gpu, cmaa: improve |do_copy| condition logic

gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc

 // Copyright 2016 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 "gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.h"
 
 #include "base/logging.h"
 #include "gpu/command_buffer/service/framebuffer_manager.h"
 #include "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
+#include "gpu/command_buffer/service/texture_manager.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_version_info.h"
 
 #define SHADER(Src) #Src
 
 namespace gpu {
 namespace gles2 {
 
 ApplyFramebufferAttachmentCMAAINTELResourceManager::
@@ skipping 213 matching lines @@
         continue;
       GLsizei width = attachment->width();
       GLsizei height = attachment->height();
       GLenum internal_format = attachment->internal_format();
 
       // Resize internal structures - only if needed.
       OnSize(width, height);
 
       // CMAA internally expects GL_RGBA8 textures.
       // Process using a GL_RGBA8 copy if this is not the case.
-      bool do_copy = internal_format != GL_RGBA8;
+      const bool rgba_immutable =
+          attachment->IsTextureAttachmentImmutable() &&

[piman, 2016/12/02 20:36:46]

Well, you already know you have a texture attachment, so, rather than adding an
extra API, why don't you grab the TextureRef/Texture from the TextureManager,
and have access to all fields that you may need (e.g. you probably also want to
check that if internal_format == GL_RGBA, that type == GL_UNSIGNED_BYTE, because
it could be e.g. GL_FLOAT or GL_HALF_FLOAT instead).

[dshwang, 2016/12/02 23:40:24]

We cannot get TextureRef/Texture from Framebuffer::Attachemnt. New patch set
added GetTexture(), instead of ad-hoc IsTextureAttachmentImmutable().
As immutable texture is only allowed, this code needs to know only
internal_format.

void glTexStorage2D(GLenum target, GLsizei levels, GLenum internalformat,
GLsizei width, GLsizei height);

[piman, 2016/12/05 20:07:08]

attachment->object_name() gives you the client texture id.
TextureManager::GetTexture(client_id) will give you the TextureRef.

[dshwang, 2016/12/09 03:23:27]

Done. Thank you for educating :)

+          TextureManager::ExtractFormatFromStorageFormat(internal_format) ==
+              GL_RGBA;
+      const bool do_copy = !rgba_immutable;
 
       // CMAA Effect
       if (do_copy) {
         ApplyCMAAEffectTexture(source_texture, rgba8_texture_, do_copy);
 
         copier->DoCopySubTexture(
             decoder, GL_TEXTURE_2D, rgba8_texture_, GL_RGBA8, GL_TEXTURE_2D,
             source_texture, internal_format, 0, 0, 0, 0, width_, height_,
             width_, height_, width_, height_, false, false, false);
       } else {
@@ skipping 1586 matching lines @@
     \n#endif\n
     \n#if defined DISPLAY_EDGES\n
       DisplayEdges();
     \n#endif\n
     }
   );
 /* clang-format on */
 
 }  // namespace gles2
 }  // namespace gpu