src/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoderTest.cpp

   1 /*
   2  * Copyright (C) 2013 Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #include "config.h"
  32
  33 #include "platform/image-decoders/gif/GIFImageDecoder.h"
  34
  35 #include "platform/SharedBuffer.h"
  36 #include "public/platform/Platform.h"
  37 #include "public/platform/WebData.h"
  38 #include "public/platform/WebSize.h"
  39 #include "public/platform/WebUnitTestSupport.h"
  40 #include "wtf/OwnPtr.h"
  41 #include "wtf/PassOwnPtr.h"
  42 #include "wtf/StringHasher.h"
  43 #include "wtf/Vector.h"
  44 #include <gtest/gtest.h>
  45
  46 using namespace WebCore;
  47 using namespace blink;
  48
  49 namespace {
  50
  51 PassRefPtr<SharedBuffer> readFile(const char* fileName)
  52 {
  53     String filePath = Platform::current()->unitTestSupport()->webKitRootDir();
  54     filePath.append(fileName);
  55
  56     return Platform::current()->unitTestSupport()->readFromFile(filePath);
  57 }
  58
  59 PassOwnPtr<GIFImageDecoder> createDecoder()
  60 {
  61     return adoptPtr(new GIFImageDecoder(ImageSource::AlphaNotPremultiplied, ImageSource::GammaAndColorProfileApplied, ImageDecoder::noDecodedImageByteLimit));
  62 }
  63
  64 unsigned hashSkBitmap(const SkBitmap& bitmap)
  65 {
  66     return StringHasher::hashMemory(bitmap.getPixels(), bitmap.getSize());
  67 }
  68
  69 void createDecodingBaseline(SharedBuffer* data, Vector<unsigned>* baselineHashes)
  70 {
  71     OwnPtr<GIFImageDecoder> decoder = createDecoder();
  72     decoder->setData(data, true);
  73     size_t frameCount = decoder->frameCount();
  74     for (size_t i = 0; i < frameCount; ++i) {
  75         ImageFrame* frame = decoder->frameBufferAtIndex(i);
  76         baselineHashes->append(hashSkBitmap(frame->getSkBitmap()));
  77     }
  78 }
  79
  80 void testRandomFrameDecode(const char* gifFile)
  81 {
  82     SCOPED_TRACE(gifFile);
  83
  84     RefPtr<SharedBuffer> fullData = readFile(gifFile);
  85     ASSERT_TRUE(fullData.get());
  86     Vector<unsigned> baselineHashes;
  87     createDecodingBaseline(fullData.get(), &baselineHashes);
  88     size_t frameCount = baselineHashes.size();
  89
  90     // Random decoding should get the same results as sequential decoding.
  91     OwnPtr<GIFImageDecoder> decoder = createDecoder();
  92     decoder->setData(fullData.get(), true);
  93     const size_t skippingStep = 5;
  94     for (size_t i = 0; i < skippingStep; ++i) {
  95         for (size_t j = i; j < frameCount; j += skippingStep) {
  96             SCOPED_TRACE(testing::Message() << "Random i:" << i << " j:" << j);
  97             ImageFrame* frame = decoder->frameBufferAtIndex(j);
  98             EXPECT_EQ(baselineHashes[j], hashSkBitmap(frame->getSkBitmap()));
  99         }
 100     }
 101
 102     // Decoding in reverse order.
