dom/canvas/WebGLContext.cpp

   1 /* -*- Mode: C++; tab-width: 20; 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
   8 #include <algorithm>
   9 #include <bitset>
  10 #include <queue>
  11 #include <regex>
  12
  13 #include "AccessCheck.h"
  14 #include "CompositableHost.h"
  15 #include "gfxConfig.h"
  16 #include "gfxContext.h"
  17 #include "gfxCrashReporterUtils.h"
  18 #include "gfxEnv.h"
  19 #include "gfxPattern.h"
  20 #include "MozFramebuffer.h"
  21 #include "GLBlitHelper.h"
  22 #include "GLContext.h"
  23 #include "GLContextProvider.h"
  24 #include "GLReadTexImageHelper.h"
  25 #include "GLScreenBuffer.h"
  26 #include "ImageContainer.h"
  27 #include "ImageEncoder.h"
  28 #include "LayerUserData.h"
  29 #include "mozilla/dom/BindingUtils.h"
  30 #include "mozilla/dom/ContentChild.h"
  31 #include "mozilla/dom/Document.h"
  32 #include "mozilla/dom/Event.h"
  33 #include "mozilla/dom/HTMLVideoElement.h"
  34 #include "mozilla/dom/ImageData.h"
  35 #include "mozilla/dom/WebGLContextEvent.h"
  36 #include "mozilla/EnumeratedArrayCycleCollection.h"
  37 #include "mozilla/EnumeratedRange.h"
  38 #include "mozilla/gfx/gfxVars.h"
  39 #include "mozilla/Preferences.h"
  40 #include "mozilla/ProcessPriorityManager.h"
  41 #include "mozilla/ResultVariant.h"
  42 #include "mozilla/ScopeExit.h"
  43 #include "mozilla/Services.h"
  44 #include "mozilla/StaticPrefs_webgl.h"
  45 #include "mozilla/SVGObserverUtils.h"
  46 #include "mozilla/Telemetry.h"
  47 #include "nsContentUtils.h"
  48 #include "nsDisplayList.h"
  49 #include "nsError.h"
  50 #include "nsIClassInfoImpl.h"
  51 #include "nsIWidget.h"
  52 #include "nsServiceManagerUtils.h"
  53 #include "SharedSurfaceGL.h"
  54 #include "prenv.h"
  55 #include "ScopedGLHelpers.h"
  56 #include "VRManagerChild.h"
  57 #include "mozilla/gfx/Swizzle.h"
  58 #include "mozilla/layers/BufferTexture.h"
  59 #include "mozilla/layers/RemoteTextureMap.h"
  60 #include "mozilla/layers/CompositorBridgeChild.h"
  61 #include "mozilla/layers/ImageBridgeChild.h"
  62 #include "mozilla/layers/WebRenderUserData.h"
  63 #include "mozilla/layers/WebRenderCanvasRenderer.h"
  64
  65 // Local
  66 #include "CanvasUtils.h"
  67 #include "ClientWebGLContext.h"
  68 #include "HostWebGLContext.h"
  69 #include "WebGLBuffer.h"
  70 #include "WebGLChild.h"
  71 #include "WebGLContextLossHandler.h"
  72 #include "WebGLContextUtils.h"
  73 #include "WebGLExtensions.h"
  74 #include "WebGLFormats.h"
  75 #include "WebGLFramebuffer.h"
  76 #include "WebGLMemoryTracker.h"
  77 #include "WebGLObjectModel.h"
  78 #include "WebGLParent.h"
  79 #include "WebGLProgram.h"
  80 #include "WebGLQuery.h"
  81 #include "WebGLSampler.h"
  82 #include "WebGLShader.h"
  83 #include "WebGLShaderValidator.h"
  84 #include "WebGLSync.h"
  85 #include "WebGLTransformFeedback.h"
  86 #include "WebGLValidateStrings.h"
  87 #include "WebGLVertexArray.h"
  88
  89 #ifdef XP_WIN
  90 #  include "WGLLibrary.h"
  91 #endif
  92
  93 // Generated
  94 #include "mozilla/dom/WebGLRenderingContextBinding.h"
  95
  96 namespace mozilla {
  97
  98 WebGLContextOptions::WebGLContextOptions() {
  99   // Set default alpha state based on preference.
 100   alpha = !StaticPrefs::webgl_default_no_alpha();
 101   antialias = StaticPrefs::webgl_default_antialias();
 102 }
 103
 104 StaticMutex WebGLContext::sLruMutex;
 105 std::list<WebGLContext*> WebGLContext::sLru;
 106
 107 WebGLContext::LruPosition::LruPosition() {
 108   StaticMutexAutoLock lock(sLruMutex);
 109   mItr = sLru.end();
 110 }  // NOLINT
 111
 112 WebGLContext::LruPosition::LruPosition(WebGLContext& context) {
 113   StaticMutexAutoLock lock(sLruMutex);
 114   mItr = sLru.insert(sLru.end(), &context);
 115 }
 116
 117 void WebGLContext::LruPosition::AssignLocked(WebGLContext& aContext) {
 118   ResetLocked();
 119   mItr = sLru.insert(sLru.end(), &aContext);
 120 }
 121
 122 void WebGLContext::LruPosition::ResetLocked() {
 123   const auto end = sLru.end();
 124   if (mItr != end) {
 125     sLru.erase(mItr);
 126     mItr = end;
 127   }
 128 }
 129
 130 void WebGLContext::LruPosition::Reset() {
 131   StaticMutexAutoLock lock(sLruMutex);
 132   ResetLocked();
 133 }
 134
 135 bool WebGLContext::LruPosition::IsInsertedLocked() const {
 136   return mItr != sLru.end();
 137 }
 138
 139 WebGLContext::WebGLContext(HostWebGLContext* host,
 140                            const webgl::InitContextDesc& desc)
 141     : gl(mGL_OnlyClearInDestroyResourcesAndContext),  // const reference
 142       mHost(host),
 143       mResistFingerprinting(desc.resistFingerprinting),
 144       mOptions(desc.options),
 145       mPrincipalKey(desc.principalKey),
 146       mContextLossHandler(this),
 147       mRequestedSize(desc.size) {
 148   if (host) {
 149     host->mContext = this;
 150   }
 151   const FuncScope funcScope(*this, "<Create>");
 152   WebGLMemoryTracker::EnsureRegistered();
 153 }
 154
 155 WebGLContext::~WebGLContext() { DestroyResourcesAndContext(); }
 156
 157 void WebGLContext::DestroyResourcesAndContext() {
 158   if (mRemoteTextureOwner) {
 159     // Clean up any remote textures registered for framebuffer swap chains.
 160     mRemoteTextureOwner->UnregisterAllTextureOwners();
 161     mRemoteTextureOwner = nullptr;
 162   }
 163
 164   if (!gl) return;
 165
 166   mDefaultFB = nullptr;
 167   mResolvedDefaultFB = nullptr;
 168
 169   mBound2DTextures.Clear();
 170   mBoundCubeMapTextures.Clear();
 171   mBound3DTextures.Clear();
 172   mBound2DArrayTextures.Clear();
 173   mBoundSamplers.Clear();
 174   mBoundArrayBuffer = nullptr;
 175   mBoundCopyReadBuffer = nullptr;
 176   mBoundCopyWriteBuffer = nullptr;
 177   mBoundPixelPackBuffer = nullptr;
 178   mBoundPixelUnpackBuffer = nullptr;
 179   mBoundTransformFeedbackBuffer = nullptr;
 180   mBoundUniformBuffer = nullptr;
 181   mCurrentProgram = nullptr;
 182   mActiveProgramLinkInfo = nullptr;
 183   mBoundDrawFramebuffer = nullptr;
 184   mBoundReadFramebuffer = nullptr;
 185   mBoundVertexArray = nullptr;
 186   mDefaultVertexArray = nullptr;
 187   mBoundTransformFeedback = nullptr;
 188   mDefaultTransformFeedback = nullptr;
 189
 190   mQuerySlot_SamplesPassed = nullptr;
 191   mQuerySlot_TFPrimsWritten = nullptr;
 192   mQuerySlot_TimeElapsed = nullptr;
 193
 194   mIndexedUniformBufferBindings.clear();
 195
 196   //////
 197
 198   if (mEmptyTFO) {
 199     gl->fDeleteTransformFeedbacks(1, &mEmptyTFO);
 200     mEmptyTFO = 0;
 201   }
 202
 203   //////
 204
 205   if (mFakeVertexAttrib0BufferObject) {
 206     gl->fDeleteBuffers(1, &mFakeVertexAttrib0BufferObject);
 207     mFakeVertexAttrib0BufferObject = 0;
 208   }
 209
 210   // disable all extensions except "WEBGL_lose_context". see bug #927969
 211   // spec: http://www.khronos.org/registry/webgl/specs/latest/1.0/#5.15.2
 212   for (size_t i = 0; i < size_t(WebGLExtensionID::Max); ++i) {
 213     WebGLExtensionID extension = WebGLExtensionID(i);
 214     if (extension == WebGLExtensionID::WEBGL_lose_context) continue;
 215     mExtensions[extension] = nullptr;
 216   }
 217
 218   // We just got rid of everything, so the context had better
 219   // have been going away.
 220   if (gl::GLContext::ShouldSpew()) {
 221     printf_stderr("--- WebGL context destroyed: %p\n", gl.get());
 222   }
 223
 224   MOZ_ASSERT(gl);
 225   gl->MarkDestroyed();
 226   mGL_OnlyClearInDestroyResourcesAndContext = nullptr;
 227   MOZ_ASSERT(!gl);
 228 }
 229
 230 void ClientWebGLContext::MarkCanvasDirty() {
 231   if (!mCanvasElement && !mOffscreenCanvas) return;
 232
 233   mFrameCaptureState = FrameCaptureState::DIRTY;
 234
 235   if (mIsCanvasDirty) return;
 236   mIsCanvasDirty = true;
 237
 238   if (mCanvasElement) {
 239     SVGObserverUtils::InvalidateDirectRenderingObservers(mCanvasElement);
 240     mCanvasElement->InvalidateCanvasContent(nullptr);
 241   } else if (mOffscreenCanvas) {
 242     mOffscreenCanvas->QueueCommitToCompositor();
 243   }
 244 }
 245
 246 void WebGLContext::OnMemoryPressure() {
 247   bool shouldLoseContext = mLoseContextOnMemoryPressure;
 248
 249   if (!mCanLoseContextInForeground &&
 250       ProcessPriorityManager::CurrentProcessIsForeground()) {
 251     shouldLoseContext = false;
 252   }
 253
 254   if (shouldLoseContext) LoseContext();
 255 }
 256
 257 // --
 258
 259 bool WebGLContext::CreateAndInitGL(
 260     bool forceEnabled, std::vector<FailureReason>* const out_failReasons) {
 261   const FuncScope funcScope(*this, "<Create>");
 262
 263   // WebGL2 is separately blocked:
 264   if (IsWebGL2() && !forceEnabled) {
 265     FailureReason reason;
 266     if (!gfx::gfxVars::AllowWebgl2()) {
 267       reason.info =
 268           "AllowWebgl2:false restricts context creation on this system.";
 269       out_failReasons->push_back(reason);
 270       GenerateWarning("%s", reason.info.BeginReading());
 271       return false;
 272     }
 273   }
 274
 275   auto flags = gl::CreateContextFlags::PREFER_ROBUSTNESS;
 276
 277   if (StaticPrefs::webgl_gl_khr_no_error()) {
 278     flags |= gl::CreateContextFlags::NO_VALIDATION;
 279   }
 280
 281   // -
 282
 283   if (StaticPrefs::webgl_forbid_hardware()) {
 284     flags |= gl::CreateContextFlags::FORBID_HARDWARE;
 285   }
 286   if (StaticPrefs::webgl_forbid_software()) {
 287     flags |= gl::CreateContextFlags::FORBID_SOFTWARE;
 288   }
 289
 290   if (forceEnabled) {
 291     flags &= ~gl::CreateContextFlags::FORBID_HARDWARE;
 292     flags &= ~gl::CreateContextFlags::FORBID_SOFTWARE;
 293   }
 294
 295   if ((flags & gl::CreateContextFlags::FORBID_HARDWARE) &&
 296       (flags & gl::CreateContextFlags::FORBID_SOFTWARE)) {
 297     FailureReason reason;
 298     reason.info = "Both hardware and software were forbidden by config.";
 299     out_failReasons->push_back(reason);
 300     GenerateWarning("%s", reason.info.BeginReading());
 301     return false;
 302   }
 303
 304   // -
 305
 306   if (StaticPrefs::webgl_cgl_multithreaded()) {
 307     flags |= gl::CreateContextFlags::PREFER_MULTITHREADED;
 308   }
 309
 310   if (IsWebGL2()) {
 311     flags |= gl::CreateContextFlags::PREFER_ES3;
 312   } else {
 313     // Request and prefer ES2 context for WebGL1.
