image/decoders/nsWebPDecoder.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "ImageLogging.h"  // Must appear first
   8 #include "gfxPlatform.h"
   9 #include "mozilla/TelemetryHistogramEnums.h"
  10 #include "nsWebPDecoder.h"
  11
  12 #include "RasterImage.h"
  13 #include "SurfacePipeFactory.h"
  14
  15 using namespace mozilla::gfx;
  16
  17 namespace mozilla {
  18 namespace image {
  19
  20 static LazyLogModule sWebPLog("WebPDecoder");
  21
  22 nsWebPDecoder::nsWebPDecoder(RasterImage* aImage)
  23     : Decoder(aImage),
  24       mDecoder(nullptr),
  25       mBlend(BlendMethod::OVER),
  26       mDisposal(DisposalMethod::KEEP),
  27       mTimeout(FrameTimeout::Forever()),
  28       mFormat(SurfaceFormat::OS_RGBX),
  29       mLastRow(0),
  30       mCurrentFrame(0),
  31       mData(nullptr),
  32       mLength(0),
  33       mIteratorComplete(false),
  34       mNeedDemuxer(true),
  35       mGotColorProfile(false) {
  36   MOZ_LOG(sWebPLog, LogLevel::Debug,
  37           ("[this=%p] nsWebPDecoder::nsWebPDecoder", this));
  38 }
  39
  40 nsWebPDecoder::~nsWebPDecoder() {
  41   MOZ_LOG(sWebPLog, LogLevel::Debug,
  42           ("[this=%p] nsWebPDecoder::~nsWebPDecoder", this));
  43   if (mDecoder) {
  44     WebPIDelete(mDecoder);
  45     WebPFreeDecBuffer(&mBuffer);
  46   }
  47 }
  48
  49 LexerResult nsWebPDecoder::ReadData() {
  50   MOZ_ASSERT(mData);
  51   MOZ_ASSERT(mLength > 0);
  52
  53   WebPDemuxer* demuxer = nullptr;
  54   bool complete = mIteratorComplete;
  55
  56   if (mNeedDemuxer) {
  57     WebPDemuxState state;
  58     WebPData fragment;
  59     fragment.bytes = mData;
  60     fragment.size = mLength;
  61
  62     demuxer = WebPDemuxPartial(&fragment, &state);
  63     if (state == WEBP_DEMUX_PARSE_ERROR) {
  64       MOZ_LOG(
  65           sWebPLog, LogLevel::Error,
  66           ("[this=%p] nsWebPDecoder::ReadData -- demux parse error\n", this));
  67       WebPDemuxDelete(demuxer);
  68       return LexerResult(TerminalState::FAILURE);
  69     }
  70
  71     if (state == WEBP_DEMUX_PARSING_HEADER) {
  72       WebPDemuxDelete(demuxer);
  73       return LexerResult(Yield::NEED_MORE_DATA);
  74     }
  75
  76     if (!demuxer) {
  77       MOZ_LOG(sWebPLog, LogLevel::Error,
  78               ("[this=%p] nsWebPDecoder::ReadData -- no demuxer\n", this));
  79       return LexerResult(TerminalState::FAILURE);
  80     }
  81
  82     complete = complete || state == WEBP_DEMUX_DONE;
  83   }
  84
  85   LexerResult rv(TerminalState::FAILURE);
  86   if (!HasSize()) {
  87     rv = ReadHeader(demuxer, complete);
  88   } else {
  89     rv = ReadPayload(demuxer, complete);
  90   }
  91
  92   WebPDemuxDelete(demuxer);
  93   return rv;
  94 }
  95
  96 LexerResult nsWebPDecoder::DoDecode(SourceBufferIterator& aIterator,
  97                                     IResumable* aOnResume) {
  98   while (true) {
  99     SourceBufferIterator::State state = SourceBufferIterator::COMPLETE;
 100     if (!mIteratorComplete) {
 101       state = aIterator.AdvanceOrScheduleResume(SIZE_MAX, aOnResume);
 102
 103       // We need to remember since we can't advance a complete iterator.
