cc: Use the correct internal format for glCopyTexImage2D calls.

cc/resources/resource_format.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 "cc/resources/resource_format.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 
 namespace cc {
@@ skipping 45 matching lines @@
       GL_BGRA_EXT,       // BGRA_8888
       GL_ALPHA,          // ALPHA_8
       GL_LUMINANCE,      // LUMINANCE_8
       GL_RGB,            // RGB_565
       GL_ETC1_RGB8_OES,  // ETC1
       GL_RED_EXT,        // RED_8
       GL_LUMINANCE,      // LUMINANCE_F16
   };
   static_assert(arraysize(format_gl_data_format) == (RESOURCE_FORMAT_MAX + 1),
                 "format_gl_data_format does not handle all cases.");
-
   return format_gl_data_format[format];
 }
 
 GLenum GLInternalFormat(ResourceFormat format) {
+  // In GLES2, the internal format must match the texture format. (It no longer
+  // is true in GLES3, however it still holds for the BGRA extension.)
   return GLDataFormat(format);
 }
 
+GLenum GLCopyTextureInternalFormat(ResourceFormat format) {
+  // In GLES2, valid formats for glCopyTexImage2D are: GL_ALPHA, GL_LUMINANCE,
+  // GL_LUMINANCE_ALPHA, GL_RGB, or GL_RGBA.
+  // Extensions typically used for glTexImage2D do not also work for
+  // glCopyTexImage2D. For instance GL_BGRA_EXT may not be used for
+  // anything but gl(Sub)TexImage2D:
+  // https://www.khronos.org/registry/gles/extensions/EXT/EXT_texture_format_BGRA8888.txt
+  DCHECK_LE(format, RESOURCE_FORMAT_MAX);
+  static const GLenum format_gl_data_format[] = {
+      GL_RGBA,       // RGBA_8888
+      GL_RGBA,       // RGBA_4444
+      GL_RGBA,       // BGRA_8888
+      GL_ALPHA,      // ALPHA_8
+      GL_LUMINANCE,  // LUMINANCE_8
+      GL_RGB,        // RGB_565
+      GL_RGB,        // ETC1
+      GL_LUMINANCE,  // RED_8
+      GL_LUMINANCE,  // LUMINANCE_F16
+  };
+  static_assert(arraysize(format_gl_data_format) == (RESOURCE_FORMAT_MAX + 1),
+                "format_gl_data_format does not handle all cases.");
+  return format_gl_data_format[format];
+}
+
 gfx::BufferFormat BufferFormat(ResourceFormat format) {
   switch (format) {
     case BGRA_8888:
       return gfx::BufferFormat::BGRA_8888;
     case RED_8:
       return gfx::BufferFormat::R_8;
     case RGBA_4444:
       return gfx::BufferFormat::RGBA_4444;
     case RGBA_8888:
       return gfx::BufferFormat::RGBA_8888;
@@ skipping 25 matching lines @@
     case ETC1:
     case RED_8:
     case LUMINANCE_F16:
       return false;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace cc