 103     decoder = createDecoder();
 104     decoder->setData(fullData.get(), true);
 105     for (size_t i = frameCount; i; --i) {
 106         SCOPED_TRACE(testing::Message() << "Reverse i:" << i);
 107         ImageFrame* frame = decoder->frameBufferAtIndex(i - 1);
 108         EXPECT_EQ(baselineHashes[i - 1], hashSkBitmap(frame->getSkBitmap()));
 109     }
 110 }
 111
 112 void testRandomDecodeAfterClearFrameBufferCache(const char* gifFile)
 113 {
 114     SCOPED_TRACE(gifFile);
 115
 116     RefPtr<SharedBuffer> data = readFile(gifFile);
 117     ASSERT_TRUE(data.get());
 118     Vector<unsigned> baselineHashes;
 119     createDecodingBaseline(data.get(), &baselineHashes);
 120     size_t frameCount = baselineHashes.size();
 121
 122     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 123     decoder->setData(data.get(), true);
 124     for (size_t clearExceptFrame = 0; clearExceptFrame < frameCount; ++clearExceptFrame) {
 125         decoder->clearCacheExceptFrame(clearExceptFrame);
 126         const size_t skippingStep = 5;
 127         for (size_t i = 0; i < skippingStep; ++i) {
 128             for (size_t j = 0; j < frameCount; j += skippingStep) {
 129                 SCOPED_TRACE(testing::Message() << "Random i:" << i << " j:" << j);
 130                 ImageFrame* frame = decoder->frameBufferAtIndex(j);
 131                 EXPECT_EQ(baselineHashes[j], hashSkBitmap(frame->getSkBitmap()));
 132             }
 133         }
 134     }
 135 }
 136
 137 } // namespace
 138
 139 TEST(GIFImageDecoderTest, decodeTwoFrames)
 140 {
 141     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 142
 143     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 144     ASSERT_TRUE(data.get());
 145     decoder->setData(data.get(), true);
 146     EXPECT_EQ(cAnimationLoopOnce, decoder->repetitionCount());
 147
 148     ImageFrame* frame = decoder->frameBufferAtIndex(0);
 149     uint32_t generationID0 = frame->getSkBitmap().getGenerationID();
 150     EXPECT_EQ(ImageFrame::FrameComplete, frame->status());
 151     EXPECT_EQ(16, frame->getSkBitmap().width());
 152     EXPECT_EQ(16, frame->getSkBitmap().height());
 153
 154     frame = decoder->frameBufferAtIndex(1);
 155     uint32_t generationID1 = frame->getSkBitmap().getGenerationID();
 156     EXPECT_EQ(ImageFrame::FrameComplete, frame->status());
 157     EXPECT_EQ(16, frame->getSkBitmap().width());
 158     EXPECT_EQ(16, frame->getSkBitmap().height());
 159     EXPECT_TRUE(generationID0 != generationID1);
 160
 161     EXPECT_EQ(2u, decoder->frameCount());
 162     EXPECT_EQ(cAnimationLoopInfinite, decoder->repetitionCount());
 163 }
 164
 165 TEST(GIFImageDecoderTest, parseAndDecode)
 166 {
 167     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 168
 169     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 170     ASSERT_TRUE(data.get());
 171     decoder->setData(data.get(), true);
 172     EXPECT_EQ(cAnimationLoopOnce, decoder->repetitionCount());
 173
 174     // This call will parse the entire file.
 175     EXPECT_EQ(2u, decoder->frameCount());
 176
 177     ImageFrame* frame = decoder->frameBufferAtIndex(0);
 178     EXPECT_EQ(ImageFrame::FrameComplete, frame->status());
 179     EXPECT_EQ(16, frame->getSkBitmap().width());
 180     EXPECT_EQ(16, frame->getSkBitmap().height());
 181
 182     frame = decoder->frameBufferAtIndex(1);
 183     EXPECT_EQ(ImageFrame::FrameComplete, frame->status());
 184     EXPECT_EQ(16, frame->getSkBitmap().width());
 185     EXPECT_EQ(16, frame->getSkBitmap().height());
 186     EXPECT_EQ(cAnimationLoopInfinite, decoder->repetitionCount());
 187 }
 188
 189 TEST(GIFImageDecoderTest, parseByteByByte)
 190 {
 191     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 192
 193     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 194     ASSERT_TRUE(data.get());
 195
 196     size_t frameCount = 0;
 197
 198     // Pass data to decoder byte by byte.
 199     for (size_t length = 1; length <= data->size(); ++length) {
 200         RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(), length);
 201         decoder->setData(tempData.get(), length == data->size());
 202
 203         EXPECT_LE(frameCount, decoder->frameCount());
 204         frameCount = decoder->frameCount();
 205     }
 206
 207     EXPECT_EQ(2u, decoder->frameCount());
 208
 209     decoder->frameBufferAtIndex(0);
 210     decoder->frameBufferAtIndex(1);
 211     EXPECT_EQ(cAnimationLoopInfinite, decoder->repetitionCount());
 212 }
 213
 214 TEST(GIFImageDecoderTest, parseAndDecodeByteByByte)
 215 {
 216     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 217
 218     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated-gif-with-offsets.gif");
 219     ASSERT_TRUE(data.get());
 220
 221     size_t frameCount = 0;
 222     size_t framesDecoded = 0;
 223
 224     // Pass data to decoder byte by byte.