 104       mIteratorComplete = state == SourceBufferIterator::COMPLETE;
 105     }
 106
 107     if (state == SourceBufferIterator::WAITING) {
 108       return LexerResult(Yield::NEED_MORE_DATA);
 109     }
 110
 111     LexerResult rv = UpdateBuffer(aIterator, state);
 112     if (rv.is<Yield>() && rv.as<Yield>() == Yield::NEED_MORE_DATA) {
 113       // We need to check the iterator to see if more is available before
 114       // giving up unless we are already complete.
 115       if (mIteratorComplete) {
 116         MOZ_LOG(sWebPLog, LogLevel::Error,
 117                 ("[this=%p] nsWebPDecoder::DoDecode -- read all data, "
 118                  "but needs more\n",
 119                  this));
 120         return LexerResult(TerminalState::FAILURE);
 121       }
 122       continue;
 123     }
 124
 125     return rv;
 126   }
 127 }
 128
 129 LexerResult nsWebPDecoder::UpdateBuffer(SourceBufferIterator& aIterator,
 130                                         SourceBufferIterator::State aState) {
 131   MOZ_ASSERT(!HasError(), "Shouldn't call DoDecode after error!");
 132
 133   switch (aState) {
 134     case SourceBufferIterator::READY:
 135       if (!aIterator.IsContiguous()) {
 136         // We need to buffer. This should be rare, but expensive.
 137         break;
 138       }
 139       if (!mData) {
 140         // For as long as we hold onto an iterator, we know the data pointers
 141         // to the chunks cannot change underneath us, so save the pointer to
 142         // the first block.
 143         MOZ_ASSERT(mLength == 0);
 144         mData = reinterpret_cast<const uint8_t*>(aIterator.Data());
 145       }
 146       mLength += aIterator.Length();
 147       return ReadData();
 148     case SourceBufferIterator::COMPLETE:
 149       if (!mData) {
 150         // We must have hit an error, such as an OOM, when buffering the
 151         // first set of encoded data.
 152         MOZ_LOG(
 153             sWebPLog, LogLevel::Error,
 154             ("[this=%p] nsWebPDecoder::DoDecode -- complete no data\n", this));
 155         return LexerResult(TerminalState::FAILURE);
 156       }
 157       return ReadData();
 158     default:
 159       MOZ_LOG(sWebPLog, LogLevel::Error,
 160               ("[this=%p] nsWebPDecoder::DoDecode -- bad state\n", this));
 161       return LexerResult(TerminalState::FAILURE);
 162   }
 163
 164   // We need to buffer. If we have no data buffered, we need to get everything
 165   // from the first chunk of the source buffer before appending the new data.
 166   if (mBufferedData.empty()) {
 167     MOZ_ASSERT(mData);
 168     MOZ_ASSERT(mLength > 0);
 169
 170     if (!mBufferedData.append(mData, mLength)) {
 171       MOZ_LOG(sWebPLog, LogLevel::Error,
 172               ("[this=%p] nsWebPDecoder::DoDecode -- oom, initialize %zu\n",
 173                this, mLength));
 174       return LexerResult(TerminalState::FAILURE);
 175     }
 176
 177     MOZ_LOG(sWebPLog, LogLevel::Debug,
 178             ("[this=%p] nsWebPDecoder::DoDecode -- buffered %zu bytes\n", this,
 179              mLength));
 180   }
 181
 182   // Append the incremental data from the iterator.
