dom/canvas/WebGLContextGL.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "WebGLContext.h"
   7 #include "WebGL2Context.h"
   8
   9 #include "WebGLContextUtils.h"
  10 #include "WebGLBuffer.h"
  11 #include "WebGLShader.h"
  12 #include "WebGLProgram.h"
  13 #include "WebGLFormats.h"
  14 #include "WebGLFramebuffer.h"
  15 #include "WebGLQuery.h"
  16 #include "WebGLRenderbuffer.h"
  17 #include "WebGLTexture.h"
  18 #include "WebGLVertexArray.h"
  19
  20 #include "nsDebug.h"
  21 #include "nsReadableUtils.h"
  22 #include "nsString.h"
  23
  24 #include "gfxContext.h"
  25 #include "gfxPlatform.h"
  26 #include "GLContext.h"
  27
  28 #include "nsContentUtils.h"
  29 #include "nsError.h"
  30 #include "nsLayoutUtils.h"
  31
  32 #include "CanvasUtils.h"
  33 #include "gfxUtils.h"
  34 #include "MozFramebuffer.h"
  35
  36 #include "jsfriendapi.h"
  37
  38 #include "WebGLTexelConversions.h"
  39 #include "WebGLValidateStrings.h"
  40 #include <algorithm>
  41
  42 // needed to check if current OS is lower than 10.7
  43 #if defined(MOZ_WIDGET_COCOA)
  44 #  include "nsCocoaFeatures.h"
  45 #endif
  46
  47 #include "mozilla/DebugOnly.h"
  48 #include "mozilla/dom/BindingUtils.h"
  49 #include "mozilla/dom/ImageData.h"
  50 #include "mozilla/dom/WebGLRenderingContextBinding.h"
  51 #include "mozilla/EndianUtils.h"
  52 #include "mozilla/RefPtr.h"
  53 #include "mozilla/UniquePtrExtensions.h"
  54 #include "mozilla/StaticPrefs_webgl.h"
  55
  56 namespace mozilla {
  57
  58 using namespace mozilla::dom;
  59 using namespace mozilla::gfx;
  60 using namespace mozilla::gl;
  61
  62 //
  63 //  WebGL API
  64 //
  65
  66 void WebGLContext::ActiveTexture(uint32_t texUnit) {
  67   FuncScope funcScope(*this, "activeTexture");
  68   if (IsContextLost()) return;
  69   funcScope.mBindFailureGuard = true;
  70
  71   if (texUnit >= Limits().maxTexUnits) {
  72     return ErrorInvalidEnum("Texture unit %u out of range (%u).", texUnit,
  73                             Limits().maxTexUnits);
  74   }
  75
  76   mActiveTexture = texUnit;
  77   gl->fActiveTexture(LOCAL_GL_TEXTURE0 + texUnit);
  78
  79   funcScope.mBindFailureGuard = false;
  80 }
  81
  82 void WebGLContext::AttachShader(WebGLProgram& prog, WebGLShader& shader) {
  83   FuncScope funcScope(*this, "attachShader");
  84   if (IsContextLost()) return;
  85   funcScope.mBindFailureGuard = true;
  86
  87   prog.AttachShader(shader);
  88
  89   funcScope.mBindFailureGuard = false;
  90 }
  91
  92 void WebGLContext::BindAttribLocation(WebGLProgram& prog, GLuint location,
  93                                       const std::string& name) const {
  94   const FuncScope funcScope(*this, "bindAttribLocation");
  95   if (IsContextLost()) return;
  96
  97   prog.BindAttribLocation(location, name);
  98 }
  99
 100 void WebGLContext::BindFramebuffer(GLenum target, WebGLFramebuffer* wfb) {
 101   FuncScope funcScope(*this, "bindFramebuffer");
 102   if (IsContextLost()) return;
 103   funcScope.mBindFailureGuard = true;
 104
 105   if (!ValidateFramebufferTarget(target)) return;
 106
 107   if (!wfb) {
 108     gl->fBindFramebuffer(target, 0);
 109   } else {
 110     GLuint framebuffername = wfb->mGLName;
 111     gl->fBindFramebuffer(target, framebuffername);
 112     wfb->mHasBeenBound = true;
 113   }
 114
 115   switch (target) {
 116     case LOCAL_GL_FRAMEBUFFER:
 117       mBoundDrawFramebuffer = wfb;
 118       mBoundReadFramebuffer = wfb;
 119       break;
 120     case LOCAL_GL_DRAW_FRAMEBUFFER:
 121       mBoundDrawFramebuffer = wfb;
 122       break;
 123     case LOCAL_GL_READ_FRAMEBUFFER:
 124       mBoundReadFramebuffer = wfb;
 125       break;
 126     default:
 127       return;
 128   }
 129   funcScope.mBindFailureGuard = false;
 130 }
 131
 132 void WebGLContext::BlendEquationSeparate(Maybe<GLuint> i, GLenum modeRGB,
 133                                          GLenum modeAlpha) {
 134   const FuncScope funcScope(*this, "blendEquationSeparate");
 135   if (IsContextLost()) return;
 136
 137   if (!ValidateBlendEquationEnum(modeRGB, "modeRGB") ||
 138       !ValidateBlendEquationEnum(modeAlpha, "modeAlpha")) {
 139     return;
 140   }
 141
 142   if (i) {
 143     MOZ_RELEASE_ASSERT(
 144         IsExtensionEnabled(WebGLExtensionID::OES_draw_buffers_indexed));
 145     const auto limit = MaxValidDrawBuffers();
 146     if (*i >= limit) {
 147       ErrorInvalidValue("`index` (%u) must be < %s (%u)", *i,
 148                         "MAX_DRAW_BUFFERS", limit);
 149       return;
 150     }
 151
 152     gl->fBlendEquationSeparatei(*i, modeRGB, modeAlpha);
 153   } else {
 154     gl->fBlendEquationSeparate(modeRGB, modeAlpha);
 155   }
 156 }
 157
 158 static bool ValidateBlendFuncEnum(WebGLContext* webgl, GLenum factor,
 159                                   const char* varName) {
 160   switch (factor) {
 161     case LOCAL_GL_ZERO:
 162     case LOCAL_GL_ONE:
 163     case LOCAL_GL_SRC_COLOR:
 164     case LOCAL_GL_ONE_MINUS_SRC_COLOR:
 165     case LOCAL_GL_DST_COLOR:
 166     case LOCAL_GL_ONE_MINUS_DST_COLOR:
 167     case LOCAL_GL_SRC_ALPHA:
 168     case LOCAL_GL_ONE_MINUS_SRC_ALPHA:
 169     case LOCAL_GL_DST_ALPHA:
 170     case LOCAL_GL_ONE_MINUS_DST_ALPHA:
 171     case LOCAL_GL_CONSTANT_COLOR:
 172     case LOCAL_GL_ONE_MINUS_CONSTANT_COLOR:
 173     case LOCAL_GL_CONSTANT_ALPHA:
 174     case LOCAL_GL_ONE_MINUS_CONSTANT_ALPHA:
 175     case LOCAL_GL_SRC_ALPHA_SATURATE:
 176       return true;
 177
 178     default:
 179       webgl->ErrorInvalidEnumInfo(varName, factor);
 180       return false;
 181   }
 182 }
 183
 184 static bool ValidateBlendFuncEnums(WebGLContext* webgl, GLenum srcRGB,
 185                                    GLenum srcAlpha, GLenum dstRGB,