 225     for (size_t length = 1; length <= data->size(); ++length) {
 226         RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(), length);
 227         decoder->setData(tempData.get(), length == data->size());
 228
 229         EXPECT_LE(frameCount, decoder->frameCount());
 230         frameCount = decoder->frameCount();
 231
 232         ImageFrame* frame = decoder->frameBufferAtIndex(frameCount - 1);
 233         if (frame && frame->status() == ImageFrame::FrameComplete && framesDecoded < frameCount)
 234             ++framesDecoded;
 235     }
 236
 237     EXPECT_EQ(5u, decoder->frameCount());
 238     EXPECT_EQ(5u, framesDecoded);
 239     EXPECT_EQ(cAnimationLoopInfinite, decoder->repetitionCount());
 240 }
 241
 242 TEST(GIFImageDecoderTest, brokenSecondFrame)
 243 {
 244     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 245
 246     RefPtr<SharedBuffer> data = readFile("/Source/web/tests/data/broken.gif");
 247     ASSERT_TRUE(data.get());
 248     decoder->setData(data.get(), true);
 249
 250     // One frame is detected but cannot be decoded.
 251     EXPECT_EQ(1u, decoder->frameCount());
 252     ImageFrame* frame = decoder->frameBufferAtIndex(1);
 253     EXPECT_FALSE(frame);
 254 }
 255
 256 TEST(GIFImageDecoderTest, progressiveDecode)
 257 {
 258     RefPtr<SharedBuffer> fullData = readFile("/Source/web/tests/data/radient.gif");
 259     ASSERT_TRUE(fullData.get());
 260     const size_t fullLength = fullData->size();
 261
 262     OwnPtr<GIFImageDecoder> decoder;
 263     ImageFrame* frame;
 264
 265     Vector<unsigned> truncatedHashes;
 266     Vector<unsigned> progressiveHashes;
 267
 268     // Compute hashes when the file is truncated.
 269     const size_t increment = 1;
 270     for (size_t i = 1; i <= fullLength; i += increment) {
 271         decoder = createDecoder();
 272         RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), i);
 273         decoder->setData(data.get(), i == fullLength);
 274         frame = decoder->frameBufferAtIndex(0);
 275         if (!frame) {
 276             truncatedHashes.append(0);
 277             continue;
 278         }
 279         truncatedHashes.append(hashSkBitmap(frame->getSkBitmap()));
 280     }
 281
 282     // Compute hashes when the file is progressively decoded.
 283     decoder = createDecoder();
 284     EXPECT_EQ(cAnimationLoopOnce, decoder->repetitionCount());
 285     for (size_t i = 1; i <= fullLength; i += increment) {
 286         RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), i);
 287         decoder->setData(data.get(), i == fullLength);
 288         frame = decoder->frameBufferAtIndex(0);
 289         if (!frame) {
 290             progressiveHashes.append(0);
 291             continue;
 292         }
 293         progressiveHashes.append(hashSkBitmap(frame->getSkBitmap()));
 294     }
 295     EXPECT_EQ(cAnimationNone, decoder->repetitionCount());
 296
 297     bool match = true;
 298     for (size_t i = 0; i < truncatedHashes.size(); ++i) {
 299         if (truncatedHashes[i] != progressiveHashes[i]) {
 300             match = false;
 301             break;
 302         }
 303     }
 304     EXPECT_TRUE(match);
 305 }
 306
 307 TEST(GIFImageDecoderTest, allDataReceivedTruncation)
 308 {
 309     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 310
 311     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 312     ASSERT_TRUE(data.get());
 313
 314     ASSERT_GE(data->size(), 10u);
 315     RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(), data->size() - 10);
 316     decoder->setData(tempData.get(), true);
 317
 318     EXPECT_EQ(2u, decoder->frameCount());
 319     EXPECT_FALSE(decoder->failed());
 320
 321     decoder->frameBufferAtIndex(0);
 322     EXPECT_FALSE(decoder->failed());
 323     decoder->frameBufferAtIndex(1);
 324     EXPECT_TRUE(decoder->failed());
 325 }
 326
 327 TEST(GIFImageDecoderTest, frameIsComplete)
 328 {
 329     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 330
 331     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 332     ASSERT_TRUE(data.get());
 333     decoder->setData(data.get(), true);
