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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 MOZILLA_GFX_PersistentBUFFERPROVIDER_H
#define MOZILLA_GFX_PersistentBUFFERPROVIDER_H
#include "mozilla/Assertions.h" // for MOZ_ASSERT, etc
#include "mozilla/RefPtr.h" // for RefPtr, already_AddRefed, etc
#include "mozilla/layers/KnowsCompositor.h"
#include "mozilla/layers/LayersSurfaces.h"
#include "mozilla/layers/LayersTypes.h"
#include "mozilla/RefCounted.h"
#include "mozilla/gfx/Types.h"
#include "mozilla/Vector.h"
#include "mozilla/WeakPtr.h"
namespace mozilla {
class ClientWebGLContext;
namespace gfx {
class SourceSurface;
class DrawTarget;
class DrawTargetWebgl;
} // namespace gfx
namespace layers {
class TextureClient;
/**
* A PersistentBufferProvider is for users which require the temporary use of
* a DrawTarget to draw into. When they're done drawing they return the
* DrawTarget, when they later need to continue drawing they get a DrawTarget
* from the provider again, the provider will guarantee the contents of the
* previously returned DrawTarget is persisted into the one newly returned.
*/
class PersistentBufferProvider : public RefCounted<PersistentBufferProvider>,
public SupportsWeakPtr {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProvider)
virtual ~PersistentBufferProvider() = default;
virtual bool IsShared() const { return false; }
virtual bool IsAccelerated() const { return false; }
/**
* Get a DrawTarget from the PersistentBufferProvider.
*
* \param aPersistedRect This indicates the area of the DrawTarget that needs
* to have remained the same since the call to
* ReturnDrawTarget.
*/
virtual already_AddRefed<gfx::DrawTarget> BorrowDrawTarget(
const gfx::IntRect& aPersistedRect) = 0;
/**
* Return a DrawTarget to the PersistentBufferProvider and indicate the
* contents of this DrawTarget is to be considered current by the
* BufferProvider. The caller should forget any references to the DrawTarget.
*/
virtual bool ReturnDrawTarget(already_AddRefed<gfx::DrawTarget> aDT) = 0;
virtual already_AddRefed<gfx::SourceSurface> BorrowSnapshot() = 0;
virtual void ReturnSnapshot(
already_AddRefed<gfx::SourceSurface> aSnapshot) = 0;
virtual TextureClient* GetTextureClient() { return nullptr; }
virtual void OnMemoryPressure() {}
virtual void OnShutdown() {}
virtual bool SetKnowsCompositor(KnowsCompositor* aKnowsCompositor) {
return true;
}
virtual void ClearCachedResources() {}
/**
* Return true if this provider preserves the drawing state (clips,
* transforms, etc.) across frames. In practice this means users of the
* provider can skip popping all of the clips at the end of the frames and
* pushing them back at the beginning of the following frames, which can be
* costly (cf. bug 1294351).
*/
virtual bool PreservesDrawingState() const = 0;
/**
* Whether or not the provider should be recreated, such as when profiling
* heuristics determine this type of provider is no longer advantageous to
* use.
*/
virtual bool RequiresRefresh() const { return false; }
/**
* Provide a WebGL front buffer for compositing, if available.
*/
virtual Maybe<layers::SurfaceDescriptor> GetFrontBuffer() {
return Nothing();
}
};
class PersistentBufferProviderBasic : public PersistentBufferProvider {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProviderBasic,
override)
static already_AddRefed<PersistentBufferProviderBasic> Create(
gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
gfx::BackendType aBackend);
explicit PersistentBufferProviderBasic(gfx::DrawTarget* aTarget);
already_AddRefed<gfx::DrawTarget> BorrowDrawTarget(
const gfx::IntRect& aPersistedRect) override;
bool ReturnDrawTarget(already_AddRefed<gfx::DrawTarget> aDT) override;
already_AddRefed<gfx::SourceSurface> BorrowSnapshot() override;
void ReturnSnapshot(already_AddRefed<gfx::SourceSurface> aSnapshot) override;
bool PreservesDrawingState() const override { return true; }
void OnShutdown() override { Destroy(); }
protected:
void Destroy();
~PersistentBufferProviderBasic() override;
RefPtr<gfx::DrawTarget> mDrawTarget;
RefPtr<gfx::SourceSurface> mSnapshot;
};
class PersistentBufferProviderAccelerated
: public PersistentBufferProviderBasic {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProviderAccelerated,
override)
explicit PersistentBufferProviderAccelerated(gfx::DrawTarget* aTarget);
bool IsAccelerated() const override { return true; }
Maybe<layers::SurfaceDescriptor> GetFrontBuffer() override;
already_AddRefed<gfx::DrawTarget> BorrowDrawTarget(
const gfx::IntRect& aPersistedRect) override;
bool ReturnDrawTarget(already_AddRefed<gfx::DrawTarget> aDT) override;
already_AddRefed<gfx::SourceSurface> BorrowSnapshot() override;
bool RequiresRefresh() const override;
void OnMemoryPressure() override;
protected:
~PersistentBufferProviderAccelerated() override;
gfx::DrawTargetWebgl* GetDrawTargetWebgl() const;
};
/**
* Provides access to a buffer which can be sent to the compositor without
* requiring a copy.
*/
class PersistentBufferProviderShared : public PersistentBufferProvider,
public ActiveResource {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProviderShared,
override)
static already_AddRefed<PersistentBufferProviderShared> Create(
gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
KnowsCompositor* aKnowsCompositor);
bool IsShared() const override { return true; }
already_AddRefed<gfx::DrawTarget> BorrowDrawTarget(
const gfx::IntRect& aPersistedRect) override;
bool ReturnDrawTarget(already_AddRefed<gfx::DrawTarget> aDT) override;
already_AddRefed<gfx::SourceSurface> BorrowSnapshot() override;
void ReturnSnapshot(already_AddRefed<gfx::SourceSurface> aSnapshot) override;
TextureClient* GetTextureClient() override;
void NotifyInactive() override;
void OnShutdown() override { Destroy(); }
bool SetKnowsCompositor(KnowsCompositor* aKnowsCompositor) override;
void ClearCachedResources() override;
bool PreservesDrawingState() const override { return false; }
protected:
PersistentBufferProviderShared(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
KnowsCompositor* aKnowsCompositor,
RefPtr<TextureClient>& aTexture);
~PersistentBufferProviderShared();
TextureClient* GetTexture(const Maybe<uint32_t>& aIndex);
bool CheckIndex(uint32_t aIndex) { return aIndex < mTextures.length(); }
void Destroy();
gfx::IntSize mSize;
gfx::SurfaceFormat mFormat;
RefPtr<KnowsCompositor> mKnowsCompositor;
// If the texture has its own synchronization then copying back from the
// previous texture can cause contention issues and even deadlocks. So we use
// a separate permanent back buffer and copy into the shared back buffer when
// the DrawTarget is returned, before making it the new front buffer.
RefPtr<TextureClient> mPermanentBackBuffer;
static const size_t kMaxTexturesAllowed = 5;
Vector<RefPtr<TextureClient>, kMaxTexturesAllowed + 2> mTextures;
// Offset of the texture in mTextures that the canvas uses.
Maybe<uint32_t> mBack;
// Offset of the texture in mTextures that is presented to the compositor.
Maybe<uint32_t> mFront;
RefPtr<gfx::DrawTarget> mDrawTarget;
RefPtr<gfx::SourceSurface> mSnapshot;
size_t mMaxAllowedTextures = kMaxTexturesAllowed;
};
struct AutoReturnSnapshot final {
PersistentBufferProvider* mBufferProvider;
RefPtr<gfx::SourceSurface>* mSnapshot;
explicit AutoReturnSnapshot(PersistentBufferProvider* aProvider = nullptr)
: mBufferProvider(aProvider), mSnapshot(nullptr) {}
~AutoReturnSnapshot() {
if (mBufferProvider) {
mBufferProvider->ReturnSnapshot(mSnapshot ? mSnapshot->forget()
: nullptr);
}
}
};
} // namespace layers
} // namespace mozilla
#endif