 186                                    GLenum dstAlpha) {
 187   if (!webgl->IsWebGL2()) {
 188     if (dstRGB == LOCAL_GL_SRC_ALPHA_SATURATE ||
 189         dstAlpha == LOCAL_GL_SRC_ALPHA_SATURATE) {
 190       webgl->ErrorInvalidEnum(
 191           "LOCAL_GL_SRC_ALPHA_SATURATE as a destination"
 192           " blend function is disallowed in WebGL 1 (dstRGB ="
 193           " 0x%04x, dstAlpha = 0x%04x).",
 194           dstRGB, dstAlpha);
 195       return false;
 196     }
 197   }
 198
 199   if (!ValidateBlendFuncEnum(webgl, srcRGB, "srcRGB") ||
 200       !ValidateBlendFuncEnum(webgl, srcAlpha, "srcAlpha") ||
 201       !ValidateBlendFuncEnum(webgl, dstRGB, "dstRGB") ||
 202       !ValidateBlendFuncEnum(webgl, dstAlpha, "dstAlpha")) {
 203     return false;
 204   }
 205
 206   return true;
 207 }
 208
 209 void WebGLContext::BlendFuncSeparate(Maybe<GLuint> i, GLenum srcRGB,
 210                                      GLenum dstRGB, GLenum srcAlpha,
 211                                      GLenum dstAlpha) {
 212   const FuncScope funcScope(*this, "blendFuncSeparate");
 213   if (IsContextLost()) return;
 214
 215   if (!ValidateBlendFuncEnums(this, srcRGB, srcAlpha, dstRGB, dstAlpha)) return;
 216
 217   // note that we only check compatibity for the RGB enums, no need to for the
 218   // Alpha enums, see "Section 6.8 forgetting to mention alpha factors?" thread
 219   // on the public_webgl mailing list
 220   if (!ValidateBlendFuncEnumsCompatibility(srcRGB, dstRGB, "srcRGB and dstRGB"))
 221     return;
 222
 223   if (i) {
 224     MOZ_RELEASE_ASSERT(
 225         IsExtensionEnabled(WebGLExtensionID::OES_draw_buffers_indexed));
 226     const auto limit = MaxValidDrawBuffers();
 227     if (*i >= limit) {
 228       ErrorInvalidValue("`index` (%u) must be < %s (%u)", *i,
 229                         "MAX_DRAW_BUFFERS", limit);
 230       return;
 231     }
 232
 233     gl->fBlendFuncSeparatei(*i, srcRGB, dstRGB, srcAlpha, dstAlpha);
 234   } else {
 235     gl->fBlendFuncSeparate(srcRGB, dstRGB, srcAlpha, dstAlpha);
 236   }
 237 }
 238
 239 GLenum WebGLContext::CheckFramebufferStatus(GLenum target) {
 240   const FuncScope funcScope(*this, "checkFramebufferStatus");
 241   if (IsContextLost()) return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
 242
 243   if (!ValidateFramebufferTarget(target)) return 0;
 244
 245   WebGLFramebuffer* fb;
 246   switch (target) {
 247     case LOCAL_GL_FRAMEBUFFER:
 248     case LOCAL_GL_DRAW_FRAMEBUFFER:
 249       fb = mBoundDrawFramebuffer;
 250       break;
 251
 252     case LOCAL_GL_READ_FRAMEBUFFER:
 253       fb = mBoundReadFramebuffer;
 254       break;
 255
 256     default:
 257       MOZ_CRASH("GFX: Bad target.");
 258   }
 259
 260   if (!fb) return LOCAL_GL_FRAMEBUFFER_COMPLETE;
 261
 262   return fb->CheckFramebufferStatus().get();
 263 }
 264
 265 RefPtr<WebGLProgram> WebGLContext::CreateProgram() {
 266   const FuncScope funcScope(*this, "createProgram");
 267   if (IsContextLost()) return nullptr;
 268
 269   return new WebGLProgram(this);
 270 }
 271
 272 RefPtr<WebGLShader> WebGLContext::CreateShader(GLenum type) {
 273   const FuncScope funcScope(*this, "createShader");
 274   if (IsContextLost()) return nullptr;
 275
 276   if (type != LOCAL_GL_VERTEX_SHADER && type != LOCAL_GL_FRAGMENT_SHADER) {
 277     ErrorInvalidEnumInfo("type", type);
 278     return nullptr;
 279   }
 280
 281   return new WebGLShader(this, type);
 282 }
 283
 284 void WebGLContext::CullFace(GLenum face) {
 285   const FuncScope funcScope(*this, "cullFace");
 286   if (IsContextLost()) return;
 287
 288   if (!ValidateFaceEnum(face)) return;
 289
 290   gl->fCullFace(face);
 291 }
 292
 293 void WebGLContext::DetachShader(WebGLProgram& prog, const WebGLShader& shader) {
 294   FuncScope funcScope(*this, "detachShader");
 295   if (IsContextLost()) return;
 296   funcScope.mBindFailureGuard = true;
 297
 298   prog.DetachShader(shader);
 299
 300   funcScope.mBindFailureGuard = false;
 301 }
 302
 303 static bool ValidateComparisonEnum(WebGLContext& webgl, const GLenum func) {
 304   switch (func) {
 305     case LOCAL_GL_NEVER:
 306     case LOCAL_GL_LESS:
 307     case LOCAL_GL_LEQUAL:
 308     case LOCAL_GL_GREATER:
 309     case LOCAL_GL_GEQUAL:
 310     case LOCAL_GL_EQUAL:
 311     case LOCAL_GL_NOTEQUAL:
 312     case LOCAL_GL_ALWAYS:
 313       return true;
 314
 315     default:
 316       webgl.ErrorInvalidEnumInfo("func", func);
 317       return false;
 318   }
 319 }
 320
 321 void WebGLContext::DepthFunc(GLenum func) {
 322   const FuncScope funcScope(*this, "depthFunc");
 323   if (IsContextLost()) return;
 324
 325   if (!ValidateComparisonEnum(*this, func)) return;
 326
 327   gl->fDepthFunc(func);
 328 }
 329
 330 void WebGLContext::DepthRange(GLfloat zNear, GLfloat zFar) {
 331   const FuncScope funcScope(*this, "depthRange");
 332   if (IsContextLost()) return;
 333
 334   if (zNear > zFar)
 335     return ErrorInvalidOperation(
 336         "the near value is greater than the far value!");
 337
 338   gl->fDepthRange(zNear, zFar);
 339 }
 340
 341 // -
 342
 343 void WebGLContext::FramebufferAttach(const GLenum target,
 344                                      const GLenum attachSlot,
 345                                      const GLenum bindImageTarget,
 346                                      const webgl::FbAttachInfo& toAttach) {
 347   FuncScope funcScope(*this, "framebufferAttach");
 348   funcScope.mBindFailureGuard = true;
 349   const auto& limits = *mLimits;
 350
 351   if (!ValidateFramebufferTarget(target)) return;
 352
 353   auto fb = mBoundDrawFramebuffer;
 354   if (target == LOCAL_GL_READ_FRAMEBUFFER) {
 355     fb = mBoundReadFramebuffer;
 356   }
 357   if (!fb) return;
 358
 359   // `rb` needs no validation.