 314     flags |= gl::CreateContextFlags::PREFER_EXACT_VERSION;
 315
 316     if (!StaticPrefs::webgl_1_allow_core_profiles()) {
 317       flags |= gl::CreateContextFlags::REQUIRE_COMPAT_PROFILE;
 318     }
 319   }
 320
 321   {
 322     auto powerPref = mOptions.powerPreference;
 323
 324     // If "Use hardware acceleration when available" option is disabled:
 325     if (!gfx::gfxConfig::IsEnabled(gfx::Feature::HW_COMPOSITING)) {
 326       powerPref = dom::WebGLPowerPreference::Low_power;
 327     }
 328
 329     const auto overrideVal = StaticPrefs::webgl_power_preference_override();
 330     if (overrideVal > 0) {
 331       powerPref = dom::WebGLPowerPreference::High_performance;
 332     } else if (overrideVal < 0) {
 333       powerPref = dom::WebGLPowerPreference::Low_power;
 334     }
 335
 336     if (powerPref == dom::WebGLPowerPreference::High_performance) {
 337       flags |= gl::CreateContextFlags::HIGH_POWER;
 338     }
 339   }
 340
 341   if (!gfx::gfxVars::WebglAllowCoreProfile()) {
 342     flags |= gl::CreateContextFlags::REQUIRE_COMPAT_PROFILE;
 343   }
 344
 345   // --
 346
 347   const bool useEGL = PR_GetEnv("MOZ_WEBGL_FORCE_EGL");
 348
 349   bool tryNativeGL = true;
 350   bool tryANGLE = false;
 351
 352 #ifdef XP_WIN
 353   tryNativeGL = false;
 354   tryANGLE = true;
 355
 356   if (StaticPrefs::webgl_disable_wgl()) {
 357     tryNativeGL = false;
 358   }
 359
 360   if (StaticPrefs::webgl_disable_angle() ||
 361       PR_GetEnv("MOZ_WEBGL_FORCE_OPENGL") || useEGL) {
 362     tryNativeGL = true;
 363     tryANGLE = false;
 364   }
 365 #endif
 366
 367   if (tryNativeGL && !forceEnabled) {
 368     FailureReason reason;
 369     if (!gfx::gfxVars::WebglAllowWindowsNativeGl()) {
 370       reason.info =
 371           "WebglAllowWindowsNativeGl:false restricts context creation on this "
 372           "system.";
 373
 374       out_failReasons->push_back(reason);
 375
 376       GenerateWarning("%s", reason.info.BeginReading());
 377       tryNativeGL = false;
 378     }
 379   }
 380
 381   // --
 382
 383   using fnCreateT = decltype(gl::GLContextProviderEGL::CreateHeadless);
 384   const auto fnCreate = [&](fnCreateT* const pfnCreate,
 385                             const char* const info) {
 386     nsCString failureId;
 387     const RefPtr<gl::GLContext> gl = pfnCreate({flags}, &failureId);
 388     if (!gl) {
 389       out_failReasons->push_back(WebGLContext::FailureReason(failureId, info));
 390     }
 391     return gl;
 392   };
 393
 394   const auto newGL = [&]() -> RefPtr<gl::GLContext> {
 395     if (tryNativeGL) {
 396       if (useEGL)
 397         return fnCreate(&gl::GLContextProviderEGL::CreateHeadless, "useEGL");
 398
 399       const auto ret =
 400           fnCreate(&gl::GLContextProvider::CreateHeadless, "tryNativeGL");
 401       if (ret) return ret;
 402     }
 403
 404     if (tryANGLE) {
 405       return fnCreate(&gl::GLContextProviderEGL::CreateHeadless, "tryANGLE");
 406     }
 407     return nullptr;
 408   }();
 409
 410   if (!newGL) {
 411     out_failReasons->push_back(
 412         FailureReason("FEATURE_FAILURE_WEBGL_EXHAUSTED_DRIVERS",
 413                       "Exhausted GL driver options."));
 414     return false;
 415   }
 416
 417   // --
 418
 419   FailureReason reason;
 420
 421   mGL_OnlyClearInDestroyResourcesAndContext = newGL;
 422   MOZ_RELEASE_ASSERT(gl);
 423   if (!InitAndValidateGL(&reason)) {
 424     DestroyResourcesAndContext();
 425     MOZ_RELEASE_ASSERT(!gl);
 426
 427     // The fail reason here should be specific enough for now.
 428     out_failReasons->push_back(reason);
 429     return false;
 430   }
 431
 432   const auto val = StaticPrefs::webgl_debug_incomplete_tex_color();
 433   if (val) {
 434     mIncompleteTexOverride.reset(new gl::Texture(*gl));
 435     const gl::ScopedBindTexture autoBind(gl, mIncompleteTexOverride->name);
 436     const auto heapVal = std::make_unique<uint32_t>(val);
 437     gl->fTexImage2D(LOCAL_GL_TEXTURE_2D, 0, LOCAL_GL_RGBA, 1, 1, 0,
 438                     LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_BYTE, heapVal.get());
 439   }
 440
 441   return true;
 442 }
 443
 444 // Fallback for resizes:
 445
 446 bool WebGLContext::EnsureDefaultFB() {
 447   if (mDefaultFB) {
 448     MOZ_ASSERT(*uvec2::FromSize(mDefaultFB->mSize) == mRequestedSize);
 449     return true;
 450   }
 451
 452   const bool depthStencil = mOptions.depth || mOptions.stencil;
 453   auto attemptSize = gfx::IntSize{mRequestedSize.x, mRequestedSize.y};
 454
 455   while (attemptSize.width || attemptSize.height) {
 456     attemptSize.width = std::max(attemptSize.width, 1);
 457     attemptSize.height = std::max(attemptSize.height, 1);
 458
 459     [&]() {
 460       if (mOptions.antialias) {
 461         MOZ_ASSERT(!mDefaultFB);
 462         mDefaultFB = gl::MozFramebuffer::Create(gl, attemptSize, mMsaaSamples,
 463                                                 depthStencil);
 464         if (mDefaultFB) return;
 465         if (mOptionsFrozen) return;
 466       }
 467
 468       MOZ_ASSERT(!mDefaultFB);
 469       mDefaultFB = gl::MozFramebuffer::Create(gl, attemptSize, 0, depthStencil);
 470     }();
 471
 472     if (mDefaultFB) break;
 473
 474     attemptSize.width /= 2;
 475     attemptSize.height /= 2;
 476   }
 477
 478   if (!mDefaultFB) {
 479     GenerateWarning("Backbuffer resize failed. Losing context.");
 480     LoseContext();
 481     return false;
 482   }
 483
 484   mDefaultFB_IsInvalid = true;
 485
 486   const auto actualSize = *uvec2::FromSize(mDefaultFB->mSize);
 487   if (actualSize != mRequestedSize) {
 488     GenerateWarning(
 489         "Requested size %ux%u was too large, but resize"
 490         " to %ux%u succeeded.",
 491         mRequestedSize.x, mRequestedSize.y, actualSize.x, actualSize.y);
 492   }
 493   mRequestedSize = actualSize;
 494   return true;
 495 }
 496
 497 void WebGLContext::Resize(uvec2 requestedSize) {
 498   // Zero-sized surfaces can cause problems.
 499   if (!requestedSize.x) {
 500     requestedSize.x = 1;
 501   }
 502   if (!requestedSize.y) {
 503     requestedSize.y = 1;
 504   }
 505
 506   // Kill our current default fb(s), for later lazy allocation.
 507   mRequestedSize = requestedSize;
 508   mDefaultFB = nullptr;
 509   mResetLayer = true;  // New size means new Layer.
 510 }
 511
 512 UniquePtr<webgl::FormatUsageAuthority> WebGLContext::CreateFormatUsage(
 513     gl::GLContext* gl) const {
 514   return webgl::FormatUsageAuthority::CreateForWebGL1(gl);
 515 }
 516
 517 /*static*/
 518 RefPtr<WebGLContext> WebGLContext::Create(HostWebGLContext* host,
 519                                           const webgl::InitContextDesc& desc,
 520                                           webgl::InitContextResult* const out) {
 521   AUTO_PROFILER_LABEL("WebGLContext::Create", GRAPHICS);
 522   nsCString failureId = "FEATURE_FAILURE_WEBGL_UNKOWN"_ns;
 523   const bool forceEnabled = StaticPrefs::webgl_force_enabled();
 524   ScopedGfxFeatureReporter reporter("WebGL", forceEnabled);
 525
 526   auto res = [&]() -> Result<RefPtr<WebGLContext>, std::string> {
 527     bool disabled = StaticPrefs::webgl_disabled();
 528
 529     // TODO: When we have software webgl support we should use that instead.
 530     disabled |= gfxPlatform::InSafeMode();
 531
 532     if (disabled) {
 533       if (gfxPlatform::InSafeMode()) {
 534         failureId = "FEATURE_FAILURE_WEBGL_SAFEMODE"_ns;
 535       } else {
 536         failureId = "FEATURE_FAILURE_WEBGL_DISABLED"_ns;
 537       }
 538       return Err("WebGL is currently disabled.");
 539     }
 540
 541     // Alright, now let's start trying.
 542
 543     RefPtr<WebGLContext> webgl;
 544     if (desc.isWebgl2) {
 545       webgl = new WebGL2Context(host, desc);
 546     } else {
 547       webgl = new WebGLContext(host, desc);
 548     }
 549
 550     MOZ_ASSERT(!webgl->gl);
 551     std::vector<FailureReason> failReasons;
 552     if (!webgl->CreateAndInitGL(forceEnabled, &failReasons)) {
 553       nsCString text("WebGL creation failed: ");
 554       for (const auto& cur : failReasons) {
 555         // Don't try to accumulate using an empty key if |cur.key| is empty.
 556         if (cur.key.IsEmpty()) {
 557           Telemetry::Accumulate(Telemetry::CANVAS_WEBGL_FAILURE_ID,
 558                                 "FEATURE_FAILURE_REASON_UNKNOWN"_ns);
 559         } else {
 560           Telemetry::Accumulate(Telemetry::CANVAS_WEBGL_FAILURE_ID, cur.key);
 561         }
 562
 563         const auto str = nsPrintfCString("\n* %s (%s)", cur.info.BeginReading(),
 564                                          cur.key.BeginReading());
 565         text.Append(str);
 566       }
 567       failureId = "FEATURE_FAILURE_REASON"_ns;
 568       return Err(text.BeginReading());
 569     }
 570     MOZ_ASSERT(webgl->gl);
 571
 572     if (desc.options.failIfMajorPerformanceCaveat) {
 573       if (webgl->gl->IsWARP()) {
 574         failureId = "FEATURE_FAILURE_WEBGL_PERF_WARP"_ns;
 575         return Err(
 576             "failIfMajorPerformanceCaveat: Driver is not"
 577             " hardware-accelerated.");
 578       }
 579
 580 #ifdef XP_WIN
 581       if (webgl->gl->GetContextType() == gl::GLContextType::WGL &&
 582           !gl::sWGLLib.HasDXInterop2()) {
 583         failureId = "FEATURE_FAILURE_WEBGL_DXGL_INTEROP2"_ns;
 584         return Err("failIfMajorPerformanceCaveat: WGL without DXGLInterop2.");
 585       }
 586 #endif
 587     }
 588
 589     const FuncScope funcScope(*webgl, "getContext/restoreContext");
 590
 591     MOZ_ASSERT(!webgl->mDefaultFB);
 592     if (!webgl->EnsureDefaultFB()) {
 593       MOZ_ASSERT(!webgl->mDefaultFB);
 594       MOZ_ASSERT(webgl->IsContextLost());
 595       failureId = "FEATURE_FAILURE_WEBGL_BACKBUFFER"_ns;
 596       return Err("Initializing WebGL backbuffer failed.");
 597     }
 598
 599     return webgl;
 600   }();
 601   if (res.isOk()) {
 602     failureId = "SUCCESS"_ns;
 603   }
 604   Telemetry::Accumulate(Telemetry::CANVAS_WEBGL_FAILURE_ID, failureId);
 605
 606   if (!res.isOk()) {
 607     out->error = res.unwrapErr();
 608     return nullptr;
 609   }
 610   const auto webgl = res.unwrap();
 611
 612   // Update our internal stuff:
 613   webgl->FinishInit();
 614
 615   reporter.SetSuccessful();
 616   if (gl::GLContext::ShouldSpew()) {
 617     printf_stderr("--- WebGL context created: %p\n", webgl.get());
 618   }
 619
 620   // -
 621
 622   const auto UploadableSdTypes = [&]() {
 623     webgl::EnumMask<layers::SurfaceDescriptor::Type> types;
 624     types[layers::SurfaceDescriptor::TSurfaceDescriptorBuffer] = true;
 625     // This is conditional on not using the Compositor thread because we may
 626     // need to synchronize with the RDD process over the PVideoBridge protocol
 627     // to wait for the texture to be available in the compositor process. We
 628     // cannot block on the Compositor thread, so in that configuration, we would
 629     // prefer to do the readback from the RDD which is guaranteed to work, and
 630     // only block the owning thread for WebGL.
 631     types[layers::SurfaceDescriptor::TSurfaceDescriptorGPUVideo] =
 632         gfx::gfxVars::UseCanvasRenderThread() ||
 633         !gfx::gfxVars::SupportsThreadsafeGL();
 634     if (webgl->gl->IsANGLE()) {
 635       types[layers::SurfaceDescriptor::TSurfaceDescriptorD3D10] = true;
 636       types[layers::SurfaceDescriptor::TSurfaceDescriptorDXGIYCbCr] = true;
 637     }
 638     if (kIsMacOS) {
 639       types[layers::SurfaceDescriptor::TSurfaceDescriptorMacIOSurface] = true;
 640     }
 641     if (kIsAndroid) {
 642       types[layers::SurfaceDescriptor::TSurfaceTextureDescriptor] = true;
 643     }
 644     if (kIsLinux) {
 645       types[layers::SurfaceDescriptor::TSurfaceDescriptorDMABuf] = true;
 646     }
 647     return types;
 648   };
 649
 650   // -
 651
 652   out->options = webgl->mOptions;
 653   out->limits = *webgl->mLimits;
 654   out->uploadableSdTypes = UploadableSdTypes();
 655   out->vendor = webgl->gl->Vendor();
 656   out->isRgb8Renderable = webgl->mIsRgb8Renderable;
 657
 658   return webgl;
 659 }
 660
 661 void WebGLContext::FinishInit() {
 662   mOptions.antialias &= bool(mDefaultFB->mSamples);
 663
 664   if (!mOptions.alpha) {
 665     // We always have alpha.
