image/imgTools.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 "imgTools.h"
   8
   9 #include "DecodePool.h"
  10 #include "gfxUtils.h"
  11 #include "mozilla/gfx/2D.h"
  12 #include "mozilla/gfx/Logging.h"
  13 #include "mozilla/RefPtr.h"
  14 #include "nsCOMPtr.h"
  15 #include "mozilla/dom/Document.h"
  16 #include "nsError.h"
  17 #include "imgLoader.h"
  18 #include "imgICache.h"
  19 #include "imgIContainer.h"
  20 #include "imgIEncoder.h"
  21 #include "nsComponentManagerUtils.h"
  22 #include "nsNetUtil.h"  // for NS_NewBufferedInputStream
  23 #include "nsStreamUtils.h"
  24 #include "nsStringStream.h"
  25 #include "nsContentUtils.h"
  26 #include "nsProxyRelease.h"
  27 #include "nsIStreamListener.h"
  28 #include "ImageFactory.h"
  29 #include "Image.h"
  30 #include "IProgressObserver.h"
  31 #include "ScriptedNotificationObserver.h"
  32 #include "imgIScriptedNotificationObserver.h"
  33 #include "gfxPlatform.h"
  34 #include "js/ArrayBuffer.h"
  35 #include "js/RootingAPI.h"  // JS::{Handle,Rooted}
  36 #include "js/Value.h"       // JS::Value
  37 #include "Orientation.h"
  38
  39 using namespace mozilla::gfx;
  40
  41 namespace mozilla {
  42 namespace image {
  43
  44 namespace {
  45
  46 static nsresult sniff_mimetype_callback(nsIInputStream* in, void* data,
  47                                         const char* fromRawSegment,
  48                                         uint32_t toOffset, uint32_t count,
  49                                         uint32_t* writeCount) {
  50   nsCString* mimeType = static_cast<nsCString*>(data);
  51   MOZ_ASSERT(mimeType, "mimeType is null!");
  52
  53   if (count > 0) {
  54     imgLoader::GetMimeTypeFromContent(fromRawSegment, count, *mimeType);
  55   }
  56
  57   *writeCount = 0;
  58   return NS_ERROR_FAILURE;
  59 }
  60
  61 class ImageDecoderListener final : public nsIStreamListener,
  62                                    public IProgressObserver,
  63                                    public imgIContainer {
  64  public:
  65   NS_DECL_ISUPPORTS
  66
  67   ImageDecoderListener(nsIURI* aURI, imgIContainerCallback* aCallback,
  68                        imgINotificationObserver* aObserver)
  69       : mURI(aURI),
  70         mImage(nullptr),
  71         mCallback(aCallback),
  72         mObserver(aObserver) {
  73     MOZ_ASSERT(NS_IsMainThread());
  74   }
  75
  76   NS_IMETHOD
  77   OnDataAvailable(nsIRequest* aRequest, nsIInputStream* aInputStream,
  78                   uint64_t aOffset, uint32_t aCount) override {
  79     if (!mImage) {
  80       nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
  81
  82       nsCString mimeType;
  83       channel->GetContentType(mimeType);
  84
  85       if (aInputStream) {
  86         // Look at the first few bytes and see if we can tell what the data is
  87         // from that since servers tend to lie. :(
  88         uint32_t unused;
  89         aInputStream->ReadSegments(sniff_mimetype_callback, &mimeType, aCount,
  90                                    &unused);
  91       }
  92
  93       RefPtr<ProgressTracker> tracker = new ProgressTracker();
  94       if (mObserver) {
  95         tracker->AddObserver(this);
  96       }
  97
  98       mImage = ImageFactory::CreateImage(channel, tracker, mimeType, mURI,
  99                                          /* aIsMultiPart */ false, 0);
 100
 101       if (mImage->HasError()) {
 102         return NS_ERROR_FAILURE;
 103       }
 104     }
 105
 106     return mImage->OnImageDataAvailable(aRequest, aInputStream, aOffset,
 107                                         aCount);
 108   }
 109
 110   NS_IMETHOD
 111   OnStartRequest(nsIRequest* aRequest) override { return NS_OK; }
 112
 113   NS_IMETHOD
 114   OnStopRequest(nsIRequest* aRequest, nsresult aStatus) override {
 115     // Encouter a fetch error, or no data could be fetched.