 360
 361   // `tex`
 362   const auto& tex = toAttach.tex;
 363   if (tex) {
 364     const auto err = CheckFramebufferAttach(bindImageTarget, tex->mTarget.get(),
 365                                             toAttach.mipLevel, toAttach.zLayer,
 366                                             toAttach.zLayerCount, limits);
 367     if (err) return;
 368   }
 369
 370   auto safeToAttach = toAttach;
 371   if (!toAttach.rb && !toAttach.tex) {
 372     safeToAttach = {};
 373   }
 374   if (!IsWebGL2() &&
 375       !IsExtensionEnabled(WebGLExtensionID::OES_fbo_render_mipmap)) {
 376     safeToAttach.mipLevel = 0;
 377   }
 378   if (!IsExtensionEnabled(WebGLExtensionID::OVR_multiview2)) {
 379     safeToAttach.isMultiview = false;
 380   }
 381
 382   if (!fb->FramebufferAttach(attachSlot, safeToAttach)) return;
 383
 384   funcScope.mBindFailureGuard = false;
 385 }
 386
 387 // -
 388
 389 void WebGLContext::FrontFace(GLenum mode) {
 390   const FuncScope funcScope(*this, "frontFace");
 391   if (IsContextLost()) return;
 392
 393   switch (mode) {
 394     case LOCAL_GL_CW:
 395     case LOCAL_GL_CCW:
 396       break;
 397     default:
 398       return ErrorInvalidEnumInfo("mode", mode);
 399   }
 400
 401   gl->fFrontFace(mode);
 402 }
 403
 404 Maybe<double> WebGLContext::GetBufferParameter(GLenum target, GLenum pname) {
 405   const FuncScope funcScope(*this, "getBufferParameter");
 406   if (IsContextLost()) return Nothing();
 407
 408   const auto& slot = ValidateBufferSlot(target);
 409   if (!slot) return Nothing();
 410   const auto& buffer = *slot;
 411
 412   if (!buffer) {
 413     ErrorInvalidOperation("Buffer for `target` is null.");
 414     return Nothing();
 415   }
 416
 417   switch (pname) {
 418     case LOCAL_GL_BUFFER_SIZE:
 419       return Some(buffer->ByteLength());
 420
 421     case LOCAL_GL_BUFFER_USAGE:
 422       return Some(buffer->Usage());
 423
 424     default:
 425       ErrorInvalidEnumInfo("pname", pname);
 426       return Nothing();
 427   }
 428 }
 429
 430 Maybe<double> WebGLContext::GetFramebufferAttachmentParameter(
 431     WebGLFramebuffer* const fb, GLenum attachment, GLenum pname) const {
 432   const FuncScope funcScope(*this, "getFramebufferAttachmentParameter");
 433   if (IsContextLost()) return Nothing();
 434
 435   if (fb) return fb->GetAttachmentParameter(attachment, pname);
 436
 437   ////////////////////////////////////
 438
 439   if (!IsWebGL2()) {
 440     ErrorInvalidOperation(
 441         "Querying against the default framebuffer is not"
 442         " allowed in WebGL 1.");
 443     return Nothing();
 444   }
 445
 446   switch (attachment) {
 447     case LOCAL_GL_BACK:
 448     case LOCAL_GL_DEPTH:
 449     case LOCAL_GL_STENCIL:
 450       break;
 451
 452     default:
 453       ErrorInvalidEnum(
 454           "For the default framebuffer, can only query COLOR, DEPTH,"
 455           " or STENCIL.");
 456       return Nothing();
 457   }
 458
 459   switch (pname) {
 460     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
 461       switch (attachment) {
 462         case LOCAL_GL_BACK:
 463           break;
 464         case LOCAL_GL_DEPTH:
 465           if (!mOptions.depth) {
 466             return Some(LOCAL_GL_NONE);
 467           }
 468           break;
 469         case LOCAL_GL_STENCIL:
 470           if (!mOptions.stencil) {
 471             return Some(LOCAL_GL_NONE);
 472           }
 473           break;
 474         default:
 475           ErrorInvalidEnum(
 476               "With the default framebuffer, can only query COLOR, DEPTH,"
 477               " or STENCIL for GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE");
 478           return Nothing();
 479       }
 480       return Some(LOCAL_GL_FRAMEBUFFER_DEFAULT);
 481
 482       ////////////////
 483
 484     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
 485     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
 486     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
 487       if (attachment == LOCAL_GL_BACK) return Some(8);
 488       return Some(0);
 489
 490     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
 491       if (attachment == LOCAL_GL_BACK) {
 492         if (mOptions.alpha) {
 493           return Some(8);
 494         }
 495         ErrorInvalidOperation(
 496             "The default framebuffer doesn't contain an alpha buffer");
 497         return Nothing();
 498       }
 499       return Some(0);
 500
 501     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
 502       if (attachment == LOCAL_GL_DEPTH) {
 503         if (mOptions.depth) {
 504           return Some(24);
 505         }
 506         ErrorInvalidOperation(
 507             "The default framebuffer doesn't contain an depth buffer");
 508         return Nothing();
 509       }
 510       return Some(0);
 511
 512     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
 513       if (attachment == LOCAL_GL_STENCIL) {
 514         if (mOptions.stencil) {
 515           return Some(8);
 516         }
 517         ErrorInvalidOperation(
 518             "The default framebuffer doesn't contain an stencil buffer");
 519         return Nothing();
 520       }
 521       return Some(0);
 522
 523     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
 524       if (attachment == LOCAL_GL_STENCIL) {
 525         if (mOptions.stencil) {
 526           return Some(LOCAL_GL_UNSIGNED_INT);
 527         }
 528         ErrorInvalidOperation(
 529             "The default framebuffer doesn't contain an stencil buffer");
 530       } else if (attachment == LOCAL_GL_DEPTH) {
 531         if (mOptions.depth) {
 532           return Some(LOCAL_GL_UNSIGNED_NORMALIZED);
 533         }
 534         ErrorInvalidOperation(
 535             "The default framebuffer doesn't contain an depth buffer");
 536       } else {  // LOCAL_GL_BACK
 537         return Some(LOCAL_GL_UNSIGNED_NORMALIZED);
 538       }
 539       return Nothing();
 540
 541     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
 542       if (attachment == LOCAL_GL_STENCIL) {
 543         if (!mOptions.stencil) {
 544           ErrorInvalidOperation(
 545               "The default framebuffer doesn't contain an stencil buffer");
 546           return Nothing();
 547         }
 548       } else if (attachment == LOCAL_GL_DEPTH) {
 549         if (!mOptions.depth) {
 550           ErrorInvalidOperation(
 551               "The default framebuffer doesn't contain an depth buffer");
 552           return Nothing();
 553         }
 554       }
 555       return Some(LOCAL_GL_LINEAR);
 556   }
 557
 558   ErrorInvalidEnumInfo("pname", pname);
 559   return Nothing();
 560 }
 561
 562 Maybe<double> WebGLContext::GetRenderbufferParameter(
 563     const WebGLRenderbuffer& rb, GLenum pname) const {
 564   const FuncScope funcScope(*this, "getRenderbufferParameter");
 565   if (IsContextLost()) return Nothing();
 566
 567   switch (pname) {
 568     case LOCAL_GL_RENDERBUFFER_SAMPLES:
 569       if (!IsWebGL2()) break;
 570       [[fallthrough]];
 571
 572     case LOCAL_GL_RENDERBUFFER_WIDTH:
 573     case LOCAL_GL_RENDERBUFFER_HEIGHT:
 574     case LOCAL_GL_RENDERBUFFER_RED_SIZE:
 575     case LOCAL_GL_RENDERBUFFER_GREEN_SIZE:
 576     case LOCAL_GL_RENDERBUFFER_BLUE_SIZE:
 577     case LOCAL_GL_RENDERBUFFER_ALPHA_SIZE:
 578     case LOCAL_GL_RENDERBUFFER_DEPTH_SIZE:
 579     case LOCAL_GL_RENDERBUFFER_STENCIL_SIZE:
 580     case LOCAL_GL_RENDERBUFFER_INTERNAL_FORMAT: {
 581       // RB emulation means we have to ask the RB itself.
 582       GLint i = rb.GetRenderbufferParameter(pname);
 583       return Some(i);
 584     }
 585
 586     default:
 587       break;
 588   }
 589
 590   ErrorInvalidEnumInfo("pname", pname);
 591   return Nothing();
 592 }
 593
 594 RefPtr<WebGLTexture> WebGLContext::CreateTexture() {
 595   const FuncScope funcScope(*this, "createTexture");
 596   if (IsContextLost()) return nullptr;
 597
 598   GLuint tex = 0;
 599   gl->fGenTextures(1, &tex);
 600
 601   return new WebGLTexture(this, tex);
 602 }
 603
 604 GLenum WebGLContext::GetError() {
 605   const FuncScope funcScope(*this, "getError");
 606
 607   /* WebGL 1.0: Section 5.14.3: Setting and getting state:
 608    *   If the context's webgl context lost flag is set, returns
 609    *   CONTEXT_LOST_WEBGL the first time this method is called.