 666     mNeedsFakeNoAlpha = true;
 667   }
 668
 669   if (mOptions.depth || mOptions.stencil) {
 670     // We always have depth+stencil if we have either.
 671     if (!mOptions.depth) {
 672       mNeedsFakeNoDepth = true;
 673     }
 674     if (!mOptions.stencil) {
 675       mNeedsFakeNoStencil = true;
 676     }
 677   }
 678
 679   mResetLayer = true;
 680   mOptionsFrozen = true;
 681
 682   //////
 683   // Initial setup.
 684
 685   gl->mImplicitMakeCurrent = true;
 686   gl->mElideDuplicateBindFramebuffers = true;
 687
 688   const auto& size = mDefaultFB->mSize;
 689
 690   mViewportX = mViewportY = 0;
 691   mViewportWidth = size.width;
 692   mViewportHeight = size.height;
 693   gl->fViewport(mViewportX, mViewportY, mViewportWidth, mViewportHeight);
 694
 695   mScissorRect = {0, 0, size.width, size.height};
 696   mScissorRect.Apply(*gl);
 697
 698   //////
 699   // Check everything
 700
 701   AssertCachedBindings();
 702   AssertCachedGlobalState();
 703
 704   mShouldPresent = true;
 705
 706   //////
 707   // mIsRgb8Renderable
 708
 709   {
 710     const auto tex = gl::ScopedTexture(gl);
 711     const auto fb = gl::ScopedFramebuffer(gl);
 712     gl->fBindTexture(LOCAL_GL_TEXTURE_2D, tex);
 713     gl->fTexImage2D(LOCAL_GL_TEXTURE_2D, 0, LOCAL_GL_RGB, 1, 1, 0, LOCAL_GL_RGB,
 714                     LOCAL_GL_UNSIGNED_BYTE, nullptr);
 715
 716     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, fb);
 717     gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_COLOR_ATTACHMENT0,
 718                               LOCAL_GL_TEXTURE_2D, tex, 0);
 719
 720     const auto status = gl->fCheckFramebufferStatus(LOCAL_GL_FRAMEBUFFER);
 721     mIsRgb8Renderable = (status == LOCAL_GL_FRAMEBUFFER_COMPLETE);
 722   }
 723
 724   //////
 725
 726   gl->ResetSyncCallCount("WebGLContext Initialization");
 727   LoseLruContextIfLimitExceeded();
 728 }
 729
 730 void WebGLContext::SetCompositableHost(
 731     RefPtr<layers::CompositableHost>& aCompositableHost) {
 732   mCompositableHost = aCompositableHost;
 733 }
 734
 735 void WebGLContext::BumpLruLocked() {
 736   if (!mIsContextLost && !mPendingContextLoss) {
 737     mLruPosition.AssignLocked(*this);
 738   } else {
 739     MOZ_ASSERT(!mLruPosition.IsInsertedLocked());
 740   }
 741 }
 742
 743 void WebGLContext::BumpLru() {
 744   StaticMutexAutoLock lock(sLruMutex);
 745   BumpLruLocked();
 746 }
 747
 748 void WebGLContext::LoseLruContextIfLimitExceeded() {
 749   StaticMutexAutoLock lock(sLruMutex);
 750
 751   const auto maxContexts = std::max(1u, StaticPrefs::webgl_max_contexts());
 752   const auto maxContextsPerPrincipal =
 753       std::max(1u, StaticPrefs::webgl_max_contexts_per_principal());
 754
 755   // it's important to update the index on a new context before losing old
 756   // contexts, otherwise new unused contexts would all have index 0 and we
 757   // couldn't distinguish older ones when choosing which one to lose first.
 758   BumpLruLocked();
 759
 760   {
 761     size_t forPrincipal = 0;
 762     for (const auto& context : sLru) {
 763       if (context->mPrincipalKey == mPrincipalKey) {
 764         forPrincipal += 1;
 765       }
 766     }
 767
 768     while (forPrincipal > maxContextsPerPrincipal) {
 769       const auto text = nsPrintfCString(
 770           "Exceeded %u live WebGL contexts for this principal, losing the "
 771           "least recently used one.",
 772           maxContextsPerPrincipal);
 773       JsWarning(ToString(text));
 774
 775       for (const auto& context : sLru) {
 776         if (context->mPrincipalKey == mPrincipalKey) {
 777           MOZ_ASSERT(context != this);
 778           context->LoseContextLruLocked(webgl::ContextLossReason::None);
 779           forPrincipal -= 1;
 780           break;
 781         }
 782       }
 783     }
 784   }
 785
 786   auto total = sLru.size();
 787   while (total > maxContexts) {
 788     const auto text = nsPrintfCString(
 789         "Exceeded %u live WebGL contexts, losing the least "
 790         "recently used one.",
 791         maxContexts);
 792     JsWarning(ToString(text));
 793
 794     const auto& context = sLru.front();
 795     MOZ_ASSERT(context != this);
 796     context->LoseContextLruLocked(webgl::ContextLossReason::None);
 797     total -= 1;
 798   }
 799 }
 800
 801 // -
 802
 803 namespace webgl {
 804
 805 ScopedPrepForResourceClear::ScopedPrepForResourceClear(
 806     const WebGLContext& webgl_)
 807     : webgl(webgl_) {
 808   const auto& gl = webgl.gl;
 809
 810   if (webgl.mScissorTestEnabled) {
 811     gl->fDisable(LOCAL_GL_SCISSOR_TEST);
 812   }
 813   if (webgl.mRasterizerDiscardEnabled) {
 814     gl->fDisable(LOCAL_GL_RASTERIZER_DISCARD);
 815   }
 816
 817   // "The clear operation always uses the front stencil write mask
 818   //  when clearing the stencil buffer."
 819   webgl.DoColorMask(Some(0), 0b1111);
 820   gl->fDepthMask(true);
 821   gl->fStencilMaskSeparate(LOCAL_GL_FRONT, 0xffffffff);
 822
 823   gl->fClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 824   gl->fClearDepth(1.0f);  // Depth formats are always cleared to 1.0f, not 0.0f.
 825   gl->fClearStencil(0);
 826 }
 827
 828 ScopedPrepForResourceClear::~ScopedPrepForResourceClear() {
 829   const auto& gl = webgl.gl;
 830
 831   if (webgl.mScissorTestEnabled) {
 832     gl->fEnable(LOCAL_GL_SCISSOR_TEST);
 833   }
 834   if (webgl.mRasterizerDiscardEnabled) {
 835     gl->fEnable(LOCAL_GL_RASTERIZER_DISCARD);
 836   }
 837
 838   webgl.DoColorMask(Some(0), webgl.mColorWriteMask0);
 839   gl->fDepthMask(webgl.mDepthWriteMask);
 840   gl->fStencilMaskSeparate(LOCAL_GL_FRONT, webgl.mStencilWriteMaskFront);
 841
 842   gl->fClearColor(webgl.mColorClearValue[0], webgl.mColorClearValue[1],
 843                   webgl.mColorClearValue[2], webgl.mColorClearValue[3]);
 844   gl->fClearDepth(webgl.mDepthClearValue);
 845   gl->fClearStencil(webgl.mStencilClearValue);
 846 }
 847
 848 }  // namespace webgl
 849
 850 // -
 851
 852 void WebGLContext::OnEndOfFrame() {
 853   if (StaticPrefs::webgl_perf_spew_frame_allocs()) {
 854     GeneratePerfWarning("[webgl.perf.spew-frame-allocs] %" PRIu64
 855                         " data allocations this frame.",
 856                         mDataAllocGLCallCount);
 857   }
 858   mDataAllocGLCallCount = 0;
 859   gl->ResetSyncCallCount("WebGLContext PresentScreenBuffer");
 860
 861   mDrawCallsSinceLastFlush = 0;
 862
 863   BumpLru();
 864 }
 865
 866 void WebGLContext::BlitBackbufferToCurDriverFB(
 867     WebGLFramebuffer* const srcAsWebglFb,
 868     const gl::MozFramebuffer* const srcAsMozFb, bool srcIsBGRA) const {
 869   // BlitFramebuffer ignores ColorMask().
 870
 871   if (mScissorTestEnabled) {
 872     gl->fDisable(LOCAL_GL_SCISSOR_TEST);
 873   }
 874
 875   [&]() {
 876     // If a MozFramebuffer is supplied, ensure that a WebGLFramebuffer is not
 877     // used since it might not have completeness info, while the MozFramebuffer
 878     // can still supply the needed information.
 879     MOZ_ASSERT(!(srcAsMozFb && srcAsWebglFb));
 880     const auto* mozFb = srcAsMozFb ? srcAsMozFb : mDefaultFB.get();
 881     GLuint fbo = 0;
 882     gfx::IntSize size;
 883     if (srcAsWebglFb) {
 884       fbo = srcAsWebglFb->mGLName;
 885       const auto* info = srcAsWebglFb->GetCompletenessInfo();
 886       MOZ_ASSERT(info);
 887       size = gfx::IntSize(info->width, info->height);
 888     } else {
 889       fbo = mozFb->mFB;
 890       size = mozFb->mSize;
 891     }
 892
 893     // If no format conversion is necessary, then attempt to directly blit
 894     // between framebuffers. Otherwise, if we need to convert to RGBA from
 895     // the source format, then we will need to use the texture blit path
 896     // below.
 897     if (!srcIsBGRA) {
 898       if (gl->IsSupported(gl::GLFeature::framebuffer_blit)) {
 899         gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, fbo);
 900         gl->fBlitFramebuffer(0, 0, size.width, size.height, 0, 0, size.width,
 901                              size.height, LOCAL_GL_COLOR_BUFFER_BIT,
 902                              LOCAL_GL_NEAREST);
 903         return;
 904       }
 905       if (mDefaultFB->mSamples &&
 906           gl->IsExtensionSupported(
 907               gl::GLContext::APPLE_framebuffer_multisample)) {
 908         gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, fbo);
 909         gl->fResolveMultisampleFramebufferAPPLE();
 910         return;
 911       }
 912     }
 913
 914     GLuint colorTex = 0;
 915     if (srcAsWebglFb) {
 916       const auto& attach = srcAsWebglFb->ColorAttachment0();
 917       MOZ_ASSERT(attach.Texture());
 918       colorTex = attach.Texture()->mGLName;
 919     } else {
 920       colorTex = mozFb->ColorTex();
 921     }
 922
 923     // DrawBlit handles ColorMask itself.
 924     gl->BlitHelper()->DrawBlitTextureToFramebuffer(
 925         colorTex, size, size, LOCAL_GL_TEXTURE_2D, srcIsBGRA);
 926   }();
 927
 928   if (mScissorTestEnabled) {
 929     gl->fEnable(LOCAL_GL_SCISSOR_TEST);
 930   }
 931 }
 932
 933 // -
 934
 935 template <typename T, typename... Args>
 936 constexpr auto MakeArray(Args... args) -> std::array<T, sizeof...(Args)> {
 937   return {{static_cast<T>(args)...}};
 938 }
 939
 940 inline gfx::ColorSpace2 ToColorSpace2(const WebGLContextOptions& options) {
 941   auto ret = gfx::ColorSpace2::UNKNOWN;
 942   if (true) {
 943     ret = gfx::ColorSpace2::SRGB;
 944   }
 945   if (!options.ignoreColorSpace) {
 946     ret = gfx::ToColorSpace2(options.colorSpace);
 947   }
 948   return ret;
 949 }
 950
 951 // -
 952
 953 // For an overview of how WebGL compositing works, see:
 954 // https://wiki.mozilla.org/Platform/GFX/WebGL/Compositing
 955 bool WebGLContext::PresentInto(gl::SwapChain& swapChain) {
 956   OnEndOfFrame();
 957
 958   if (!ValidateAndInitFB(nullptr)) return false;
 959
 960   {
 961     const auto colorSpace = ToColorSpace2(mOptions);
 962     auto presenter = swapChain.Acquire(mDefaultFB->mSize, colorSpace);
 963     if (!presenter) {
 964       GenerateWarning("Swap chain surface creation failed.");
 965       LoseContext();
 966       return false;
 967     }
 968
 969     const auto destFb = presenter->Fb();
 970     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, destFb);
 971
 972     BlitBackbufferToCurDriverFB();
 973
 974     if (!mOptions.preserveDrawingBuffer) {
 975       if (gl->IsSupported(gl::GLFeature::invalidate_framebuffer)) {
 976         gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, mDefaultFB->mFB);
 977         constexpr auto attachments = MakeArray<GLenum>(
 978             LOCAL_GL_COLOR_ATTACHMENT0, LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
 979         gl->fInvalidateFramebuffer(LOCAL_GL_READ_FRAMEBUFFER,
 980                                    attachments.size(), attachments.data());
 981       }
 982       mDefaultFB_IsInvalid = true;
 983     }
 984
 985 #ifdef DEBUG
 986     if (!mOptions.alpha) {
 987       gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, destFb);
 988       gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, 4);
 989       if (IsWebGL2()) {
 990         gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, 0);
 991         gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS, 0);
 992         gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, 0);
 993       }
 994       uint32_t pixel = 0xffbadbad;
 995       gl->fReadPixels(0, 0, 1, 1, LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_BYTE,
 996                       &pixel);
 997       MOZ_ASSERT((pixel & 0xff000000) == 0xff000000);
 998     }
 999 #endif
1000   }
1001
1002   return true;
1003 }
1004
1005 bool WebGLContext::PresentIntoXR(gl::SwapChain& swapChain,
1006                                  const gl::MozFramebuffer& fb) {
1007   OnEndOfFrame();
1008
1009   const auto colorSpace = ToColorSpace2(mOptions);
1010   auto presenter = swapChain.Acquire(fb.mSize, colorSpace);
1011   if (!presenter) {
1012     GenerateWarning("Swap chain surface creation failed.");
1013     LoseContext();
1014     return false;
1015   }
1016
1017   const auto destFb = presenter->Fb();
1018   gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, destFb);
1019
1020   BlitBackbufferToCurDriverFB(nullptr, &fb);
1021
1022   // https://immersive-web.github.io/webxr/#opaque-framebuffer
1023   // Opaque framebuffers will always be cleared regardless of the
1024   // associated WebGL context’s preserveDrawingBuffer value.