 334
 335     EXPECT_EQ(2u, decoder->frameCount());
 336     EXPECT_FALSE(decoder->failed());
 337     EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
 338     EXPECT_TRUE(decoder->frameIsCompleteAtIndex(1));
 339     EXPECT_EQ(cAnimationLoopInfinite, decoder->repetitionCount());
 340 }
 341
 342 TEST(GIFImageDecoderTest, frameIsCompleteLoading)
 343 {
 344     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 345
 346     RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/animated.gif");
 347     ASSERT_TRUE(data.get());
 348
 349     ASSERT_GE(data->size(), 10u);
 350     RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(), data->size() - 10);
 351     decoder->setData(tempData.get(), false);
 352
 353     EXPECT_EQ(2u, decoder->frameCount());
 354     EXPECT_FALSE(decoder->failed());
 355     EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
 356     EXPECT_FALSE(decoder->frameIsCompleteAtIndex(1));
 357
 358     decoder->setData(data.get(), true);
 359     EXPECT_EQ(2u, decoder->frameCount());
 360     EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
 361     EXPECT_TRUE(decoder->frameIsCompleteAtIndex(1));
 362 }
 363
 364 TEST(GIFImageDecoderTest, badTerminator)
 365 {
 366     RefPtr<SharedBuffer> referenceData = readFile("/Source/web/tests/data/radient.gif");
 367     RefPtr<SharedBuffer> testData = readFile("/Source/web/tests/data/radient-bad-terminator.gif");
 368     ASSERT_TRUE(referenceData.get());
 369     ASSERT_TRUE(testData.get());
 370
 371     OwnPtr<GIFImageDecoder> referenceDecoder(createDecoder());
 372     referenceDecoder->setData(referenceData.get(), true);
 373     EXPECT_EQ(1u, referenceDecoder->frameCount());
 374     ImageFrame* referenceFrame = referenceDecoder->frameBufferAtIndex(0);
 375     ASSERT(referenceFrame);
 376
 377     OwnPtr<GIFImageDecoder> testDecoder(createDecoder());
 378     testDecoder->setData(testData.get(), true);
 379     EXPECT_EQ(1u, testDecoder->frameCount());
 380     ImageFrame* testFrame = testDecoder->frameBufferAtIndex(0);
 381     ASSERT(testFrame);
 382
 383     EXPECT_EQ(hashSkBitmap(referenceFrame->getSkBitmap()), hashSkBitmap(testFrame->getSkBitmap()));
 384 }
 385
 386 TEST(GIFImageDecoderTest, updateRequiredPreviousFrameAfterFirstDecode)
 387 {
 388     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 389
 390     RefPtr<SharedBuffer> fullData = readFile("/LayoutTests/fast/images/resources/animated-10color.gif");
 391     ASSERT_TRUE(fullData.get());
 392
 393     // Give it data that is enough to parse but not decode in order to check the status
 394     // of requiredPreviousFrameIndex before decoding.
 395     size_t partialSize = 1;
 396     do {
 397         RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), partialSize);
 398         decoder->setData(data.get(), false);
 399         ++partialSize;
 400     } while (!decoder->frameCount() || decoder->frameBufferAtIndex(0)->status() == ImageFrame::FrameEmpty);
 401
 402     EXPECT_EQ(kNotFound, decoder->frameBufferAtIndex(0)->requiredPreviousFrameIndex());
 403     unsigned frameCount = decoder->frameCount();
 404     for (size_t i = 1; i < frameCount; ++i)
 405         EXPECT_EQ(i - 1, decoder->frameBufferAtIndex(i)->requiredPreviousFrameIndex());
 406
 407     decoder->setData(fullData.get(), true);
 408     for (size_t i = 0; i < frameCount; ++i)
 409         EXPECT_EQ(kNotFound, decoder->frameBufferAtIndex(i)->requiredPreviousFrameIndex());
 410 }
 411
 412 TEST(GIFImageDecoderTest, randomFrameDecode)
 413 {
 414     // Single frame image.
 415     testRandomFrameDecode("/Source/web/tests/data/radient.gif");
 416     // Multiple frame images.
 417     testRandomFrameDecode("/LayoutTests/fast/images/resources/animated-gif-with-offsets.gif");
 418     testRandomFrameDecode("/LayoutTests/fast/images/resources/animated-10color.gif");
 419 }
 420
 421 TEST(GIFImageDecoderTest, randomDecodeAfterClearFrameBufferCache)
 422 {
 423     // Single frame image.
 424     testRandomDecodeAfterClearFrameBufferCache("/Source/web/tests/data/radient.gif");
 425     // Multiple frame images.