 610    *   Afterward, returns NO_ERROR until the context has been
 611    *   restored.
 612    *
 613    * WEBGL_lose_context:
 614    *   [When this extension is enabled: ] loseContext and
 615    *   restoreContext are allowed to generate INVALID_OPERATION errors
 616    *   even when the context is lost.
 617    */
 618
 619   auto err = mWebGLError;
 620   mWebGLError = 0;
 621   if (IsContextLost() || err)  // Must check IsContextLost in all flow paths.
 622     return err;
 623
 624   // Either no WebGL-side error, or it's already been cleared.
 625   // UnderlyingGL-side errors, now.
 626   err = gl->fGetError();
 627   if (gl->IsContextLost()) {
 628     CheckForContextLoss();
 629     return GetError();
 630   }
 631   MOZ_ASSERT(err != LOCAL_GL_CONTEXT_LOST);
 632
 633   if (err) {
 634     GenerateWarning("Driver error unexpected by WebGL: 0x%04x", err);
 635     // This might be:
 636     // - INVALID_OPERATION from ANGLE due to incomplete RBAB implementation for
 637     // DrawElements
 638     //   with DYNAMIC_DRAW index buffer.
 639   }
 640   return err;
 641 }
 642
 643 webgl::GetUniformData WebGLContext::GetUniform(const WebGLProgram& prog,
 644                                                const uint32_t loc) const {
 645   const FuncScope funcScope(*this, "getUniform");
 646   webgl::GetUniformData ret;
 647   [&]() {
 648     if (IsContextLost()) return;
 649
 650     const auto& info = prog.LinkInfo();
 651     if (!info) return;
 652
 653     const auto locInfo = MaybeFind(info->locationMap, loc);
 654     if (!locInfo) return;
 655
 656     ret.type = locInfo->info.info.elemType;
 657     switch (ret.type) {
 658       case LOCAL_GL_FLOAT:
 659       case LOCAL_GL_FLOAT_VEC2:
 660       case LOCAL_GL_FLOAT_VEC3:
 661       case LOCAL_GL_FLOAT_VEC4:
 662       case LOCAL_GL_FLOAT_MAT2:
 663       case LOCAL_GL_FLOAT_MAT3:
 664       case LOCAL_GL_FLOAT_MAT4:
 665       case LOCAL_GL_FLOAT_MAT2x3:
 666       case LOCAL_GL_FLOAT_MAT2x4:
 667       case LOCAL_GL_FLOAT_MAT3x2:
 668       case LOCAL_GL_FLOAT_MAT3x4:
 669       case LOCAL_GL_FLOAT_MAT4x2:
 670       case LOCAL_GL_FLOAT_MAT4x3:
 671         gl->fGetUniformfv(prog.mGLName, loc,
 672                           reinterpret_cast<float*>(ret.data));
 673         break;
 674
 675       case LOCAL_GL_INT:
 676       case LOCAL_GL_INT_VEC2:
 677       case LOCAL_GL_INT_VEC3:
 678       case LOCAL_GL_INT_VEC4:
 679       case LOCAL_GL_SAMPLER_2D:
 680       case LOCAL_GL_SAMPLER_3D:
 681       case LOCAL_GL_SAMPLER_CUBE:
 682       case LOCAL_GL_SAMPLER_2D_SHADOW:
 683       case LOCAL_GL_SAMPLER_2D_ARRAY:
 684       case LOCAL_GL_SAMPLER_2D_ARRAY_SHADOW:
 685       case LOCAL_GL_SAMPLER_CUBE_SHADOW:
 686       case LOCAL_GL_INT_SAMPLER_2D:
 687       case LOCAL_GL_INT_SAMPLER_3D:
 688       case LOCAL_GL_INT_SAMPLER_CUBE:
 689       case LOCAL_GL_INT_SAMPLER_2D_ARRAY:
 690       case LOCAL_GL_UNSIGNED_INT_SAMPLER_2D:
 691       case LOCAL_GL_UNSIGNED_INT_SAMPLER_3D:
 692       case LOCAL_GL_UNSIGNED_INT_SAMPLER_CUBE:
 693       case LOCAL_GL_UNSIGNED_INT_SAMPLER_2D_ARRAY:
 694       case LOCAL_GL_BOOL:
 695       case LOCAL_GL_BOOL_VEC2:
 696       case LOCAL_GL_BOOL_VEC3:
 697       case LOCAL_GL_BOOL_VEC4:
 698         gl->fGetUniformiv(prog.mGLName, loc,
 699                           reinterpret_cast<int32_t*>(ret.data));
 700         break;
 701
 702       case LOCAL_GL_UNSIGNED_INT:
 703       case LOCAL_GL_UNSIGNED_INT_VEC2:
 704       case LOCAL_GL_UNSIGNED_INT_VEC3:
 705       case LOCAL_GL_UNSIGNED_INT_VEC4:
 706         gl->fGetUniformuiv(prog.mGLName, loc,
 707                            reinterpret_cast<uint32_t*>(ret.data));
 708         break;
 709
 710       default:
 711         MOZ_CRASH("GFX: Invalid elemType.");
 712     }
 713   }();
 714   return ret;
 715 }
 716
 717 void WebGLContext::Hint(GLenum target, GLenum mode) {
 718   const FuncScope funcScope(*this, "hint");
 719   if (IsContextLost()) return;
 720
 721   switch (mode) {
 722     case LOCAL_GL_FASTEST:
 723     case LOCAL_GL_NICEST:
 724     case LOCAL_GL_DONT_CARE:
 725       break;
 726     default:
 727       return ErrorInvalidEnumArg("mode", mode);
 728   }
 729
 730   // -
 731
 732   bool isValid = false;
 733
 734   switch (target) {
 735     case LOCAL_GL_GENERATE_MIPMAP_HINT:
 736       mGenerateMipmapHint = mode;
 737       isValid = true;
 738
 739       // Deprecated and removed in desktop GL Core profiles.
 740       if (gl->IsCoreProfile()) return;
 741
 742       break;
 743
 744     case LOCAL_GL_FRAGMENT_SHADER_DERIVATIVE_HINT:
 745       if (IsWebGL2() ||
 746           IsExtensionEnabled(WebGLExtensionID::OES_standard_derivatives)) {
 747         isValid = true;
 748       }
 749       break;
 750   }
 751   if (!isValid) return ErrorInvalidEnumInfo("target", target);
 752
 753   // -
 754
 755   gl->fHint(target, mode);
 756 }
 757
 758 // -
 759
 760 void WebGLContext::LinkProgram(WebGLProgram& prog) {
 761   const FuncScope funcScope(*this, "linkProgram");
 762   if (IsContextLost()) return;
 763
 764   prog.LinkProgram();
 765
 766   if (&prog == mCurrentProgram) {
 767     if (!prog.IsLinked()) {
 768       // We use to simply early-out here, and preserve the GL behavior that
 769       // failed relink doesn't invalidate the current active program link info.
 770       // The new behavior was changed for WebGL here:
 771       // https://github.com/KhronosGroup/WebGL/pull/3371
 772       mActiveProgramLinkInfo = nullptr;
 773       gl->fUseProgram(0);  // Shouldn't be needed, but let's be safe.
 774       return;
 775     }
 776     mActiveProgramLinkInfo = prog.LinkInfo();
 777     gl->fUseProgram(prog.mGLName);  // Uncontionally re-use.
 778     // Previously, we needed this re-use on nvidia as a driver workaround,
 779     // but we might as well do it unconditionally.
