Implement transferToImageBitmap() in WebGLRenderingContext

third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp

Index: third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp b/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
index 0d596995fbf8df72a8cd4bc9efdb6ec61d948881..ac88b3d3d8c066136131b2f7aa9719f45976c96e 100644
--- a/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
+++ b/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
@@ -4,8 +4,12 @@
 
 #include "platform/graphics/StaticBitmapImage.h"
 
+#include "gpu/command_buffer/client/gles2_interface.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/ImageObserver.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebGraphicsContext3DProvider.h"
+#include "skia/ext/texture_handle.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkPaint.h"
@@ -20,11 +24,20 @@ PassRefPtr<StaticBitmapImage> StaticBitmapImage::create(PassRefPtr<SkImage> imag
     return adoptRef(new StaticBitmapImage(image));
 }
 
+PassRefPtr<StaticBitmapImage> StaticBitmapImage::create(WebExternalTextureMailbox& mailbox)
+{
+    return adoptRef(new StaticBitmapImage(mailbox));
+}
+
 StaticBitmapImage::StaticBitmapImage(PassRefPtr<SkImage> image) : m_image(image)
 {
     ASSERT(m_image);
 }
 
+StaticBitmapImage::StaticBitmapImage(WebExternalTextureMailbox& mailbox) : m_mailbox(mailbox)
+{
+}
+
 StaticBitmapImage::~StaticBitmapImage() { }
 
 IntSize StaticBitmapImage::size() const
@@ -55,6 +68,34 @@ void StaticBitmapImage::draw(SkCanvas* canvas, const SkPaint& paint, const Float
 
 PassRefPtr<SkImage> StaticBitmapImage::imageForCurrentFrame()
 {
+    if (m_image)
+        return m_image;
+    DCHECK(isMainThread());
+    // In the place when we consume an ImageBitmap that is gpu texture backed,
+    // create a new SkImage from that texture.
+    // TODO(xidachen): make this work on a worker thread.
+    OwnPtr<WebGraphicsContext3DProvider> provider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
+    if (!provider)
+        return nullptr;
+    GrContext* grContext = provider->grContext();
+    if (!grContext)
+        return nullptr;
+    gpu::gles2::GLES2Interface* gl = provider->contextGL();
+    if (!gl)
+        return nullptr;
+    gl->WaitSyncTokenCHROMIUM(m_mailbox.syncToken);
+    GLuint textureId = gl->CreateAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, m_mailbox.name);
+    GrGLTextureInfo textureInfo;
+    textureInfo.fTarget = GL_TEXTURE_2D;
+    textureInfo.fID = textureId;
+    GrBackendTextureDesc backendTexture;
+    backendTexture.fOrigin = kBottomLeft_GrSurfaceOrigin;
+    backendTexture.fWidth = m_mailbox.textureSize.width;
+    backendTexture.fHeight = m_mailbox.textureSize.height;
+    backendTexture.fConfig = kSkia8888_GrPixelConfig;
+    backendTexture.fTextureHandle = skia::GrGLTextureInfoToGrBackendObject(textureInfo);
+    sk_sp<SkImage> skImage = SkImage::MakeFromAdoptedTexture(grContext, backendTexture);
+    m_image = fromSkSp(skImage);

[xidachen, 2016/05/19 20:43:51]

Here we cache this SkImage, so the next time when it gets to this function, we
have a m_image and we just return that m_image at the very beginning of this
function. Wouldn't that prevent the problem when we try to consume the texture
multiple times?

[Ken Russell (switch to Gerrit), 2016/05/19 21:38:42]

I don't think so. The same ImageBitmap might be consumed by different contexts
each time.

     return m_image;
 }