gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc - external/github.com/flutter/engine - Git at Google

 // 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_copy_texture_chromium.h"

 #include <algorithm>

 #include "base/basictypes.h"
 #include "gpu/command_buffer/service/gl_utils.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"

 #define SHADER(src)                     \
   "#ifdef GL_ES\n"                      \
   "precision mediump float;\n"          \
   "#define TexCoordPrecision mediump\n" \
   "#else\n"                             \
   "#define TexCoordPrecision\n"         \
   "#endif\n" #src
 #define SHADER_2D(src)              \
   "#define SamplerType sampler2D\n" \
   "#define TextureLookup texture2D\n" SHADER(src)
 #define SHADER_RECTANGLE_ARB(src)     \
   "#define SamplerType sampler2DRect\n" \
   "#define TextureLookup texture2DRect\n" SHADER(src)
 #define SHADER_EXTERNAL_OES(src)                     \
   "#extension GL_OES_EGL_image_external : require\n" \
   "#define SamplerType samplerExternalOES\n"         \
   "#define TextureLookup texture2D\n" SHADER(src)
 #define FRAGMENT_SHADERS(src) \
   SHADER_2D(src), SHADER_RECTANGLE_ARB(src), SHADER_EXTERNAL_OES(src)

 namespace {

 const GLfloat kIdentityMatrix[16] = {1.0f, 0.0f, 0.0f, 0.0f,
                                      0.0f, 1.0f, 0.0f, 0.0f,
                                      0.0f, 0.0f, 1.0f, 0.0f,
                                      0.0f, 0.0f, 0.0f, 1.0f};

 enum VertexShaderId {
   VERTEX_SHADER_COPY_TEXTURE,
   VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
   NUM_VERTEX_SHADERS,
 };

 enum FragmentShaderId {
   FRAGMENT_SHADER_COPY_TEXTURE_2D,
   FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
   FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
   NUM_FRAGMENT_SHADERS,
 };

 const char* vertex_shader_source[NUM_VERTEX_SHADERS] = {
   // VERTEX_SHADER_COPY_TEXTURE
   SHADER(
     uniform mat4 u_matrix;
     uniform vec2 u_half_size;
     attribute vec4 a_position;
     varying TexCoordPrecision vec2 v_uv;
     void main(void) {
       gl_Position = u_matrix * a_position;
       v_uv = a_position.xy * vec2(u_half_size.s, u_half_size.t) +
              vec2(u_half_size.s, u_half_size.t);
     }),
   // VERTEX_SHADER_COPY_TEXTURE_FLIP_Y
   SHADER(
     uniform mat4 u_matrix;
     uniform vec2 u_half_size;
     attribute vec4 a_position;
     varying TexCoordPrecision vec2 v_uv;
     void main(void) {
       gl_Position = u_matrix * a_position;
       v_uv = a_position.xy * vec2(u_half_size.s, -u_half_size.t) +
              vec2(u_half_size.s, u_half_size.t);
     }),
 };

 const char* fragment_shader_source[NUM_FRAGMENT_SHADERS] = {
   // FRAGMENT_SHADER_COPY_TEXTURE_*
   FRAGMENT_SHADERS(
     uniform SamplerType u_sampler;
     varying TexCoordPrecision vec2 v_uv;
     void main(void) {
       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
     }),
   // FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_*
   FRAGMENT_SHADERS(
     uniform SamplerType u_sampler;
     varying TexCoordPrecision vec2 v_uv;
     void main(void) {
       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
       gl_FragColor.rgb *= gl_FragColor.a;
     }),
   // FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_*
   FRAGMENT_SHADERS(
     uniform SamplerType u_sampler;
     varying TexCoordPrecision vec2 v_uv;
     void main(void) {
       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
       if (gl_FragColor.a > 0.0)
         gl_FragColor.rgb /= gl_FragColor.a;
     }),
 };

 // Returns the correct vertex shader id to evaluate the copy operation for
 // the CHROMIUM_flipy setting.
 VertexShaderId GetVertexShaderId(bool flip_y) {
   // bit 0: flip y
   static VertexShaderId shader_ids[] = {
       VERTEX_SHADER_COPY_TEXTURE,
       VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
   };

   unsigned index = flip_y ? 1 : 0;
   return shader_ids[index];
 }

 // Returns the correct fragment shader id to evaluate the copy operation for
 // the premultiply alpha pixel store settings and target.
 FragmentShaderId GetFragmentShaderId(bool premultiply_alpha,
                                      bool unpremultiply_alpha,
                                      GLenum target) {
   enum {
     SAMPLER_2D,
     SAMPLER_RECTANGLE_ARB,
     SAMPLER_EXTERNAL_OES,
     NUM_SAMPLERS
   };

   // bit 0: premultiply alpha
   // bit 1: unpremultiply alpha
   static FragmentShaderId shader_ids[][NUM_SAMPLERS] = {
       {
        FRAGMENT_SHADER_COPY_TEXTURE_2D,
        FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
        FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
       },
       {
        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
       },
       {
        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
       },
       {
        FRAGMENT_SHADER_COPY_TEXTURE_2D,
        FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
        FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
       }};

   unsigned index = (premultiply_alpha   ? (1 << 0) : 0) |
                    (unpremultiply_alpha ? (1 << 1) : 0);

   switch (target) {
     case GL_TEXTURE_2D:
       return shader_ids[index][SAMPLER_2D];
     case GL_TEXTURE_RECTANGLE_ARB:
       return shader_ids[index][SAMPLER_RECTANGLE_ARB];
     case GL_TEXTURE_EXTERNAL_OES:
       return shader_ids[index][SAMPLER_EXTERNAL_OES];
     default:
       break;
   }