 426     testRandomDecodeAfterClearFrameBufferCache("/LayoutTests/fast/images/resources/animated-gif-with-offsets.gif");
 427     testRandomDecodeAfterClearFrameBufferCache("/LayoutTests/fast/images/resources/animated-10color.gif");
 428 }
 429
 430 TEST(GIFImageDecoderTest, resumePartialDecodeAfterClearFrameBufferCache)
 431 {
 432     RefPtr<SharedBuffer> fullData = readFile("/LayoutTests/fast/images/resources/animated-10color.gif");
 433     ASSERT_TRUE(fullData.get());
 434     Vector<unsigned> baselineHashes;
 435     createDecodingBaseline(fullData.get(), &baselineHashes);
 436     size_t frameCount = baselineHashes.size();
 437
 438     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 439
 440     // Let frame 0 be partially decoded.
 441     size_t partialSize = 1;
 442     do {
 443         RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), partialSize);
 444         decoder->setData(data.get(), false);
 445         ++partialSize;
 446     } while (!decoder->frameCount() || decoder->frameBufferAtIndex(0)->status() == ImageFrame::FrameEmpty);
 447
 448     // Skip to the last frame and clear.
 449     decoder->setData(fullData.get(), true);
 450     EXPECT_EQ(frameCount, decoder->frameCount());
 451     ImageFrame* lastFrame = decoder->frameBufferAtIndex(frameCount - 1);
 452     EXPECT_EQ(baselineHashes[frameCount - 1], hashSkBitmap(lastFrame->getSkBitmap()));
 453     decoder->clearCacheExceptFrame(kNotFound);
 454
 455     // Resume decoding of the first frame.
 456     ImageFrame* firstFrame = decoder->frameBufferAtIndex(0);
 457     EXPECT_EQ(ImageFrame::FrameComplete, firstFrame->status());
 458     EXPECT_EQ(baselineHashes[0], hashSkBitmap(firstFrame->getSkBitmap()));
 459 }
 460
 461 // The first LZW codes in the image are invalid values that try to create a loop
 462 // in the dictionary. Decoding should fail, but not infinitely loop or corrupt memory.
 463 TEST(GIFImageDecoderTest, badInitialCode)
 464 {
 465     RefPtr<SharedBuffer> testData = readFile("/Source/platform/image-decoders/testing/bad-initial-code.gif");
 466     ASSERT_TRUE(testData.get());
 467
 468     OwnPtr<GIFImageDecoder> testDecoder(createDecoder());
 469     testDecoder->setData(testData.get(), true);
 470     EXPECT_EQ(1u, testDecoder->frameCount());
 471     ASSERT_TRUE(testDecoder->frameBufferAtIndex(0));
 472     EXPECT_TRUE(testDecoder->failed());
 473 }
 474
 475 // The image has an invalid LZW code that exceeds dictionary size. Decoding should fail.
 476 TEST(GIFImageDecoderTest, badCode)
 477 {
 478     RefPtr<SharedBuffer> testData = readFile("/Source/platform/image-decoders/testing/bad-code.gif");
 479     ASSERT_TRUE(testData.get());
 480
 481     OwnPtr<GIFImageDecoder> testDecoder(createDecoder());
 482     testDecoder->setData(testData.get(), true);
 483     EXPECT_EQ(1u, testDecoder->frameCount());
 484     ASSERT_TRUE(testDecoder->frameBufferAtIndex(0));
 485     EXPECT_TRUE(testDecoder->failed());
 486 }
 487
 488 TEST(GIFImageDecoderTest, invalidDisposalMethod)
 489 {
 490     OwnPtr<GIFImageDecoder> decoder = createDecoder();
 491
 492     // The image has 2 frames, with disposal method 4 and 5, respectively.
 493     RefPtr<SharedBuffer> data = readFile("/Source/web/tests/data/invalid-disposal-method.gif");
 494     ASSERT_TRUE(data.get());
 495     decoder->setData(data.get(), true);
 496
 497     EXPECT_EQ(2u, decoder->frameCount());
 498     // Disposal method 4 is converted to ImageFrame::DisposeOverwritePrevious.
 499     EXPECT_EQ(ImageFrame::DisposeOverwritePrevious, decoder->frameBufferAtIndex(0)->disposalMethod());
 500     // Disposal method 5 is ignored.
 501     EXPECT_EQ(ImageFrame::DisposeNotSpecified, decoder->frameBufferAtIndex(1)->disposalMethod());
 502 }