[Command Buffer] emulate SRGB color format for BlitFramebuffer in OpenGL

gpu/command_buffer/service/gles2_cmd_srgb_converter.h

+// Copyright (c) 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.
+
+#ifndef GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_SRGB_CONVERTER_H_
+#define GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_SRGB_CONVERTER_H_
+
+#include <array>
+
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "gpu/command_buffer/service/feature_info.h"
+#include "gpu/command_buffer/service/gl_utils.h"
+#include "gpu/gpu_export.h"
+
+namespace gpu {
+namespace gles2 {
+
+class GLES2Decoder;
+
+// This class encapsulates the resources required to implement the
+// glBlitFramebuffer command, which somtimes requires to convert sRGB
+// to linear (RGBA) color format, or vice versa.
+class GPU_EXPORT SRGBConverter {
+ public:
+  explicit SRGBConverter(const gles2::FeatureInfo* feature_info);
+  ~SRGBConverter();
+
+  void InitializeSRGBConverter(const gles2::GLES2Decoder* decoder);
+  void Destroy();
+
+  void Blit(
+      const gles2::GLES2Decoder* decoder,
+      GLint srcX0,
+      GLint srcY0,
+      GLint srcX1,
+      GLint srcY1,
+      GLint dstX0,
+      GLint dstY0,
+      GLint dstX1,
+      GLint dstY1,
+      GLbitfield mask,
+      GLenum filter,
+      const gfx::Size& framebuffer_size,
+      GLuint src_framebuffer,
+      GLenum src_framebuffer_internal_format,
+      GLenum src_framebuffer_format,
+      GLenum src_framebuffer_type,
+      GLuint dst_framebuffer,
+      bool decode,
+      bool encode);
+
+ private:
+  void InitializeSRGBConverterProgram();
+  scoped_refptr<const gles2::FeatureInfo> feature_info_;
+
+  bool srgb_converter_initialized_ = false;
+
+  GLuint srgb_converter_program_ = 0;
+
+  std::array<GLuint, 2> srgb_converter_textures_ = {{0, 0}};
+  GLuint srgb_decoder_fbo_ = 0;
+  GLuint srgb_encoder_fbo_ = 0;
+
+  GLuint srgb_converter_vao_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(SRGBConverter);
+};
+
+}  // namespace gles2.
+}  // namespace gpu.
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_SRGB_CONVERTER_H_