(size.width(), size.height(), GL_RGBA8_OES, GC3D_IMAGE_SCANOUT_CHROMIUM);
+        if (newImage) {
+            m_context->bindTexImage2DCHROMIUM(GL_TEXTURE_2D, newImage);
+            m_textureToImageChromiumMap.add(textureId, newImage);
+            return;
+        }
+    }
+
+    texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
+}
+
+void DrawingBuffer::deleteChromiumImageForTexture(Platform3DObject textureId)
+{
+    HashMap<Platform3DObject, blink::WGC3Duint>::iterator imageIter = m_textureToImageChromiumMap.find(textureId);
+    // Release the old buffer if we have any.
+    if (imageIter != m_textureToImageChromiumMap.end()) {
+        m_context->releaseTexImage2DCHROMIUM(GL_TEXTURE_2D, imageIter->value);
+        m_context->destroyImageCHROMIUM(imageIter->value);
+        m_textureToImageChromiumMap.remove(imageIter);
+    }
+}
+
 } // namespace WebCore