1 files changed, 165 insertions, 0 deletions
diff --git a/gfx/thebes/gfxBaseSharedMemorySurface.h b/gfx/thebes/gfxBaseSharedMemorySurface.h
new file mode 100644
index 0000000000..bf211edab5
--- /dev/null
+++ b/gfx/thebes/gfxBaseSharedMemorySurface.h
@@ -0,0 +1,165 @@
+// vim:set ts=4 sts=2 sw=2 et cin:
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_SHARED_MEMORYSURFACE_H
+#define GFX_SHARED_MEMORYSURFACE_H
+
+#include "mozilla/gfx/2D.h"
+#include "mozilla/ipc/Shmem.h"
+#include "mozilla/ipc/SharedMemory.h"
+
+#include "gfxASurface.h"
+#include "gfxImageSurface.h"
+#include "pratom.h"
+
+typedef struct _cairo_user_data_key cairo_user_data_key_t;
+
+struct SharedImageInfo {
+  int32_t width;
+  int32_t height;
+  gfxImageFormat format;
+  int32_t readCount;
+};
+
+inline SharedImageInfo* GetShmInfoPtr(const mozilla::ipc::Shmem& aShmem) {
+  return reinterpret_cast<SharedImageInfo*>(
+      aShmem.get<char>() + aShmem.Size<char>() - sizeof(SharedImageInfo));
+}
+
+extern const cairo_user_data_key_t SHM_KEY;
+
+template <typename Base, typename Sub>
+class gfxBaseSharedMemorySurface : public Base {
+  typedef mozilla::ipc::SharedMemory SharedMemory;
+  typedef mozilla::ipc::Shmem Shmem;
+
+ protected:
+  virtual ~gfxBaseSharedMemorySurface() {
+    MOZ_COUNT_DTOR(gfxBaseSharedMemorySurface);
+  }
+
+ public:
+  /**
+   * Return a new gfxSharedImageSurface around a shmem segment newly
+   * allocated by this function.  |aAllocator| is the object used to
+   * allocate the new shmem segment.  Null is returned if creating
+   * the surface failed.
+   *
+   * NB: the *caller* is responsible for freeing the Shmem allocated
+   * by this function.
+   */
+  template <class ShmemAllocator>
+  static already_AddRefed<Sub> Create(ShmemAllocator* aAllocator,
+                                      const mozilla::gfx::IntSize& aSize,
+                                      gfxImageFormat aFormat) {
+    return Create<ShmemAllocator, false>(aAllocator, aSize, aFormat);
+  }
+
+  /**
+   * Return a new gfxSharedImageSurface that wraps a shmem segment
+   * already created by the Create() above.  Bad things will happen
+   * if an attempt is made to wrap any other shmem segment.  Null is
+   * returned if creating the surface failed.
+   */
+  static already_AddRefed<Sub> Open(const Shmem& aShmem) {
+    SharedImageInfo* shmInfo = GetShmInfoPtr(aShmem);
+    mozilla::gfx::IntSize size(shmInfo->width, shmInfo->height);
+    if (!mozilla::gfx::Factory::CheckSurfaceSize(size)) return nullptr;
+
+    gfxImageFormat format = shmInfo->format;
+    long stride = gfxImageSurface::ComputeStride(size, format);
+
+    RefPtr<Sub> s = new Sub(size, stride, format, aShmem);
+    // We didn't create this Shmem and so don't free it on errors
+    return (s->CairoStatus() != 0) ? nullptr : s.forget();
+  }
+
+  template <class ShmemAllocator>
+  static already_AddRefed<Sub> CreateUnsafe(ShmemAllocator* aAllocator,
+                                            const mozilla::gfx::IntSize& aSize,
+                                            gfxImageFormat aFormat) {
+    return Create<ShmemAllocator, true>(aAllocator, aSize, aFormat);
+  }
+
+  Shmem& GetShmem() { return mShmem; }
+
+  static bool IsSharedImage(gfxASurface* aSurface) {
+    return (aSurface && aSurface->GetType() == gfxSurfaceType::Image &&
+            aSurface->GetData(&SHM_KEY));
+  }
+
+ protected:
+  gfxBaseSharedMemorySurface(const mozilla::gfx::IntSize& aSize, long aStride,
+                             gfxImageFormat aFormat, const Shmem& aShmem)
+      : Base(aShmem.get<unsigned char>(), aSize, aStride, aFormat) {
+    MOZ_COUNT_CTOR(gfxBaseSharedMemorySurface);
+
+    mShmem = aShmem;
+    this->SetData(&SHM_KEY, this, nullptr);
+  }
+
+ private:
+  void WriteShmemInfo() {
+    SharedImageInfo* shmInfo = GetShmInfoPtr(mShmem);
+    shmInfo->width = this->mSize.width;
+    shmInfo->height = this->mSize.height;
+    shmInfo->format = this->mFormat;
+    shmInfo->readCount = 0;
+  }
+
+  int32_t ReadLock() {
+    SharedImageInfo* shmInfo = GetShmInfoPtr(mShmem);
+    return PR_ATOMIC_INCREMENT(&shmInfo->readCount);
+  }
+
+  int32_t ReadUnlock() {
+    SharedImageInfo* shmInfo = GetShmInfoPtr(mShmem);
+    return PR_ATOMIC_DECREMENT(&shmInfo->readCount);
+  }
+
+  int32_t GetReadCount() {
+    SharedImageInfo* shmInfo = GetShmInfoPtr(mShmem);
+    return shmInfo->readCount;
+  }
+
+  static size_t GetAlignedSize(const mozilla::gfx::IntSize& aSize,
+                               long aStride) {
+#define MOZ_ALIGN_WORD(x) (((x) + 3) & ~3)
+    return MOZ_ALIGN_WORD(sizeof(SharedImageInfo) + aSize.height * aStride);
+  }
+
+  template <class ShmemAllocator, bool Unsafe>
+  static already_AddRefed<Sub> Create(ShmemAllocator* aAllocator,
+                                      const mozilla::gfx::IntSize& aSize,
+                                      gfxImageFormat aFormat) {
+    if (!mozilla::gfx::Factory::CheckSurfaceSize(aSize)) return nullptr;
+
+    Shmem shmem;
+    long stride = gfxImageSurface::ComputeStride(aSize, aFormat);
+    size_t size = GetAlignedSize(aSize, stride);
+    if (!Unsafe) {
+      if (!aAllocator->AllocShmem(size, &shmem)) return nullptr;
+    } else {
+      if (!aAllocator->AllocUnsafeShmem(size, &shmem)) return nullptr;
+    }
+
+    RefPtr<Sub> s = new Sub(aSize, stride, aFormat, shmem);
+    if (s->CairoStatus() != 0) {
+      aAllocator->DeallocShmem(shmem);
+      return nullptr;
+    }
+    s->WriteShmemInfo();
+    return s.forget();
+  }
+
+  Shmem mShmem;
+
+  // Calling these is very bad, disallow it
+  gfxBaseSharedMemorySurface(const gfxBaseSharedMemorySurface&);
+  gfxBaseSharedMemorySurface& operator=(const gfxBaseSharedMemorySurface&);
+};
+
+#endif /* GFX_SHARED_MEMORYSURFACE_H */