Decode GIF image frames on demand.

Source/WebKit/chromium/tests/ImageDecoderTest.cpp

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include "core/platform/image-decoders/ImageDecoder.h"
+
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+#include "wtf/Vector.h"
+#include <gtest/gtest.h>
+
+using namespace WebCore;
+
+class TestImageDecoder : public ImageDecoder {
+public:
+    TestImageDecoder()
+        : ImageDecoder(ImageSource::AlphaNotPremultiplied, ImageSource::GammaAndColorProfileApplied)
+    {
+    }
+
+    virtual String filenameExtension() const OVERRIDE { return ""; }
+    virtual ImageFrame* frameBufferAtIndex(size_t) OVERRIDE { return 0; }
+
+    size_t findRequiredPreviousFrame(size_t frameIndex)
+    {
+        return ImageDecoder::findRequiredPreviousFrame(frameIndex);
+    }
+
+    Vector<ImageFrame, 1>& frameBufferCache()
+    {
+        return m_frameBufferCache;
+    }
+
+    void resetRequiredPreviousFrames()
+    {
+        for (size_t i = 0; i < m_frameBufferCache.size(); ++i)
+            m_frameBufferCache[i].setRequiredPreviousFrameIndex(findRequiredPreviousFrame(i));
+    }
+};
+
+TEST(ImageDecoderTest, findRequiredPreviousFrame)
+{
+    OwnPtr<TestImageDecoder> decoder(adoptPtr(new TestImageDecoder()));
+    Vector<ImageFrame, 1>& decoderFrameBufferCache = decoder->frameBufferCache();
+
+    const size_t numFrames = 6;
+    const unsigned defaultWidth = 100;
+    const unsigned defaultHeight = 100;
+    decoder->setSize(defaultWidth, defaultHeight);
+    decoderFrameBufferCache.resize(numFrames);
+    for (size_t i = 0; i < numFrames; ++i)
+        decoderFrameBufferCache[i].setOriginalFrameRect(IntRect(0, 0, defaultWidth, defaultHeight));
+
+    decoderFrameBufferCache[1].setDisposalMethod(ImageFrame::DisposeKeep);
+    decoderFrameBufferCache[2].setDisposalMethod(ImageFrame::DisposeOverwritePrevious);
+    decoderFrameBufferCache[3].setDisposalMethod(ImageFrame::DisposeOverwritePrevious);
+    decoderFrameBufferCache[4].setDisposalMethod(ImageFrame::DisposeKeep);
+
+    // The first frame doesn't require any previous frame.
+    EXPECT_EQ(notFound, decoder->findRequiredPreviousFrame(0));
+    // The previous DisposeNotSpecified frame is required.
+    EXPECT_EQ(0u, decoder->findRequiredPreviousFrame(1));
+    // DisposeKeep is treated as DisposeNotSpecified.
+    EXPECT_EQ(1u, decoder->findRequiredPreviousFrame(2));
+    // Previous DisposeOverwritePrevious frames are skipped.
+    EXPECT_EQ(1u, decoder->findRequiredPreviousFrame(3));
+    EXPECT_EQ(1u, decoder->findRequiredPreviousFrame(4));
+    EXPECT_EQ(4u, decoder->findRequiredPreviousFrame(5));
+
+    // Fully covering DisposeOverwriteBgcolor previous frame resets the starting state.
+    decoderFrameBufferCache[1].setDisposalMethod(ImageFrame::DisposeOverwriteBgcolor);

[Alpha Left Google, 2013/05/22 20:18:09]

I suggest this be a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    EXPECT_EQ(notFound, decoder->findRequiredPreviousFrame(2));
+
+    // DisposeOverwritePrevious of the first frame is treated as DisposeOverwriteBgcolor.

[Alpha Left Google, 2013/05/22 20:18:09]

I suggest this be a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    decoderFrameBufferCache[0].setDisposalMethod(ImageFrame::DisposeOverwritePrevious);
+    EXPECT_EQ(notFound, decoder->findRequiredPreviousFrame(1));
+    decoderFrameBufferCache[0].setDisposalMethod(ImageFrame::DisposeOverwriteBgcolor);
+    EXPECT_EQ(notFound, decoder->findRequiredPreviousFrame(1));
+
+    // Partially converting DisposeOverriteBgcolor previous frame is treated DisposeKeep.