 780   }
 781 }
 782
 783 Maybe<webgl::ErrorInfo> SetPixelUnpack(
 784     const bool isWebgl2, webgl::PixelUnpackStateWebgl* const unpacking,
 785     const GLenum pname, const GLint param) {
 786   if (isWebgl2) {
 787     uint32_t* pValueSlot = nullptr;
 788     switch (pname) {
 789       case LOCAL_GL_UNPACK_IMAGE_HEIGHT:
 790         pValueSlot = &unpacking->imageHeight;
 791         break;
 792
 793       case LOCAL_GL_UNPACK_SKIP_IMAGES:
 794         pValueSlot = &unpacking->skipImages;
 795         break;
 796
 797       case LOCAL_GL_UNPACK_ROW_LENGTH:
 798         pValueSlot = &unpacking->rowLength;
 799         break;
 800
 801       case LOCAL_GL_UNPACK_SKIP_ROWS:
 802         pValueSlot = &unpacking->skipRows;
 803         break;
 804
 805       case LOCAL_GL_UNPACK_SKIP_PIXELS:
 806         pValueSlot = &unpacking->skipPixels;
 807         break;
 808     }
 809
 810     if (pValueSlot) {
 811       *pValueSlot = static_cast<uint32_t>(param);
 812       return {};
 813     }
 814   }
 815
 816   switch (pname) {
 817     case dom::WebGLRenderingContext_Binding::UNPACK_FLIP_Y_WEBGL:
 818       unpacking->flipY = bool(param);
 819       return {};
 820
 821     case dom::WebGLRenderingContext_Binding::UNPACK_PREMULTIPLY_ALPHA_WEBGL:
 822       unpacking->premultiplyAlpha = bool(param);
 823       return {};
 824
 825     case dom::WebGLRenderingContext_Binding::UNPACK_COLORSPACE_CONVERSION_WEBGL:
 826       switch (param) {
 827         case LOCAL_GL_NONE:
 828         case dom::WebGLRenderingContext_Binding::BROWSER_DEFAULT_WEBGL:
 829           break;
 830
 831         default: {
 832           const nsPrintfCString text("Bad UNPACK_COLORSPACE_CONVERSION: %s",
 833                                      EnumString(param).c_str());
 834           return Some(webgl::ErrorInfo{LOCAL_GL_INVALID_VALUE, ToString(text)});
 835         }
 836       }
 837       unpacking->colorspaceConversion = param;
 838       return {};
 839
 840     case dom::MOZ_debug_Binding::UNPACK_REQUIRE_FASTPATH:
 841       unpacking->requireFastPath = bool(param);
 842       return {};
 843
 844     case LOCAL_GL_UNPACK_ALIGNMENT:
 845       switch (param) {
 846         case 1:
 847         case 2:
 848         case 4:
 849         case 8:
 850           break;
 851
 852         default: {
 853           const nsPrintfCString text(
 854               "UNPACK_ALIGNMENT must be [1,2,4,8], was %i", param);
 855           return Some(webgl::ErrorInfo{LOCAL_GL_INVALID_VALUE, ToString(text)});
 856         }
 857       }
 858       unpacking->alignmentInTypeElems = param;
 859       return {};
 860
 861     default:
 862       break;
 863   }
 864   const nsPrintfCString text("Bad `pname`: %s", EnumString(pname).c_str());
 865   return Some(webgl::ErrorInfo{LOCAL_GL_INVALID_ENUM, ToString(text)});
 866 }
 867
 868 bool WebGLContext::DoReadPixelsAndConvert(
 869     const webgl::FormatInfo* const srcFormat, const webgl::ReadPixelsDesc& desc,
 870     const uintptr_t dest, const uint64_t destSize, const uint32_t rowStride) {
 871   const auto& x = desc.srcOffset.x;
 872   const auto& y = desc.srcOffset.y;
 873   const auto size = *ivec2::From(desc.size);
 874   const auto& pi = desc.pi;
 875
 876   // On at least Win+NV, we'll get PBO errors if we don't have at least
 877   // `rowStride * height` bytes available to read into.
 878   const auto naiveBytesNeeded = CheckedInt<uint64_t>(rowStride) * size.y;
 879   const bool isDangerCloseToEdge =
 880       (!naiveBytesNeeded.isValid() || naiveBytesNeeded.value() > destSize);
 881   const bool useParanoidHandling =
 882       (gl->WorkAroundDriverBugs() && isDangerCloseToEdge &&
 883        mBoundPixelPackBuffer);
 884   if (!useParanoidHandling) {
 885     gl->fReadPixels(x, y, size.x, size.y, pi.format, pi.type,
 886                     reinterpret_cast<void*>(dest));
 887     return true;
 888   }
 889
 890   // Read everything but the last row.
 891   const auto bodyHeight = size.y - 1;
 892   if (bodyHeight) {
 893     gl->fReadPixels(x, y, size.x, bodyHeight, pi.format, pi.type,
 894                     reinterpret_cast<void*>(dest));
 895   }
 896
 897   // Now read the last row.
 898   gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, 1);
 899   gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, 0);
 900   gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, 0);
 901
 902   const auto tailRowOffset =
 903       reinterpret_cast<uint8_t*>(dest) + rowStride * bodyHeight;
 904   gl->fReadPixels(x, y + bodyHeight, size.x, 1, pi.format, pi.type,
 905                   tailRowOffset);
 906
 907   return true;
 908 }
 909
 910 webgl::ReadPixelsResult WebGLContext::ReadPixelsInto(
 911     const webgl::ReadPixelsDesc& desc, const Range<uint8_t>& dest) {
 912   const FuncScope funcScope(*this, "readPixels");
 913   if (IsContextLost()) return {};
 914
 915   if (mBoundPixelPackBuffer) {
 916     ErrorInvalidOperation("PIXEL_PACK_BUFFER must be null.");
 917     return {};
 918   }
 919
 920   return ReadPixelsImpl(desc, reinterpret_cast<uintptr_t>(dest.begin().get()),
 921                         dest.length());
 922 }
 923
 924 void WebGLContext::ReadPixelsPbo(const webgl::ReadPixelsDesc& desc,
 925                                  const uint64_t offset) {
 926   const FuncScope funcScope(*this, "readPixels");
 927   if (IsContextLost()) return;
 928
 929   const auto& buffer = ValidateBufferSelection(LOCAL_GL_PIXEL_PACK_BUFFER);
 930   if (!buffer) return;
 931
 932   //////
 933
 934   {
 935     const auto pii = webgl::PackingInfoInfo::For(desc.pi);
 936     if (!pii) {
 937       GLenum err = LOCAL_GL_INVALID_OPERATION;
 938       if (!desc.pi.format || !desc.pi.type) {
 939         err = LOCAL_GL_INVALID_ENUM;
 940       }
 941       GenerateError(err, "`format` (%s) and/or `type` (%s) not acceptable.",
 942                     EnumString(desc.pi.format).c_str(),
 943                     EnumString(desc.pi.type).c_str());
 944       return;
 945     }
 946
 947     if (offset % pii->bytesPerElement != 0) {
 948       ErrorInvalidOperation(
 949           "`offset` must be divisible by the size of `type`"
 950           " in bytes.");
 951       return;
 952     }
 953   }
 954
 955   //////
 956
 957   auto bytesAvailable = buffer->ByteLength();
 958   if (offset > bytesAvailable) {
 959     ErrorInvalidOperation("`offset` too large for bound PIXEL_PACK_BUFFER.");
 960     return;
 961   }
 962   bytesAvailable -= offset;
 963
 964   // -
 965
 966   const ScopedLazyBind lazyBind(gl, LOCAL_GL_PIXEL_PACK_BUFFER, buffer);
 967
 968   ReadPixelsImpl(desc, offset, bytesAvailable);
 969
 970   buffer->ResetLastUpdateFenceId();
 971 }
 972
 973 static webgl::PackingInfo DefaultReadPixelPI(
 974     const webgl::FormatUsageInfo* usage) {
 975   MOZ_ASSERT(usage->IsRenderable());
 976   const auto& format = *usage->format;
 977   switch (format.componentType) {
 978     case webgl::ComponentType::NormUInt:
 979       if (format.r == 16) {
 980         return {LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_SHORT};
 981       }
 982       return {LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_BYTE};
 983
 984     case webgl::ComponentType::Int:
 985       return {LOCAL_GL_RGBA_INTEGER, LOCAL_GL_INT};
 986
 987     case webgl::ComponentType::UInt:
 988       return {LOCAL_GL_RGBA_INTEGER, LOCAL_GL_UNSIGNED_INT};
 989
 990     case webgl::ComponentType::Float:
 991       return {LOCAL_GL_RGBA, LOCAL_GL_FLOAT};
 992
 993     default:
 994       MOZ_CRASH();
 995   }
 996 }
 997
 998 static bool ArePossiblePackEnums(const WebGLContext* webgl,
 999                                  const webgl::PackingInfo& pi) {
1000   // OpenGL ES 2.0 $4.3.1 - IMPLEMENTATION_COLOR_READ_{TYPE/FORMAT} is a valid
1001   // combination for glReadPixels()...
