Introduce components/display_compositor

content/browser/compositor/gl_helper_readback_support.h

-// Copyright 2014 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 CONTENT_BROWSER_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_
-#define CONTENT_BROWSER_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_
-
-#include <stddef.h>
-
-#include <vector>
-
-#include "content/browser/compositor/gl_helper.h"
-
-namespace content {
-
-class CONTENT_EXPORT GLHelperReadbackSupport {
- public:
-  enum FormatSupport { SUPPORTED, SWIZZLE, NOT_SUPPORTED };
-
-  GLHelperReadbackSupport(gpu::gles2::GLES2Interface* gl);
-
-  ~GLHelperReadbackSupport();
-
-  // For a given color type retrieve whether readback is supported and if so
-  // how it should be performed. The |format|, |type| and |bytes_per_pixel| are
-  // the values that should be used with glReadPixels to facilitate the
-  // readback. If |can_swizzle| is true then this method will return SWIZZLE if
-  // the data needs to be swizzled before using the returned |format| otherwise
-  // the method will return SUPPORTED to indicate that readback is permitted of
-  // this color othewise NOT_SUPPORTED will be returned.  This method always
-  // overwrites the out values irrespective of the return value.
-  FormatSupport GetReadbackConfig(SkColorType color_type,
-                                  bool can_swizzle,
-                                  GLenum* format,
-                                  GLenum* type,
-                                  size_t* bytes_per_pixel);
-  // Provides the additional readback format/type pairing for a render target
-  // of a given format/type pairing
-  void GetAdditionalFormat(GLenum format,
-                           GLenum type,
-                           GLenum* format_out,
-                           GLenum* type_out);
-
- private:
-  struct FormatCacheEntry {
-    GLenum format;
-    GLenum type;
-    GLenum read_format;
-    GLenum read_type;
-  };
-
-  // This populates the format_support_table with the list of supported
-  // formats.
-  void InitializeReadbackSupport();
-
-  // This api is called  once per format and it is done in the
-  // InitializeReadbackSupport. We should not use this any where
-  // except the InitializeReadbackSupport.Calling this at other places
-  // can distrub the state of normal gl operations.
-  void CheckForReadbackSupport(SkColorType texture_format);
-
-  // Helper functions for checking the supported texture formats.
-  // Avoid using this API in between texture operations, as this does some
-  // teture opertions (bind, attach) internally.
-  bool SupportsFormat(GLenum format, GLenum type);
-
-  FormatSupport format_support_table_[kLastEnum_SkColorType + 1];
-
-  gpu::gles2::GLES2Interface* gl_;
-  std::vector<struct FormatCacheEntry> format_cache_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_