[Alpha Left Google, 2013/05/22 20:18:09]

nit: I can't parse this sentence please rewrite it.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    decoderFrameBufferCache[1].setOriginalFrameRect(IntRect(50, 50, 50, 50));

[Alpha Left Google, 2013/05/22 20:18:09]

I suggest this be a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    EXPECT_EQ(1u, decoder->findRequiredPreviousFrame(2));
+

[Alpha Left Google, 2013/05/22 20:18:09]

Please add a condition that a DisposeKeep or DisposeUnspecified and doesn't have
alpha will also reset the starting state.

[Xianzhu, 2013/05/22 23:43:29]

This will be tested in GIFImageDecoderTest because the status is updated after
decoding.

+    // The above rule doesn't apply if the previous frame is the first frame.
+    decoderFrameBufferCache[0].setOriginalFrameRect(IntRect(50, 50, 50, 50));
+    EXPECT_EQ(notFound, decoder->findRequiredPreviousFrame(1));
+}
+
+TEST(ImageDecoderTest, clearFrameBufferCache)
+{
+    OwnPtr<TestImageDecoder> decoder(adoptPtr(new TestImageDecoder()));
+    Vector<ImageFrame, 1>& decoderFrameBufferCache = decoder->frameBufferCache();
+
+    const unsigned defaultWidth = 100;
+    const unsigned defaultHeight = 100;
+    decoder->setSize(defaultWidth, defaultHeight);
+
+    // This should no nothing.

[Alpha Left Google, 2013/05/22 20:18:09]

nit: do

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    decoder->clearFrameBufferCache(0);
+
+    const size_t numFrames = 20;
+    decoderFrameBufferCache.resize(numFrames);
+    for (size_t i = 0; i < numFrames; ++i) {
+        decoderFrameBufferCache[i].setOriginalFrameRect(IntRect(0, 0, defaultWidth, defaultHeight));
+        decoderFrameBufferCache[i].setStatus(ImageFrame::FrameComplete);
+    }
+
+    decoderFrameBufferCache[9].setStatus(ImageFrame::FramePartial);
+    decoder->resetRequiredPreviousFrames();
+
+    decoder->clearFrameBufferCache(7);
+    // Should preserve the the clearExceptFrame.
+    EXPECT_EQ(ImageFrame::FrameComplete, decoderFrameBufferCache[7].status());
+    // Should preserve non-completed frames.
+    EXPECT_EQ(ImageFrame::FramePartial, decoderFrameBufferCache[9].status());

[Alpha Left Google, 2013/05/22 20:18:09]

The test only clear (7) which doesn't cover 9 anyway. I'd suggest moving this to
a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    // All other frames should be cleared.
+    for (size_t i = 0; i < numFrames; ++i) {
+        if (i != 7 && i != 9)
+            EXPECT_EQ(ImageFrame::FrameEmpty, decoderFrameBufferCache[i].status());

[Alpha Left Google, 2013/05/22 20:18:09]

nit: If this expect fails it's not clear from the log which frame fails, I'd
suggest you check that [7] and [9] are non empty and when check every other is
empty.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    }
+
+    // Repeated clearFrameBufferCache should not change the state.

[Alpha Left Google, 2013/05/22 20:18:09]

This should be a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+    decoder->resetRequiredPreviousFrames();
+    Vector<ImageFrame, 1> oldFrameBufferCache = decoderFrameBufferCache;
+    decoder->clearFrameBufferCache(7);
+    for (size_t i = 0; i < numFrames; ++i)
+        EXPECT_EQ(oldFrameBufferCache[i].status(), decoderFrameBufferCache[i].status());
+
+    decoderFrameBufferCache[5].setStatus(ImageFrame::FrameComplete);
+    decoderFrameBufferCache[7].setDisposalMethod(ImageFrame::DisposeOverwritePrevious);
+    decoderFrameBufferCache[8].setDisposalMethod(ImageFrame::DisposeOverwritePrevious);
+    decoderFrameBufferCache[9].clearPixelData();
+    decoder->resetRequiredPreviousFrames();
+
+    decoder->clearFrameBufferCache(9);
+    // Should preserve the frame that is required to decode the clearExceptFrame.
+    EXPECT_EQ(ImageFrame::FrameComplete, decoderFrameBufferCache[5].status());
+
+    // This should not crash.
+    decoder->clearFrameBufferCache(notFound);

[Alpha Left Google, 2013/05/22 20:18:09]

This should be a separate test case.

[Xianzhu, 2013/05/22 23:43:29]

Done.

+}