1002
1003   // Only valid when pulled from:
1004   // * GLES 2.0.25 p105:
1005   //   "table 3.4, excluding formats LUMINANCE and LUMINANCE_ALPHA."
1006   // * GLES 3.0.4 p193:
1007   //   "table 3.2, excluding formats DEPTH_COMPONENT and DEPTH_STENCIL."
1008   switch (pi.format) {
1009     case LOCAL_GL_LUMINANCE:
1010     case LOCAL_GL_LUMINANCE_ALPHA:
1011     case LOCAL_GL_DEPTH_COMPONENT:
1012     case LOCAL_GL_DEPTH_STENCIL:
1013       return false;
1014   }
1015
1016   if (pi.type == LOCAL_GL_UNSIGNED_INT_24_8) return false;
1017
1018   const auto pii = webgl::PackingInfoInfo::For(pi);
1019   if (!pii) return false;
1020
1021   return true;
1022 }
1023
1024 webgl::PackingInfo WebGLContext::ValidImplementationColorReadPI(
1025     const webgl::FormatUsageInfo* usage) const {
1026   const auto defaultPI = DefaultReadPixelPI(usage);
1027
1028   // ES2_compatibility always returns RGBA/UNSIGNED_BYTE, so branch on actual
1029   // IsGLES(). Also OSX+NV generates an error here.
1030   if (!gl->IsGLES()) return defaultPI;
1031
1032   webgl::PackingInfo implPI;
1033   gl->fGetIntegerv(LOCAL_GL_IMPLEMENTATION_COLOR_READ_FORMAT,
1034                    (GLint*)&implPI.format);
1035   gl->fGetIntegerv(LOCAL_GL_IMPLEMENTATION_COLOR_READ_TYPE,
1036                    (GLint*)&implPI.type);
1037
1038   if (!ArePossiblePackEnums(this, implPI)) return defaultPI;
1039
1040   return implPI;
1041 }
1042
1043 static bool ValidateReadPixelsFormatAndType(
1044     const webgl::FormatUsageInfo* srcUsage, const webgl::PackingInfo& pi,
1045     gl::GLContext* gl, WebGLContext* webgl) {
1046   if (!ArePossiblePackEnums(webgl, pi)) {
1047     webgl->ErrorInvalidEnum("Unexpected format or type.");
1048     return false;
1049   }
1050
1051   const auto defaultPI = DefaultReadPixelPI(srcUsage);
1052   if (pi == defaultPI) return true;
1053
1054   ////
1055
1056   // OpenGL ES 3.0.4 p194 - When the internal format of the rendering surface is
1057   // RGB10_A2, a third combination of format RGBA and type
1058   // UNSIGNED_INT_2_10_10_10_REV is accepted.
1059
1060   if (webgl->IsWebGL2() &&
1061       srcUsage->format->effectiveFormat == webgl::EffectiveFormat::RGB10_A2 &&
1062       pi.format == LOCAL_GL_RGBA &&
1063       pi.type == LOCAL_GL_UNSIGNED_INT_2_10_10_10_REV) {
1064     return true;
1065   }
1066
1067   ////
1068
1069   MOZ_ASSERT(gl->IsCurrent());
1070   const auto implPI = webgl->ValidImplementationColorReadPI(srcUsage);
1071   if (pi == implPI) return true;
1072
1073   ////
1074
1075   // clang-format off
1076   webgl->ErrorInvalidOperation(
1077       "Format and type %s/%s incompatible with this %s attachment."
1078       " This framebuffer requires either %s/%s or"
1079       " getParameter(IMPLEMENTATION_COLOR_READ_FORMAT/_TYPE) %s/%s.",
1080       EnumString(pi.format).c_str(), EnumString(pi.type).c_str(),
1081       srcUsage->format->name,
1082       EnumString(defaultPI.format).c_str(), EnumString(defaultPI.type).c_str(),
1083       EnumString(implPI.format).c_str(), EnumString(implPI.type).c_str());
1084   // clang-format on
1085
1086   return false;
1087 }
1088
1089 webgl::ReadPixelsResult WebGLContext::ReadPixelsImpl(
1090     const webgl::ReadPixelsDesc& desc, const uintptr_t dest,
1091     const uint64_t availBytes) {
1092   const webgl::FormatUsageInfo* srcFormat;
1093   uint32_t srcWidth;
1094   uint32_t srcHeight;
1095   if (!BindCurFBForColorRead(&srcFormat, &srcWidth, &srcHeight)) return {};
1096
1097   //////
1098
1099   if (!ValidateReadPixelsFormatAndType(srcFormat, desc.pi, gl, this)) return {};
1100
1101   //////
1102
1103   const auto& srcOffset = desc.srcOffset;
1104   const auto& size = desc.size;
1105
1106   if (!ivec2::From(size)) {
1107     ErrorInvalidValue("width and height must be non-negative.");
1108     return {};
1109   }
1110
1111   const auto& packing = desc.packState;
1112   const auto explicitPackingRes = webgl::ExplicitPixelPackingState::ForUseWith(
1113       packing, LOCAL_GL_TEXTURE_2D, {size.x, size.y, 1}, desc.pi, {});
1114   if (!explicitPackingRes.isOk()) {
1115     ErrorInvalidOperation("%s", explicitPackingRes.inspectErr().c_str());
1116     return {};
1117   }
1118   const auto& explicitPacking = explicitPackingRes.inspect();
1119   const auto& rowStride = explicitPacking.metrics.bytesPerRowStride;
1120   const auto& bytesNeeded = explicitPacking.metrics.totalBytesUsed;
1121   if (bytesNeeded > availBytes) {
1122     ErrorInvalidOperation("buffer too small");
1123     return {};
1124   }
1125
1126   ////
1127
1128   int32_t readX, readY;
1129   int32_t writeX, writeY;
1130   int32_t rwWidth, rwHeight;
1131   if (!Intersect(srcWidth, srcOffset.x, size.x, &readX, &writeX, &rwWidth) ||
1132       !Intersect(srcHeight, srcOffset.y, size.y, &readY, &writeY, &rwHeight)) {
1133     ErrorOutOfMemory("Bad subrect selection.");
1134     return {};
1135   }
1136
1137   ////////////////
1138   // Now that the errors are out of the way, on to actually reading!
1139
1140   gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, packing.alignmentInTypeElems);
1141   if (IsWebGL2()) {
1142     gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, packing.rowLength);
1143     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS, packing.skipPixels);
1144     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, packing.skipRows);
1145   }
1146
1147   if (!rwWidth || !rwHeight) {
1148     // Disjoint rects, so we're done already.
1149     DummyReadFramebufferOperation();
1150     return {};
1151   }
1152   const auto rwSize = *uvec2::From(rwWidth, rwHeight);
1153
1154   const auto res = webgl::ReadPixelsResult{
1155       {{writeX, writeY}, {rwSize.x, rwSize.y}}, rowStride};
1156
1157   if (rwSize == size) {
1158     DoReadPixelsAndConvert(srcFormat->format, desc, dest, bytesNeeded,
1159                            rowStride);
1160     return res;
1161   }
1162
1163   // Read request contains out-of-bounds pixels. Unfortunately:
1164   // GLES 3.0.4 p194 "Obtaining Pixels from the Framebuffer":
1165   // "If any of these pixels lies outside of the window allocated to the current
1166   // GL context, or outside of the image attached to the currently bound
1167   // framebuffer object, then the values obtained for those pixels are
1168   // undefined."