 183   if (!mBufferedData.append(aIterator.Data(), aIterator.Length())) {
 184     MOZ_LOG(sWebPLog, LogLevel::Error,
 185             ("[this=%p] nsWebPDecoder::DoDecode -- oom, append %zu on %zu\n",
 186              this, aIterator.Length(), mBufferedData.length()));
 187     return LexerResult(TerminalState::FAILURE);
 188   }
 189
 190   MOZ_LOG(sWebPLog, LogLevel::Debug,
 191           ("[this=%p] nsWebPDecoder::DoDecode -- buffered %zu -> %zu bytes\n",
 192            this, aIterator.Length(), mBufferedData.length()));
 193   mData = mBufferedData.begin();
 194   mLength = mBufferedData.length();
 195   return ReadData();
 196 }
 197
 198 nsresult nsWebPDecoder::CreateFrame(const OrientedIntRect& aFrameRect) {
 199   MOZ_ASSERT(HasSize());
 200   MOZ_ASSERT(!mDecoder);
 201
 202   MOZ_LOG(
 203       sWebPLog, LogLevel::Debug,
 204       ("[this=%p] nsWebPDecoder::CreateFrame -- frame %u, (%d, %d) %d x %d\n",
 205        this, mCurrentFrame, aFrameRect.x, aFrameRect.y, aFrameRect.width,
 206        aFrameRect.height));
 207
 208   if (aFrameRect.width <= 0 || aFrameRect.height <= 0) {
 209     MOZ_LOG(sWebPLog, LogLevel::Error,
 210             ("[this=%p] nsWebPDecoder::CreateFrame -- bad frame rect\n", this));
 211     return NS_ERROR_FAILURE;
 212   }
 213
 214   // If this is our first frame in an animation and it doesn't cover the
 215   // full frame, then we are transparent even if there is no alpha
 216   if (mCurrentFrame == 0 && !aFrameRect.IsEqualEdges(FullFrame())) {
 217     MOZ_ASSERT(HasAnimation());
 218     mFormat = SurfaceFormat::OS_RGBA;
 219     PostHasTransparency();
 220   }
 221
 222   if (!WebPInitDecBuffer(&mBuffer)) {
 223     MOZ_LOG(
 224         sWebPLog, LogLevel::Error,
 225         ("[this=%p] nsWebPDecoder::CreateFrame -- WebPInitDecBuffer failed\n",
 226          this));
 227     return NS_ERROR_FAILURE;
 228   }
 229
 230   switch (SurfaceFormat::OS_RGBA) {
 231     case SurfaceFormat::B8G8R8A8:
 232       mBuffer.colorspace = MODE_BGRA;
 233       break;
 234     case SurfaceFormat::A8R8G8B8:
 235       mBuffer.colorspace = MODE_ARGB;
 236       break;
 237     case SurfaceFormat::R8G8B8A8:
 238       mBuffer.colorspace = MODE_RGBA;
 239       break;
 240     default:
 241       MOZ_ASSERT_UNREACHABLE("Unknown OS_RGBA");
 242       return NS_ERROR_FAILURE;
 243   }
 244
 245   mDecoder = WebPINewDecoder(&mBuffer);
 246   if (!mDecoder) {
 247     MOZ_LOG(sWebPLog, LogLevel::Error,
 248             ("[this=%p] nsWebPDecoder::CreateFrame -- create decoder error\n",
 249              this));
 250     return NS_ERROR_FAILURE;
 251   }
 252
 253   // WebP doesn't guarantee that the alpha generated matches the hint in the
 254   // header, so we always need to claim the input is BGRA. If the output is
 255   // BGRX, swizzling will mask off the alpha channel.