1025   if (gl->IsSupported(gl::GLFeature::invalidate_framebuffer)) {
1026     gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, fb.mFB);
1027     constexpr auto attachments = MakeArray<GLenum>(
1028         LOCAL_GL_COLOR_ATTACHMENT0, LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
1029     gl->fInvalidateFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, attachments.size(),
1030                                attachments.data());
1031   }
1032
1033   return true;
1034 }
1035
1036 // Initialize a swap chain's surface factory given the desired surface type.
1037 void InitSwapChain(gl::GLContext& gl, gl::SwapChain& swapChain,
1038                    const layers::TextureType consumerType) {
1039   if (!swapChain.mFactory) {
1040     auto typedFactory = gl::SurfaceFactory::Create(&gl, consumerType);
1041     if (typedFactory) {
1042       swapChain.mFactory = std::move(typedFactory);
1043     }
1044   }
1045   if (!swapChain.mFactory) {
1046     NS_WARNING("Failed to make an ideal SurfaceFactory.");
1047     swapChain.mFactory = MakeUnique<gl::SurfaceFactory_Basic>(gl);
1048   }
1049   MOZ_ASSERT(swapChain.mFactory);
1050 }
1051
1052 void WebGLContext::Present(WebGLFramebuffer* const xrFb,
1053                            const layers::TextureType consumerType,
1054                            const bool webvr,
1055                            const webgl::SwapChainOptions& options) {
1056   const FuncScope funcScope(*this, "<Present>");
1057   if (IsContextLost()) {
1058     EnsureContextLostRemoteTextureOwner(options);
1059     return;
1060   }
1061
1062   auto swapChain = GetSwapChain(xrFb, webvr);
1063   const gl::MozFramebuffer* maybeFB = nullptr;
1064   if (xrFb) {
1065     maybeFB = xrFb->mOpaque.get();
1066   } else {
1067     mResolvedDefaultFB = nullptr;
1068   }
1069
1070   InitSwapChain(*gl, *swapChain, consumerType);
1071
1072   bool valid =
1073       maybeFB ? PresentIntoXR(*swapChain, *maybeFB) : PresentInto(*swapChain);
1074   if (!valid) {
1075     EnsureContextLostRemoteTextureOwner(options);
1076     return;
1077   }
1078
1079   bool useAsync = options.remoteTextureOwnerId.IsValid() &&
1080                   options.remoteTextureId.IsValid();
1081   if (useAsync) {
1082     PushRemoteTexture(nullptr, *swapChain, swapChain->FrontBuffer(), options);
1083   }
1084 }
1085
1086 void WebGLContext::WaitForTxn(layers::RemoteTextureOwnerId ownerId,
1087                               layers::RemoteTextureTxnType txnType,
1088                               layers::RemoteTextureTxnId txnId) {
1089   if (!ownerId.IsValid() || !txnType || !txnId) {
1090     return;
1091   }
1092   if (mRemoteTextureOwner && mRemoteTextureOwner->IsRegistered(ownerId)) {
1093     mRemoteTextureOwner->WaitForTxn(ownerId, txnType, txnId);
1094   }
1095 }
1096
1097 bool WebGLContext::CopyToSwapChain(
1098     WebGLFramebuffer* const srcFb, const layers::TextureType consumerType,
1099     const webgl::SwapChainOptions& options,
1100     layers::RemoteTextureOwnerClient* ownerClient) {
1101   const FuncScope funcScope(*this, "<CopyToSwapChain>");
1102   if (IsContextLost()) {
1103     return false;
1104   }
1105
1106   OnEndOfFrame();
1107
1108   if (!srcFb) {
1109     return false;
1110   }
1111   const auto* info = srcFb->GetCompletenessInfo();
1112   if (!info) {
1113     return false;
1114   }
1115   gfx::IntSize size(info->width, info->height);
1116
1117   InitSwapChain(*gl, srcFb->mSwapChain, consumerType);
1118
1119   bool useAsync = options.remoteTextureOwnerId.IsValid() &&
1120                   options.remoteTextureId.IsValid();
1121   // If we're using async present and if there is no way to serialize surfaces,
1122   // then a readback is required to do the copy. In this case, there's no reason
1123   // to copy into a separate shared surface for the front buffer. Just directly
1124   // read back the WebGL framebuffer into and push it as a remote texture.
1125   if (useAsync && srcFb->mSwapChain.mFactory->GetConsumerType() ==
1126                       layers::TextureType::Unknown) {
1127     return PushRemoteTexture(srcFb, srcFb->mSwapChain, nullptr, options,
1128                              ownerClient);
1129   }
1130
1131   {
1132     // ColorSpace will need to be part of SwapChainOptions for DTWebgl.
1133     const auto colorSpace = ToColorSpace2(mOptions);
1134     auto presenter = srcFb->mSwapChain.Acquire(size, colorSpace);
1135     if (!presenter) {
1136       GenerateWarning("Swap chain surface creation failed.");
1137       LoseContext();
1138       return false;
1139     }
1140
1141     const ScopedFBRebinder saveFB(this);
1142
1143     const auto destFb = presenter->Fb();
1144     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, destFb);
1145
1146     BlitBackbufferToCurDriverFB(srcFb, nullptr, options.bgra);
1147   }
1148
1149   if (useAsync) {
1150     return PushRemoteTexture(srcFb, srcFb->mSwapChain,
1151                              srcFb->mSwapChain.FrontBuffer(), options,
1152                              ownerClient);
1153   }
1154   return true;
1155 }
1156
1157 bool WebGLContext::PushRemoteTexture(
1158     WebGLFramebuffer* fb, gl::SwapChain& swapChain,
1159     std::shared_ptr<gl::SharedSurface> surf,
1160     const webgl::SwapChainOptions& options,
1161     layers::RemoteTextureOwnerClient* ownerClient) {
1162   const auto onFailure = [&]() -> bool {
1163     GenerateWarning("Remote texture creation failed.");
1164     LoseContext();
1165     if (ownerClient && ownerClient == mRemoteTextureOwner) {
1166       ownerClient->PushDummyTexture(options.remoteTextureId,
1167                                     options.remoteTextureOwnerId);
1168     }
1169     return false;
1170   };
1171
1172   if (!ownerClient) {
1173     if (!mRemoteTextureOwner) {
1174       // Ensure we have a remote texture owner client for WebGLParent.
1175       const auto* outOfProcess =
1176           mHost ? mHost->mOwnerData.outOfProcess : nullptr;
1177       if (!outOfProcess) {
1178         return onFailure();
1179       }
1180       auto pid = outOfProcess->OtherPid();
1181       mRemoteTextureOwner = MakeRefPtr<layers::RemoteTextureOwnerClient>(pid);
1182     }
1183     ownerClient = mRemoteTextureOwner;
1184   }
1185
1186   layers::RemoteTextureOwnerId ownerId = options.remoteTextureOwnerId;
1187   layers::RemoteTextureId textureId = options.remoteTextureId;
1188
1189   if (!ownerClient->IsRegistered(ownerId)) {
1190     // Register a texture owner to represent the swap chain.
1191     RefPtr<layers::RemoteTextureOwnerClient> textureOwner = ownerClient;
1192     auto destroyedCallback = [textureOwner, ownerId]() {
1193       textureOwner->UnregisterTextureOwner(ownerId);
1194     };
1195
1196     swapChain.SetDestroyedCallback(destroyedCallback);
1197     ownerClient->RegisterTextureOwner(ownerId,
1198                                       /* aSharedRecycling */ !!fb);
1199   }
1200
1201   MOZ_ASSERT(fb || surf);
1202   gfx::IntSize size;
1203   if (surf) {
1204     size = surf->mDesc.size;
1205   } else {
1206     const auto* info = fb->GetCompletenessInfo();
1207     MOZ_ASSERT(info);
1208     size = gfx::IntSize(info->width, info->height);
1209   }
1210
1211   const auto surfaceFormat = mOptions.alpha ? gfx::SurfaceFormat::B8G8R8A8
1212                                             : gfx::SurfaceFormat::B8G8R8X8;
1213   Maybe<layers::SurfaceDescriptor> desc;
1214   if (surf) {
1215     desc = surf->ToSurfaceDescriptor();
1216   }
1217   if (!desc) {
1218     if (surf && surf->mDesc.type != gl::SharedSurfaceType::Basic) {
1219       return onFailure();
1220     }
1221     // If we can't serialize to a surface descriptor, then we need to create
1222     // a buffer to read back into that will become the remote texture.
1223     auto data = ownerClient->CreateOrRecycleBufferTextureData(
1224         size, surfaceFormat, ownerId);
1225     if (!data) {
1226       gfxCriticalNoteOnce << "Failed to allocate BufferTextureData";
1227       return onFailure();
1228     }
1229
1230     layers::MappedTextureData mappedData;
1231     if (!data->BorrowMappedData(mappedData)) {
1232       return onFailure();
1233     }
1234
1235     Range<uint8_t> range = {mappedData.data,
1236                             data->AsBufferTextureData()->GetBufferSize()};
1237
1238     // If we have a surface representing the front buffer, then try to snapshot
1239     // that. Otherwise, when there is no surface, we read back directly from the
1240     // WebGL framebuffer.
1241     auto valid =
1242         surf ? FrontBufferSnapshotInto(surf, Some(range),
1243                                        Some(mappedData.stride))
1244              : SnapshotInto(fb->mGLName, size, range, Some(mappedData.stride));
1245     if (!valid) {
1246       return onFailure();
1247     }
1248
1249     if (!options.bgra) {
1250       // If the buffer is already BGRA, we don't need to swizzle. However, if it
1251       // is RGBA, then a swizzle to BGRA is required.
1252       bool rv = gfx::SwizzleData(mappedData.data, mappedData.stride,
1253                                  gfx::SurfaceFormat::R8G8B8A8, mappedData.data,
1254                                  mappedData.stride,
1255                                  gfx::SurfaceFormat::B8G8R8A8, mappedData.size);
1256       MOZ_RELEASE_ASSERT(rv, "SwizzleData failed!");
1257     }
1258
1259     ownerClient->PushTexture(textureId, ownerId, std::move(data));
1260     return true;
1261   }
1262
1263   // SharedSurfaces of SurfaceDescriptorD3D10 and SurfaceDescriptorMacIOSurface
1264   // need to be kept alive. They will be recycled by
1265   // RemoteTextureOwnerClient::GetRecycledSharedSurface() when their usages are
1266   // ended.
1267   std::shared_ptr<gl::SharedSurface> keepAlive;
1268   switch (desc->type()) {
1269     case layers::SurfaceDescriptor::TSurfaceDescriptorD3D10:
1270     case layers::SurfaceDescriptor::TSurfaceDescriptorMacIOSurface:
1271     case layers::SurfaceDescriptor::TSurfaceTextureDescriptor:
1272     case layers::SurfaceDescriptor::TSurfaceDescriptorAndroidHardwareBuffer:
1273     case layers::SurfaceDescriptor::TSurfaceDescriptorDMABuf:
1274       keepAlive = surf;
1275       break;
1276     default:
1277       break;
1278   }
1279
1280   ownerClient->PushTexture(textureId, ownerId, keepAlive, size, surfaceFormat,
1281                            *desc);
1282
1283   // Look for a recycled surface that matches the swap chain.
1284   while (auto recycledSurface = ownerClient->GetRecycledSharedSurface(
1285              size, surfaceFormat, desc->type(), ownerId)) {
1286     if (swapChain.StoreRecycledSurface(recycledSurface)) {
1287       break;
1288     }
1289   }
1290   return true;
1291 }
1292
1293 void WebGLContext::EnsureContextLostRemoteTextureOwner(
1294     const webgl::SwapChainOptions& options) {
1295   if (!options.remoteTextureOwnerId.IsValid()) {
1296     return;
1297   }
1298
1299   if (!mRemoteTextureOwner) {
1300     // Ensure we have a remote texture owner client for WebGLParent.