1169
1170   // This is a slow-path, so warn people away!
1171   GenerateWarning(
1172       "Out-of-bounds reads with readPixels are deprecated, and"
1173       " may be slow.");
1174
1175   ////////////////////////////////////
1176   // Read only the in-bounds pixels.
1177
1178   if (IsWebGL2()) {
1179     if (!packing.rowLength) {
1180       gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, packing.skipPixels + size.x);
1181     }
1182     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS, packing.skipPixels + writeX);
1183     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, packing.skipRows + writeY);
1184
1185     auto desc2 = desc;
1186     desc2.srcOffset = {readX, readY};
1187     desc2.size = rwSize;
1188
1189     DoReadPixelsAndConvert(srcFormat->format, desc2, dest, bytesNeeded,
1190                            rowStride);
1191   } else {
1192     // I *did* say "hilariously slow".
1193
1194     auto desc2 = desc;
1195     desc2.srcOffset = {readX, readY};
1196     desc2.size = {rwSize.x, 1};
1197
1198     const auto skipBytes = writeX * explicitPacking.metrics.bytesPerPixel;
1199     const auto usedRowBytes = rwSize.x * explicitPacking.metrics.bytesPerPixel;
1200     for (const auto j : IntegerRange(rwSize.y)) {
1201       desc2.srcOffset.y = readY + j;
1202       const auto destWriteBegin = dest + skipBytes + (writeY + j) * rowStride;
1203       MOZ_RELEASE_ASSERT(dest <= destWriteBegin);
1204       MOZ_RELEASE_ASSERT(destWriteBegin <= dest + availBytes);
1205
1206       const auto destWriteEnd = destWriteBegin + usedRowBytes;
1207       MOZ_RELEASE_ASSERT(dest <= destWriteEnd);
1208       MOZ_RELEASE_ASSERT(destWriteEnd <= dest + availBytes);
1209
1210       DoReadPixelsAndConvert(srcFormat->format, desc2, destWriteBegin,
1211                              destWriteEnd - destWriteBegin, rowStride);
1212     }
1213   }
1214
1215   return res;
1216 }
1217
1218 void WebGLContext::RenderbufferStorageMultisample(WebGLRenderbuffer& rb,
1219                                                   uint32_t samples,
1220                                                   GLenum internalFormat,
1221                                                   uint32_t width,
1222                                                   uint32_t height) const {
1223   const FuncScope funcScope(*this, "renderbufferStorage(Multisample)?");
1224   if (IsContextLost()) return;
1225
1226   rb.RenderbufferStorage(samples, internalFormat, width, height);
1227 }
1228
1229 void WebGLContext::Scissor(GLint x, GLint y, GLsizei width, GLsizei height) {
1230   const FuncScope funcScope(*this, "scissor");
1231   if (IsContextLost()) return;
1232
1233   if (!ValidateNonNegative("width", width) ||
1234       !ValidateNonNegative("height", height)) {
1235     return;
1236   }
1237
1238   mScissorRect = {x, y, width, height};
1239   mScissorRect.Apply(*gl);
1240 }
1241
1242 void WebGLContext::StencilFuncSeparate(GLenum face, GLenum func, GLint ref,
1243                                        GLuint mask) {
1244   const FuncScope funcScope(*this, "stencilFuncSeparate");
1245   if (IsContextLost()) return;
1246
1247   if (!ValidateFaceEnum(face) || !ValidateComparisonEnum(*this, func)) {
1248     return;
1249   }
1250
1251   switch (face) {
1252     case LOCAL_GL_FRONT_AND_BACK:
1253       mStencilRefFront = ref;
1254       mStencilRefBack = ref;
1255       mStencilValueMaskFront = mask;
1256       mStencilValueMaskBack = mask;
1257       break;
1258     case LOCAL_GL_FRONT:
1259       mStencilRefFront = ref;
1260       mStencilValueMaskFront = mask;
1261       break;
1262     case LOCAL_GL_BACK:
1263       mStencilRefBack = ref;
1264       mStencilValueMaskBack = mask;
1265       break;
1266   }
1267
1268   gl->fStencilFuncSeparate(face, func, ref, mask);
1269 }
1270
1271 void WebGLContext::StencilOpSeparate(GLenum face, GLenum sfail, GLenum dpfail,
1272                                      GLenum dppass) {
1273   const FuncScope funcScope(*this, "stencilOpSeparate");
1274   if (IsContextLost()) return;
1275
1276   if (!ValidateFaceEnum(face) || !ValidateStencilOpEnum(sfail, "sfail") ||
1277       !ValidateStencilOpEnum(dpfail, "dpfail") ||
1278       !ValidateStencilOpEnum(dppass, "dppass"))
1279     return;
1280
1281   gl->fStencilOpSeparate(face, sfail, dpfail, dppass);
1282 }
1283
1284 ////////////////////////////////////////////////////////////////////////////////
1285 // Uniform setters.
1286
1287 void WebGLContext::UniformData(
1288     const uint32_t loc, const bool transpose,
1289     const Range<const webgl::UniformDataVal>& data) const {
1290   const FuncScope funcScope(*this, "uniform setter");
1291
1292   if (!IsWebGL2() && transpose) {
1293     GenerateError(LOCAL_GL_INVALID_VALUE, "`transpose`:true requires WebGL 2.");
1294     return;
1295   }
1296
1297   // -
1298
1299   const auto& link = mActiveProgramLinkInfo;
1300   if (!link) return;
1301
1302   const auto locInfo = MaybeFind(link->locationMap, loc);
1303   if (!locInfo) {
1304     // Null WebGLUniformLocations become -1, which will end up here.
1305     return;
1306   }
1307
1308   const auto& validationInfo = locInfo->info;
1309   const auto& activeInfo = validationInfo.info;
1310   const auto& channels = validationInfo.channelsPerElem;
1311   const auto& pfn = validationInfo.pfn;
1312
1313   // -
1314
1315   const auto lengthInType = data.length();
1316   const auto elemCount = lengthInType / channels;
1317   if (elemCount > 1 && !validationInfo.isArray) {
1318     GenerateError(
1319         LOCAL_GL_INVALID_OPERATION,
1320         "(uniform %s) `values` length (%u) must exactly match size of %s.",
1321         activeInfo.name.c_str(), lengthInType,
1322         EnumString(activeInfo.elemType).c_str());
1323     return;
1324   }
1325
1326   // -
1327
1328   const auto& samplerInfo = locInfo->samplerInfo;
1329   if (samplerInfo) {
1330     const auto idata = reinterpret_cast<const uint32_t*>(data.begin().get());
1331     const auto maxTexUnits = GLMaxTextureUnits();
1332     for (const auto& val : Range<const uint32_t>(idata, elemCount)) {
1333       if (val >= maxTexUnits) {
1334         ErrorInvalidValue(
1335             "This uniform location is a sampler, but %d"
1336             " is not a valid texture unit.",
1337             val);
1338         return;
1339       }
1340     }
1341   }
1342
1343   // -
1344
1345   // This is a little galaxy-brain, sorry!
