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      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
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "core/platform/graphics/chromium/DiscardablePixelRef.h"
     28 
     29 #include "public/platform/Platform.h"
     30 #include "wtf/StdLibExtras.h"
     31 
     32 namespace WebCore {
     33 
     34 namespace {
     35 
     36 // URI label for a discardable SkPixelRef.
     37 const char labelDiscardable[] = "discardable";
     38 
     39 } // namespace
     40 
     41 
     42 bool DiscardablePixelRefAllocator::allocPixelRef(SkBitmap* dst, SkColorTable* ctable)
     43 {
     44     // It should not be possible to have a non-null color table in Blink.
     45     ASSERT(!ctable);
     46 
     47     Sk64 size = dst->getSize64();
     48     if (size.isNeg() || !size.is32())
     49         return false;
     50 
     51     SkAutoTUnref<DiscardablePixelRef> pixelRef(new DiscardablePixelRef(adoptPtr(new SkMutex())));
     52     if (pixelRef->allocAndLockDiscardableMemory(size.get32())) {
     53         pixelRef->setURI(labelDiscardable);
     54         dst->setPixelRef(pixelRef.get());
     55         // This method is only called when a DiscardablePixelRef is created to back a SkBitmap.
     56         // It is necessary to lock this SkBitmap to have a valid pointer to pixels. Otherwise,
     57         // this SkBitmap could be assigned to another SkBitmap and locking/unlocking the other
     58         // SkBitmap will make this one losing its pixels.
     59         dst->lockPixels();
     60         return true;
     61     }
     62 
     63     // Fallback to heap allocator if discardable memory is not available.
     64     return dst->allocPixels();
     65 }
     66 
     67 DiscardablePixelRef::DiscardablePixelRef(PassOwnPtr<SkMutex> mutex)
     68     : SkPixelRef(mutex.get())
     69     , m_lockedMemory(0)
     70     , m_mutex(mutex)
     71 {
     72 }
     73 
     74 DiscardablePixelRef::~DiscardablePixelRef()
     75 {
     76 }
     77 
     78 bool DiscardablePixelRef::allocAndLockDiscardableMemory(size_t bytes)
     79 {
     80     m_discardable = adoptPtr(WebKit::Platform::current()->allocateAndLockDiscardableMemory(bytes));
     81     if (m_discardable) {
     82         m_lockedMemory = m_discardable->data();
     83         return true;
     84     }
     85     return false;
     86 }
     87 
     88 void* DiscardablePixelRef::onLockPixels(SkColorTable** ctable)
     89 {
     90     if (!m_lockedMemory && m_discardable->lock())
     91         m_lockedMemory = m_discardable->data();
     92 
     93     *ctable = 0;
     94     return m_lockedMemory;
     95 }
     96 
     97 void DiscardablePixelRef::onUnlockPixels()
     98 {
     99     if (m_lockedMemory)
    100         m_discardable->unlock();
    101     m_lockedMemory = 0;
    102 }
    103 
    104 bool DiscardablePixelRef::isDiscardable(SkPixelRef* pixelRef)
    105 {
    106     // FIXME: DEFINE_STATIC_LOCAL is not thread safe.
    107     // ImageDecodingStore provides the synchronization for this.
    108     DEFINE_STATIC_LOCAL(const SkString, discardable, (labelDiscardable));
    109     return pixelRef && pixelRef->getURI() && discardable.equals(pixelRef->getURI());
    110 }
    111 
    112 } // namespace WebCore
    113