 116     if (!mImage || NS_FAILED(aStatus)) {
 117       mCallback->OnImageReady(nullptr, mImage ? aStatus : NS_ERROR_FAILURE);
 118       return NS_OK;
 119     }
 120
 121     mImage->OnImageDataComplete(aRequest, aStatus, true);
 122     nsCOMPtr<imgIContainer> container = this;
 123     mCallback->OnImageReady(container, aStatus);
 124     return NS_OK;
 125   }
 126
 127   virtual void Notify(int32_t aType,
 128                       const nsIntRect* aRect = nullptr) override {
 129     if (mObserver) {
 130       mObserver->Notify(nullptr, aType, aRect);
 131     }
 132   }
 133
 134   virtual void OnLoadComplete(bool aLastPart) override {}
 135
 136   // Other notifications are ignored.
 137   virtual void SetHasImage() override {}
 138   virtual bool NotificationsDeferred() const override { return false; }
 139   virtual void MarkPendingNotify() override {}
 140   virtual void ClearPendingNotify() override {}
 141
 142   // imgIContainer
 143   NS_FORWARD_IMGICONTAINER(mImage->)
 144
 145  private:
 146   virtual ~ImageDecoderListener() = default;
 147
 148   nsCOMPtr<nsIURI> mURI;
 149   RefPtr<image::Image> mImage;
 150   nsCOMPtr<imgIContainerCallback> mCallback;
 151   nsCOMPtr<imgINotificationObserver> mObserver;
 152 };
 153
 154 NS_IMPL_ISUPPORTS(ImageDecoderListener, nsIStreamListener, imgIContainer)
 155
 156 class ImageDecoderHelper final : public Runnable,
 157                                  public nsIInputStreamCallback {
 158  public:
 159   NS_DECL_ISUPPORTS_INHERITED
 160
 161   ImageDecoderHelper(already_AddRefed<image::Image> aImage,
 162                      already_AddRefed<nsIInputStream> aInputStream,
 163                      nsIEventTarget* aEventTarget,
 164                      imgIContainerCallback* aCallback,
 165                      nsIEventTarget* aCallbackEventTarget)
 166       : Runnable("ImageDecoderHelper"),
 167         mImage(std::move(aImage)),
 168         mInputStream(std::move(aInputStream)),
 169         mEventTarget(aEventTarget),
 170         mCallback(aCallback),
 171         mCallbackEventTarget(aCallbackEventTarget),
 172         mStatus(NS_OK) {
 173     MOZ_ASSERT(NS_IsMainThread());
 174   }
 175
 176   NS_IMETHOD
 177   Run() override {
 178     // This runnable is dispatched on the Image thread when reading data, but
 179     // at the end, it goes back to the main-thread in order to complete the
 180     // operation.
 181     if (NS_IsMainThread()) {
 182       // Let the Image know we've sent all the data.
 183       mImage->OnImageDataComplete(nullptr, mStatus, true);
 184
 185       RefPtr<ProgressTracker> tracker = mImage->GetProgressTracker();
 186       tracker->SyncNotifyProgress(FLAG_LOAD_COMPLETE);
 187
 188       nsCOMPtr<imgIContainer> container;
 189       if (NS_SUCCEEDED(mStatus)) {
 190         container = mImage;
 191       }
 192
 193       mCallback->OnImageReady(container, mStatus);
 194       return NS_OK;
 195     }
 196
 197     uint64_t length;
 198     nsresult rv = mInputStream->Available(&length);
 199     if (rv == NS_BASE_STREAM_CLOSED) {
 200       return OperationCompleted(NS_OK);
 201     }
 202
 203     if (NS_WARN_IF(NS_FAILED(rv))) {
 204       return OperationCompleted(rv);
 205     }
 206
 207     // Nothing else to read, but maybe we just need to wait.