   NOTREACHED();
   return shader_ids[0][SAMPLER_2D];
 }

 void CompileShader(GLuint shader, const char* shader_source) {
   glShaderSource(shader, 1, &shader_source, 0);
   glCompileShader(shader);
 #ifndef NDEBUG
   GLint compile_status;
   glGetShaderiv(shader, GL_COMPILE_STATUS, &compile_status);
   if (GL_TRUE != compile_status)
     DLOG(ERROR) << "CopyTextureCHROMIUM: shader compilation failure.";
 #endif
 }

 void DeleteShader(GLuint shader) {
   if (shader)
     glDeleteShader(shader);
 }

 bool BindFramebufferTexture2D(GLenum target,
                               GLuint texture_id,
                               GLuint framebuffer) {
   DCHECK(target == GL_TEXTURE_2D || target == GL_TEXTURE_RECTANGLE_ARB);
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(target, texture_id);
   // NVidia drivers require texture settings to be a certain way
   // or they won't report FRAMEBUFFER_COMPLETE.
   glTexParameterf(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameterf(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer);
   glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target,
                             texture_id, 0);

 #ifndef NDEBUG
   GLenum fb_status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
   if (GL_FRAMEBUFFER_COMPLETE != fb_status) {
     DLOG(ERROR) << "CopyTextureCHROMIUM: Incomplete framebuffer.";
     return false;
   }
 #endif
   return true;
 }

 void DoCopyTexImage2D(const gpu::gles2::GLES2Decoder* decoder,
                       GLenum source_target,
                       GLuint source_id,
                       GLuint dest_id,
                       GLenum dest_internal_format,
                       GLsizei width,
                       GLsizei height,
                       GLuint framebuffer) {
   DCHECK(source_target == GL_TEXTURE_2D ||
          source_target == GL_TEXTURE_RECTANGLE_ARB);
   if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
     glBindTexture(GL_TEXTURE_2D, dest_id);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glCopyTexImage2D(GL_TEXTURE_2D, 0 /* level */, dest_internal_format,
                      0 /* x */, 0 /* y */, width, height, 0 /* border */);
   }

   decoder->RestoreTextureState(source_id);
   decoder->RestoreTextureState(dest_id);
   decoder->RestoreTextureUnitBindings(0);
   decoder->RestoreActiveTexture();
   decoder->RestoreFramebufferBindings();
 }

 void DoCopyTexSubImage2D(const gpu::gles2::GLES2Decoder* decoder,
                          GLenum source_target,
                          GLuint source_id,
                          GLuint dest_id,
                          GLint xoffset,
                          GLint yoffset,
                          GLsizei source_width,
                          GLsizei source_height,
                          GLuint framebuffer) {
   DCHECK(source_target == GL_TEXTURE_2D ||
          source_target == GL_TEXTURE_RECTANGLE_ARB);
   if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
     glBindTexture(GL_TEXTURE_2D, dest_id);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glCopyTexSubImage2D(GL_TEXTURE_2D, 0 /* level */, xoffset, yoffset,
                         0 /* x */, 0 /* y */, source_width, source_height);
   }

   decoder->RestoreTextureState(source_id);
   decoder->RestoreTextureState(dest_id);
   decoder->RestoreTextureUnitBindings(0);
   decoder->RestoreActiveTexture();
   decoder->RestoreFramebufferBindings();
 }

 // Copy from SkMatrix44::preTranslate
 void PreTranslate(GLfloat* matrix, GLfloat dx, GLfloat dy, GLfloat dz) {
   if (!dx && !dy && !dz)
     return;

   for (int i = 0; i < 4; ++i) {
     matrix[(3 * 4) + i] = matrix[(0 * 4) + i] * dx + matrix[(1 * 4) + i] * dy +
                           matrix[(2 * 4) + i] * dz + matrix[(3 * 4) + i];
   }
 }

 }  // namespace

 namespace gpu {

 CopyTextureCHROMIUMResourceManager::CopyTextureCHROMIUMResourceManager()
     : initialized_(false),
       vertex_shaders_(NUM_VERTEX_SHADERS, 0u),
       fragment_shaders_(NUM_FRAGMENT_SHADERS, 0u),
       buffer_id_(0u),
       framebuffer_(0u) {}

 CopyTextureCHROMIUMResourceManager::~CopyTextureCHROMIUMResourceManager() {
   // |buffer_id_| and |framebuffer_| can be not-null because when GPU context is
   // lost, this class can be deleted without releasing resources like
   // GLES2DecoderImpl.
 }

 void CopyTextureCHROMIUMResourceManager::Initialize(
     const gles2::GLES2Decoder* decoder) {
   static_assert(
       kVertexPositionAttrib == 0u,
       "kVertexPositionAttrib must be 0");
   DCHECK(!buffer_id_);
   DCHECK(!framebuffer_);
   DCHECK(programs_.empty());

   // Initialize all of the GPU resources required to perform the copy.
   glGenBuffersARB(1, &buffer_id_);
   glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
   const GLfloat kQuadVertices[] = {-1.0f, -1.0f,
                                     1.0f, -1.0f,
                                     1.0f,  1.0f,
                                    -1.0f,  1.0f};
   glBufferData(
       GL_ARRAY_BUFFER, sizeof(kQuadVertices), kQuadVertices, GL_STATIC_DRAW);

   glGenFramebuffersEXT(1, &framebuffer_);

   decoder->RestoreBufferBindings();

   initialized_ = true;
 }

 void CopyTextureCHROMIUMResourceManager::Destroy() {
   if (!initialized_)
     return;

   glDeleteFramebuffersEXT(1, &framebuffer_);
   framebuffer_ = 0;

   std::for_each(vertex_shaders_.begin(), vertex_shaders_.end(), DeleteShader);
   std::for_each(
       fragment_shaders_.begin(), fragment_shaders_.end(), DeleteShader);

   for (ProgramMap::const_iterator it = programs_.begin(); it != programs_.end();
        ++it) {
     const ProgramInfo& info = it->second;
     glDeleteProgram(info.program);
   }

   glDeleteBuffersARB(1, &buffer_id_);
   buffer_id_ = 0;
 }

 void CopyTextureCHROMIUMResourceManager::DoCopyTexture(
     const gles2::GLES2Decoder* decoder,
     GLenum source_target,
     GLuint source_id,
     GLenum source_internal_format,
     GLuint dest_id,
     GLenum dest_internal_format,
     GLsizei width,
     GLsizei height,
     bool flip_y,
     bool premultiply_alpha,
     bool unpremultiply_alpha) {
   bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
   // GL_INVALID_OPERATION is generated if the currently bound framebuffer's
   // format does not contain a superset of the components required by the base
   // format of internalformat.
   // https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
   bool source_format_contain_superset_of_dest_format =
       (source_internal_format == dest_internal_format &&
        source_internal_format != GL_BGRA_EXT) ||
       (source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
   // GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
   // so restrict this to GL_TEXTURE_2D.
   if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
       source_format_contain_superset_of_dest_format) {
     DoCopyTexImage2D(decoder,
                      source_target,
                      source_id,
                      dest_id,
                      dest_internal_format,
                      width,
                      height,
                      framebuffer_);
     return;
   }

   // Use kIdentityMatrix if no transform passed in.
   DoCopyTextureWithTransform(decoder, source_target, source_id, dest_id, width,
                              height, flip_y, premultiply_alpha,
                              unpremultiply_alpha, kIdentityMatrix);
 }

 void CopyTextureCHROMIUMResourceManager::DoCopySubTexture(
     const gles2::GLES2Decoder* decoder,
     GLenum source_target,
     GLuint source_id,
     GLenum source_internal_format,
     GLuint dest_id,
     GLenum dest_internal_format,
     GLint xoffset,
     GLint yoffset,
     GLsizei dest_width,
     GLsizei dest_height,
     GLsizei source_width,
     GLsizei source_height,
     bool flip_y,
     bool premultiply_alpha,
     bool unpremultiply_alpha) {
   bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
   // GL_INVALID_OPERATION is generated if the currently bound framebuffer's
   // format does not contain a superset of the components required by the base
   // format of internalformat.
   // https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
   bool source_format_contain_superset_of_dest_format =
       (source_internal_format == dest_internal_format &&
        source_internal_format != GL_BGRA_EXT) ||
       (source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
   // GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
   // so restrict this to GL_TEXTURE_2D.
   if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
       source_format_contain_superset_of_dest_format) {
     DoCopyTexSubImage2D(decoder, source_target, source_id, dest_id, xoffset,
                         yoffset, source_width, source_height, framebuffer_);
     return;
   }

   // Use kIdentityMatrix if no transform passed in.
   DoCopySubTextureWithTransform(
       decoder, source_target, source_id, dest_id, xoffset, yoffset, dest_width,
       dest_height, source_width, source_height, flip_y, premultiply_alpha,
       unpremultiply_alpha, kIdentityMatrix);
 }

 void CopyTextureCHROMIUMResourceManager::DoCopyTextureWithTransform(
     const gles2::GLES2Decoder* decoder,
     GLenum source_target,
     GLuint source_id,
     GLuint dest_id,
     GLsizei width,
     GLsizei height,
     bool flip_y,
     bool premultiply_alpha,
     bool unpremultiply_alpha,
     const GLfloat transform_matrix[16]) {
   GLsizei dest_width = width;
   GLsizei dest_height = height;
   DoCopyTextureInternal(decoder, source_target, source_id, dest_id, 0, 0,
                         dest_width, dest_height, width, height, flip_y,
                         premultiply_alpha, unpremultiply_alpha,
                         transform_matrix);
 }

 void CopyTextureCHROMIUMResourceManager::DoCopySubTextureWithTransform(
     const gles2::GLES2Decoder* decoder,
     GLenum source_target,
     GLuint source_id,
     GLuint dest_id,
     GLint xoffset,
     GLint yoffset,
     GLsizei dest_width,
     GLsizei dest_height,
     GLsizei source_width,
     GLsizei source_height,
     bool flip_y,
     bool premultiply_alpha,
     bool unpremultiply_alpha,
     const GLfloat transform_matrix[16]) {
   DoCopyTextureInternal(decoder, source_target, source_id, dest_id, xoffset,
                         yoffset, dest_width, dest_height, source_width,
                         source_height, flip_y, premultiply_alpha,
                         unpremultiply_alpha, transform_matrix);
 }

 void CopyTextureCHROMIUMResourceManager::DoCopyTextureInternal(
     const gles2::GLES2Decoder* decoder,
     GLenum source_target,
     GLuint source_id,
     GLuint dest_id,
     GLint xoffset,
     GLint yoffset,
     GLsizei dest_width,
     GLsizei dest_height,
     GLsizei source_width,
     GLsizei source_height,
     bool flip_y,
     bool premultiply_alpha,
     bool unpremultiply_alpha,
     const GLfloat transform_matrix[16]) {
   DCHECK(source_target == GL_TEXTURE_2D ||
          source_target == GL_TEXTURE_RECTANGLE_ARB ||
          source_target == GL_TEXTURE_EXTERNAL_OES);
   DCHECK(xoffset >= 0 && xoffset + source_width <= dest_width);
   DCHECK(yoffset >= 0 && yoffset + source_height <= dest_height);
   if (!initialized_) {
     DLOG(ERROR) << "CopyTextureCHROMIUM: Uninitialized manager.";
     return;
   }

   VertexShaderId vertex_shader_id = GetVertexShaderId(flip_y);
   DCHECK_LT(static_cast<size_t>(vertex_shader_id), vertex_shaders_.size());
   FragmentShaderId fragment_shader_id = GetFragmentShaderId(
       premultiply_alpha, unpremultiply_alpha, source_target);
   DCHECK_LT(static_cast<size_t>(fragment_shader_id), fragment_shaders_.size());

   ProgramMapKey key(vertex_shader_id, fragment_shader_id);
   ProgramInfo* info = &programs_[key];
   // Create program if necessary.
   if (!info->program) {
     info->program = glCreateProgram();
     GLuint* vertex_shader = &vertex_shaders_[vertex_shader_id];
     if (!*vertex_shader) {
       *vertex_shader = glCreateShader(GL_VERTEX_SHADER);
       CompileShader(*vertex_shader, vertex_shader_source[vertex_shader_id]);
     }
     glAttachShader(info->program, *vertex_shader);
     GLuint* fragment_shader = &fragment_shaders_[fragment_shader_id];
     if (!*fragment_shader) {
       *fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
       CompileShader(*fragment_shader,
                     fragment_shader_source[fragment_shader_id]);
     }
     glAttachShader(info->program, *fragment_shader);
     glBindAttribLocation(info->program, kVertexPositionAttrib, "a_position");
     glLinkProgram(info->program);
 #ifndef NDEBUG
     GLint linked;
     glGetProgramiv(info->program, GL_LINK_STATUS, &linked);
     if (!linked)
       DLOG(ERROR) << "CopyTextureCHROMIUM: program link failure.";
 #endif
     info->matrix_handle = glGetUniformLocation(info->program, "u_matrix");
     info->half_size_handle = glGetUniformLocation(info->program, "u_half_size");
     info->sampler_handle = glGetUniformLocation(info->program, "u_sampler");
   }
   glUseProgram(info->program);

   if (!xoffset && !yoffset) {
     glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, transform_matrix);
   } else {
     // transform offsets from ([0, dest_width], [0, dest_height]) coord.
     // to ([-1, 1], [-1, 1]) coord.
     GLfloat xoffset_on_vertex = ((2.f * xoffset) / dest_width);
     GLfloat yoffset_on_vertex = ((2.f * yoffset) / dest_height);

     // Pass view_matrix * offset_matrix to the program.
     GLfloat view_transform[16];
     memcpy(view_transform, transform_matrix, 16 * sizeof(GLfloat));
     PreTranslate(view_transform, xoffset_on_vertex, yoffset_on_vertex, 0);
     glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, view_transform);
   }
   if (source_target == GL_TEXTURE_RECTANGLE_ARB)
     glUniform2f(info->half_size_handle, source_width / 2.0f,
                 source_height / 2.0f);
   else
     glUniform2f(info->half_size_handle, 0.5f, 0.5f);

   if (BindFramebufferTexture2D(GL_TEXTURE_2D, dest_id, framebuffer_)) {
 #ifndef NDEBUG
     // glValidateProgram of MACOSX validates FBO unlike other platforms, so
     // glValidateProgram must be called after FBO binding. crbug.com/463439
     glValidateProgram(info->program);
     GLint validation_status;
     glGetProgramiv(info->program, GL_VALIDATE_STATUS, &validation_status);
     if (GL_TRUE != validation_status) {
       DLOG(ERROR) << "CopyTextureCHROMIUM: Invalid shader.";
       return;
     }
 #endif
     decoder->ClearAllAttributes();
     glEnableVertexAttribArray(kVertexPositionAttrib);

     glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
     glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);

     glUniform1i(info->sampler_handle, 0);

     glBindTexture(source_target, source_id);
     glTexParameterf(source_target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameterf(source_target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glTexParameteri(source_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameteri(source_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

     glDisable(GL_DEPTH_TEST);
     glDisable(GL_SCISSOR_TEST);
     glDisable(GL_STENCIL_TEST);
     glDisable(GL_CULL_FACE);
     glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     glDepthMask(GL_FALSE);
     glDisable(GL_BLEND);

     glViewport(0, 0, dest_width, dest_height);
     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
   }

   decoder->RestoreAllAttributes();
   decoder->RestoreTextureState(source_id);
   decoder->RestoreTextureState(dest_id);
   decoder->RestoreTextureUnitBindings(0);
   decoder->RestoreActiveTexture();
   decoder->RestoreProgramBindings();
   decoder->RestoreBufferBindings();
   decoder->RestoreFramebufferBindings();
   decoder->RestoreGlobalState();
 }

 }  // namespace gpu
	// 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_copy_texture_chromium.h"

	#include <algorithm>

	#include "base/basictypes.h"
	#include "gpu/command_buffer/service/gl_utils.h"
	#include "gpu/command_buffer/service/gles2_cmd_decoder.h"

	#define SHADER(src) \
	"#ifdef GL_ES\n" \
	"precision mediump float;\n" \
	"#define TexCoordPrecision mediump\n" \
	"#else\n" \
	"#define TexCoordPrecision\n" \
	"#endif\n" #src
	#define SHADER_2D(src) \
	"#define SamplerType sampler2D\n" \
	"#define TextureLookup texture2D\n" SHADER(src)
	#define SHADER_RECTANGLE_ARB(src) \
	"#define SamplerType sampler2DRect\n" \
	"#define TextureLookup texture2DRect\n" SHADER(src)
	#define SHADER_EXTERNAL_OES(src) \
	"#extension GL_OES_EGL_image_external : require\n" \
	"#define SamplerType samplerExternalOES\n" \
	"#define TextureLookup texture2D\n" SHADER(src)
	#define FRAGMENT_SHADERS(src) \
	SHADER_2D(src), SHADER_RECTANGLE_ARB(src), SHADER_EXTERNAL_OES(src)

	namespace {

	const GLfloat kIdentityMatrix[16] = {1.0f, 0.0f, 0.0f, 0.0f,
	0.0f, 1.0f, 0.0f, 0.0f,
	0.0f, 0.0f, 1.0f, 0.0f,
	0.0f, 0.0f, 0.0f, 1.0f};

	enum VertexShaderId {
	VERTEX_SHADER_COPY_TEXTURE,
	VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
	NUM_VERTEX_SHADERS,
	};

	enum FragmentShaderId {
	FRAGMENT_SHADER_COPY_TEXTURE_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
	NUM_FRAGMENT_SHADERS,
	};

	const char* vertex_shader_source[NUM_VERTEX_SHADERS] = {
	// VERTEX_SHADER_COPY_TEXTURE
	SHADER(
	uniform mat4 u_matrix;
	uniform vec2 u_half_size;
	attribute vec4 a_position;
	varying TexCoordPrecision vec2 v_uv;
	void main(void) {
	gl_Position = u_matrix * a_position;
	v_uv = a_position.xy * vec2(u_half_size.s, u_half_size.t) +
	vec2(u_half_size.s, u_half_size.t);
	}),
	// VERTEX_SHADER_COPY_TEXTURE_FLIP_Y
	SHADER(
	uniform mat4 u_matrix;
	uniform vec2 u_half_size;
	attribute vec4 a_position;
	varying TexCoordPrecision vec2 v_uv;
	void main(void) {
	gl_Position = u_matrix * a_position;
	v_uv = a_position.xy * vec2(u_half_size.s, -u_half_size.t) +
	vec2(u_half_size.s, u_half_size.t);
	}),
	};

	const char* fragment_shader_source[NUM_FRAGMENT_SHADERS] = {
	// FRAGMENT_SHADER_COPY_TEXTURE_*
	FRAGMENT_SHADERS(
	uniform SamplerType u_sampler;
	varying TexCoordPrecision vec2 v_uv;
	void main(void) {
	gl_FragColor = TextureLookup(u_sampler, v_uv.st);
	}),
	// FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_*
	FRAGMENT_SHADERS(
	uniform SamplerType u_sampler;
	varying TexCoordPrecision vec2 v_uv;
	void main(void) {
	gl_FragColor = TextureLookup(u_sampler, v_uv.st);
	gl_FragColor.rgb *= gl_FragColor.a;
	}),
	// FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_*
	FRAGMENT_SHADERS(
	uniform SamplerType u_sampler;
	varying TexCoordPrecision vec2 v_uv;
	void main(void) {
	gl_FragColor = TextureLookup(u_sampler, v_uv.st);
	if (gl_FragColor.a > 0.0)
	gl_FragColor.rgb /= gl_FragColor.a;
	}),
	};

	// Returns the correct vertex shader id to evaluate the copy operation for
	// the CHROMIUM_flipy setting.
	VertexShaderId GetVertexShaderId(bool flip_y) {
	// bit 0: flip y
	static VertexShaderId shader_ids[] = {
	VERTEX_SHADER_COPY_TEXTURE,
	VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
	};

	unsigned index = flip_y ? 1 : 0;
	return shader_ids[index];
	}

	// Returns the correct fragment shader id to evaluate the copy operation for
	// the premultiply alpha pixel store settings and target.
	FragmentShaderId GetFragmentShaderId(bool premultiply_alpha,
	bool unpremultiply_alpha,
	GLenum target) {
	enum {
	SAMPLER_2D,
	SAMPLER_RECTANGLE_ARB,
	SAMPLER_EXTERNAL_OES,
	NUM_SAMPLERS
	};

	// bit 0: premultiply alpha
	// bit 1: unpremultiply alpha
	static FragmentShaderId shader_ids[][NUM_SAMPLERS] = {
	{
	FRAGMENT_SHADER_COPY_TEXTURE_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
	},
	{
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
	},
	{
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
	},
	{
	FRAGMENT_SHADER_COPY_TEXTURE_2D,
	FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
	FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
	}};

	unsigned index = (premultiply_alpha ? (1 << 0) : 0) \|
	(unpremultiply_alpha ? (1 << 1) : 0);

	switch (target) {
	case GL_TEXTURE_2D:
	return shader_ids[index][SAMPLER_2D];
	case GL_TEXTURE_RECTANGLE_ARB:
	return shader_ids[index][SAMPLER_RECTANGLE_ARB];
	case GL_TEXTURE_EXTERNAL_OES:
	return shader_ids[index][SAMPLER_EXTERNAL_OES];
	default:
	break;
	}

	NOTREACHED();
	return shader_ids[0][SAMPLER_2D];
	}

	void CompileShader(GLuint shader, const char* shader_source) {
	glShaderSource(shader, 1, &shader_source, 0);
	glCompileShader(shader);
	#ifndef NDEBUG
	GLint compile_status;
	glGetShaderiv(shader, GL_COMPILE_STATUS, &compile_status);
	if (GL_TRUE != compile_status)
	DLOG(ERROR) << "CopyTextureCHROMIUM: shader compilation failure.";
	#endif
	}

	void DeleteShader(GLuint shader) {
	if (shader)
	glDeleteShader(shader);
	}

	bool BindFramebufferTexture2D(GLenum target,
	GLuint texture_id,
	GLuint framebuffer) {
	DCHECK(target == GL_TEXTURE_2D \|\| target == GL_TEXTURE_RECTANGLE_ARB);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(target, texture_id);
	// NVidia drivers require texture settings to be a certain way
	// or they won't report FRAMEBUFFER_COMPLETE.
	glTexParameterf(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameterf(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target,
	texture_id, 0);

	#ifndef NDEBUG
	GLenum fb_status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
	if (GL_FRAMEBUFFER_COMPLETE != fb_status) {
	DLOG(ERROR) << "CopyTextureCHROMIUM: Incomplete framebuffer.";
	return false;
	}
	#endif
	return true;
	}

	void DoCopyTexImage2D(const gpu::gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLuint dest_id,
	GLenum dest_internal_format,
	GLsizei width,
	GLsizei height,
	GLuint framebuffer) {
	DCHECK(source_target == GL_TEXTURE_2D \|\|
	source_target == GL_TEXTURE_RECTANGLE_ARB);
	if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
	glBindTexture(GL_TEXTURE_2D, dest_id);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glCopyTexImage2D(GL_TEXTURE_2D, 0 /* level */, dest_internal_format,
	0 /* x /, 0 / y /, width, height, 0 / border */);
	}

	decoder->RestoreTextureState(source_id);
	decoder->RestoreTextureState(dest_id);
	decoder->RestoreTextureUnitBindings(0);
	decoder->RestoreActiveTexture();
	decoder->RestoreFramebufferBindings();
	}

	void DoCopyTexSubImage2D(const gpu::gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLuint dest_id,
	GLint xoffset,
	GLint yoffset,
	GLsizei source_width,
	GLsizei source_height,
	GLuint framebuffer) {
	DCHECK(source_target == GL_TEXTURE_2D \|\|
	source_target == GL_TEXTURE_RECTANGLE_ARB);
	if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
	glBindTexture(GL_TEXTURE_2D, dest_id);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glCopyTexSubImage2D(GL_TEXTURE_2D, 0 /* level */, xoffset, yoffset,
	0 /* x /, 0 / y */, source_width, source_height);
	}

	decoder->RestoreTextureState(source_id);
	decoder->RestoreTextureState(dest_id);
	decoder->RestoreTextureUnitBindings(0);
	decoder->RestoreActiveTexture();
	decoder->RestoreFramebufferBindings();
	}

	// Copy from SkMatrix44::preTranslate
	void PreTranslate(GLfloat* matrix, GLfloat dx, GLfloat dy, GLfloat dz) {
	if (!dx && !dy && !dz)
	return;

	for (int i = 0; i < 4; ++i) {
	matrix[(3 * 4) + i] = matrix[(0 * 4) + i] * dx + matrix[(1 * 4) + i] * dy +
	matrix[(2 * 4) + i] * dz + matrix[(3 * 4) + i];
	}
	}

	} // namespace

	namespace gpu {

	CopyTextureCHROMIUMResourceManager::CopyTextureCHROMIUMResourceManager()
	: initialized_(false),
	vertex_shaders_(NUM_VERTEX_SHADERS, 0u),
	fragment_shaders_(NUM_FRAGMENT_SHADERS, 0u),
	buffer_id_(0u),
	framebuffer_(0u) {}

	CopyTextureCHROMIUMResourceManager::~CopyTextureCHROMIUMResourceManager() {
	// \|buffer_id_\| and \|framebuffer_\| can be not-null because when GPU context is
	// lost, this class can be deleted without releasing resources like
	// GLES2DecoderImpl.
	}

	void CopyTextureCHROMIUMResourceManager::Initialize(
	const gles2::GLES2Decoder* decoder) {
	static_assert(
	kVertexPositionAttrib == 0u,
	"kVertexPositionAttrib must be 0");
	DCHECK(!buffer_id_);
	DCHECK(!framebuffer_);
	DCHECK(programs_.empty());

	// Initialize all of the GPU resources required to perform the copy.
	glGenBuffersARB(1, &buffer_id_);
	glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
	const GLfloat kQuadVertices[] = {-1.0f, -1.0f,
	1.0f, -1.0f,
	1.0f, 1.0f,
	-1.0f, 1.0f};
	glBufferData(
	GL_ARRAY_BUFFER, sizeof(kQuadVertices), kQuadVertices, GL_STATIC_DRAW);

	glGenFramebuffersEXT(1, &framebuffer_);

	decoder->RestoreBufferBindings();

	initialized_ = true;
	}

	void CopyTextureCHROMIUMResourceManager::Destroy() {
	if (!initialized_)
	return;

	glDeleteFramebuffersEXT(1, &framebuffer_);
	framebuffer_ = 0;

	std::for_each(vertex_shaders_.begin(), vertex_shaders_.end(), DeleteShader);
	std::for_each(
	fragment_shaders_.begin(), fragment_shaders_.end(), DeleteShader);

	for (ProgramMap::const_iterator it = programs_.begin(); it != programs_.end();
	++it) {
	const ProgramInfo& info = it->second;
	glDeleteProgram(info.program);
	}

	glDeleteBuffersARB(1, &buffer_id_);
	buffer_id_ = 0;
	}

	void CopyTextureCHROMIUMResourceManager::DoCopyTexture(
	const gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLenum source_internal_format,
	GLuint dest_id,
	GLenum dest_internal_format,
	GLsizei width,
	GLsizei height,
	bool flip_y,
	bool premultiply_alpha,
	bool unpremultiply_alpha) {
	bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
	// GL_INVALID_OPERATION is generated if the currently bound framebuffer's
	// format does not contain a superset of the components required by the base
	// format of internalformat.
	// https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
	bool source_format_contain_superset_of_dest_format =
	(source_internal_format == dest_internal_format &&
	source_internal_format != GL_BGRA_EXT) \|\|
	(source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
	// GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
	// so restrict this to GL_TEXTURE_2D.
	if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
	source_format_contain_superset_of_dest_format) {
	DoCopyTexImage2D(decoder,
	source_target,
	source_id,
	dest_id,
	dest_internal_format,
	width,
	height,
	framebuffer_);
	return;
	}

	// Use kIdentityMatrix if no transform passed in.
	DoCopyTextureWithTransform(decoder, source_target, source_id, dest_id, width,
	height, flip_y, premultiply_alpha,
	unpremultiply_alpha, kIdentityMatrix);
	}

	void CopyTextureCHROMIUMResourceManager::DoCopySubTexture(
	const gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLenum source_internal_format,
	GLuint dest_id,
	GLenum dest_internal_format,
	GLint xoffset,
	GLint yoffset,
	GLsizei dest_width,
	GLsizei dest_height,
	GLsizei source_width,
	GLsizei source_height,
	bool flip_y,
	bool premultiply_alpha,
	bool unpremultiply_alpha) {
	bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
	// GL_INVALID_OPERATION is generated if the currently bound framebuffer's
	// format does not contain a superset of the components required by the base
	// format of internalformat.
	// https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
	bool source_format_contain_superset_of_dest_format =
	(source_internal_format == dest_internal_format &&
	source_internal_format != GL_BGRA_EXT) \|\|
	(source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
	// GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
	// so restrict this to GL_TEXTURE_2D.
	if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
	source_format_contain_superset_of_dest_format) {
	DoCopyTexSubImage2D(decoder, source_target, source_id, dest_id, xoffset,
	yoffset, source_width, source_height, framebuffer_);
	return;
	}

	// Use kIdentityMatrix if no transform passed in.
	DoCopySubTextureWithTransform(
	decoder, source_target, source_id, dest_id, xoffset, yoffset, dest_width,
	dest_height, source_width, source_height, flip_y, premultiply_alpha,
	unpremultiply_alpha, kIdentityMatrix);
	}

	void CopyTextureCHROMIUMResourceManager::DoCopyTextureWithTransform(
	const gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLuint dest_id,
	GLsizei width,
	GLsizei height,
	bool flip_y,
	bool premultiply_alpha,
	bool unpremultiply_alpha,
	const GLfloat transform_matrix[16]) {
	GLsizei dest_width = width;
	GLsizei dest_height = height;
	DoCopyTextureInternal(decoder, source_target, source_id, dest_id, 0, 0,
	dest_width, dest_height, width, height, flip_y,
	premultiply_alpha, unpremultiply_alpha,
	transform_matrix);
	}

	void CopyTextureCHROMIUMResourceManager::DoCopySubTextureWithTransform(
	const gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLuint dest_id,
	GLint xoffset,
	GLint yoffset,
	GLsizei dest_width,
	GLsizei dest_height,
	GLsizei source_width,
	GLsizei source_height,
	bool flip_y,
	bool premultiply_alpha,
	bool unpremultiply_alpha,
	const GLfloat transform_matrix[16]) {
	DoCopyTextureInternal(decoder, source_target, source_id, dest_id, xoffset,
	yoffset, dest_width, dest_height, source_width,
	source_height, flip_y, premultiply_alpha,
	unpremultiply_alpha, transform_matrix);
	}

	void CopyTextureCHROMIUMResourceManager::DoCopyTextureInternal(
	const gles2::GLES2Decoder* decoder,
	GLenum source_target,
	GLuint source_id,
	GLuint dest_id,
	GLint xoffset,
	GLint yoffset,
	GLsizei dest_width,
	GLsizei dest_height,
	GLsizei source_width,
	GLsizei source_height,
	bool flip_y,
	bool premultiply_alpha,
	bool unpremultiply_alpha,
	const GLfloat transform_matrix[16]) {
	DCHECK(source_target == GL_TEXTURE_2D \|\|
	source_target == GL_TEXTURE_RECTANGLE_ARB \|\|
	source_target == GL_TEXTURE_EXTERNAL_OES);
	DCHECK(xoffset >= 0 && xoffset + source_width <= dest_width);
	DCHECK(yoffset >= 0 && yoffset + source_height <= dest_height);
	if (!initialized_) {
	DLOG(ERROR) << "CopyTextureCHROMIUM: Uninitialized manager.";
	return;
	}

