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// 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 COMPONENTS_DISPLAY_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_
#define COMPONENTS_DISPLAY_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_
#include <stddef.h>
#include <vector>
#include "components/display_compositor/display_compositor_export.h"
#include "components/display_compositor/gl_helper.h"
namespace display_compositor {
class DISPLAY_COMPOSITOR_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 display_compositor
#endif // COMPONENTS_DISPLAY_COMPOSITOR_GL_HELPER_READBACK_SUPPORT_H_
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