 208     if (length == 0) {
 209       nsCOMPtr<nsIAsyncInputStream> asyncInputStream =
 210           do_QueryInterface(mInputStream);
 211       if (asyncInputStream) {
 212         rv = asyncInputStream->AsyncWait(this, 0, 0, mEventTarget);
 213         if (NS_WARN_IF(NS_FAILED(rv))) {
 214           return OperationCompleted(rv);
 215         }
 216         return NS_OK;
 217       }
 218
 219       // We really have nothing else to read.
 220       if (length == 0) {
 221         return OperationCompleted(NS_OK);
 222       }
 223     }
 224
 225     // Send the source data to the Image.
 226     rv = mImage->OnImageDataAvailable(nullptr, mInputStream, 0,
 227                                       uint32_t(length));
 228     if (NS_WARN_IF(NS_FAILED(rv))) {
 229       return OperationCompleted(rv);
 230     }
 231
 232     rv = mEventTarget->Dispatch(this, NS_DISPATCH_NORMAL);
 233     if (NS_WARN_IF(NS_FAILED(rv))) {
 234       return OperationCompleted(rv);
 235     }
 236
 237     return NS_OK;
 238   }
 239
 240   NS_IMETHOD
 241   OnInputStreamReady(nsIAsyncInputStream* aAsyncInputStream) override {
 242     MOZ_ASSERT(!NS_IsMainThread());
 243     return Run();
 244   }
 245
 246   nsresult OperationCompleted(nsresult aStatus) {
 247     MOZ_ASSERT(!NS_IsMainThread());
 248
 249     mStatus = aStatus;
 250     mCallbackEventTarget->Dispatch(this, NS_DISPATCH_NORMAL);
 251     return NS_OK;
 252   }
 253
 254  private:
 255   ~ImageDecoderHelper() {
 256     SurfaceCache::ReleaseImageOnMainThread(mImage.forget());
 257     NS_ReleaseOnMainThread("ImageDecoderHelper::mCallback", mCallback.forget());
 258   }
 259
 260   RefPtr<image::Image> mImage;
 261
 262   nsCOMPtr<nsIInputStream> mInputStream;
 263   nsCOMPtr<nsIEventTarget> mEventTarget;
 264   nsCOMPtr<imgIContainerCallback> mCallback;
 265   nsCOMPtr<nsIEventTarget> mCallbackEventTarget;
 266
 267   nsresult mStatus;
 268 };
 269
 270 NS_IMPL_ISUPPORTS_INHERITED(ImageDecoderHelper, Runnable,
 271                             nsIInputStreamCallback)
 272
 273 }  // namespace
 274
 275 /* ========== imgITools implementation ========== */
 276
 277 NS_IMPL_ISUPPORTS(imgTools, imgITools)
 278
 279 imgTools::imgTools() { /* member initializers and constructor code */
 280 }
 281
 282 imgTools::~imgTools() { /* destructor code */
 283 }
 284
 285 NS_IMETHODIMP
 286 imgTools::DecodeImageFromArrayBuffer(JS::Handle<JS::Value> aArrayBuffer,
 287                                      const nsACString& aMimeType,
 288                                      JSContext* aCx,
 289                                      imgIContainer** aContainer) {
 290   if (!aArrayBuffer.isObject()) {
 291     return NS_ERROR_FAILURE;
 292   }
 293
 294   JS::Rooted<JSObject*> obj(aCx,
 295                             JS::UnwrapArrayBuffer(&aArrayBuffer.toObject()));
 296   if (!obj) {
 297     return NS_ERROR_FAILURE;
 298   }
 299
 300   uint8_t* bufferData = nullptr;
 301   size_t bufferLength = 0;
 302   bool isSharedMemory = false;
 303
 304   JS::GetArrayBufferLengthAndData(obj, &bufferLength, &isSharedMemory,
 305                                   &bufferData);
 306
 307   // Throw for large ArrayBuffers to prevent truncation.
