Update GL_IMPLEMENTATION_COLOR_READ_FORMAT for BGRA

gpu/command_buffer/common/gles2_cmd_utils.cc

 // Copyright (c) 2012 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.
 
 // This file is here so other GLES2 related files can have a common set of
 // includes where appropriate.
 
 #include <sstream>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
@@ skipping 960 matching lines @@
     case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
       return 4;
     case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
       return 5;
     default:
       NOTREACHED();
       return 0;
   }
 }
 
-uint32_t GLES2Util::GetGLReadPixelsImplementationFormat(
-    uint32_t internal_format) {
+uint32_t GLES2Util::GetGLReadPixelsAdditionalFormat(uint32_t internal_format,
+                                                    uint32_t texture_type) {
+  // GL_RGBA is supported by default. According to the spec, this function
+  // should return a second, implementaiton-chosen format. For consumers of

[piman, 2016/03/04 20:55:36]

typo: implementaiton->implementation

+  // this API to get the most benefit (as many efficient options as
+  // possible), this function attempts to return a non GL_RGBA format in
+  // cases where GL_RGBA would be returned.
   switch (internal_format) {
     case GL_R8:
     case GL_R16F:
     case GL_R32F:
       return GL_RED;
     case GL_R8UI:
     case GL_R8I:
     case GL_R16UI:
     case GL_R16I:
     case GL_R32UI:
@@ skipping 18 matching lines @@
     case GL_RGB32F:
       return GL_RGB;
     case GL_RGBA8UI:
     case GL_RGBA8I:
     case GL_RGB10_A2UI:
     case GL_RGBA16UI:
     case GL_RGBA16I:
     case GL_RGBA32UI:
     case GL_RGBA32I:
       return GL_RGBA_INTEGER;
+    case GL_RGBA:
+    case GL_RGBA8:
+    case GL_BGRA_EXT:
+    case GL_BGRA8_EXT:
+      // We would return GL_RGBA here, but that is uninteresting, as it is
+      // supported by default. If the texture's type is GL_UNSIGNED_BYTE, we
+      // can also support GL_BGRA_EXT, so return this as another option.
+      if (texture_type == GL_UNSIGNED_BYTE)
+        return GL_BGRA_EXT;

[piman, 2016/03/04 20:55:37]

We're only allowed to return this if we expose GL_EXT_read_format_bgra to the
client - otherwise, the client would try to use it, but glReadPixels would fail.
See the code around enable_read_format_bgra in feature_info.cc

+      else
+        return GL_RGBA;
     default:
       return GL_RGBA;
   }
 }
 
-uint32_t GLES2Util::GetGLReadPixelsImplementationType(uint32_t internal_format,
-                                                      uint32_t texture_type) {
+uint32_t GLES2Util::GetGLReadPixelsTypeForAdditionalFormat(
+    uint32_t internal_format,
+    uint32_t texture_type) {
   switch (internal_format) {
     case GL_R16UI:
     case GL_RG16UI:
     case GL_RGBA16UI:
     case GL_RGB10_A2:
     case GL_RGB10_A2UI:
       return GL_UNSIGNED_SHORT;
     case GL_R32UI:
     case GL_RG32UI:
     case GL_RGBA32UI:
@@ skipping 488 matching lines @@
   }
 
   return true;
 }
 
 #include "gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu