gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/basictypes.h"
  10 #include "gpu/command_buffer/service/gl_utils.h"
  11 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
  12
  13 #define SHADER(src)                     \
  14   "#ifdef GL_ES\n"                      \
  15   "precision mediump float;\n"          \
  16   "#define TexCoordPrecision mediump\n" \
  17   "#else\n"                             \
  18   "#define TexCoordPrecision\n"         \
  19   "#endif\n" #src
  20 #define SHADER_2D(src)              \
  21   "#define SamplerType sampler2D\n" \
  22   "#define TextureLookup texture2D\n" SHADER(src)
  23 #define SHADER_RECTANGLE_ARB(src)     \
  24   "#define SamplerType sampler2DRect\n" \
  25   "#define TextureLookup texture2DRect\n" SHADER(src)
  26 #define SHADER_EXTERNAL_OES(src)                     \
  27   "#extension GL_OES_EGL_image_external : require\n" \
  28   "#define SamplerType samplerExternalOES\n"         \
  29   "#define TextureLookup texture2D\n" SHADER(src)
  30 #define FRAGMENT_SHADERS(src) \
  31   SHADER_2D(src), SHADER_RECTANGLE_ARB(src), SHADER_EXTERNAL_OES(src)
  32
  33 namespace {
  34
  35 const GLfloat kIdentityMatrix[16] = {1.0f, 0.0f, 0.0f, 0.0f,
  36                                      0.0f, 1.0f, 0.0f, 0.0f,
  37                                      0.0f, 0.0f, 1.0f, 0.0f,
  38                                      0.0f, 0.0f, 0.0f, 1.0f};
  39
  40 enum VertexShaderId {
  41   VERTEX_SHADER_COPY_TEXTURE,
  42   VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
  43   NUM_VERTEX_SHADERS,
  44 };
  45
  46 enum FragmentShaderId {
  47   FRAGMENT_SHADER_COPY_TEXTURE_2D,
  48   FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
  49   FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
  50   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
  51   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
  52   FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
  53   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
  54   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
  55   FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
  56   NUM_FRAGMENT_SHADERS,
  57 };
  58
  59 const char* vertex_shader_source[NUM_VERTEX_SHADERS] = {
  60   // VERTEX_SHADER_COPY_TEXTURE
  61   SHADER(
  62     uniform mat4 u_matrix;
  63     uniform vec2 u_half_size;
  64     attribute vec4 a_position;
  65     varying TexCoordPrecision vec2 v_uv;
  66     void main(void) {
  67       gl_Position = u_matrix * a_position;
  68       v_uv = a_position.xy * vec2(u_half_size.s, u_half_size.t) +
  69              vec2(u_half_size.s, u_half_size.t);
  70     }),
  71   // VERTEX_SHADER_COPY_TEXTURE_FLIP_Y
  72   SHADER(
  73     uniform mat4 u_matrix;
  74     uniform vec2 u_half_size;
  75     attribute vec4 a_position;
  76     varying TexCoordPrecision vec2 v_uv;
  77     void main(void) {
  78       gl_Position = u_matrix * a_position;
  79       v_uv = a_position.xy * vec2(u_half_size.s, -u_half_size.t) +
  80              vec2(u_half_size.s, u_half_size.t);
  81     }),
  82 };
  83
  84 const char* fragment_shader_source[NUM_FRAGMENT_SHADERS] = {
  85   // FRAGMENT_SHADER_COPY_TEXTURE_*
  86   FRAGMENT_SHADERS(
  87     uniform SamplerType u_sampler;
  88     varying TexCoordPrecision vec2 v_uv;
  89     void main(void) {
  90       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
  91     }),
  92   // FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_*
  93   FRAGMENT_SHADERS(
  94     uniform SamplerType u_sampler;
  95     varying TexCoordPrecision vec2 v_uv;
  96     void main(void) {
  97       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
  98       gl_FragColor.rgb *= gl_FragColor.a;
  99     }),
 100   // FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_*
 101   FRAGMENT_SHADERS(
 102     uniform SamplerType u_sampler;
 103     varying TexCoordPrecision vec2 v_uv;
 104     void main(void) {
 105       gl_FragColor = TextureLookup(u_sampler, v_uv.st);
 106       if (gl_FragColor.a > 0.0)
 107         gl_FragColor.rgb /= gl_FragColor.a;
 108     }),
 109 };
 110
 111 // Returns the correct vertex shader id to evaluate the copy operation for
 112 // the CHROMIUM_flipy setting.
 113 VertexShaderId GetVertexShaderId(bool flip_y) {
 114   // bit 0: flip y
 115   static VertexShaderId shader_ids[] = {
 116       VERTEX_SHADER_COPY_TEXTURE,
 117       VERTEX_SHADER_COPY_TEXTURE_FLIP_Y,
 118   };
 119
 120   unsigned index = flip_y ? 1 : 0;
 121   return shader_ids[index];
 122 }
 123
 124 // Returns the correct fragment shader id to evaluate the copy operation for
 125 // the premultiply alpha pixel store settings and target.
 126 FragmentShaderId GetFragmentShaderId(bool premultiply_alpha,
 127                                      bool unpremultiply_alpha,
 128                                      GLenum target) {
 129   enum {
 130     SAMPLER_2D,
 131     SAMPLER_RECTANGLE_ARB,
 132     SAMPLER_EXTERNAL_OES,
 133     NUM_SAMPLERS
 134   };
 135
 136   // bit 0: premultiply alpha
 137   // bit 1: unpremultiply alpha
 138   static FragmentShaderId shader_ids[][NUM_SAMPLERS] = {
 139       {
 140        FRAGMENT_SHADER_COPY_TEXTURE_2D,
 141        FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
 142        FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
 143       },
 144       {
 145        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_2D,
 146        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_RECTANGLE_ARB,
 147        FRAGMENT_SHADER_COPY_TEXTURE_PREMULTIPLY_ALPHA_EXTERNAL_OES,
 148       },
 149       {
 150        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_2D,
 151        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_RECTANGLE_ARB,
 152        FRAGMENT_SHADER_COPY_TEXTURE_UNPREMULTIPLY_ALPHA_EXTERNAL_OES,
 153       },
 154       {
 155        FRAGMENT_SHADER_COPY_TEXTURE_2D,
 156        FRAGMENT_SHADER_COPY_TEXTURE_RECTANGLE_ARB,
 157        FRAGMENT_SHADER_COPY_TEXTURE_EXTERNAL_OES,
 158       }};
 159
 160   unsigned index = (premultiply_alpha   ? (1 << 0) : 0) |
 161                    (unpremultiply_alpha ? (1 << 1) : 0);
 162
 163   switch (target) {
 164     case GL_TEXTURE_2D:
 165       return shader_ids[index][SAMPLER_2D];
 166     case GL_TEXTURE_RECTANGLE_ARB:
 167       return shader_ids[index][SAMPLER_RECTANGLE_ARB];
 168     case GL_TEXTURE_EXTERNAL_OES:
 169       return shader_ids[index][SAMPLER_EXTERNAL_OES];
 170     default:
 171       break;
 172   }
 173
 174   NOTREACHED();
 175   return shader_ids[0][SAMPLER_2D];
 176 }
 177
 178 void CompileShader(GLuint shader, const char* shader_source) {
 179   glShaderSource(shader, 1, &shader_source, 0);
 180   glCompileShader(shader);
 181 #ifndef NDEBUG
 182   GLint compile_status;
 183   glGetShaderiv(shader, GL_COMPILE_STATUS, &compile_status);
 184   if (GL_TRUE != compile_status)
 185     DLOG(ERROR) << "CopyTextureCHROMIUM: shader compilation failure.";
 186 #endif
 187 }
 188
 189 void DeleteShader(GLuint shader) {
 190   if (shader)
 191     glDeleteShader(shader);
 192 }
 193
 194 bool BindFramebufferTexture2D(GLenum target,
 195                               GLuint texture_id,
 196                               GLuint framebuffer) {
 197   DCHECK(target == GL_TEXTURE_2D || target == GL_TEXTURE_RECTANGLE_ARB);
 198   glActiveTexture(GL_TEXTURE0);
 199   glBindTexture(target, texture_id);
 200   // NVidia drivers require texture settings to be a certain way
 201   // or they won't report FRAMEBUFFER_COMPLETE.
 202   glTexParameterf(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 203   glTexParameterf(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 204   glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 205   glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 206   glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer);
 207   glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target,
 208                             texture_id, 0);
 209
 210 #ifndef NDEBUG
 211   GLenum fb_status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
 212   if (GL_FRAMEBUFFER_COMPLETE != fb_status) {
 213     DLOG(ERROR) << "CopyTextureCHROMIUM: Incomplete framebuffer.";
 214     return false;
 215   }
 216 #endif
 217   return true;
 218 }
 219
 220 void DoCopyTexImage2D(const gpu::gles2::GLES2Decoder* decoder,
 221                       GLenum source_target,
 222                       GLuint source_id,
 223                       GLuint dest_id,
 224                       GLenum dest_internal_format,
 225                       GLsizei width,
 226                       GLsizei height,
 227                       GLuint framebuffer) {
 228   DCHECK(source_target == GL_TEXTURE_2D ||
 229          source_target == GL_TEXTURE_RECTANGLE_ARB);
 230   if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
 231     glBindTexture(GL_TEXTURE_2D, dest_id);
 232     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 233     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 234     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 235     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 236     glCopyTexImage2D(GL_TEXTURE_2D, 0 /* level */, dest_internal_format,
 237                      0 /* x */, 0 /* y */, width, height, 0 /* border */);
 238   }
 239
 240   decoder->RestoreTextureState(source_id);
 241   decoder->RestoreTextureState(dest_id);
 242   decoder->RestoreTextureUnitBindings(0);
 243   decoder->RestoreActiveTexture();
 244   decoder->RestoreFramebufferBindings();
 245 }
 246
 247 void DoCopyTexSubImage2D(const gpu::gles2::GLES2Decoder* decoder,
 248                          GLenum source_target,
 249                          GLuint source_id,
 250                          GLuint dest_id,
 251                          GLint xoffset,
 252                          GLint yoffset,
 253                          GLint source_x,
 254                          GLint source_y,
 255                          GLsizei source_width,
 256                          GLsizei source_height,
 257                          GLuint framebuffer) {
 258   DCHECK(source_target == GL_TEXTURE_2D ||
 259          source_target == GL_TEXTURE_RECTANGLE_ARB);
 260   if (BindFramebufferTexture2D(source_target, source_id, framebuffer)) {
 261     glBindTexture(GL_TEXTURE_2D, dest_id);
 262     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 263     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 264     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 265     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 266     glCopyTexSubImage2D(GL_TEXTURE_2D, 0 /* level */, xoffset, yoffset,
 267                         source_x, source_y, source_width, source_height);
 268   }
 269
 270   decoder->RestoreTextureState(source_id);
 271   decoder->RestoreTextureState(dest_id);
 272   decoder->RestoreTextureUnitBindings(0);
 273   decoder->RestoreActiveTexture();
 274   decoder->RestoreFramebufferBindings();
 275 }
 276
 277 // Copy from SkMatrix44::preTranslate
 278 void PreTranslate(GLfloat* matrix, GLfloat dx, GLfloat dy, GLfloat dz) {
 279   if (!dx && !dy && !dz)
 280     return;
 281
 282   for (int i = 0; i < 4; ++i) {
 283     matrix[(3 * 4) + i] = matrix[(0 * 4) + i] * dx + matrix[(1 * 4) + i] * dy +
 284                           matrix[(2 * 4) + i] * dz + matrix[(3 * 4) + i];
 285   }
 286 }
 287
 288 }  // namespace
 289
 290 namespace gpu {
 291
 292 CopyTextureCHROMIUMResourceManager::CopyTextureCHROMIUMResourceManager()
 293     : initialized_(false),
 294       vertex_shaders_(NUM_VERTEX_SHADERS, 0u),
 295       fragment_shaders_(NUM_FRAGMENT_SHADERS, 0u),
 296       buffer_id_(0u),
 297       framebuffer_(0u) {}
 298
 299 CopyTextureCHROMIUMResourceManager::~CopyTextureCHROMIUMResourceManager() {
 300   // |buffer_id_| and |framebuffer_| can be not-null because when GPU context is
 301   // lost, this class can be deleted without releasing resources like
 302   // GLES2DecoderImpl.
 303 }
 304
 305 void CopyTextureCHROMIUMResourceManager::Initialize(
 306     const gles2::GLES2Decoder* decoder) {
 307   static_assert(
 308       kVertexPositionAttrib == 0u,
 309       "kVertexPositionAttrib must be 0");
 310   DCHECK(!buffer_id_);
 311   DCHECK(!framebuffer_);
 312   DCHECK(programs_.empty());
 313
 314   // Initialize all of the GPU resources required to perform the copy.
 315   glGenBuffersARB(1, &buffer_id_);
 316   glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
 317   const GLfloat kQuadVertices[] = {-1.0f, -1.0f,
 318                                     1.0f, -1.0f,
 319                                     1.0f,  1.0f,
 320                                    -1.0f,  1.0f};
 321   glBufferData(
 322       GL_ARRAY_BUFFER, sizeof(kQuadVertices), kQuadVertices, GL_STATIC_DRAW);
 323
 324   glGenFramebuffersEXT(1, &framebuffer_);
 325
 326   decoder->RestoreBufferBindings();
 327
 328   initialized_ = true;
 329 }
 330
 331 void CopyTextureCHROMIUMResourceManager::Destroy() {
 332   if (!initialized_)
 333     return;
 334
 335   glDeleteFramebuffersEXT(1, &framebuffer_);
 336   framebuffer_ = 0;
 337
 338   std::for_each(vertex_shaders_.begin(), vertex_shaders_.end(), DeleteShader);
 339   std::for_each(
 340       fragment_shaders_.begin(), fragment_shaders_.end(), DeleteShader);
 341
 342   for (ProgramMap::const_iterator it = programs_.begin(); it != programs_.end();
 343        ++it) {
 344     const ProgramInfo& info = it->second;
 345     glDeleteProgram(info.program);
 346   }
 347
 348   glDeleteBuffersARB(1, &buffer_id_);
 349   buffer_id_ = 0;
 350 }
 351
 352 void CopyTextureCHROMIUMResourceManager::DoCopyTexture(
 353     const gles2::GLES2Decoder* decoder,
 354     GLenum source_target,
 355     GLuint source_id,
 356     GLenum source_internal_format,
 357     GLuint dest_id,
 358     GLenum dest_internal_format,
 359     GLsizei width,
 360     GLsizei height,
 361     bool flip_y,
 362     bool premultiply_alpha,
 363     bool unpremultiply_alpha) {
 364   bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
 365   // GL_INVALID_OPERATION is generated if the currently bound framebuffer's
 366   // format does not contain a superset of the components required by the base
 367   // format of internalformat.
 368   // https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
 369   bool source_format_contain_superset_of_dest_format =
 370       (source_internal_format == dest_internal_format &&
 371        source_internal_format != GL_BGRA_EXT) ||
 372       (source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
 373   // GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
 374   // so restrict this to GL_TEXTURE_2D.
 375   if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
 376       source_format_contain_superset_of_dest_format) {
 377     DoCopyTexImage2D(decoder,
 378                      source_target,
 379                      source_id,
 380                      dest_id,
 381                      dest_internal_format,
 382                      width,
 383                      height,
 384                      framebuffer_);
 385     return;
 386   }
 387
 388   // Use kIdentityMatrix if no transform passed in.
 389   DoCopyTextureWithTransform(decoder, source_target, source_id, dest_id, width,
 390                              height, flip_y, premultiply_alpha,
 391                              unpremultiply_alpha, kIdentityMatrix);
 392 }
 393
 394 void CopyTextureCHROMIUMResourceManager::DoCopySubTexture(
 395     const gles2::GLES2Decoder* decoder,
 396     GLenum source_target,
 397     GLuint source_id,
 398     GLenum source_internal_format,
 399     GLuint dest_id,
 400     GLenum dest_internal_format,
 401     GLint xoffset,
 402     GLint yoffset,
 403     GLint x,
 404     GLint y,
 405     GLsizei width,
 406     GLsizei height,
 407     GLsizei dest_width,
 408     GLsizei dest_height,
 409     GLsizei source_width,
 410     GLsizei source_height,
 411     bool flip_y,
 412     bool premultiply_alpha,
 413     bool unpremultiply_alpha) {
 414   bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
 415   // GL_INVALID_OPERATION is generated if the currently bound framebuffer's
 416   // format does not contain a superset of the components required by the base
 417   // format of internalformat.
 418   // https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCopyTexImage2D.xml
 419   bool source_format_contain_superset_of_dest_format =
 420       (source_internal_format == dest_internal_format &&
 421        source_internal_format != GL_BGRA_EXT) ||
 422       (source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
 423   // GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
 424   // so restrict this to GL_TEXTURE_2D.
 425   if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
 426       source_format_contain_superset_of_dest_format) {
 427     DoCopyTexSubImage2D(decoder, source_target, source_id, dest_id, xoffset,
 428                         yoffset, x, y, width, height, framebuffer_);
 429     return;
 430   }
 431
 432   DoCopyTextureInternal(decoder, source_target, source_id, dest_id, xoffset - x,
 433                         yoffset - y, dest_width, dest_height, source_width,
 434                         source_height, flip_y, premultiply_alpha,
 435                         unpremultiply_alpha, kIdentityMatrix, xoffset, yoffset,
 436                         width, height);
 437 }
 438
 439 void CopyTextureCHROMIUMResourceManager::DoCopyTextureWithTransform(
 440     const gles2::GLES2Decoder* decoder,
 441     GLenum source_target,
 442     GLuint source_id,
 443     GLuint dest_id,
 444     GLsizei width,
 445     GLsizei height,
 446     bool flip_y,
 447     bool premultiply_alpha,
 448     bool unpremultiply_alpha,
 449     const GLfloat transform_matrix[16]) {
 450   GLsizei dest_width = width;
 451   GLsizei dest_height = height;
 452   DoCopyTextureInternal(decoder, source_target, source_id, dest_id, 0, 0,
 453                         dest_width, dest_height, width, height, flip_y,
 454                         premultiply_alpha, unpremultiply_alpha,
 455                         transform_matrix, 0, 0, dest_width, dest_height);
 456 }
 457
 458 void CopyTextureCHROMIUMResourceManager::DoCopyTextureInternal(
 459     const gles2::GLES2Decoder* decoder,
 460     GLenum source_target,
 461     GLuint source_id,
 462     GLuint dest_id,
 463     GLint xoffset,
 464     GLint yoffset,
 465     GLsizei dest_width,
 466     GLsizei dest_height,
 467     GLsizei source_width,
 468     GLsizei source_height,
 469     bool flip_y,
 470     bool premultiply_alpha,
 471     bool unpremultiply_alpha,
 472     const GLfloat transform_matrix[16],
 473     GLint scissor_x,
 474     GLint scissor_y,
 475     GLsizei scissor_width,
 476     GLsizei scissor_height) {
 477   DCHECK(source_target == GL_TEXTURE_2D ||
 478          source_target == GL_TEXTURE_RECTANGLE_ARB ||
 479          source_target == GL_TEXTURE_EXTERNAL_OES);
 480   DCHECK(xoffset >= 0 && xoffset + source_width <= dest_width);
 481   DCHECK(yoffset >= 0 && yoffset + source_height <= dest_height);
 482   if (!initialized_) {
 483     DLOG(ERROR) << "CopyTextureCHROMIUM: Uninitialized manager.";
 484     return;
 485   }
 486
 487   VertexShaderId vertex_shader_id = GetVertexShaderId(flip_y);
 488   DCHECK_LT(static_cast<size_t>(vertex_shader_id), vertex_shaders_.size());
 489   FragmentShaderId fragment_shader_id = GetFragmentShaderId(
 490       premultiply_alpha, unpremultiply_alpha, source_target);
 491   DCHECK_LT(static_cast<size_t>(fragment_shader_id), fragment_shaders_.size());
 492
 493   ProgramMapKey key(vertex_shader_id, fragment_shader_id);
 494   ProgramInfo* info = &programs_[key];
 495   // Create program if necessary.