 308   if (bufferLength > INT32_MAX) {
 309     return NS_ERROR_ILLEGAL_VALUE;
 310   }
 311
 312   return DecodeImageFromBuffer((char*)bufferData, bufferLength, aMimeType,
 313                                aContainer);
 314 }
 315
 316 NS_IMETHODIMP
 317 imgTools::DecodeImageFromBuffer(const char* aBuffer, uint32_t aSize,
 318                                 const nsACString& aMimeType,
 319                                 imgIContainer** aContainer) {
 320   MOZ_ASSERT(NS_IsMainThread());
 321
 322   NS_ENSURE_ARG_POINTER(aBuffer);
 323
 324   // Create a new image container to hold the decoded data.
 325   nsAutoCString mimeType(aMimeType);
 326   RefPtr<image::Image> image =
 327       ImageFactory::CreateAnonymousImage(mimeType, aSize);
 328   RefPtr<ProgressTracker> tracker = image->GetProgressTracker();
 329
 330   if (image->HasError()) {
 331     return NS_ERROR_FAILURE;
 332   }
 333
 334   // Let's create a temporary inputStream.
 335   nsCOMPtr<nsIInputStream> stream;
 336   nsresult rv = NS_NewByteInputStream(
 337       getter_AddRefs(stream), Span(aBuffer, aSize), NS_ASSIGNMENT_DEPEND);
 338   NS_ENSURE_SUCCESS(rv, rv);
 339   MOZ_ASSERT(stream);
 340   MOZ_ASSERT(NS_InputStreamIsBuffered(stream));
 341
 342   rv = image->OnImageDataAvailable(nullptr, stream, 0, aSize);
 343   NS_ENSURE_SUCCESS(rv, rv);
 344
 345   // Let the Image know we've sent all the data.
 346   rv = image->OnImageDataComplete(nullptr, NS_OK, true);
 347   tracker->SyncNotifyProgress(FLAG_LOAD_COMPLETE);
 348   NS_ENSURE_SUCCESS(rv, rv);
 349
 350   // All done.
 351   image.forget(aContainer);
 352   return NS_OK;
 353 }
 354
 355 NS_IMETHODIMP
 356 imgTools::DecodeImageFromChannelAsync(nsIURI* aURI, nsIChannel* aChannel,
 357                                       imgIContainerCallback* aCallback,
 358                                       imgINotificationObserver* aObserver) {
 359   MOZ_ASSERT(NS_IsMainThread());
 360
 361   NS_ENSURE_ARG_POINTER(aURI);
 362   NS_ENSURE_ARG_POINTER(aChannel);
 363   NS_ENSURE_ARG_POINTER(aCallback);
 364
 365   RefPtr<ImageDecoderListener> listener =
 366       new ImageDecoderListener(aURI, aCallback, aObserver);
 367
 368   return aChannel->AsyncOpen(listener);
 369 }
 370
 371 NS_IMETHODIMP
 372 imgTools::DecodeImageAsync(nsIInputStream* aInStr, const nsACString& aMimeType,
 373                            imgIContainerCallback* aCallback,
 374                            nsIEventTarget* aEventTarget) {
 375   MOZ_ASSERT(NS_IsMainThread());
 376
 377   NS_ENSURE_ARG_POINTER(aInStr);
 378   NS_ENSURE_ARG_POINTER(aCallback);
 379   NS_ENSURE_ARG_POINTER(aEventTarget);
 380
 381   nsresult rv;
 382
 383   // Let's continuing the reading on a separate thread.
 384   DecodePool* decodePool = DecodePool::Singleton();
 385   MOZ_ASSERT(decodePool);
 386
 387   RefPtr<nsIEventTarget> target = decodePool->GetIOEventTarget();
 388   NS_ENSURE_TRUE(target, NS_ERROR_FAILURE);
 389
 390   // Prepare the input stream.
 391   nsCOMPtr<nsIInputStream> stream = aInStr;
 392   if (!NS_InputStreamIsBuffered(aInStr)) {
 393     nsCOMPtr<nsIInputStream> bufStream;
 394     rv = NS_NewBufferedInputStream(getter_AddRefs(bufStream), stream.forget(),
 395                                    1024);
 396     NS_ENSURE_SUCCESS(rv, rv);
 397     stream = std::move(bufStream);
 398   }
 399
 400   // Create a new image container to hold the decoded data.
