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// Copyright (c) 2013 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_RENDERER_HOST_COMPOSITING_IOSURFACE_SHADER_PROGRAMS_MAC_H_
#define CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_SHADER_PROGRAMS_MAC_H_
#include <OpenGL/gl.h>
#include "base/basictypes.h"
namespace content {
// Provides caching of the compile-and-link step for shader programs at runtime
// since, once compiled and linked, the programs can be shared. Callers invoke
// one of the UseXXX() methods within a GL context to glUseProgram() the program
// and have its uniform variables bound with the given parameters.
class CompositingIOSurfaceShaderPrograms {
public:
CompositingIOSurfaceShaderPrograms();
~CompositingIOSurfaceShaderPrograms();
// Reset the cache, deleting any references to currently-cached shader
// programs. This must be called within an active OpenGL context just before
// destruction.
void Reset();
// Begin using the "blit" program, which is set up to sample the texture at
// GL_TEXTURE_0. Returns false on error.
bool UseBlitProgram();
// Begin using the program that just draws solid white very efficiently.
// Returns false on error.
bool UseSolidWhiteProgram();
// Begin using one of the two RGB-to-YV12 color conversion programs, as
// specified by |pass_number| 1 or 2. The programs will sample the texture at
// GL_TEXTURE0, and account for scaling in the X direction by |texel_scale_x|.
// Returns false on error.
bool UseRGBToYV12Program(int pass_number, float texel_scale_x);
private:
enum { kNumShaderPrograms = 4 };
// Helper methods to cache uniform variable locations.
GLuint GetShaderProgram(int which);
void BindUniformTextureVariable(int which, int texture_unit_offset);
void BindUniformTexelScaleXVariable(int which, float texel_scale_x);
// Cached values for previously-compiled/linked shader programs, and the
// locations of their uniform variables.
GLuint shader_programs_[kNumShaderPrograms];
GLint texture_var_locations_[kNumShaderPrograms];
GLint texel_scale_x_var_locations_[kNumShaderPrograms];
DISALLOW_COPY_AND_ASSIGN(CompositingIOSurfaceShaderPrograms);
};
} // namespace content
#endif // CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_SHADER_PROGRAMS_MAC_H_
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