	VertexShaderId vertex_shader_id = GetVertexShaderId(flip_y);
	DCHECK_LT(static_cast<size_t>(vertex_shader_id), vertex_shaders_.size());
	FragmentShaderId fragment_shader_id = GetFragmentShaderId(
	premultiply_alpha, unpremultiply_alpha, source_target);
	DCHECK_LT(static_cast<size_t>(fragment_shader_id), fragment_shaders_.size());

	ProgramMapKey key(vertex_shader_id, fragment_shader_id);
	ProgramInfo* info = &programs_[key];
	// Create program if necessary.
	if (!info->program) {
	info->program = glCreateProgram();
	GLuint* vertex_shader = &vertex_shaders_[vertex_shader_id];
	if (!*vertex_shader) {
	*vertex_shader = glCreateShader(GL_VERTEX_SHADER);
	CompileShader(*vertex_shader, vertex_shader_source[vertex_shader_id]);
	}
	glAttachShader(info->program, *vertex_shader);
	GLuint* fragment_shader = &fragment_shaders_[fragment_shader_id];
	if (!*fragment_shader) {
	*fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
	CompileShader(*fragment_shader,
	fragment_shader_source[fragment_shader_id]);
	}
	glAttachShader(info->program, *fragment_shader);
	glBindAttribLocation(info->program, kVertexPositionAttrib, "a_position");
	glLinkProgram(info->program);
	#ifndef NDEBUG
	GLint linked;
	glGetProgramiv(info->program, GL_LINK_STATUS, &linked);
	if (!linked)
	DLOG(ERROR) << "CopyTextureCHROMIUM: program link failure.";
	#endif
	info->matrix_handle = glGetUniformLocation(info->program, "u_matrix");
	info->half_size_handle = glGetUniformLocation(info->program, "u_half_size");
	info->sampler_handle = glGetUniformLocation(info->program, "u_sampler");
	}
	glUseProgram(info->program);

	if (!xoffset && !yoffset) {
	glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, transform_matrix);
	} else {
	// transform offsets from ([0, dest_width], [0, dest_height]) coord.
	// to ([-1, 1], [-1, 1]) coord.
	GLfloat xoffset_on_vertex = ((2.f * xoffset) / dest_width);
	GLfloat yoffset_on_vertex = ((2.f * yoffset) / dest_height);

	// Pass view_matrix * offset_matrix to the program.
	GLfloat view_transform[16];
	memcpy(view_transform, transform_matrix, 16 * sizeof(GLfloat));
	PreTranslate(view_transform, xoffset_on_vertex, yoffset_on_vertex, 0);
	glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, view_transform);
	}
	if (source_target == GL_TEXTURE_RECTANGLE_ARB)
	glUniform2f(info->half_size_handle, source_width / 2.0f,
	source_height / 2.0f);
	else
	glUniform2f(info->half_size_handle, 0.5f, 0.5f);

	if (BindFramebufferTexture2D(GL_TEXTURE_2D, dest_id, framebuffer_)) {
	#ifndef NDEBUG
	// glValidateProgram of MACOSX validates FBO unlike other platforms, so
	// glValidateProgram must be called after FBO binding. crbug.com/463439
	glValidateProgram(info->program);
	GLint validation_status;
	glGetProgramiv(info->program, GL_VALIDATE_STATUS, &validation_status);
	if (GL_TRUE != validation_status) {
	DLOG(ERROR) << "CopyTextureCHROMIUM: Invalid shader.";
	return;
	}
	#endif
	decoder->ClearAllAttributes();
	glEnableVertexAttribArray(kVertexPositionAttrib);

	glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
	glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);

	glUniform1i(info->sampler_handle, 0);

	glBindTexture(source_target, source_id);
	glTexParameterf(source_target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameterf(source_target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(source_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(source_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

	glDisable(GL_DEPTH_TEST);
	glDisable(GL_SCISSOR_TEST);
	glDisable(GL_STENCIL_TEST);
	glDisable(GL_CULL_FACE);
	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
	glDepthMask(GL_FALSE);
	glDisable(GL_BLEND);

	glViewport(0, 0, dest_width, dest_height);
	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
	}

	decoder->RestoreAllAttributes();
	decoder->RestoreTextureState(source_id);
	decoder->RestoreTextureState(dest_id);
	decoder->RestoreTextureUnitBindings(0);
	decoder->RestoreActiveTexture();
	decoder->RestoreProgramBindings();
	decoder->RestoreBufferBindings();
	decoder->RestoreFramebufferBindings();
	decoder->RestoreGlobalState();
	}

	} // namespace gpu