Avoid GPU readback in tex(Sub)Image2D(ImageBitmap)

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 ac88b3d3d8c066136131b2f7aa9719f45976c96e..5cb8b3a9a780cffa5f266b7947935ac8e74841ce 100644
--- a/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
+++ b/third_party/WebKit/Source/platform/graphics/StaticBitmapImage.cpp
@@ -14,6 +14,7 @@
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkShader.h"
+#include "third_party/skia/include/gpu/GrContext.h"
 
 namespace blink {
 
@@ -42,9 +43,16 @@ StaticBitmapImage::~StaticBitmapImage() { }
 
 IntSize StaticBitmapImage::size() const
 {
+    if (!m_image)
+        return IntSize(m_mailbox.textureSize.width, m_mailbox.textureSize.height);
     return IntSize(m_image->width(), m_image->height());
 }
 
+bool StaticBitmapImage::isTextureBacked()
+{
+    return m_image && m_image->isTextureBacked();
+}
+
 bool StaticBitmapImage::currentFrameKnownToBeOpaque(MetadataMode)
 {
     return m_image->isOpaque();
@@ -66,28 +74,21 @@ void StaticBitmapImage::draw(SkCanvas* canvas, const SkPaint& paint, const Float
         observer->didDraw(this);
 }
 
-PassRefPtr<SkImage> StaticBitmapImage::imageForCurrentFrame()
+void StaticBitmapImage::switchStorageToSkImage(WebGraphicsContext3DProvider* provider)
 {
-    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;
+        return;
     GrContext* grContext = provider->grContext();
     if (!grContext)
-        return nullptr;
+        return;
     gpu::gles2::GLES2Interface* gl = provider->contextGL();
     if (!gl)
-        return nullptr;
+        return;
     gl->WaitSyncTokenCHROMIUM(m_mailbox.syncToken);
-    GLuint textureId = gl->CreateAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, m_mailbox.name);
+    m_textureId = gl->CreateAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, m_mailbox.name);
     GrGLTextureInfo textureInfo;
     textureInfo.fTarget = GL_TEXTURE_2D;
-    textureInfo.fID = textureId;
+    textureInfo.fID = m_textureId;
     GrBackendTextureDesc backendTexture;
     backendTexture.fOrigin = kBottomLeft_GrSurfaceOrigin;
     backendTexture.fWidth = m_mailbox.textureSize.width;
@@ -96,6 +97,93 @@ PassRefPtr<SkImage> StaticBitmapImage::imageForCurrentFrame()
     backendTexture.fTextureHandle = skia::GrGLTextureInfoToGrBackendObject(textureInfo);
     sk_sp<SkImage> skImage = SkImage::MakeFromAdoptedTexture(grContext, backendTexture);
     m_image = fromSkSp(skImage);
+}
+
+void StaticBitmapImage::copyToTexture(WebGraphicsContext3DProvider* provider, GLuint destinationTexture, GLenum internalFormat, GLenum destType, bool flipY)
+{
+    gpu::gles2::GLES2Interface* gl = provider->contextGL();
+    if (!gl)
+        return;
+    gl->CopyTextureCHROMIUM(m_textureId, destinationTexture, internalFormat, destType, flipY, false, false);
+    const GLuint64 fenceSync = gl->InsertFenceSyncCHROMIUM();
+    GLbyte syncToken[24];
+    gl->GenSyncTokenCHROMIUM(fenceSync, syncToken);
+}
+
+bool StaticBitmapImage::switchStorageToMailbox(WebGraphicsContext3DProvider* provider)
+{
+    m_mailbox.textureSize = WebSize(m_image->width(), m_image->height());
+    GrContext* grContext = provider->grContext();
+    if (!grContext)
+        return false;
+    grContext->flush();
+    m_mailbox.textureTarget = GL_TEXTURE_2D;
+    gpu::gles2::GLES2Interface* gl = provider->contextGL();
+    if (!gl)
+        return false;
+    GLuint textureID = skia::GrBackendObjectToGrGLTextureInfo(m_image->getTextureHandle(true))->fID;
+    gl->BindTexture(GL_TEXTURE_2D, textureID);
+
+    gl->GenMailboxCHROMIUM(m_mailbox.name);
+    gl->ProduceTextureCHROMIUM(GL_TEXTURE_2D, m_mailbox.name);
+    const GLuint64 fenceSync = gl->InsertFenceSyncCHROMIUM();
+    gl->Flush();
+    gl->GenSyncTokenCHROMIUM(fenceSync, m_mailbox.syncToken);
+    m_mailbox.validSyncToken = true;
+    gl->BindTexture(GL_TEXTURE_2D, 0);
+    grContext->resetContext(kTextureBinding_GrGLBackendState);
+    m_image = nullptr;
+    return true;
+}
+
+PassRefPtr<SkImage> StaticBitmapImage::imageForCurrentFrame(WebGraphicsContext3DProvider* contextProvider)
+{
+    if (m_image) {
+        // If the SkImage is not texture-backed
+        if (!m_image->isTextureBacked())
+            return m_image;
+        // SkImage is texture-backed, but no mailbox exists. virtual/gpu/ cases.
+        if (!hasMailbox()) {
+            // SkImage is texture-backed on the shared context
+            if (contextProvider) {
+                OwnPtr<WebGraphicsContext3DProvider> sharedProvider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
+                if (!switchStorageToMailbox(sharedProvider.get()))
+                    return nullptr;
+                switchStorageToSkImage(contextProvider);
+                RefPtr<SkImage> retVal = m_image;
+                // Get a new mailbox because we cannot retain a texture in the WebGL context.
+                if (!switchStorageToMailbox(contextProvider))
+                    return nullptr;
+                return retVal;
+            }
+            return m_image;
+        }
+        // Has mailbox, but contextProvider is null (2D).
+        if (!contextProvider)
+            return m_image;
+        // 3D context, consume mailbox, prepare a new mailbox.
+        switchStorageToSkImage(contextProvider);
+        RefPtr<SkImage> retVal = m_image;
+        if (!switchStorageToMailbox(contextProvider))
+            return nullptr;
+        return retVal;
+    }
+    // No mailbox, return null;
+    if (!hasMailbox())
+        return nullptr;
+    // Has mailbox, consume mailbox, prepare a new mailbox if contextProvider is not null (3D).
+    if (!contextProvider) {
+        DCHECK(isMainThread());
+        // TODO(xidachen): make this work on a worker thread.
+        OwnPtr<WebGraphicsContext3DProvider> sharedProvider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
+        switchStorageToSkImage(sharedProvider.get());
+    } else {
+        switchStorageToSkImage(contextProvider);
+        RefPtr<SkImage> retVal = m_image;
+        if (!switchStorageToMailbox(contextProvider))
+            return nullptr;
+        return retVal;
+    }
     return m_image;
 }