1301     const auto* outOfProcess = mHost ? mHost->mOwnerData.outOfProcess : nullptr;
1302     if (!outOfProcess) {
1303       return;
1304     }
1305     auto pid = outOfProcess->OtherPid();
1306     mRemoteTextureOwner = MakeRefPtr<layers::RemoteTextureOwnerClient>(pid);
1307   }
1308
1309   layers::RemoteTextureOwnerId ownerId = options.remoteTextureOwnerId;
1310
1311   if (!mRemoteTextureOwner->IsRegistered(ownerId)) {
1312     mRemoteTextureOwner->RegisterTextureOwner(ownerId);
1313   }
1314   mRemoteTextureOwner->NotifyContextLost();
1315 }
1316
1317 void WebGLContext::EndOfFrame() {
1318   const FuncScope funcScope(*this, "<EndOfFrame>");
1319   if (IsContextLost()) return;
1320
1321   OnEndOfFrame();
1322 }
1323
1324 gl::SwapChain* WebGLContext::GetSwapChain(WebGLFramebuffer* const xrFb,
1325                                           const bool webvr) {
1326   auto swapChain = webvr ? &mWebVRSwapChain : &mSwapChain;
1327   if (xrFb) {
1328     swapChain = &xrFb->mSwapChain;
1329   }
1330   return swapChain;
1331 }
1332
1333 Maybe<layers::SurfaceDescriptor> WebGLContext::GetFrontBuffer(
1334     WebGLFramebuffer* const xrFb, const bool webvr) {
1335   auto* swapChain = GetSwapChain(xrFb, webvr);
1336   if (!swapChain) return {};
1337   const auto& front = swapChain->FrontBuffer();
1338   if (!front) return {};
1339
1340   return front->ToSurfaceDescriptor();
1341 }
1342
1343 Maybe<uvec2> WebGLContext::FrontBufferSnapshotInto(
1344     const Maybe<Range<uint8_t>> maybeDest, const Maybe<size_t> destStride) {
1345   const auto& front = mSwapChain.FrontBuffer();
1346   if (!front) return {};
1347   return FrontBufferSnapshotInto(front, maybeDest, destStride);
1348 }
1349
1350 Maybe<uvec2> WebGLContext::FrontBufferSnapshotInto(
1351     const std::shared_ptr<gl::SharedSurface>& front,
1352     const Maybe<Range<uint8_t>> maybeDest, const Maybe<size_t> destStride) {
1353   const auto& size = front->mDesc.size;
1354   if (!maybeDest) return Some(*uvec2::FromSize(size));
1355
1356   // -
1357
1358   front->WaitForBufferOwnership();
1359   front->LockProd();
1360   front->ProducerReadAcquire();
1361   auto reset = MakeScopeExit([&] {
1362     front->ProducerReadRelease();
1363     front->UnlockProd();
1364   });
1365
1366   // -
1367
1368   return SnapshotInto(front->mFb ? front->mFb->mFB : 0, size, *maybeDest,
1369                       destStride);
1370 }
1371
1372 Maybe<uvec2> WebGLContext::SnapshotInto(GLuint srcFb, const gfx::IntSize& size,
1373                                         const Range<uint8_t>& dest,
1374                                         const Maybe<size_t> destStride) {
1375   const auto minStride = CheckedInt<size_t>(size.width) * 4;
1376   if (!minStride.isValid()) {
1377     gfxCriticalError() << "SnapshotInto: invalid stride, width:" << size.width;
1378     return {};
1379   }
1380   size_t stride = destStride.valueOr(minStride.value());
1381   if (stride < minStride.value() || (stride % 4) != 0) {
1382     gfxCriticalError() << "SnapshotInto: invalid stride, width:" << size.width
1383                        << ", stride:" << stride;
1384     return {};
1385   }
1386
1387   gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, 1);
1388   if (IsWebGL2()) {
1389     gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH,
1390                      stride > minStride.value() ? stride / 4 : 0);
1391     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS, 0);
1392     gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, 0);
1393   }
1394
1395   // -
1396
1397   const auto readFbWas = mBoundReadFramebuffer;
1398   const auto pboWas = mBoundPixelPackBuffer;
1399
1400   GLenum fbTarget = LOCAL_GL_READ_FRAMEBUFFER;
1401   if (!IsWebGL2()) {
1402     fbTarget = LOCAL_GL_FRAMEBUFFER;
1403   }
1404   auto reset2 = MakeScopeExit([&] {
1405     DoBindFB(readFbWas, fbTarget);
1406     if (pboWas) {
1407       BindBuffer(LOCAL_GL_PIXEL_PACK_BUFFER, pboWas);
1408     }
1409   });
1410
1411   gl->fBindFramebuffer(fbTarget, srcFb);
1412   if (pboWas) {
1413     BindBuffer(LOCAL_GL_PIXEL_PACK_BUFFER, nullptr);
1414   }
1415
1416   // -
1417
1418   const auto srcByteCount = CheckedInt<size_t>(stride) * size.height;
1419   if (!srcByteCount.isValid()) {
1420     gfxCriticalError() << "SnapshotInto: invalid srcByteCount, width:"
1421                        << size.width << ", height:" << size.height;
1422     return {};
1423   }
1424   const auto dstByteCount = dest.length();
1425   if (srcByteCount.value() > dstByteCount) {
1426     gfxCriticalError() << "SnapshotInto: srcByteCount:" << srcByteCount.value()
1427                        << " > dstByteCount:" << dstByteCount;
1428     return {};
1429   }
1430   uint8_t* dstPtr = dest.begin().get();
1431   gl->fReadPixels(0, 0, size.width, size.height, LOCAL_GL_RGBA,
1432                   LOCAL_GL_UNSIGNED_BYTE, dstPtr);
1433
1434   if (!IsWebGL2() && stride > minStride.value() && size.height > 1) {
1435     // WebGL 1 doesn't support PACK_ROW_LENGTH. Instead, we read the data tight
1436     // into the front of the buffer, and use memmove (since the source and dest
1437     // may overlap) starting from the back to move it to the correct stride
1438     // offsets. We don't move the first row as it is already in the right place.
1439     uint8_t* destRow = dstPtr + stride * (size.height - 1);
1440     const uint8_t* srcRow = dstPtr + minStride.value() * (size.height - 1);
1441     while (destRow > dstPtr) {
1442       memmove(destRow, srcRow, minStride.value());
1443       destRow -= stride;
1444       srcRow -= minStride.value();
1445     }
1446   }
1447
1448   return Some(*uvec2::FromSize(size));
1449 }
1450
1451 void WebGLContext::ClearVRSwapChain() { mWebVRSwapChain.ClearPool(); }
1452
1453 // ------------------------
1454
1455 RefPtr<gfx::DataSourceSurface> GetTempSurface(const gfx::IntSize& aSize,
1456                                               gfx::SurfaceFormat& aFormat) {
1457   uint32_t stride =
1458       gfx::GetAlignedStride<8>(aSize.width, BytesPerPixel(aFormat));
1459   return gfx::Factory::CreateDataSourceSurfaceWithStride(aSize, aFormat,
1460                                                          stride);
1461 }
1462
1463 void WebGLContext::DummyReadFramebufferOperation() {
1464   if (!mBoundReadFramebuffer) return;  // Infallible.
1465
1466   const auto status = mBoundReadFramebuffer->CheckFramebufferStatus();
1467   if (status != LOCAL_GL_FRAMEBUFFER_COMPLETE) {
1468     ErrorInvalidFramebufferOperation("Framebuffer must be complete.");
1469   }
1470 }
1471
1472 dom::ContentParentId WebGLContext::GetContentId() const {
1473   const auto* outOfProcess = mHost ? mHost->mOwnerData.outOfProcess : nullptr;
1474   if (outOfProcess) {
1475     return outOfProcess->mContentId;
1476   }
1477   if (XRE_IsContentProcess()) {
1478     return dom::ContentChild::GetSingleton()->GetID();
1479   }
1480   return dom::ContentParentId();
1481 }
1482
1483 bool WebGLContext::Has64BitTimestamps() const {
1484   // 'sync' provides glGetInteger64v either by supporting ARB_sync, GL3+, or
1485   // GLES3+.
1486   return gl->IsSupported(gl::GLFeature::sync);
1487 }
1488
1489 static bool CheckContextLost(gl::GLContext* gl, bool* const out_isGuilty) {
1490   MOZ_ASSERT(gl);
1491
1492   const auto resetStatus = gl->fGetGraphicsResetStatus();
1493   if (resetStatus == LOCAL_GL_NO_ERROR) {
1494     *out_isGuilty = false;
1495     return false;
1496   }
1497
1498   // Assume guilty unless we find otherwise!
1499   bool isGuilty = true;
1500   switch (resetStatus) {
1501     case LOCAL_GL_INNOCENT_CONTEXT_RESET_ARB:
1502     case LOCAL_GL_PURGED_CONTEXT_RESET_NV:
1503       // Either nothing wrong, or not our fault.
1504       isGuilty = false;
1505       break;
1506     case LOCAL_GL_GUILTY_CONTEXT_RESET_ARB:
1507       NS_WARNING(
1508           "WebGL content on the page definitely caused the graphics"
1509           " card to reset.");
1510       break;
1511     case LOCAL_GL_UNKNOWN_CONTEXT_RESET_ARB:
1512       NS_WARNING(
1513           "WebGL content on the page might have caused the graphics"
1514           " card to reset");
1515       // If we can't tell, assume not-guilty.
1516       // Todo: Implement max number of "unknown" resets per document or time.
1517       isGuilty = false;
1518       break;
1519     default:
1520       gfxCriticalError() << "Unexpected glGetGraphicsResetStatus: "
1521                          << gfx::hexa(resetStatus);
1522       break;
1523   }
1524
1525   if (isGuilty) {
1526     NS_WARNING(
1527         "WebGL context on this page is considered guilty, and will"
1528         " not be restored.");
1529   }
1530
1531   *out_isGuilty = isGuilty;
1532   return true;
1533 }
1534
1535 void WebGLContext::RunContextLossTimer() { mContextLossHandler.RunTimer(); }
1536
1537 // We use this timer for many things. Here are the things that it is activated
1538 // for:
1539 // 1) If a script is using the MOZ_WEBGL_lose_context extension.
1540 // 2) If we are using EGL and _NOT ANGLE_, we query periodically to see if the
1541 //    CONTEXT_LOST_WEBGL error has been triggered.
1542 // 3) If we are using ANGLE, or anything that supports ARB_robustness, query the
1543 //    GPU periodically to see if the reset status bit has been set.
1544 // In all of these situations, we use this timer to send the script context lost
1545 // and restored events asynchronously. For example, if it triggers a context
1546 // loss, the webglcontextlost event will be sent to it the next time the
1547 // robustness timer fires.
1548 // Note that this timer mechanism is not used unless one of these 3 criteria are
1549 // met.
1550 // At a bare minimum, from context lost to context restores, it would take 3
1551 // full timer iterations: detection, webglcontextlost, webglcontextrestored.
1552 void WebGLContext::CheckForContextLoss() {
1553   bool isGuilty = true;
1554   const auto isContextLost = CheckContextLost(gl, &isGuilty);
1555   if (!isContextLost) return;
1556
1557   mWebGLError = LOCAL_GL_CONTEXT_LOST;
1558
1559   auto reason = webgl::ContextLossReason::None;
1560   if (isGuilty) {
1561     reason = webgl::ContextLossReason::Guilty;
1562   }
1563   LoseContext(reason);
1564 }
1565
1566 void WebGLContext::HandlePendingContextLoss() {
1567   mIsContextLost = true;
1568   if (mHost) {
1569     mHost->OnContextLoss(mPendingContextLossReason);
1570   }
1571 }
1572
1573 void WebGLContext::LoseContextLruLocked(const webgl::ContextLossReason reason) {
1574   printf_stderr("WebGL(%p)::LoseContext(%u)\n", this,
1575                 static_cast<uint32_t>(reason));
1576   mLruPosition.ResetLocked();
1577   mPendingContextLossReason = reason;
1578   mPendingContextLoss = true;
1579 }
1580
1581 void WebGLContext::LoseContext(const webgl::ContextLossReason reason) {
1582   StaticMutexAutoLock lock(sLruMutex);
1583   LoseContextLruLocked(reason);
1584   HandlePendingContextLoss();
1585   if (mRemoteTextureOwner) {
1586     mRemoteTextureOwner->NotifyContextLost();
1587   }
1588 }
1589
1590 void WebGLContext::DidRefresh() {
1591   if (gl) {
1592     gl->FlushIfHeavyGLCallsSinceLastFlush();
1593   }
1594 }
1595
1596 ////////////////////////////////////////////////////////////////////////////////
1597
1598 uvec2 WebGLContext::DrawingBufferSize() {
1599   const FuncScope funcScope(*this, "width/height");
1600   if (IsContextLost()) return {};
1601
1602   if (!EnsureDefaultFB()) return {};
1603
1604   return *uvec2::FromSize(mDefaultFB->mSize);
1605 }
1606
1607 bool WebGLContext::ValidateAndInitFB(const WebGLFramebuffer* const fb,
1608                                      const GLenum incompleteFbError) {
1609   if (fb) return fb->ValidateAndInitAttachments(incompleteFbError);
1610
1611   if (!EnsureDefaultFB()) return false;
1612
1613   if (mDefaultFB_IsInvalid) {
1614     // Clear it!