 256   SurfaceFormat inFormat = SurfaceFormat::OS_RGBA;
 257
 258   SurfacePipeFlags pipeFlags = SurfacePipeFlags();
 259   if (mFormat == SurfaceFormat::OS_RGBA &&
 260       !(GetSurfaceFlags() & SurfaceFlags::NO_PREMULTIPLY_ALPHA)) {
 261     pipeFlags |= SurfacePipeFlags::PREMULTIPLY_ALPHA;
 262   }
 263
 264   Maybe<AnimationParams> animParams;
 265   if (!IsFirstFrameDecode()) {
 266     animParams.emplace(aFrameRect.ToUnknownRect(), mTimeout, mCurrentFrame,
 267                        mBlend, mDisposal);
 268   }
 269
 270   Maybe<SurfacePipe> pipe = SurfacePipeFactory::CreateSurfacePipe(
 271       this, Size(), OutputSize(), aFrameRect, inFormat, mFormat, animParams,
 272       mTransform, pipeFlags);
 273   if (!pipe) {
 274     MOZ_LOG(sWebPLog, LogLevel::Error,
 275             ("[this=%p] nsWebPDecoder::CreateFrame -- no pipe\n", this));
 276     return NS_ERROR_FAILURE;
 277   }
 278
 279   mFrameRect = aFrameRect;
 280   mPipe = std::move(*pipe);
 281   return NS_OK;
 282 }
 283
 284 void nsWebPDecoder::EndFrame() {
 285   MOZ_ASSERT(HasSize());
 286   MOZ_ASSERT(mDecoder);
 287
 288   auto opacity = mFormat == SurfaceFormat::OS_RGBA ? Opacity::SOME_TRANSPARENCY
 289                                                    : Opacity::FULLY_OPAQUE;
 290
 291   MOZ_LOG(sWebPLog, LogLevel::Debug,
 292           ("[this=%p] nsWebPDecoder::EndFrame -- frame %u, opacity %d, "
 293            "disposal %d, timeout %d, blend %d\n",
 294            this, mCurrentFrame, (int)opacity, (int)mDisposal,
 295            mTimeout.AsEncodedValueDeprecated(), (int)mBlend));
 296
 297   PostFrameStop(opacity);
 298   WebPIDelete(mDecoder);
 299   WebPFreeDecBuffer(&mBuffer);
 300   mDecoder = nullptr;
 301   mLastRow = 0;
 302   ++mCurrentFrame;
 303 }
 304
 305 void nsWebPDecoder::ApplyColorProfile(const char* aProfile, size_t aLength) {
 306   MOZ_ASSERT(!mGotColorProfile);
 307   mGotColorProfile = true;
 308
 309   if (mCMSMode == CMSMode::Off || !GetCMSOutputProfile() ||
 310       (mCMSMode == CMSMode::TaggedOnly && !aProfile)) {
 311     return;
 312   }
 313
 314   if (!aProfile) {
 315     MOZ_LOG(sWebPLog, LogLevel::Debug,
 316             ("[this=%p] nsWebPDecoder::ApplyColorProfile -- not tagged, use "
 317              "sRGB transform\n",
 318              this));
 319     mTransform = GetCMSsRGBTransform(SurfaceFormat::OS_RGBA);
 320     return;
 321   }
 322
 323   mInProfile = qcms_profile_from_memory(aProfile, aLength);
 324   if (!mInProfile) {
 325     MOZ_LOG(
 326         sWebPLog, LogLevel::Error,
 327         ("[this=%p] nsWebPDecoder::ApplyColorProfile -- bad color profile\n",
 328          this));
 329     return;
 330   }
 331
 332   uint32_t profileSpace = qcms_profile_get_color_space(mInProfile);
 333   if (profileSpace != icSigRgbData) {
 334     // WebP doesn't produce grayscale data, this must be corrupt.
 335     MOZ_LOG(sWebPLog, LogLevel::Error,
 336             ("[this=%p] nsWebPDecoder::ApplyColorProfile -- ignoring non-rgb "
 337              "color profile\n",
 338              this));
 339     return;
 340   }
 341
 342   // Calculate rendering intent.
 343   int intent = gfxPlatform::GetRenderingIntent();
 344   if (intent == -1) {
 345     intent = qcms_profile_get_rendering_intent(mInProfile);
 346   }
 347
 348   // Create the color management transform.