 401   nsAutoCString mimeType(aMimeType);
 402   RefPtr<image::Image> image = ImageFactory::CreateAnonymousImage(mimeType, 0);
 403
 404   // Already an error?
 405   if (image->HasError()) {
 406     return NS_ERROR_FAILURE;
 407   }
 408
 409   RefPtr<ImageDecoderHelper> helper = new ImageDecoderHelper(
 410       image.forget(), stream.forget(), target, aCallback, aEventTarget);
 411   rv = target->Dispatch(helper.forget(), NS_DISPATCH_NORMAL);
 412   NS_ENSURE_SUCCESS(rv, rv);
 413
 414   return NS_OK;
 415 }
 416
 417 /**
 418  * This takes a DataSourceSurface rather than a SourceSurface because some
 419  * of the callers have a DataSourceSurface and we don't want to call
 420  * GetDataSurface on such surfaces since that may incur a conversion to
 421  * SurfaceType::DATA which we don't need.
 422  */
 423 static nsresult EncodeImageData(DataSourceSurface* aDataSurface,
 424                                 DataSourceSurface::ScopedMap& aMap,
 425                                 const nsACString& aMimeType,
 426                                 const nsAString& aOutputOptions,
 427                                 nsIInputStream** aStream) {
 428   MOZ_ASSERT(aDataSurface->GetFormat() == SurfaceFormat::B8G8R8A8 ||
 429                  aDataSurface->GetFormat() == SurfaceFormat::B8G8R8X8,
 430              "We're assuming B8G8R8A8/X8");
 431
 432   // Get an image encoder for the media type
 433   nsAutoCString encoderCID("@mozilla.org/image/encoder;2?type="_ns + aMimeType);
 434
 435   nsCOMPtr<imgIEncoder> encoder = do_CreateInstance(encoderCID.get());
 436   if (!encoder) {
 437     return NS_IMAGELIB_ERROR_NO_ENCODER;
 438   }
 439
 440   IntSize size = aDataSurface->GetSize();
 441   uint32_t dataLength = aMap.GetStride() * size.height;
 442
 443   // Encode the bitmap
 444   nsresult rv = encoder->InitFromData(
 445       aMap.GetData(), dataLength, size.width, size.height, aMap.GetStride(),
 446       imgIEncoder::INPUT_FORMAT_HOSTARGB, aOutputOptions);
 447   NS_ENSURE_SUCCESS(rv, rv);
 448
 449   encoder.forget(aStream);
 450   return NS_OK;
 451 }
 452
 453 static nsresult EncodeImageData(DataSourceSurface* aDataSurface,
 454                                 const nsACString& aMimeType,
 455                                 const nsAString& aOutputOptions,
 456                                 nsIInputStream** aStream) {
 457   DataSourceSurface::ScopedMap map(aDataSurface, DataSourceSurface::READ);
 458   if (!map.IsMapped()) {
 459     return NS_ERROR_FAILURE;
 460   }
 461
 462   return EncodeImageData(aDataSurface, map, aMimeType, aOutputOptions, aStream);
 463 }
 464
 465 NS_IMETHODIMP
 466 imgTools::EncodeImage(imgIContainer* aContainer, const nsACString& aMimeType,
 467                       const nsAString& aOutputOptions,
 468                       nsIInputStream** aStream) {
 469   // Use frame 0 from the image container.
