webgl: optimize webgl.texSubImage2D(video) path.

content/renderer/media/android/webmediaplayer_android.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/android/webmediaplayer_android.h"
 
 #include <limits>
 
 #include "base/android/build_info.h"
 #include "base/bind.h"
@@ skipping 616 matching lines @@
   // a new one based on video size.
   if (!IsSkBitmapProperlySizedTexture(&bitmap_, naturalSize())) {
     if (!AllocateSkBitmapTexture(provider->grContext(), &bitmap_,
                                  naturalSize())) {
       return;
     }
   }
 
   unsigned textureId = static_cast<unsigned>(
     (bitmap_.getTexture())->getTextureHandle());
-  if (!copyVideoTextureToPlatformTexture(context3D, textureId,
-      GL_RGBA, GL_UNSIGNED_BYTE, true, false)) {
+  if (!copyVideoTextureToPlatformTexture(
+          context3D,
+          {CopyVideoTextureParams::FullCopy, GL_TEXTURE_2D, textureId, GL_RGBA,

[DaleCurtis, 2015/10/21 18:35:50]

Hmm, does this work by way of a C++11 initializer list? I don't remember this
working otherwise. I think you need to use a temporary "BlahBlah a = {...}"
here. 

[dshwang, 2015/10/21 19:31:07]

Yes, it's by C++11 initializer list;
https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Braced_Initi...
Is it banned in chromium?

As I remember, initializer list for std::vector is banned but initializer list
for struct might be fine...

[DaleCurtis, 2015/10/22 00:35:28]

Yup, banned wholesale currently https://chromium-cpp.appspot.com/ -- see uniform
initialization syntax.

[dshwang, 2015/10/22 13:23:03]

Thanks for investigation. I replace it to constructor.

FYI, constructor in struct is allowed by coding style;
https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Structs_vs._...

+           GL_UNSIGNED_BYTE, 0, 0, 0, true, false})) {
     return;
   }
 
   // Draw the texture based bitmap onto the Canvas. If the canvas is
   // hardware based, this will do a GPU-GPU texture copy.
   // If the canvas is software based, the texture based bitmap will be
   // readbacked to system memory then draw onto the canvas.
   SkRect dest;
   dest.set(rect.x, rect.y, rect.x + rect.width, rect.y + rect.height);
   SkPaint paint;
   paint.setAlpha(alpha);
   paint.setXfermodeMode(mode);
   // It is not necessary to pass the dest into the drawBitmap call since all
   // the context have been set up before calling paintCurrentFrameInContext.
   canvas->drawBitmapRect(bitmap_, dest, &paint);
 }
 
 bool WebMediaPlayerAndroid::copyVideoTextureToPlatformTexture(
     blink::WebGraphicsContext3D* web_graphics_context,
-    unsigned int texture,
-    unsigned int internal_format,
-    unsigned int type,
-    bool premultiply_alpha,
-    bool flip_y) {
+    const CopyVideoTextureParams& params) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
+  DCHECK((params.copyType == CopyVideoTextureParams::FullCopy &&
+          !params.xoffset && !params.yoffset) ||
+         (params.copyType == CopyVideoTextureParams::SubCopy &&
+          !params.internalFormat && !params.type));
   // Don't allow clients to copy an encrypted video frame.
   if (needs_external_surface_)
     return false;
 
   scoped_refptr<VideoFrame> video_frame;
   {
     base::AutoLock auto_lock(current_frame_lock_);
     video_frame = current_frame_;
   }
 
@@ skipping 10 matching lines @@
   // Ensure the target of texture is set before copyTextureCHROMIUM, otherwise
   // an invalid texture target may be used for copy texture.
   uint32 src_texture =
       web_graphics_context->createAndConsumeTextureCHROMIUM(
           mailbox_holder.texture_target, mailbox_holder.mailbox.name);
 
   // Application itself needs to take care of setting the right flip_y
   // value down to get the expected result.
   // flip_y==true means to reverse the video orientation while
   // flip_y==false means to keep the intrinsic orientation.
-  web_graphics_context->copyTextureCHROMIUM(
-      GL_TEXTURE_2D, src_texture, texture, internal_format, type,
-      flip_y, premultiply_alpha, false);
+  if (params.copyType == CopyVideoTextureParams::FullCopy) {
+    web_graphics_context->copyTextureCHROMIUM(
+        params.target, src_texture, params.texture, params.internalFormat,
+        params.type, params.flipY, params.premultiplyAlpha, false);
+  } else {
+    web_graphics_context->copySubTextureCHROMIUM(
+        params.target, src_texture, params.texture, params.xoffset,
+        params.yoffset, 0, 0, video_frame->natural_size().width(),
+        video_frame->natural_size().height(), params.flipY,
+        params.premultiplyAlpha, false);
+  }
 
   web_graphics_context->deleteTexture(src_texture);
   web_graphics_context->flush();
 
   SyncPointClientImpl client(web_graphics_context);
   video_frame->UpdateReleaseSyncPoint(&client);
   return true;
 }
 
 bool WebMediaPlayerAndroid::hasSingleSecurityOrigin() const {
@@ skipping 1207 matching lines @@
 
   bool is_hls = IsHLSStream();
   UMA_HISTOGRAM_BOOLEAN("Media.Android.IsHttpLiveStreamingMedia", is_hls);
   if (is_hls) {
     media::RecordOriginOfHLSPlayback(
         GURL(frame_->document().securityOrigin().toString()));
   }
 }
 
 }  // namespace content