1346   const auto ptr = static_cast<const void*>(data.begin().get());
1347   (*pfn)(*gl, static_cast<GLint>(loc), elemCount, transpose, ptr);
1348
1349   // -
1350
1351   if (samplerInfo) {
1352     auto& texUnits = samplerInfo->texUnits;
1353
1354     const auto srcBegin = reinterpret_cast<const uint32_t*>(data.begin().get());
1355     auto destIndex = locInfo->indexIntoUniform;
1356     for (const auto& val : Range<const uint32_t>(srcBegin, elemCount)) {
1357       if (destIndex >= texUnits.size()) break;
1358       texUnits.at(destIndex) = AssertedCast<uint8_t>(val);
1359       destIndex += 1;
1360     }
1361   }
1362 }
1363
1364 ////////////////////////////////////////////////////////////////////////////////
1365
1366 void WebGLContext::UseProgram(WebGLProgram* prog) {
1367   FuncScope funcScope(*this, "useProgram");
1368   if (IsContextLost()) return;
1369   funcScope.mBindFailureGuard = true;
1370
1371   if (!prog) {
1372     mCurrentProgram = nullptr;
1373     mActiveProgramLinkInfo = nullptr;
1374     funcScope.mBindFailureGuard = false;
1375     return;
1376   }
1377
1378   if (!ValidateObject("prog", *prog)) return;
1379
1380   if (!prog->UseProgram()) return;
1381
1382   mCurrentProgram = prog;
1383   mActiveProgramLinkInfo = mCurrentProgram->LinkInfo();
1384
1385   funcScope.mBindFailureGuard = false;
1386 }
1387
1388 bool WebGLContext::ValidateProgram(const WebGLProgram& prog) const {
1389   const FuncScope funcScope(*this, "validateProgram");
1390   if (IsContextLost()) return false;
1391
1392   return prog.ValidateProgram();
1393 }
1394
1395 RefPtr<WebGLFramebuffer> WebGLContext::CreateFramebuffer() {
1396   const FuncScope funcScope(*this, "createFramebuffer");
1397   if (IsContextLost()) return nullptr;
1398
1399   GLuint fbo = 0;
1400   gl->fGenFramebuffers(1, &fbo);
1401
1402   return new WebGLFramebuffer(this, fbo);
1403 }
1404
1405 RefPtr<WebGLFramebuffer> WebGLContext::CreateOpaqueFramebuffer(
1406     const webgl::OpaqueFramebufferOptions& options) {
1407   const FuncScope funcScope(*this, "createOpaqueFramebuffer");
1408   if (IsContextLost()) return nullptr;
1409
1410   uint32_t samples = options.antialias ? StaticPrefs::webgl_msaa_samples() : 0;
1411   samples = std::min(samples, gl->MaxSamples());
1412   const gfx::IntSize size = {options.width, options.height};
1413
1414   auto fbo =
1415       gl::MozFramebuffer::Create(gl, size, samples, options.depthStencil);
1416   if (!fbo) {
1417     return nullptr;
1418   }
1419
1420   return new WebGLFramebuffer(this, std::move(fbo));
1421 }
1422
1423 RefPtr<WebGLRenderbuffer> WebGLContext::CreateRenderbuffer() {
1424   const FuncScope funcScope(*this, "createRenderbuffer");
1425   if (IsContextLost()) return nullptr;
1426
1427   return new WebGLRenderbuffer(this);
1428 }
1429
1430 void WebGLContext::Viewport(GLint x, GLint y, GLsizei width, GLsizei height) {
1431   const FuncScope funcScope(*this, "viewport");
1432   if (IsContextLost()) return;
1433
1434   if (!ValidateNonNegative("width", width) ||
1435       !ValidateNonNegative("height", height)) {
1436     return;
1437   }
1438
1439   const auto& limits = Limits();
1440   width = std::min(width, static_cast<GLsizei>(limits.maxViewportDim));
1441   height = std::min(height, static_cast<GLsizei>(limits.maxViewportDim));
1442
1443   gl->fViewport(x, y, width, height);
1444
1445   mViewportX = x;
1446   mViewportY = y;
1447   mViewportWidth = width;
1448   mViewportHeight = height;
1449 }
1450
1451 void WebGLContext::CompileShader(WebGLShader& shader) {
1452   const FuncScope funcScope(*this, "compileShader");
1453   if (IsContextLost()) return;
1454
1455   if (!ValidateObject("shader", shader)) return;
1456
1457   shader.CompileShader();
1458 }
1459
1460 Maybe<webgl::ShaderPrecisionFormat> WebGLContext::GetShaderPrecisionFormat(
1461     GLenum shadertype, GLenum precisiontype) const {
1462   const FuncScope funcScope(*this, "getShaderPrecisionFormat");
1463   if (IsContextLost()) return Nothing();
1464
1465   switch (shadertype) {
1466     case LOCAL_GL_FRAGMENT_SHADER:
1467     case LOCAL_GL_VERTEX_SHADER:
1468       break;
1469     default:
1470       ErrorInvalidEnumInfo("shadertype", shadertype);
1471       return Nothing();
1472   }
1473
1474   switch (precisiontype) {
1475     case LOCAL_GL_LOW_FLOAT:
1476     case LOCAL_GL_MEDIUM_FLOAT:
1477     case LOCAL_GL_HIGH_FLOAT:
1478     case LOCAL_GL_LOW_INT:
1479     case LOCAL_GL_MEDIUM_INT:
1480     case LOCAL_GL_HIGH_INT:
1481       break;
1482     default:
1483       ErrorInvalidEnumInfo("precisiontype", precisiontype);
1484       return Nothing();
1485   }
1486
1487   GLint range[2], precision;
1488
1489   if (mDisableFragHighP && shadertype == LOCAL_GL_FRAGMENT_SHADER &&
1490       (precisiontype == LOCAL_GL_HIGH_FLOAT ||
1491        precisiontype == LOCAL_GL_HIGH_INT)) {
1492     precision = 0;
1493     range[0] = 0;
1494     range[1] = 0;
1495   } else {
1496     gl->fGetShaderPrecisionFormat(shadertype, precisiontype, range, &precision);
1497   }
1498
1499   return Some(webgl::ShaderPrecisionFormat{range[0], range[1], precision});
1500 }
1501
1502 void WebGLContext::ShaderSource(WebGLShader& shader,
1503                                 const std::string& source) const {
1504   const FuncScope funcScope(*this, "shaderSource");
1505   if (IsContextLost()) return;
1506
1507   shader.ShaderSource(source);
1508 }
1509
1510 void WebGLContext::BlendColor(GLfloat r, GLfloat g, GLfloat b, GLfloat a) {
1511   const FuncScope funcScope(*this, "blendColor");
1512   if (IsContextLost()) return;
1513
1514   gl->fBlendColor(r, g, b, a);
1515 }
1516
1517 void WebGLContext::Flush() {
1518   const FuncScope funcScope(*this, "flush");
1519   if (IsContextLost()) return;
1520
1521   gl->fFlush();
1522 }
1523
1524 void WebGLContext::Finish() {
1525   const FuncScope funcScope(*this, "finish");
1526   if (IsContextLost()) return;
1527
1528   gl->fFinish();
1529
1530   mCompletedFenceId = mNextFenceId;
1531   mNextFenceId += 1;
1532 }
1533
1534 void WebGLContext::LineWidth(GLfloat width) {
1535   const FuncScope funcScope(*this, "lineWidth");
1536   if (IsContextLost()) return;
1537
1538   // Doing it this way instead of `if (width <= 0.0)` handles NaNs.
1539   const bool isValid = width > 0.0;
1540   if (!isValid) {
1541     ErrorInvalidValue("`width` must be positive and non-zero.");
1542     return;
1543   }
1544
1545   mLineWidth = width;
1546
1547   if (gl->IsCoreProfile() && width > 1.0) {
1548     width = 1.0;
1549   }
1550
1551   gl->fLineWidth(width);
1552 }
1553
1554 void WebGLContext::PolygonOffset(GLfloat factor, GLfloat units) {
1555   const FuncScope funcScope(*this, "polygonOffset");
1556   if (IsContextLost()) return;
1557
1558   gl->fPolygonOffset(factor, units);
1559 }
1560
1561 void WebGLContext::SampleCoverage(GLclampf value, WebGLboolean invert) {
1562   const FuncScope funcScope(*this, "sampleCoverage");
1563   if (IsContextLost()) return;
1564
1565   gl->fSampleCoverage(value, invert);
1566 }
1567
1568 }  // namespace mozilla