 470   RefPtr<SourceSurface> frame = aContainer->GetFrame(
 471       imgIContainer::FRAME_FIRST,
 472       imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
 473   NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
 474
 475   RefPtr<DataSourceSurface> dataSurface;
 476
 477   if (frame->GetFormat() == SurfaceFormat::B8G8R8A8 ||
 478       frame->GetFormat() == SurfaceFormat::B8G8R8X8) {
 479     dataSurface = frame->GetDataSurface();
 480   } else {
 481     // Convert format to SurfaceFormat::B8G8R8A8
 482     dataSurface = gfxUtils::CopySurfaceToDataSourceSurfaceWithFormat(
 483         frame, SurfaceFormat::B8G8R8A8);
 484   }
 485
 486   NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
 487
 488   return EncodeImageData(dataSurface, aMimeType, aOutputOptions, aStream);
 489 }
 490
 491 NS_IMETHODIMP
 492 imgTools::EncodeScaledImage(imgIContainer* aContainer,
 493                             const nsACString& aMimeType, int32_t aScaledWidth,
 494                             int32_t aScaledHeight,
 495                             const nsAString& aOutputOptions,
 496                             nsIInputStream** aStream) {
 497   NS_ENSURE_ARG(aScaledWidth >= 0 && aScaledHeight >= 0);
 498
 499   // If no scaled size is specified, we'll just encode the image at its
 500   // original size (no scaling).
 501   if (aScaledWidth == 0 && aScaledHeight == 0) {
 502     return EncodeImage(aContainer, aMimeType, aOutputOptions, aStream);
 503   }
 504
 505   // Retrieve the image's size.
 506   int32_t imageWidth = 0;
 507   int32_t imageHeight = 0;
 508   aContainer->GetWidth(&imageWidth);
 509   aContainer->GetHeight(&imageHeight);
 510
 511   // If the given width or height is zero we'll replace it with the image's
 512   // original dimensions.
 513   IntSize scaledSize(aScaledWidth == 0 ? imageWidth : aScaledWidth,
 514                      aScaledHeight == 0 ? imageHeight : aScaledHeight);
 515
 516   // Use frame 0 from the image container.
 517   RefPtr<SourceSurface> frame = aContainer->GetFrameAtSize(
 518       scaledSize, imgIContainer::FRAME_FIRST,
 519       imgIContainer::FLAG_HIGH_QUALITY_SCALING |
 520           imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
 521   NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
 522
 523   // If the given surface is the right size/format, we can encode it directly.
 524   if (scaledSize == frame->GetSize() &&
 525       (frame->GetFormat() == SurfaceFormat::B8G8R8A8 ||
 526        frame->GetFormat() == SurfaceFormat::B8G8R8X8)) {
 527     RefPtr<DataSourceSurface> dataSurface = frame->GetDataSurface();
 528     if (dataSurface) {
 529       return EncodeImageData(dataSurface, aMimeType, aOutputOptions, aStream);
 530     }
 531   }
 532
 533   // Otherwise we need to scale it using a draw target.
 534   RefPtr<DataSourceSurface> dataSurface =
 535       Factory::CreateDataSourceSurface(scaledSize, SurfaceFormat::B8G8R8A8);
 536   if (NS_WARN_IF(!dataSurface)) {
 537     return NS_ERROR_FAILURE;
 538   }
 539
 540   DataSourceSurface::ScopedMap map(dataSurface, DataSourceSurface::READ_WRITE);
 541   if (!map.IsMapped()) {
 542     return NS_ERROR_FAILURE;
 543   }
 544
 545   RefPtr<DrawTarget> dt = Factory::CreateDrawTargetForData(
 546       BackendType::SKIA, map.GetData(), dataSurface->GetSize(), map.GetStride(),
 547       SurfaceFormat::B8G8R8A8);
 548   if (!dt) {
 549     gfxWarning() << "imgTools::EncodeImage failed in CreateDrawTargetForData";
 550     return NS_ERROR_OUT_OF_MEMORY;
 551   }
 552
 553   IntSize frameSize = frame->GetSize();
 554   dt->DrawSurface(frame, Rect(0, 0, scaledSize.width, scaledSize.height),
 555                   Rect(0, 0, frameSize.width, frameSize.height),
 556                   DrawSurfaceOptions(),
 557                   DrawOptions(1.0f, CompositionOp::OP_SOURCE));
 558
 559   return EncodeImageData(dataSurface, map, aMimeType, aOutputOptions, aStream);
 560 }
 561
 562 NS_IMETHODIMP
 563 imgTools::EncodeCroppedImage(imgIContainer* aContainer,
 564                              const nsACString& aMimeType, int32_t aOffsetX,
 565                              int32_t aOffsetY, int32_t aWidth, int32_t aHeight,
 566                              const nsAString& aOutputOptions,
 567                              nsIInputStream** aStream) {
 568   NS_ENSURE_ARG(aOffsetX >= 0 && aOffsetY >= 0 && aWidth >= 0 && aHeight >= 0);
 569
 570   // Offsets must be zero when no width and height are given or else we're out
 571   // of bounds.