 349   qcms_data_type type = gfxPlatform::GetCMSOSRGBAType();
 350   mTransform = qcms_transform_create(mInProfile, type, GetCMSOutputProfile(),
 351                                      type, (qcms_intent)intent);
 352   MOZ_LOG(sWebPLog, LogLevel::Debug,
 353           ("[this=%p] nsWebPDecoder::ApplyColorProfile -- use tagged "
 354            "transform\n",
 355            this));
 356 }
 357
 358 LexerResult nsWebPDecoder::ReadHeader(WebPDemuxer* aDemuxer, bool aIsComplete) {
 359   MOZ_ASSERT(aDemuxer);
 360
 361   MOZ_LOG(
 362       sWebPLog, LogLevel::Debug,
 363       ("[this=%p] nsWebPDecoder::ReadHeader -- %zu bytes\n", this, mLength));
 364
 365   uint32_t flags = WebPDemuxGetI(aDemuxer, WEBP_FF_FORMAT_FLAGS);
 366
 367   if (!IsMetadataDecode() && !mGotColorProfile) {
 368     if (flags & WebPFeatureFlags::ICCP_FLAG) {
 369       WebPChunkIterator iter;
 370       if (WebPDemuxGetChunk(aDemuxer, "ICCP", 1, &iter)) {
 371         ApplyColorProfile(reinterpret_cast<const char*>(iter.chunk.bytes),
 372                           iter.chunk.size);
 373         WebPDemuxReleaseChunkIterator(&iter);
 374
 375       } else {
 376         if (!aIsComplete) {
 377           return LexerResult(Yield::NEED_MORE_DATA);
 378         }
 379
 380         MOZ_LOG(sWebPLog, LogLevel::Warning,
 381                 ("[this=%p] nsWebPDecoder::ReadHeader header specified ICCP "
 382                  "but no ICCP chunk found, ignoring\n",
 383                  this));
 384
 385         ApplyColorProfile(nullptr, 0);
 386       }
 387     } else {
 388       ApplyColorProfile(nullptr, 0);
 389     }
 390   }
 391
 392   if (flags & WebPFeatureFlags::ANIMATION_FLAG) {
 393     // A metadata decode expects to get the correct first frame timeout which
 394     // sadly is not provided by the normal WebP header parsing.
 395     WebPIterator iter;
 396     if (!WebPDemuxGetFrame(aDemuxer, 1, &iter)) {
 397       return aIsComplete ? LexerResult(TerminalState::FAILURE)
 398                          : LexerResult(Yield::NEED_MORE_DATA);
 399     }
 400
 401     PostIsAnimated(FrameTimeout::FromRawMilliseconds(iter.duration));
 402     WebPDemuxReleaseIterator(&iter);
 403   } else {
 404     // Single frames don't need a demuxer to be created.
 405     mNeedDemuxer = false;
 406   }
 407
 408   uint32_t width = WebPDemuxGetI(aDemuxer, WEBP_FF_CANVAS_WIDTH);
 409   uint32_t height = WebPDemuxGetI(aDemuxer, WEBP_FF_CANVAS_HEIGHT);
 410   if (width > INT32_MAX || height > INT32_MAX) {
 411     return LexerResult(TerminalState::FAILURE);
 412   }
 413
 414   PostSize(width, height);
 415
 416   bool alpha = flags & WebPFeatureFlags::ALPHA_FLAG;
 417   if (alpha) {
 418     mFormat = SurfaceFormat::OS_RGBA;
 419     PostHasTransparency();
 420   }
 421
 422   MOZ_LOG(sWebPLog, LogLevel::Debug,
 423           ("[this=%p] nsWebPDecoder::ReadHeader -- %u x %u, alpha %d, "
 424            "animation %d, metadata decode %d, first frame decode %d\n",
 425            this, width, height, alpha, HasAnimation(), IsMetadataDecode(),
 426            IsFirstFrameDecode()));
 427
 428   if (IsMetadataDecode()) {
 429     return LexerResult(TerminalState::SUCCESS);
 430   }
 431
 432   return ReadPayload(aDemuxer, aIsComplete);
 433 }
 434
 435 LexerResult nsWebPDecoder::ReadPayload(WebPDemuxer* aDemuxer,
 436                                        bool aIsComplete) {
 437   if (!HasAnimation()) {
 438     auto rv = ReadSingle(mData, mLength, FullFrame());
 439     if (rv.is<TerminalState>() &&
 440         rv.as<TerminalState>() == TerminalState::SUCCESS) {
 441       PostDecodeDone();
 442     }
 443     return rv;
 444   }
 445   return ReadMultiple(aDemuxer, aIsComplete);
 446 }
 447
 448 LexerResult nsWebPDecoder::ReadSingle(const uint8_t* aData, size_t aLength,
 449                                       const OrientedIntRect& aFrameRect) {
 450   MOZ_ASSERT(!IsMetadataDecode());
 451   MOZ_ASSERT(aData);
 452   MOZ_ASSERT(aLength > 0);
 453
 454   MOZ_LOG(
 455       sWebPLog, LogLevel::Debug,
 456       ("[this=%p] nsWebPDecoder::ReadSingle -- %zu bytes\n", this, aLength));
 457
 458   if (!mDecoder && NS_FAILED(CreateFrame(aFrameRect))) {
 459     return LexerResult(TerminalState::FAILURE);
 460   }
 461
 462   bool complete;
 463   do {
 464     VP8StatusCode status = WebPIUpdate(mDecoder, aData, aLength);
 465     switch (status) {
 466       case VP8_STATUS_OK:
 467         complete = true;
 468         break;
 469       case VP8_STATUS_SUSPENDED:
 470         complete = false;
 471         break;
 472       default:
 473         MOZ_LOG(sWebPLog, LogLevel::Error,
 474                 ("[this=%p] nsWebPDecoder::ReadSingle -- append error %d\n",
 475                  this, status));
 476         return LexerResult(TerminalState::FAILURE);
 477     }
 478
 479     int lastRow = -1;
 480     int width = 0;
 481     int height = 0;
 482     int stride = 0;
 483     uint8_t* rowStart =
 484         WebPIDecGetRGB(mDecoder, &lastRow, &width, &height, &stride);
 485
 486     MOZ_LOG(
 487         sWebPLog, LogLevel::Debug,
 488         ("[this=%p] nsWebPDecoder::ReadSingle -- complete %d, read %d rows, "
 489          "has %d rows available\n",
 490          this, complete, mLastRow, lastRow));
 491
 492     if (!rowStart || lastRow == -1 || lastRow == mLastRow) {
 493       return LexerResult(Yield::NEED_MORE_DATA);
 494     }
 495
 496     if (width != mFrameRect.width || height != mFrameRect.height ||
 497         stride < mFrameRect.width * 4 || lastRow > mFrameRect.height) {
 498       MOZ_LOG(sWebPLog, LogLevel::Error,
 499               ("[this=%p] nsWebPDecoder::ReadSingle -- bad (w,h,s) = (%d, %d, "
 500                "%d)\n",
 501                this, width, height, stride));
 502       return LexerResult(TerminalState::FAILURE);
 503     }
 504
 505     for (int row = mLastRow; row < lastRow; row++) {
 506       uint32_t* src = reinterpret_cast<uint32_t*>(rowStart + row * stride);
 507       WriteState result = mPipe.WriteBuffer(src);
 508
 509       Maybe<SurfaceInvalidRect> invalidRect = mPipe.TakeInvalidRect();
 510       if (invalidRect) {
 511         PostInvalidation(invalidRect->mInputSpaceRect,
 512                          Some(invalidRect->mOutputSpaceRect));
 513       }
 514
 515       if (result == WriteState::FAILURE) {
 516         MOZ_LOG(sWebPLog, LogLevel::Error,
 517                 ("[this=%p] nsWebPDecoder::ReadSingle -- write pixels error\n",
