emulate srgb format for generateMipmap

gpu/command_buffer/service/gles2_cmd_decoder.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.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 6093 matching lines @@
       target == GL_TEXTURE_2D) {
     if (base_level != 0 &&
         !tex->GetLevelType(target, 0, &type, &internal_format) &&
         tex->GetLevelType(target, tex->base_level(), &type, &internal_format)) {
       format = TextureManager::ExtractFormatFromStorageFormat(internal_format);
       glTexImage2D(target, 0, internal_format, 1, 1, 0, format, type, nullptr);
       texture_zero_level_set = true;
     }
   }
 
-  glGenerateMipmapEXT(target);
+  bool enable_srgb = 0;
+  if (target == GL_TEXTURE_2D) {
+    tex->GetLevelType(target, tex->base_level(), &type, &internal_format);
+    enable_srgb =
+        GetColorEncodingFromInternalFormat(internal_format) == GL_SRGB;
+  }
+  if (!enable_srgb || !feature_info_->feature_flags().desktop_srgb_support ||
+      !workarounds().decode_encode_srgb_for_generatemipmap) {
+    if (feature_info_->feature_flags().desktop_srgb_support) {
+      state_.EnableDisableFramebufferSRGB(enable_srgb);
+    }
+    glGenerateMipmapEXT(target);
+  } else {
+    if (target == GL_TEXTURE_2D) {
+      state_.EnableDisableFramebufferSRGB(true);
+      if (!InitializeSRGBConverter("generateMipmap")) {
+        return;
+      }
+      srgb_converter_->GenerateMipmap(this, tex, target);
+    } else {
+      // TODO(yizhou): If the target is GL_TEXTURE_3D or GL_TEXTURE_2D_ARRAY,
+      // this change can not generate correct mipmap.
+      glGenerateMipmapEXT(target);
+    }
+  }
 
   if (texture_zero_level_set) {
     // This may have some unwanted side effects, but we expect command buffer
     // validation to prevent you from doing anything weird with the texture
     // after this, like calling texSubImage2D sucessfully.
     glTexImage2D(target, 0, internal_format, 0, 0, 0, format, type, nullptr);
   }
 
   if (workarounds().set_texture_filter_before_generating_mipmap) {
     glTexParameteri(target, GL_TEXTURE_MIN_FILTER,
@@ skipping 12383 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu