WebKit Merge 39143:39309, Part 8 (port side)

Review URL: http://codereview.chromium.org/14140

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@7040 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 85 insertions, 9 deletions

diff --git a/webkit/port/platform/graphics/skia/BitmapImageSingleFrameSkia.h b/webkit/port/platform/graphics/skia/BitmapImageSingleFrameSkia.h
index 2ec3fbd..74ac230 100644
--- a/webkit/port/platform/graphics/skia/BitmapImageSingleFrameSkia.h
+++ b/webkit/port/platform/graphics/skia/BitmapImageSingleFrameSkia.h
@@ -33,7 +33,7 @@ public:
     }
 
     // Do nothing, as we only have the one representation of data (decoded).
-    virtual void destroyDecodedData(bool, bool preserveNearbyFrames = false) { }
+    virtual void destroyDecodedData(bool destroyAll = true) { }
 
     virtual unsigned decodedSize() const
     {
diff --git a/webkit/port/platform/graphics/skia/ImageSourceSkia.cpp b/webkit/port/platform/graphics/skia/ImageSourceSkia.cpp
index 95a335d..af5bb82 100644
--- a/webkit/port/platform/graphics/skia/ImageSourceSkia.cpp
+++ b/webkit/port/platform/graphics/skia/ImageSourceSkia.cpp
@@ -92,13 +92,19 @@ ImageSource::ImageSource()
 
 ImageSource::~ImageSource()
 {
-    clear();
+    clear(true);
 }
 
-void ImageSource::clear()
+void ImageSource::clear(bool destroyAll, size_t clearBeforeFrame)
 {
-    delete m_decoder;
-    m_decoder = 0;
+    if (destroyAll) {
+        delete m_decoder;
+        m_decoder = 0;
+        return;
+    }
+
+    if (m_decoder)
+        m_decoder->clearFrameBufferCache(clearBeforeFrame);
 }
 
 bool ImageSource::initialized() const
@@ -229,4 +235,10 @@ void ImageSourceSkia::setData(SharedBuffer* data,
     ImageSource::setData(data, allDataReceived);
 }
 
+String ImageSource::filenameExtension() const
+{
+    // TODO(pkasting): Implement me!
+    return String();
+}
+
 }
diff --git a/webkit/port/platform/image-decoders/ImageDecoder.h b/webkit/port/platform/image-decoders/ImageDecoder.h
index c4b6e20..f13c055 100644
--- a/webkit/port/platform/image-decoders/ImageDecoder.h
+++ b/webkit/port/platform/image-decoders/ImageDecoder.h
@@ -119,6 +119,14 @@ public:
         return *this;
     }
 
+    void clear() {
+      m_bitmapRef = RefCountedNativeImageSkia::create();
+      m_rect = IntRect();
+      m_status = FrameEmpty;
+      m_duration = 0;
+      m_disposalMethod = DisposeNotSpecified;
+    }
+
     // This function creates a new copy of the image data in |other|, so the
     // two images can be modified independently.
     void copyBitmapData(const RGBA32Buffer& other) {
@@ -257,6 +265,14 @@ public:
     bool failed() const { return m_failed; }
     void setFailed() { m_failed = true; }
 
+    // Wipe out frames in the frame buffer cache before |clearBeforeFrame|,
+    // assuming this can be done without breaking decoding.  Different decoders
+    // place different restrictions on what frames are safe to destroy, so this
+    // is left to them to implement.
+    // For convenience's sake, we provide a default (empty) implementation,
+    // since in practice only GIFs will ever use this.
+    virtual void clearFrameBufferCache(size_t clearBeforeFrame) { }
+
 protected:
     // Called by the image decoders to set their decoded size, this also check
     // the size for validity. It will return true if the size was set, or false
diff --git a/webkit/port/platform/image-decoders/gif/GIFImageDecoder.cpp b/webkit/port/platform/image-decoders/gif/GIFImageDecoder.cpp
index 678e080..6bc4133 100644
--- a/webkit/port/platform/image-decoders/gif/GIFImageDecoder.cpp
+++ b/webkit/port/platform/image-decoders/gif/GIFImageDecoder.cpp
@@ -157,9 +157,18 @@ int GIFImageDecoder::repetitionCount() const
     // packets sent back by the webserver) not always.  Our caller is
     // responsible for waiting until image decoding has finished to ask this if
     // it needs an authoritative answer.  In the meantime, we should default to
-    // "loop once", both in the reader and here.
-    if (m_reader)
-        m_repetitionCount = m_reader->repetitionCount();
+    // "loop once".
+    if (m_reader) {
+        // Added wrinkle: ImageSource::clear() may destroy the reader, making
+        // the result from the reader _less_ authoritative on future calls.  To
+        // detect this, the reader returns cLoopCountNotSeen (-2) instead of
+        // cAnimationLoopOnce (-1) when its current incarnation hasn't actually
+        // seen a loop count yet; in this case we return our previously-cached
+        // value.
+        const int repetitionCount = m_reader->repetitionCount();
+        if (repetitionCount != cLoopCountNotSeen)
+            m_repetitionCount = repetitionCount;
+    }
     return m_repetitionCount;
 }
 
@@ -175,6 +184,40 @@ RGBA32Buffer* GIFImageDecoder::frameBufferAtIndex(size_t index)
     return &frame;
 }
 
+void GIFImageDecoder::clearFrameBufferCache(size_t clearBeforeFrame)
+{
+    // In some cases, like if the decoder was destroyed while animating, we
+    // can be asked to clear more frames than we currently have.
+    if (m_frameBufferCache.isEmpty())
+        return;  // Nothing to do.
+    // The "-1" here is tricky.  It does not mean that |clearBeforeFrame| is the
+    // last frame we wish to preserve, but rather that we never want to clear
+    // the very last frame in the cache: it's empty (so clearing it is
+    // pointless), it's partial (so we don't want to clear it anyway), or the
+    // cache could be enlarged with a future setData() call and it could be
+    // needed to construct the next frame (see comments below).  Callers can
+    // always use ImageSource::clear(true, ...) to completely free the memory in
+    // this case.
+    clearBeforeFrame = std::min(clearBeforeFrame, m_frameBufferCache.size() - 1);
+    const Vector<RGBA32Buffer>::iterator end(m_frameBufferCache.begin() + clearBeforeFrame);
+    for (Vector<RGBA32Buffer>::iterator i(m_frameBufferCache.begin()); i != end; ++i) {
+        if (i->status() == RGBA32Buffer::FrameEmpty)
+            continue;  // Nothing to do.
+
+        // The layout of frames is:
+        // [empty frames][complete frames][partial frame][empty frames]
+        // ...where each of these groups may be empty.  We should not clear a
+        // partial frame since that's what's being decoded right now, and we
+        // also should not clear the last complete frame, since it may be needed
+        // when constructing the next frame.  Note that "i + 1" is safe since
+        // i < end < m_frameBufferCache.end().
+        if ((i->status() == RGBA32Buffer::FramePartial) || ((i + 1)->status() != RGBA32Buffer::FrameComplete))
+            break;
+
+        i->clear();
+    }
+}
+
 // Feed data to the GIF reader.
 void GIFImageDecoder::decode(GIFQuery query, unsigned haltAtFrame) const
 {
@@ -232,6 +275,7 @@ bool GIFImageDecoder::initFrameBuffer(unsigned frameIndex)
         // first frame specifies this method, it will get treated like
         // DisposeOverwriteBgcolor below and reset to a completely empty image.)
         const RGBA32Buffer* prevBuffer = &m_frameBufferCache[--frameIndex];
+        ASSERT(prevBuffer->status() == RGBA32Buffer::FrameComplete);
         RGBA32Buffer::FrameDisposalMethod prevMethod =
             prevBuffer->disposalMethod();
         while ((frameIndex > 0) &&
diff --git a/webkit/port/platform/image-decoders/gif/GIFImageDecoder.h b/webkit/port/platform/image-decoders/gif/GIFImageDecoder.h
index a93f7c1..a8b16df 100644
--- a/webkit/port/platform/image-decoders/gif/GIFImageDecoder.h
+++ b/webkit/port/platform/image-decoders/gif/GIFImageDecoder.h
@@ -54,6 +54,8 @@ public:
 
     virtual RGBA32Buffer* frameBufferAtIndex(size_t index);
 
+    virtual void clearFrameBufferCache(size_t clearBeforeFrame);
+
     virtual unsigned frameDurationAtIndex(size_t index) { return 0; }
 
     enum GIFQuery { GIFFullQuery, GIFSizeQuery, GIFFrameCountQuery };
diff --git a/webkit/port/platform/image-decoders/gif/GIFImageReader.h b/webkit/port/platform/image-decoders/gif/GIFImageReader.h
index c05c80b..09d15ea 100644
--- a/webkit/port/platform/image-decoders/gif/GIFImageReader.h
+++ b/webkit/port/platform/image-decoders/gif/GIFImageReader.h
@@ -47,6 +47,8 @@
 #define MAX_COLORS           256
 #define MAX_HOLD_SIZE        256
 
+const int cLoopCountNotSeen = -2;
+
 /* gif2.h  
    The interface for the GIF87/89a decoder. 
 */
@@ -187,7 +189,7 @@ struct GIFImageReader {
         screen_bgcolor = version = 0;
         screen_width = screen_height = 0;
         global_colormap_size = images_decoded = images_count = 0;
-        loop_count = -1;
+        loop_count = cLoopCountNotSeen;
         count = 0;
     }