gfx/thebes/gfxReusableSharedImageSurfaceWrapper.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   3  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "gfxReusableSharedImageSurfaceWrapper.h"
   6 #include "gfxSharedImageSurface.h"
   7 #include "mozilla/layers/ISurfaceAllocator.h"
   8
   9 using mozilla::ipc::Shmem;
  10 using mozilla::layers::ISurfaceAllocator;
  11
  12 gfxReusableSharedImageSurfaceWrapper::gfxReusableSharedImageSurfaceWrapper(ISurfaceAllocator* aAllocator,
  13                                                                            gfxSharedImageSurface* aSurface)
  14   : mAllocator(aAllocator)
  15   , mSurface(aSurface)
  16 {
  17   MOZ_COUNT_CTOR(gfxReusableSharedImageSurfaceWrapper);
  18   ReadLock();
  19 }
  20
  21 gfxReusableSharedImageSurfaceWrapper::~gfxReusableSharedImageSurfaceWrapper()
  22 {
  23   MOZ_COUNT_DTOR(gfxReusableSharedImageSurfaceWrapper);
  24   ReadUnlock();
  25 }
  26
  27 void
  28 gfxReusableSharedImageSurfaceWrapper::ReadLock()
  29 {
  30   NS_ASSERT_OWNINGTHREAD(gfxReusableSharedImageSurfaceWrapper);
  31   mSurface->ReadLock();
  32 }
  33
  34 void
  35 gfxReusableSharedImageSurfaceWrapper::ReadUnlock()
  36 {
  37   int32_t readCount = mSurface->ReadUnlock();
  38   NS_ABORT_IF_FALSE(readCount >= 0, "Read count should not be negative");
  39
  40   if (readCount == 0) {
  41     mAllocator->DeallocShmem(mSurface->GetShmem());
  42   }
  43 }
  44
  45 gfxReusableSurfaceWrapper*
  46 gfxReusableSharedImageSurfaceWrapper::GetWritable(gfxImageSurface** aSurface)
  47 {
  48   NS_ASSERT_OWNINGTHREAD(gfxReusableSharedImageSurfaceWrapper);
  49
  50   int32_t readCount = mSurface->GetReadCount();
  51   NS_ABORT_IF_FALSE(readCount > 0, "A ReadLock must be held when calling GetWritable");
  52   if (readCount == 1) {
  53     *aSurface = mSurface;
  54     return this;
  55   }
  56
  57   // Something else is reading the surface, copy it
  58   nsRefPtr<gfxSharedImageSurface> copySurface =
  59     gfxSharedImageSurface::CreateUnsafe(mAllocator.get(), mSurface->GetSize(), mSurface->Format());
  60   copySurface->CopyFrom(mSurface);
  61   *aSurface = copySurface;
  62
  63   // We need to create a new wrapper since this wrapper has an external ReadLock
  64   gfxReusableSurfaceWrapper* wrapper = new gfxReusableSharedImageSurfaceWrapper(mAllocator, copySurface);
  65
  66   // No need to release the ReadLock on the surface, this will happen when
  67   // the wrapper is destroyed.
  68
  69   return wrapper;
  70 }
  71
  72 const unsigned char*
  73 gfxReusableSharedImageSurfaceWrapper::GetReadOnlyData() const
  74 {
  75   NS_ABORT_IF_FALSE(mSurface->GetReadCount() > 0, "Should have read lock");
  76   return mSurface->Data();
  77 }
  78
  79 gfxImageFormat
  80 gfxReusableSharedImageSurfaceWrapper::Format()
  81 {
  82   return mSurface->Format();
  83 }
  84
  85 Shmem&
  86 gfxReusableSharedImageSurfaceWrapper::GetShmem()
  87 {
  88   return mSurface->GetShmem();
  89 }
  90
  91 /* static */ already_AddRefed<gfxReusableSharedImageSurfaceWrapper>
  92 gfxReusableSharedImageSurfaceWrapper::Open(ISurfaceAllocator* aAllocator, const Shmem& aShmem)
  93 {
  94   nsRefPtr<gfxSharedImageSurface> sharedImage = gfxSharedImageSurface::Open(aShmem);
  95   nsRefPtr<gfxReusableSharedImageSurfaceWrapper> wrapper = new gfxReusableSharedImageSurfaceWrapper(aAllocator, sharedImage);
  96   wrapper->ReadUnlock();
  97   return wrapper.forget();
  98 }