 572   NS_ENSURE_ARG(aWidth + aHeight > 0 || aOffsetX + aOffsetY == 0);
 573
 574   // If no size is specified then we'll preserve the image's original dimensions
 575   // and don't need to crop.
 576   if (aWidth == 0 && aHeight == 0) {
 577     return EncodeImage(aContainer, aMimeType, aOutputOptions, aStream);
 578   }
 579
 580   // Use frame 0 from the image container.
 581   RefPtr<SourceSurface> frame = aContainer->GetFrame(
 582       imgIContainer::FRAME_FIRST,
 583       imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
 584   NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
 585
 586   int32_t frameWidth = frame->GetSize().width;
 587   int32_t frameHeight = frame->GetSize().height;
 588
 589   // If the given width or height is zero we'll replace it with the image's
 590   // original dimensions.
 591   if (aWidth == 0) {
 592     aWidth = frameWidth;
 593   } else if (aHeight == 0) {
 594     aHeight = frameHeight;
 595   }
 596
 597   // Check that the given crop rectangle is within image bounds.
 598   NS_ENSURE_ARG(frameWidth >= aOffsetX + aWidth &&
 599                 frameHeight >= aOffsetY + aHeight);
 600
 601   RefPtr<DataSourceSurface> dataSurface = Factory::CreateDataSourceSurface(
 602       IntSize(aWidth, aHeight), SurfaceFormat::B8G8R8A8,
 603       /* aZero = */ true);
 604   if (NS_WARN_IF(!dataSurface)) {
 605     return NS_ERROR_FAILURE;
 606   }
 607
 608   DataSourceSurface::ScopedMap map(dataSurface, DataSourceSurface::READ_WRITE);
 609   if (!map.IsMapped()) {
 610     return NS_ERROR_FAILURE;
 611   }
 612
 613   RefPtr<DrawTarget> dt = Factory::CreateDrawTargetForData(
 614       BackendType::SKIA, map.GetData(), dataSurface->GetSize(), map.GetStride(),
 615       SurfaceFormat::B8G8R8A8);
 616   if (!dt) {
 617     gfxWarning()
 618         << "imgTools::EncodeCroppedImage failed in CreateDrawTargetForData";
 619     return NS_ERROR_OUT_OF_MEMORY;
 620   }
 621   dt->CopySurface(frame, IntRect(aOffsetX, aOffsetY, aWidth, aHeight),
 622                   IntPoint(0, 0));
 623
 624   return EncodeImageData(dataSurface, map, aMimeType, aOutputOptions, aStream);
 625 }
 626
 627 NS_IMETHODIMP
 628 imgTools::CreateScriptedObserver(imgIScriptedNotificationObserver* aInner,
 629                                  imgINotificationObserver** aObserver) {
 630   NS_ADDREF(*aObserver = new ScriptedNotificationObserver(aInner));
 631   return NS_OK;
 632 }
 633
 634 NS_IMETHODIMP
 635 imgTools::GetImgLoaderForDocument(dom::Document* aDoc, imgILoader** aLoader) {
 636   NS_IF_ADDREF(*aLoader = nsContentUtils::GetImgLoaderForDocument(aDoc));
 637   return NS_OK;
 638 }
 639
 640 NS_IMETHODIMP
 641 imgTools::GetImgCacheForDocument(dom::Document* aDoc, imgICache** aCache) {
 642   nsCOMPtr<imgILoader> loader;
 643   nsresult rv = GetImgLoaderForDocument(aDoc, getter_AddRefs(loader));
 644   NS_ENSURE_SUCCESS(rv, rv);
 645   return CallQueryInterface(loader, aCache);
 646 }
 647
 648 }  // namespace image
 649 }  // namespace mozilla