Use GLHelper for glReadPixels and format detection

GLHelper has functionality for testing for appropriate GL readback
format support, caching this information where appropriate. This change
switches RendererGpuVideoAcceleratorFactories over to using that code
for supported format identification and glReadPixels in the desired
format. The code continues to do a software swizzle if necessary.

TEST=WebGL conformance tests
BUG=None

Review URL: https://codereview.chromium.org/456823002

Cr-Commit-Position: refs/heads/master@{#293358}

content/renderer/media/renderer_gpu_video_accelerator_factories.cc

@@ -10,6 +10,7 @@
 #include "base/bind.h"
 #include "content/child/child_thread.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
+#include "content/common/gpu/client/gl_helper.h"
 #include "content/common/gpu/client/gpu_channel_host.h"
 #include "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 #include "content/renderer/render_thread_impl.h"
@@ -64,11 +65,24 @@ RendererGpuVideoAcceleratorFactories::GetContext3d() {
   if (context_provider_->IsContextLost()) {
     context_provider_->VerifyContexts();
     context_provider_ = NULL;
+    gl_helper_.reset(NULL);
     return NULL;
   }
   return context_provider_->WebContext3D();
 }
 
+GLHelper* RendererGpuVideoAcceleratorFactories::GetGLHelper() {
+  if (!GetContext3d())
+    return NULL;
+
+  if (gl_helper_.get() == NULL) {
+    gl_helper_.reset(new GLHelper(GetContext3d()->GetImplementation(),
+                                  GetContext3d()->GetContextSupport()));
+  }
+
+  return gl_helper_.get();
+}
+
 scoped_ptr<media::VideoDecodeAccelerator>
 RendererGpuVideoAcceleratorFactories::CreateVideoDecodeAccelerator() {
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ -178,59 +192,29 @@ void RendererGpuVideoAcceleratorFactories::ReadPixels(
     const SkBitmap& pixels) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
+  GLHelper* gl_helper = GetGLHelper();
   WebGraphicsContext3DCommandBufferImpl* context = GetContext3d();
-  if (!context)
-    return;
 
-  gpu::gles2::GLES2Implementation* gles2 = context->GetImplementation();
+  if (!gl_helper || !context)
+    return;
 
+  // Copy texture from texture_id to tmp_texture as texture might be external
+  // (GL_TEXTURE_EXTERNAL_OES)
   GLuint tmp_texture;
-  gles2->GenTextures(1, &tmp_texture);
-  gles2->BindTexture(GL_TEXTURE_2D, tmp_texture);
-  gles2->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-  gles2->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-  gles2->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-  gles2->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  tmp_texture = gl_helper->CreateTexture();
   context->copyTextureCHROMIUM(
       GL_TEXTURE_2D, texture_id, tmp_texture, 0, GL_RGBA, GL_UNSIGNED_BYTE);
 
-  GLuint fb;
-  gles2->GenFramebuffers(1, &fb);
-  gles2->BindFramebuffer(GL_FRAMEBUFFER, fb);
-  gles2->FramebufferTexture2D(
-      GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tmp_texture, 0);
-  gles2->PixelStorei(GL_PACK_ALIGNMENT, 4);
-
-#if SK_B32_SHIFT == 0 && SK_G32_SHIFT == 8 && SK_R32_SHIFT == 16 && \
-    SK_A32_SHIFT == 24
-  GLenum skia_format = GL_BGRA_EXT;
-  GLenum read_format = GL_BGRA_EXT;
-  GLint supported_format = 0;
-  GLint supported_type = 0;
-  gles2->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &supported_format);
-  gles2->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &supported_type);
-  if (supported_format != GL_BGRA_EXT || supported_type != GL_UNSIGNED_BYTE) {
-    read_format = GL_RGBA;
-  }
-#elif SK_R32_SHIFT == 0 && SK_G32_SHIFT == 8 && SK_B32_SHIFT == 16 && \
-    SK_A32_SHIFT == 24
-  GLenum skia_format = GL_RGBA;
-  GLenum read_format = GL_RGBA;
-#else
-#error Unexpected Skia ARGB_8888 layout!
-#endif
-  gles2->ReadPixels(visible_rect.x(),
-                    visible_rect.y(),
-                    visible_rect.width(),
-                    visible_rect.height(),
-                    read_format,
-                    GL_UNSIGNED_BYTE,
-                    pixels.pixelRef()->pixels());
-  gles2->DeleteFramebuffers(1, &fb);
-  gles2->DeleteTextures(1, &tmp_texture);
-
-  if (skia_format != read_format) {
-    DCHECK(read_format == GL_RGBA);
+  unsigned char* pixel_data =
+      static_cast<unsigned char*>(pixels.pixelRef()->pixels());
+
+  if (gl_helper->IsReadbackConfigSupported(pixels.colorType())) {
+    gl_helper->ReadbackTextureSync(
+        tmp_texture, visible_rect, pixel_data, pixels.colorType());
+  } else if (pixels.colorType() == kN32_SkColorType) {
+    gl_helper->ReadbackTextureSync(
+        tmp_texture, visible_rect, pixel_data, kRGBA_8888_SkColorType);
+
     int pixel_count = visible_rect.width() * visible_rect.height();
     uint32_t* pixels_ptr = static_cast<uint32_t*>(pixels.pixelRef()->pixels());
     for (int i = 0; i < pixel_count; ++i) {
@@ -243,9 +227,11 @@ void RendererGpuVideoAcceleratorFactories::ReadPixels(
                         (b << SK_B32_SHIFT) |
                         (a << SK_A32_SHIFT);
     }
+  } else {
+    NOTREACHED();
   }
 
-  DCHECK_EQ(gles2->GetError(), static_cast<GLenum>(GL_NO_ERROR));
+  gl_helper->DeleteTexture(tmp_texture);
 }
 
 base::SharedMemory* RendererGpuVideoAcceleratorFactories::CreateSharedMemory(

content/renderer/media/renderer_gpu_video_accelerator_factories.h

@@ -22,6 +22,7 @@ class WaitableEvent;
 
 namespace content {
 class ContextProviderCommandBuffer;
+class GLHelper;
 class GpuChannelHost;
 class WebGraphicsContext3DCommandBufferImpl;
 
@@ -78,10 +79,12 @@ class CONTENT_EXPORT RendererGpuVideoAcceleratorFactories
   // Helper to get a pointer to the WebGraphicsContext3DCommandBufferImpl,
   // if it has not been lost yet.
   WebGraphicsContext3DCommandBufferImpl* GetContext3d();
+  GLHelper* GetGLHelper();
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   scoped_refptr<GpuChannelHost> gpu_channel_host_;
   scoped_refptr<ContextProviderCommandBuffer> context_provider_;
+  scoped_ptr<GLHelper> gl_helper_;
 
   // For sending requests to allocate shared memory in the Browser process.
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;