1615     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mDefaultFB->mFB);
1616     const webgl::ScopedPrepForResourceClear scopedPrep(*this);
1617     if (!mOptions.alpha) {
1618       gl->fClearColor(0, 0, 0, 1);
1619     }
1620     const GLbitfield bits = LOCAL_GL_COLOR_BUFFER_BIT |
1621                             LOCAL_GL_DEPTH_BUFFER_BIT |
1622                             LOCAL_GL_STENCIL_BUFFER_BIT;
1623     gl->fClear(bits);
1624
1625     mDefaultFB_IsInvalid = false;
1626   }
1627   return true;
1628 }
1629
1630 void WebGLContext::DoBindFB(const WebGLFramebuffer* const fb,
1631                             const GLenum target) const {
1632   const GLenum driverFB = fb ? fb->mGLName : mDefaultFB->mFB;
1633   gl->fBindFramebuffer(target, driverFB);
1634 }
1635
1636 bool WebGLContext::BindCurFBForDraw() {
1637   const auto& fb = mBoundDrawFramebuffer;
1638   if (!ValidateAndInitFB(fb)) return false;
1639
1640   DoBindFB(fb);
1641   return true;
1642 }
1643
1644 bool WebGLContext::BindCurFBForColorRead(
1645     const webgl::FormatUsageInfo** const out_format, uint32_t* const out_width,
1646     uint32_t* const out_height, const GLenum incompleteFbError) {
1647   const auto& fb = mBoundReadFramebuffer;
1648
1649   if (fb) {
1650     if (!ValidateAndInitFB(fb, incompleteFbError)) return false;
1651     if (!fb->ValidateForColorRead(out_format, out_width, out_height))
1652       return false;
1653
1654     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, fb->mGLName);
1655     return true;
1656   }
1657
1658   if (!BindDefaultFBForRead()) return false;
1659
1660   if (mDefaultFB_ReadBuffer == LOCAL_GL_NONE) {
1661     ErrorInvalidOperation(
1662         "Can't read from backbuffer when readBuffer mode is NONE.");
1663     return false;
1664   }
1665
1666   auto effFormat = mOptions.alpha ? webgl::EffectiveFormat::RGBA8
1667                                   : webgl::EffectiveFormat::RGB8;
1668
1669   *out_format = mFormatUsage->GetUsage(effFormat);
1670   MOZ_ASSERT(*out_format);
1671
1672   *out_width = mDefaultFB->mSize.width;
1673   *out_height = mDefaultFB->mSize.height;
1674   return true;
1675 }
1676
1677 bool WebGLContext::BindDefaultFBForRead() {
1678   if (!ValidateAndInitFB(nullptr)) return false;
1679
1680   if (!mDefaultFB->mSamples) {
1681     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mDefaultFB->mFB);
1682     return true;
1683   }
1684
1685   if (!mResolvedDefaultFB) {
1686     mResolvedDefaultFB =
1687         gl::MozFramebuffer::Create(gl, mDefaultFB->mSize, 0, false);
1688     if (!mResolvedDefaultFB) {
1689       gfxCriticalNote << FuncName() << ": Failed to create mResolvedDefaultFB.";
1690       return false;
1691     }
1692   }
1693
1694   gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mResolvedDefaultFB->mFB);
1695   BlitBackbufferToCurDriverFB();
1696
1697   gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mResolvedDefaultFB->mFB);
1698   return true;
1699 }
1700
1701 void WebGLContext::DoColorMask(Maybe<GLuint> i, const uint8_t bitmask) const {
1702   if (!IsExtensionEnabled(WebGLExtensionID::OES_draw_buffers_indexed)) {
1703     i = Nothing();
1704   }
1705   const auto bs = std::bitset<4>(bitmask);
1706   if (i) {
1707     gl->fColorMaski(*i, bs[0], bs[1], bs[2], bs[3]);
1708   } else {
1709     gl->fColorMask(bs[0], bs[1], bs[2], bs[3]);
1710   }
1711 }
1712
1713 ////////////////////////////////////////////////////////////////////////////////
1714
1715 ScopedDrawCallWrapper::ScopedDrawCallWrapper(WebGLContext& webgl)
1716     : mWebGL(webgl) {
1717   uint8_t driverColorMask0 = mWebGL.mColorWriteMask0;
1718   bool driverDepthTest = mWebGL.mDepthTestEnabled;
1719   bool driverStencilTest = mWebGL.mStencilTestEnabled;
1720   const auto& fb = mWebGL.mBoundDrawFramebuffer;
1721   if (!fb) {
1722     if (mWebGL.mDefaultFB_DrawBuffer0 == LOCAL_GL_NONE) {
1723       driverColorMask0 = 0;  // Is this well-optimized enough for depth-first
1724                              // rendering?
1725     } else {
1726       driverColorMask0 &= ~(uint8_t(mWebGL.mNeedsFakeNoAlpha) << 3);
1727     }
1728     driverDepthTest &= !mWebGL.mNeedsFakeNoDepth;
1729     driverStencilTest &= !mWebGL.mNeedsFakeNoStencil;
1730   }
1731
1732   const auto& gl = mWebGL.gl;
1733   mWebGL.DoColorMask(Some(0), driverColorMask0);
1734   if (mWebGL.mDriverDepthTest != driverDepthTest) {
1735     // "When disabled, the depth comparison and subsequent possible updates to
1736     // the
1737     //  depth buffer value are bypassed and the fragment is passed to the next
1738     //  operation." [GLES 3.0.5, p177]
1739     mWebGL.mDriverDepthTest = driverDepthTest;
1740     gl->SetEnabled(LOCAL_GL_DEPTH_TEST, mWebGL.mDriverDepthTest);
1741   }
1742   if (mWebGL.mDriverStencilTest != driverStencilTest) {
1743     // "When disabled, the stencil test and associated modifications are not
1744     // made, and
1745     //  the fragment is always passed." [GLES 3.0.5, p175]
1746     mWebGL.mDriverStencilTest = driverStencilTest;
1747     gl->SetEnabled(LOCAL_GL_STENCIL_TEST, mWebGL.mDriverStencilTest);
1748   }
1749 }
1750
1751 ScopedDrawCallWrapper::~ScopedDrawCallWrapper() {
1752   if (mWebGL.mBoundDrawFramebuffer) return;
1753
1754   mWebGL.mResolvedDefaultFB = nullptr;
1755   mWebGL.mShouldPresent = true;
1756 }
1757
1758 // -
1759
1760 void WebGLContext::ScissorRect::Apply(gl::GLContext& gl) const {
1761   gl.fScissor(x, y, w, h);
1762 }
1763
1764 ////////////////////////////////////////
1765
1766 IndexedBufferBinding::IndexedBufferBinding() = default;
1767 IndexedBufferBinding::~IndexedBufferBinding() = default;
1768
1769 uint64_t IndexedBufferBinding::ByteCount() const {
1770   if (!mBufferBinding) return 0;
1771
1772   uint64_t bufferSize = mBufferBinding->ByteLength();
1773   if (!mRangeSize)  // BindBufferBase
1774     return bufferSize;
1775
1776   if (mRangeStart >= bufferSize) return 0;
1777   bufferSize -= mRangeStart;
1778
1779   return std::min(bufferSize, mRangeSize);
1780 }
1781
1782 ////////////////////////////////////////
1783
1784 ScopedFBRebinder::~ScopedFBRebinder() {
1785   const auto fnName = [&](WebGLFramebuffer* fb) {
1786     return fb ? fb->mGLName : 0;
1787   };
1788
1789   const auto& gl = mWebGL->gl;
1790   if (mWebGL->IsWebGL2()) {
1791     gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER,
1792                          fnName(mWebGL->mBoundDrawFramebuffer));
1793     gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER,
1794                          fnName(mWebGL->mBoundReadFramebuffer));
1795   } else {
1796     MOZ_ASSERT(mWebGL->mBoundDrawFramebuffer == mWebGL->mBoundReadFramebuffer);
1797     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER,
1798                          fnName(mWebGL->mBoundDrawFramebuffer));
1799   }
1800 }
1801
1802 ////////////////////
1803
1804 void DoBindBuffer(gl::GLContext& gl, const GLenum target,
1805                   const WebGLBuffer* const buffer) {
1806   gl.fBindBuffer(target, buffer ? buffer->mGLName : 0);
1807 }
1808
1809 ////////////////////////////////////////
1810
1811 bool Intersect(const int32_t srcSize, const int32_t read0,
1812                const int32_t readSize, int32_t* const out_intRead0,
1813                int32_t* const out_intWrite0, int32_t* const out_intSize) {
1814   MOZ_ASSERT(srcSize >= 0);
1815   MOZ_ASSERT(readSize >= 0);
1816   const auto read1 = int64_t(read0) + readSize;
1817
1818   int32_t intRead0 = read0;  // Clearly doesn't need validation.
1819   int64_t intWrite0 = 0;
1820   int64_t intSize = readSize;
1821
1822   if (read1 <= 0 || read0 >= srcSize) {
1823     // Disjoint ranges.
1824     intSize = 0;
1825   } else {
1826     if (read0 < 0) {
1827       const auto diff = int64_t(0) - read0;
1828       MOZ_ASSERT(diff >= 0);
1829       intRead0 = 0;
1830       intWrite0 = diff;
1831       intSize -= diff;
1832     }
1833     if (read1 > srcSize) {
1834       const auto diff = int64_t(read1) - srcSize;
1835       MOZ_ASSERT(diff >= 0);
1836       intSize -= diff;
1837     }
1838
1839     if (!CheckedInt<int32_t>(intWrite0).isValid() ||
1840         !CheckedInt<int32_t>(intSize).isValid()) {
1841       return false;
1842     }
1843   }
1844
1845   *out_intRead0 = intRead0;
1846   *out_intWrite0 = intWrite0;
1847   *out_intSize = intSize;
1848   return true;
1849 }
1850
1851 // --
1852
1853 uint64_t AvailGroups(const uint64_t totalAvailItems,
1854                      const uint64_t firstItemOffset, const uint32_t groupSize,
1855                      const uint32_t groupStride) {
1856   MOZ_ASSERT(groupSize && groupStride);
1857   MOZ_ASSERT(groupSize <= groupStride);
1858
1859   if (totalAvailItems <= firstItemOffset) return 0;
1860   const size_t availItems = totalAvailItems - firstItemOffset;
1861
1862   size_t availGroups = availItems / groupStride;
1863   const size_t tailItems = availItems % groupStride;
1864   if (tailItems >= groupSize) {
1865     availGroups += 1;
1866   }
1867   return availGroups;
1868 }
1869
1870 ////////////////////////////////////////////////////////////////////////////////
1871
1872 const char* WebGLContext::FuncName() const {
1873   const char* ret;
1874   if (MOZ_LIKELY(mFuncScope)) {
1875     ret = mFuncScope->mFuncName;
1876   } else {
1877     NS_WARNING("FuncScope not on stack!");
1878     ret = "<unknown function>";
1879   }
1880   return ret;
1881 }
1882
1883 // -
1884
1885 WebGLContext::FuncScope::FuncScope(const WebGLContext& webgl,
1886                                    const char* const funcName)
1887     : mWebGL(webgl), mFuncName(bool(mWebGL.mFuncScope) ? nullptr : funcName) {
1888   if (!mFuncName) return;
1889   mWebGL.mFuncScope = this;
1890 }
1891
1892 WebGLContext::FuncScope::~FuncScope() {
1893   if (mBindFailureGuard) {
1894     gfxCriticalError() << "mBindFailureGuard failure: Early exit from "
1895                        << mWebGL.FuncName();
1896   }
1897
1898   if (!mFuncName) return;
1899   mWebGL.mFuncScope = nullptr;
1900 }
1901
1902 // --
1903
1904 bool ClientWebGLContext::IsXRCompatible() const { return mXRCompatible; }
1905
1906 already_AddRefed<dom::Promise> ClientWebGLContext::MakeXRCompatible(
1907     ErrorResult& aRv) {
1908   const FuncScope funcScope(*this, "MakeXRCompatible");
1909   nsCOMPtr<nsIGlobalObject> global = GetParentObject();
1910   if (!global) {
1911     aRv.ThrowInvalidAccessError(
1912         "Using a WebGL context that is not attached to either a canvas or an "
1913         "OffscreenCanvas");
1914     return nullptr;
1915   }
1916   RefPtr<dom::Promise> promise = dom::Promise::Create(global, aRv);
1917   NS_ENSURE_TRUE(!aRv.Failed(), nullptr);
1918
1919   if (IsContextLost()) {
1920     promise->MaybeRejectWithInvalidStateError(
1921         "Can not make context XR compatible when context is already lost.");
1922     return promise.forget();
1923   }
1924
1925   // TODO: Bug 1580258 - WebGLContext.MakeXRCompatible needs to switch to
1926   //                     the device connected to the XR hardware
1927   // This should update `options` and lose+restore the context.