 518                  this));
 519         return LexerResult(TerminalState::FAILURE);
 520       }
 521
 522       if (result == WriteState::FINISHED) {
 523         MOZ_ASSERT(row == lastRow - 1, "There was more data to read?");
 524         complete = true;
 525         break;
 526       }
 527     }
 528
 529     mLastRow = lastRow;
 530   } while (!complete);
 531
 532   if (!complete) {
 533     return LexerResult(Yield::NEED_MORE_DATA);
 534   }
 535
 536   EndFrame();
 537   return LexerResult(TerminalState::SUCCESS);
 538 }
 539
 540 LexerResult nsWebPDecoder::ReadMultiple(WebPDemuxer* aDemuxer,
 541                                         bool aIsComplete) {
 542   MOZ_ASSERT(!IsMetadataDecode());
 543   MOZ_ASSERT(aDemuxer);
 544
 545   MOZ_LOG(sWebPLog, LogLevel::Debug,
 546           ("[this=%p] nsWebPDecoder::ReadMultiple\n", this));
 547
 548   bool complete = aIsComplete;
 549   WebPIterator iter;
 550   auto rv = LexerResult(Yield::NEED_MORE_DATA);
 551   if (WebPDemuxGetFrame(aDemuxer, mCurrentFrame + 1, &iter)) {
 552     switch (iter.blend_method) {
 553       case WEBP_MUX_BLEND:
 554         mBlend = BlendMethod::OVER;
 555         break;
 556       case WEBP_MUX_NO_BLEND:
 557         mBlend = BlendMethod::SOURCE;
 558         break;
 559       default:
 560         MOZ_ASSERT_UNREACHABLE("Unhandled blend method");
 561         break;
 562     }
 563
 564     switch (iter.dispose_method) {
 565       case WEBP_MUX_DISPOSE_NONE:
 566         mDisposal = DisposalMethod::KEEP;
 567         break;
 568       case WEBP_MUX_DISPOSE_BACKGROUND:
 569         mDisposal = DisposalMethod::CLEAR;
 570         break;
 571       default:
 572         MOZ_ASSERT_UNREACHABLE("Unhandled dispose method");
 573         break;
 574     }
 575
 576     mFormat = iter.has_alpha || mCurrentFrame > 0 ? SurfaceFormat::OS_RGBA
 577                                                   : SurfaceFormat::OS_RGBX;
 578     mTimeout = FrameTimeout::FromRawMilliseconds(iter.duration);
 579     OrientedIntRect frameRect(iter.x_offset, iter.y_offset, iter.width,
 580                               iter.height);
 581
 582     rv = ReadSingle(iter.fragment.bytes, iter.fragment.size, frameRect);
 583     complete = complete && !WebPDemuxNextFrame(&iter);
 584     WebPDemuxReleaseIterator(&iter);
 585   }
 586
 587   if (rv.is<TerminalState>() &&
 588       rv.as<TerminalState>() == TerminalState::SUCCESS) {
 589     // If we extracted one frame, and it is not the last, we need to yield to
 590     // the lexer to allow the upper layers to acknowledge the frame.
 591     if (!complete && !IsFirstFrameDecode()) {
 592       rv = LexerResult(Yield::OUTPUT_AVAILABLE);
 593     } else {
 594       uint32_t loopCount = WebPDemuxGetI(aDemuxer, WEBP_FF_LOOP_COUNT);
 595
 596       MOZ_LOG(sWebPLog, LogLevel::Debug,
 597               ("[this=%p] nsWebPDecoder::ReadMultiple -- loop count %u\n", this,
 598                loopCount));
 599       PostDecodeDone(loopCount - 1);
 600     }
 601   }
 602
 603   return rv;
 604 }
 605
 606 Maybe<Telemetry::HistogramID> nsWebPDecoder::SpeedHistogram() const {
 607   return Some(Telemetry::IMAGE_DECODE_SPEED_WEBP);
 608 }
 609
 610 }  // namespace image
 611 }  // namespace mozilla