 496   if (!info->program) {
 497     info->program = glCreateProgram();
 498     GLuint* vertex_shader = &vertex_shaders_[vertex_shader_id];
 499     if (!*vertex_shader) {
 500       *vertex_shader = glCreateShader(GL_VERTEX_SHADER);
 501       CompileShader(*vertex_shader, vertex_shader_source[vertex_shader_id]);
 502     }
 503     glAttachShader(info->program, *vertex_shader);
 504     GLuint* fragment_shader = &fragment_shaders_[fragment_shader_id];
 505     if (!*fragment_shader) {
 506       *fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
 507       CompileShader(*fragment_shader,
 508                     fragment_shader_source[fragment_shader_id]);
 509     }
 510     glAttachShader(info->program, *fragment_shader);
 511     glBindAttribLocation(info->program, kVertexPositionAttrib, "a_position");
 512     glLinkProgram(info->program);
 513 #ifndef NDEBUG
 514     GLint linked;
 515     glGetProgramiv(info->program, GL_LINK_STATUS, &linked);
 516     if (!linked)
 517       DLOG(ERROR) << "CopyTextureCHROMIUM: program link failure.";
 518 #endif
 519     info->matrix_handle = glGetUniformLocation(info->program, "u_matrix");
 520     info->half_size_handle = glGetUniformLocation(info->program, "u_half_size");
 521     info->sampler_handle = glGetUniformLocation(info->program, "u_sampler");
 522   }
 523   glUseProgram(info->program);
 524
 525   if (!xoffset && !yoffset) {
 526     glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, transform_matrix);
 527   } else {
 528     // transform offsets from ([0, dest_width], [0, dest_height]) coord.
 529     // to ([-1, 1], [-1, 1]) coord.
 530     GLfloat xoffset_on_vertex = ((2.f * xoffset) / dest_width);
 531     GLfloat yoffset_on_vertex = ((2.f * yoffset) / dest_height);
 532
 533     // Pass view_matrix * offset_matrix to the program.
 534     GLfloat view_transform[16];
 535     memcpy(view_transform, transform_matrix, 16 * sizeof(GLfloat));
 536     PreTranslate(view_transform, xoffset_on_vertex, yoffset_on_vertex, 0);
 537     glUniformMatrix4fv(info->matrix_handle, 1, GL_FALSE, view_transform);
 538   }
 539   if (source_target == GL_TEXTURE_RECTANGLE_ARB)
 540     glUniform2f(info->half_size_handle, source_width / 2.0f,
 541                 source_height / 2.0f);
 542   else
 543     glUniform2f(info->half_size_handle, 0.5f, 0.5f);
 544
 545   if (BindFramebufferTexture2D(GL_TEXTURE_2D, dest_id, framebuffer_)) {
 546 #ifndef NDEBUG
 547     // glValidateProgram of MACOSX validates FBO unlike other platforms, so
 548     // glValidateProgram must be called after FBO binding. crbug.com/463439
 549     glValidateProgram(info->program);
 550     GLint validation_status;
 551     glGetProgramiv(info->program, GL_VALIDATE_STATUS, &validation_status);
 552     if (GL_TRUE != validation_status) {
 553       DLOG(ERROR) << "CopyTextureCHROMIUM: Invalid shader.";
 554       return;
 555     }
 556 #endif
 557     decoder->ClearAllAttributes();
 558     glEnableVertexAttribArray(kVertexPositionAttrib);
 559
 560     glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
 561     glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
 562
 563     glUniform1i(info->sampler_handle, 0);
 564
 565     glBindTexture(source_target, source_id);
 566     glTexParameterf(source_target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 567     glTexParameterf(source_target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 568     glTexParameteri(source_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 569     glTexParameteri(source_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 570
 571     glDisable(GL_DEPTH_TEST);
 572     glDisable(GL_STENCIL_TEST);
 573     glDisable(GL_CULL_FACE);
 574     glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 575     glDepthMask(GL_FALSE);
 576     glDisable(GL_BLEND);
 577
 578     glEnable(GL_SCISSOR_TEST);
 579     glScissor(scissor_x, scissor_y, scissor_width, scissor_height);
 580     glViewport(0, 0, dest_width, dest_height);
 581     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 582   }
 583
 584   decoder->RestoreAllAttributes();
 585   decoder->RestoreTextureState(source_id);
 586   decoder->RestoreTextureState(dest_id);
 587   decoder->RestoreTextureUnitBindings(0);
 588   decoder->RestoreActiveTexture();
 589   decoder->RestoreProgramBindings();
 590   decoder->RestoreBufferBindings();
 591   decoder->RestoreFramebufferBindings();
 592   decoder->RestoreGlobalState();
 593 }
 594
 595 }  // namespace gpu