1928   mXRCompatible = true;
1929   promise->MaybeResolveWithUndefined();
1930   return promise.forget();
1931 }
1932
1933 // --
1934
1935 webgl::AvailabilityRunnable& ClientWebGLContext::EnsureAvailabilityRunnable()
1936     const {
1937   if (!mAvailabilityRunnable) {
1938     mAvailabilityRunnable = new webgl::AvailabilityRunnable(this);
1939     auto forgettable = mAvailabilityRunnable;
1940     NS_DispatchToCurrentThread(forgettable.forget());
1941   }
1942   return *mAvailabilityRunnable;
1943 }
1944
1945 webgl::AvailabilityRunnable::AvailabilityRunnable(
1946     const ClientWebGLContext* const webgl)
1947     : DiscardableRunnable("webgl::AvailabilityRunnable"), mWebGL(webgl) {}
1948
1949 webgl::AvailabilityRunnable::~AvailabilityRunnable() {
1950   MOZ_ASSERT(mQueries.empty());
1951   MOZ_ASSERT(mSyncs.empty());
1952 }
1953
1954 nsresult webgl::AvailabilityRunnable::Run() {
1955   for (const auto& cur : mQueries) {
1956     if (!cur) continue;
1957     cur->mCanBeAvailable = true;
1958   }
1959   mQueries.clear();
1960
1961   for (const auto& cur : mSyncs) {
1962     if (!cur) continue;
1963     cur->mCanBeAvailable = true;
1964   }
1965   mSyncs.clear();
1966
1967   if (mWebGL) {
1968     mWebGL->mAvailabilityRunnable = nullptr;
1969   }
1970   return NS_OK;
1971 }
1972
1973 // -
1974
1975 void WebGLContext::JsWarning(const std::string& text) const {
1976   if (mHost) {
1977     mHost->JsWarning(text);
1978   }
1979 #ifdef DEBUG
1980   if (!mHost) {
1981     NS_WARNING(text.c_str());
1982   }
1983 #endif
1984 }
1985
1986 void WebGLContext::GenerateErrorImpl(const GLenum errOrWarning,
1987                                      const std::string& text) const {
1988   auto err = errOrWarning;
1989   bool isPerfWarning = false;
1990   if (err == webgl::kErrorPerfWarning) {
1991     err = 0;
1992     isPerfWarning = true;
1993   }
1994
1995   if (err && mFuncScope && mFuncScope->mBindFailureGuard) {
1996     gfxCriticalError() << "mBindFailureGuard failure: Generating error "
1997                        << EnumString(err) << ": " << text;
1998   }
1999
2000   /* ES2 section 2.5 "GL Errors" states that implementations can have
2001    * multiple 'flags', as errors might be caught in different parts of
2002    * a distributed implementation.
2003    * We're signing up as a distributed implementation here, with
2004    * separate flags for WebGL and the underlying GLContext.
2005    */
2006   if (!mWebGLError) mWebGLError = err;
2007
2008   if (!mHost) return;  // Impossible?
2009
2010   // -
2011
2012   const auto ShouldWarn = [&]() {
2013     if (isPerfWarning) {
2014       return ShouldGeneratePerfWarnings();
2015     }
2016     return ShouldGenerateWarnings();
2017   };
2018   if (!ShouldWarn()) return;
2019
2020   // -
2021
2022   auto* pNumWarnings = &mWarningCount;
2023   const char* warningsType = "warnings";
2024   if (isPerfWarning) {
2025     pNumWarnings = &mNumPerfWarnings;
2026     warningsType = "perf warnings";
2027   }
2028
2029   if (isPerfWarning) {
2030     const auto perfText = std::string("WebGL perf warning: ") + text;
2031     JsWarning(perfText);
2032   } else {
2033     JsWarning(text);
2034   }
2035   *pNumWarnings += 1;
2036
2037   if (!ShouldWarn()) {
2038     const auto& msg = nsPrintfCString(
2039         "After reporting %i, no further %s will be reported for this WebGL "
2040         "context.",
2041         int(*pNumWarnings), warningsType);
2042     JsWarning(ToString(msg));
2043   }
2044 }
2045
2046 // -
2047
2048 Maybe<std::string> WebGLContext::GetString(const GLenum pname) const {
2049   const WebGLContext::FuncScope funcScope(*this, "getParameter");
2050   if (IsContextLost()) return {};
2051
2052   const auto FromRaw = [](const char* const raw) -> Maybe<std::string> {
2053     if (!raw) return {};
2054     return Some(std::string(raw));
2055   };
2056
2057   switch (pname) {
2058     case LOCAL_GL_EXTENSIONS: {
2059       if (!gl->IsCoreProfile()) {
2060         const auto rawExt = (const char*)gl->fGetString(LOCAL_GL_EXTENSIONS);
2061         return FromRaw(rawExt);
2062       }
2063       std::string ret;
2064       const auto& numExts = gl->GetIntAs<GLuint>(LOCAL_GL_NUM_EXTENSIONS);
2065       for (GLuint i = 0; i < numExts; i++) {
2066         const auto rawExt =
2067             (const char*)gl->fGetStringi(LOCAL_GL_EXTENSIONS, i);
2068         if (!rawExt) continue;
2069
2070         if (i > 0) {
2071           ret += " ";
2072         }
2073         ret += rawExt;
2074       }
2075       return Some(std::move(ret));
2076     }
2077
2078     case LOCAL_GL_RENDERER:
2079     case LOCAL_GL_VENDOR:
2080     case LOCAL_GL_VERSION: {
2081       const auto raw = (const char*)gl->fGetString(pname);
2082       return FromRaw(raw);
2083     }
2084
2085     case dom::MOZ_debug_Binding::WSI_INFO: {
2086       nsCString info;
2087       gl->GetWSIInfo(&info);
2088       return Some(std::string(info.BeginReading()));
2089     }
2090
2091     default:
2092       ErrorInvalidEnumArg("pname", pname);
2093       return {};
2094   }
2095 }
2096
2097 // ---------------------------------
2098
2099 Maybe<webgl::IndexedName> webgl::ParseIndexed(const std::string& str) {
2100   static const std::regex kRegex("(.*)\\[([0-9]+)\\]");
2101
2102   std::smatch match;
2103   if (!std::regex_match(str, match, kRegex)) return {};
2104
2105   const auto index = std::stoull(match[2]);
2106   return Some(webgl::IndexedName{match[1], index});
2107 }
2108
2109 // ExplodeName("foo.bar[3].x") -> ["foo", ".", "bar", "[", "3", "]", ".", "x"]
2110 static std::vector<std::string> ExplodeName(const std::string& str) {
2111   std::vector<std::string> ret;
2112
2113   static const std::regex kSep("[.[\\]]");
2114
2115   auto itr = std::regex_token_iterator<decltype(str.begin())>(
2116       str.begin(), str.end(), kSep, {-1, 0});
2117   const auto end = decltype(itr)();
2118
2119   for (; itr != end; ++itr) {
2120     const auto& part = itr->str();
2121     if (part.size()) {
2122       ret.push_back(part);
2123     }
2124   }
2125   return ret;
2126 }
2127
2128 //-
2129
2130 // #define DUMP_MakeLinkResult
2131
2132 webgl::LinkActiveInfo GetLinkActiveInfo(
2133     gl::GLContext& gl, const GLuint prog, const bool webgl2,
2134     const std::unordered_map<std::string, std::string>& nameUnmap) {
2135   webgl::LinkActiveInfo ret;
2136   [&]() {
2137     const auto fnGetProgramui = [&](const GLenum pname) {
2138       GLint ret = 0;
2139       gl.fGetProgramiv(prog, pname, &ret);
2140       return static_cast<uint32_t>(ret);
2141     };
2142
2143     std::vector<char> stringBuffer(1);
2144     const auto fnEnsureCapacity = [&](const GLenum pname) {
2145       const auto maxWithNull = fnGetProgramui(pname);
2146       if (maxWithNull > stringBuffer.size()) {
2147         stringBuffer.resize(maxWithNull);
2148       }
2149     };
2150
2151     fnEnsureCapacity(LOCAL_GL_ACTIVE_ATTRIBUTE_MAX_LENGTH);
2152     fnEnsureCapacity(LOCAL_GL_ACTIVE_UNIFORM_MAX_LENGTH);
2153     if (webgl2) {
2154       fnEnsureCapacity(LOCAL_GL_ACTIVE_UNIFORM_BLOCK_MAX_NAME_LENGTH);
2155       fnEnsureCapacity(LOCAL_GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH);
2156     }
2157
2158     // -
2159
2160     const auto fnUnmapName = [&](const std::string& mappedName) {
2161       const auto parts = ExplodeName(mappedName);
2162
2163       std::ostringstream ret;
2164       for (const auto& part : parts) {
2165         const auto maybe = MaybeFind(nameUnmap, part);
2166         if (maybe) {
2167           ret << *maybe;
2168         } else {
2169           ret << part;
2170         }
2171       }
2172       return ret.str();
2173     };
2174
2175     // -
2176
2177     {
2178       const auto count = fnGetProgramui(LOCAL_GL_ACTIVE_ATTRIBUTES);
2179       ret.activeAttribs.reserve(count);
2180       for (const auto i : IntegerRange(count)) {
2181         GLsizei lengthWithoutNull = 0;
2182         GLint elemCount = 0;  // `size`
2183         GLenum elemType = 0;  // `type`
2184         gl.fGetActiveAttrib(prog, i, stringBuffer.size(), &lengthWithoutNull,
2185                             &elemCount, &elemType, stringBuffer.data());
2186         if (!elemType) {
2187           const auto error = gl.fGetError();
2188           if (error != LOCAL_GL_CONTEXT_LOST) {
2189             gfxCriticalError() << "Failed to do glGetActiveAttrib: " << error;
2190           }
2191           return;
2192         }
2193         const auto mappedName =
2194             std::string(stringBuffer.data(), lengthWithoutNull);
2195         const auto userName = fnUnmapName(mappedName);
2196
2197         auto loc = gl.fGetAttribLocation(prog, mappedName.c_str());
2198         if (mappedName.find("gl_") == 0) {
2199           // Bug 1328559: Appears problematic on ANGLE and OSX, but not Linux or
2200           // Win+GL.
2201           loc = -1;
2202         }
2203
2204 #ifdef DUMP_MakeLinkResult
2205         printf_stderr("[attrib %u/%u] @%i %s->%s\n", i, count, loc,
2206                       userName.c_str(), mappedName.c_str());
2207 #endif
2208         webgl::ActiveAttribInfo info;
2209         info.elemType = elemType;
2210         info.elemCount = elemCount;
2211         info.name = userName;
2212         info.location = loc;
2213         info.baseType = webgl::ToAttribBaseType(info.elemType);
2214         ret.activeAttribs.push_back(std::move(info));
2215       }
2216     }
2217
2218     // -
2219
2220     {
2221       const auto count = fnGetProgramui(LOCAL_GL_ACTIVE_UNIFORMS);
2222       ret.activeUniforms.reserve(count);
2223
2224       std::vector<GLint> blockIndexList(count, -1);
2225       std::vector<GLint> blockOffsetList(count, -1);
2226       std::vector<GLint> blockArrayStrideList(count, -1);
2227       std::vector<GLint> blockMatrixStrideList(count, -1);
2228       std::vector<GLint> blockIsRowMajorList(count, 0);
2229
2230       if (webgl2 && count) {
2231         std::vector<GLuint> activeIndices;
2232         activeIndices.reserve(count);
2233         for (const auto i : IntegerRange(count)) {
2234           activeIndices.push_back(i);
2235         }
2236
2237         gl.fGetActiveUniformsiv(
2238             prog, activeIndices.size(), activeIndices.data(),
2239             LOCAL_GL_UNIFORM_BLOCK_INDEX, blockIndexList.data());
2240
2241         gl.fGetActiveUniformsiv(prog, activeIndices.size(),
2242                                 activeIndices.data(), LOCAL_GL_UNIFORM_OFFSET,
2243                                 blockOffsetList.data());
2244
2245         gl.fGetActiveUniformsiv(
2246             prog, activeIndices.size(), activeIndices.data(),
2247             LOCAL_GL_UNIFORM_ARRAY_STRIDE, blockArrayStrideList.data());
2248
2249         gl.fGetActiveUniformsiv(
2250             prog, activeIndices.size(), activeIndices.data(),
2251             LOCAL_GL_UNIFORM_MATRIX_STRIDE, blockMatrixStrideList.data());
2252
2253         gl.fGetActiveUniformsiv(
2254             prog, activeIndices.size(), activeIndices.data(),
2255             LOCAL_GL_UNIFORM_IS_ROW_MAJOR, blockIsRowMajorList.data());
2256       }
2257
2258       for (const auto i : IntegerRange(count)) {
2259         GLsizei lengthWithoutNull = 0;
2260         GLint elemCount = 0;  // `size`
2261         GLenum elemType = 0;  // `type`
2262         gl.fGetActiveUniform(prog, i, stringBuffer.size(), &lengthWithoutNull,
2263                              &elemCount, &elemType, stringBuffer.data());
2264         if (!elemType) {
2265           const auto error = gl.fGetError();
2266           if (error != LOCAL_GL_CONTEXT_LOST) {
2267             gfxCriticalError() << "Failed to do glGetActiveUniform: " << error;
2268           }
2269           return;
2270         }
2271         auto mappedName = std::string(stringBuffer.data(), lengthWithoutNull);
2272
2273         // Get true name
2274
2275         auto baseMappedName = mappedName;
2276
2277         const bool isArray = [&]() {
2278           const auto maybe = webgl::ParseIndexed(mappedName);
2279           if (maybe) {
2280             MOZ_ASSERT(maybe->index == 0);
2281             baseMappedName = std::move(maybe->name);
2282             return true;
2283           }
2284           return false;
2285         }();
2286
2287         const auto userName = fnUnmapName(mappedName);
2288         if (StartsWith(userName, "webgl_")) continue;
2289
2290         // -
2291
2292         webgl::ActiveUniformInfo info;
2293         info.elemType = elemType;
2294         info.elemCount = static_cast<uint32_t>(elemCount);
2295         info.name = userName;
2296         info.block_index = blockIndexList[i];
2297         info.block_offset = blockOffsetList[i];
2298         info.block_arrayStride = blockArrayStrideList[i];
2299         info.block_matrixStride = blockMatrixStrideList[i];
2300         info.block_isRowMajor = bool(blockIsRowMajorList[i]);
2301
2302 #ifdef DUMP_MakeLinkResult
2303         printf_stderr("[uniform %u/%u] %s->%s\n", i + 1, count,
2304                       userName.c_str(), mappedName.c_str());
2305 #endif
2306
2307         // Get uniform locations
2308         {
2309           auto locName = baseMappedName;
2310           const auto baseLength = locName.size();
2311           for (const auto i : IntegerRange(info.elemCount)) {
2312             if (isArray) {
2313               locName.erase(
2314                   baseLength);  // Erase previous [N], but retain capacity.
2315               locName += '[';
2316               locName += std::to_string(i);
2317               locName += ']';
2318             }
2319             const auto loc = gl.fGetUniformLocation(prog, locName.c_str());
2320             if (loc != -1) {
2321               info.locByIndex[i] = static_cast<uint32_t>(loc);
2322 #ifdef DUMP_MakeLinkResult
2323               printf_stderr("   [%u] @%i\n", i, loc);
2324 #endif
2325             }
2326           }
2327         }  // anon
2328
2329         ret.activeUniforms.push_back(std::move(info));
2330       }  // for i
2331     }    // anon
2332
2333     if (webgl2) {
2334       // -------------------------------------
2335       // active uniform blocks
2336       {
2337         const auto count = fnGetProgramui(LOCAL_GL_ACTIVE_UNIFORM_BLOCKS);
2338         ret.activeUniformBlocks.reserve(count);
2339
2340         for (const auto i : IntegerRange(count)) {
2341           GLsizei lengthWithoutNull = 0;
2342           gl.fGetActiveUniformBlockName(prog, i, stringBuffer.size(),
2343                                         &lengthWithoutNull,
2344                                         stringBuffer.data());
2345           const auto mappedName =
2346               std::string(stringBuffer.data(), lengthWithoutNull);
2347           const auto userName = fnUnmapName(mappedName);
2348
2349           // -
2350
2351           auto info = webgl::ActiveUniformBlockInfo{userName};
2352           GLint val = 0;
2353
2354           gl.fGetActiveUniformBlockiv(prog, i, LOCAL_GL_UNIFORM_BLOCK_DATA_SIZE,
2355                                       &val);
2356           info.dataSize = static_cast<uint32_t>(val);
2357
2358           gl.fGetActiveUniformBlockiv(
2359               prog, i, LOCAL_GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS, &val);
2360           info.activeUniformIndices.resize(val);
2361           gl.fGetActiveUniformBlockiv(
2362               prog, i, LOCAL_GL_UNIFORM_BLOCK_ACTIVE_UNIFORM_INDICES,
2363               reinterpret_cast<GLint*>(info.activeUniformIndices.data()));
2364
2365           gl.fGetActiveUniformBlockiv(
2366               prog, i, LOCAL_GL_UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER,
2367               &val);
2368           info.referencedByVertexShader = bool(val);
2369
2370           gl.fGetActiveUniformBlockiv(
2371               prog, i, LOCAL_GL_UNIFORM_BLOCK_REFERENCED_BY_FRAGMENT_SHADER,
2372               &val);
2373           info.referencedByFragmentShader = bool(val);
2374
2375           ret.activeUniformBlocks.push_back(std::move(info));
2376         }  // for i
2377       }    // anon
2378
2379       // -------------------------------------
2380       // active tf varyings
2381       {
2382         const auto count = fnGetProgramui(LOCAL_GL_TRANSFORM_FEEDBACK_VARYINGS);
2383         ret.activeTfVaryings.reserve(count);
2384
2385         for (const auto i : IntegerRange(count)) {
2386           GLsizei lengthWithoutNull = 0;
2387           GLsizei elemCount = 0;  // `size`
2388           GLenum elemType = 0;    // `type`
2389           gl.fGetTransformFeedbackVarying(prog, i, stringBuffer.size(),
2390                                           &lengthWithoutNull, &elemCount,
2391                                           &elemType, stringBuffer.data());
2392           const auto mappedName =
2393               std::string(stringBuffer.data(), lengthWithoutNull);
2394           const auto userName = fnUnmapName(mappedName);
2395
2396           ret.activeTfVaryings.push_back(
2397               {elemType, static_cast<uint32_t>(elemCount), userName});
2398         }
2399       }
2400     }  // if webgl2
2401   }();
2402   return ret;
2403 }
2404
2405 nsCString ToCString(const std::string& s) {
2406   return nsCString(s.data(), s.size());
2407 }
2408
2409 webgl::CompileResult WebGLContext::GetCompileResult(
2410     const WebGLShader& shader) const {
2411   webgl::CompileResult ret;
2412   [&]() {
2413     ret.pending = false;
2414     const auto& info = shader.CompileResults();
2415     if (!info) return;
2416     if (!info->mValid) {
2417       ret.log = info->mInfoLog.c_str();
2418       return;
2419     }
2420     // TODO: These could be large and should be made fallible.
2421     ret.translatedSource = ToCString(info->mObjectCode);
2422     ret.log = ToCString(shader.CompileLog());
2423     if (!shader.IsCompiled()) return;
2424     ret.success = true;
2425   }();
2426   return ret;
2427 }
2428
2429 webgl::LinkResult WebGLContext::GetLinkResult(const WebGLProgram& prog) const {
2430   webgl::LinkResult ret;
2431   [&]() {
2432     ret.pending = false;  // Link status polling not yet implemented.
2433     ret.log = ToCString(prog.LinkLog());
2434     const auto& info = prog.LinkInfo();
2435     if (!info) return;
2436     ret.success = true;
2437     ret.active = info->active;
2438     ret.tfBufferMode = info->transformFeedbackBufferMode;
2439   }();
2440   return ret;
2441 }
2442
2443 // -
2444
2445 GLint WebGLContext::GetFragDataLocation(const WebGLProgram& prog,
2446                                         const std::string& userName) const {
2447   const auto err = CheckGLSLVariableName(IsWebGL2(), userName);
2448   if (err) {
2449     GenerateError(err->type, "%s", err->info.c_str());
2450     return -1;
2451   }
2452
2453   const auto& info = prog.LinkInfo();
2454   if (!info) return -1;
2455   const auto& nameMap = info->nameMap;
2456
2457   const auto parts = ExplodeName(userName);
2458
2459   std::ostringstream ret;
2460   for (const auto& part : parts) {
2461     const auto maybe = MaybeFind(nameMap, part);
2462     if (maybe) {
2463       ret << *maybe;
2464     } else {
2465       ret << part;
2466     }
2467   }
2468   const auto mappedName = ret.str();
2469
2470   if (gl->WorkAroundDriverBugs() && gl->IsMesa()) {
2471     // Mesa incorrectly generates INVALID_OPERATION for gl_ prefixes here.
2472     if (mappedName.find("gl_") == 0) {
2473       return -1;
2474     }
2475   }
2476
2477   return gl->fGetFragDataLocation(prog.mGLName, mappedName.c_str());
2478 }
2479
2480 // -
2481
2482 WebGLContextBoundObject::WebGLContextBoundObject(WebGLContext* webgl)
2483     : mContext(webgl) {}
2484
2485 // -
2486
2487 Result<webgl::ExplicitPixelPackingState, std::string>
2488 webgl::ExplicitPixelPackingState::ForUseWith(
2489     const webgl::PixelPackingState& stateOrZero, const GLenum target,
2490     const uvec3& subrectSize, const webgl::PackingInfo& pi,
2491     const Maybe<size_t> bytesPerRowStrideOverride) {
2492   auto state = stateOrZero;
2493
2494   if (!IsTexTarget3D(target)) {
2495     state.skipImages = 0;
2496     state.imageHeight = 0;
2497   }
2498   if (!state.rowLength) {
2499     state.rowLength = subrectSize.x;
2500   }
2501   if (!state.imageHeight) {
2502     state.imageHeight = subrectSize.y;
2503   }
2504
2505   // -
2506
2507   const auto mpii = PackingInfoInfo::For(pi);
2508   if (!mpii) {
2509     const auto text =
2510         nsPrintfCString("Invalid pi: { 0x%x, 0x%x}", pi.format, pi.type);
2511     return Err(mozilla::ToString(text));
2512   }
2513   const auto pii = *mpii;
2514   const auto bytesPerPixel = pii.BytesPerPixel();
2515
2516   const auto ElemsPerRowStride = [&]() {
2517     // GLES 3.0.6 p116:
2518     // p: `Elem*` pointer to the first element of the first row
2519     // N: row number, starting at 0
2520     // l: groups (pixels) per row
2521     // n: elements per group (pixel) in [1,2,3,4]
2522     // s: bytes per element in [1,2,4,8]
2523     // a: UNPACK_ALIGNMENT in [1,2,4,8]
2524     // Pointer to first element of Nth row: p + N*k
2525     // k(s>=a): n*l
2526     // k(s<a): a/s * ceil(s*n*l/a)
2527     const auto n__elemsPerPixel = pii.elementsPerPixel;
2528     const auto l__pixelsPerRow = state.rowLength;
2529     const auto a__alignment = state.alignmentInTypeElems;
2530     const auto s__bytesPerElem = pii.bytesPerElement;
2531
2532     const auto nl = CheckedInt<size_t>(n__elemsPerPixel) * l__pixelsPerRow;
2533     auto k__elemsPerRowStride = nl;
2534     if (s__bytesPerElem < a__alignment) {
2535       // k = a/s * ceil(s*n*l/a)
2536       k__elemsPerRowStride =
2537           a__alignment / s__bytesPerElem *
2538           ((nl * s__bytesPerElem + a__alignment - 1) / a__alignment);
2539     }
2540     return k__elemsPerRowStride;
2541   };
2542
2543   // -
2544
2545   if (bytesPerRowStrideOverride) {  // E.g. HTMLImageElement
2546     const size_t bytesPerRowStrideRequired = *bytesPerRowStrideOverride;
2547     // We have to reverse-engineer an ALIGNMENT and ROW_LENGTH for this.
2548
2549     // GL does this in elems not bytes, so we should too.
2550     MOZ_RELEASE_ASSERT(bytesPerRowStrideRequired % pii.bytesPerElement == 0);
2551     const auto elemsPerRowStrideRequired =
2552         bytesPerRowStrideRequired / pii.bytesPerElement;
2553
2554     state.rowLength = bytesPerRowStrideRequired / bytesPerPixel;
2555     state.alignmentInTypeElems = 8;
2556     while (true) {
2557       const auto elemPerRowStride = ElemsPerRowStride();
2558       if (elemPerRowStride.isValid() &&
2559           elemPerRowStride.value() == elemsPerRowStrideRequired) {
2560         break;
2561       }
2562       state.alignmentInTypeElems /= 2;
2563       if (!state.alignmentInTypeElems) {
2564         const auto text = nsPrintfCString(
2565             "No valid alignment found: pi: { 0x%x, 0x%x},"
2566             " bytesPerRowStrideRequired: %zu",
2567             pi.format, pi.type, bytesPerRowStrideRequired);
2568         return Err(mozilla::ToString(text));
2569       }
2570     }
2571   }
2572
2573   // -
2574
2575   const auto usedPixelsPerRow =
2576       CheckedInt<size_t>(state.skipPixels) + subrectSize.x;
2577   if (!usedPixelsPerRow.isValid() ||
2578       usedPixelsPerRow.value() > state.rowLength) {
2579     return Err("UNPACK_SKIP_PIXELS + width > UNPACK_ROW_LENGTH.");
2580   }
2581
2582   if (subrectSize.y > state.imageHeight) {
2583     return Err("height > UNPACK_IMAGE_HEIGHT.");
2584   }
2585   // The spec doesn't bound SKIP_ROWS + height <= IMAGE_HEIGHT, unfortunately.
2586
2587   // -
2588
2589   auto metrics = Metrics{};
2590
2591   metrics.usedSize = subrectSize;
2592   metrics.bytesPerPixel = BytesPerPixel(pi);
2593
2594   // -
2595
2596   const auto elemsPerRowStride = ElemsPerRowStride();
2597   const auto bytesPerRowStride = pii.bytesPerElement * elemsPerRowStride;
2598   if (!bytesPerRowStride.isValid()) {
2599     return Err("ROW_LENGTH or width too large for packing.");
2600   }
2601   metrics.bytesPerRowStride = bytesPerRowStride.value();
2602
2603   // -
2604
2605   const auto firstImageTotalRows =
2606       CheckedInt<size_t>(state.skipRows) + metrics.usedSize.y;
2607   const auto totalImages =
2608       CheckedInt<size_t>(state.skipImages) + metrics.usedSize.z;
2609   auto totalRows = CheckedInt<size_t>(0);
2610   if (metrics.usedSize.y && metrics.usedSize.z) {
2611     totalRows = firstImageTotalRows + state.imageHeight * (totalImages - 1);
2612   }
2613   if (!totalRows.isValid()) {
2614     return Err(
2615         "SKIP_ROWS, height, IMAGE_HEIGHT, SKIP_IMAGES, or depth too large for "
2616         "packing.");
2617   }
2618   metrics.totalRows = totalRows.value();
2619
2620   // -
2621
2622   const auto totalBytesStrided = totalRows * metrics.bytesPerRowStride;
2623   if (!totalBytesStrided.isValid()) {
2624     return Err("Total byte count too large for packing.");
2625   }
2626   metrics.totalBytesStrided = totalBytesStrided.value();
2627
2628   metrics.totalBytesUsed = metrics.totalBytesStrided;
2629   if (metrics.usedSize.x && metrics.usedSize.y && metrics.usedSize.z) {
2630     const auto usedBytesPerRow =
2631         usedPixelsPerRow.value() * metrics.bytesPerPixel;
2632     metrics.totalBytesUsed -= metrics.bytesPerRowStride;
2633     metrics.totalBytesUsed += usedBytesPerRow;
2634   }
2635
2636   // -
2637
2638   return {{state, metrics}};
2639 }
2640
2641 }  // namespace mozilla