gecko-dev/gfx/layers/PersistentBufferProvider.h

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/* -*- 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 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/LayersTypes.h"
#include "mozilla/layers/CompositableForwarder.h"
#include "mozilla/gfx/Types.h"
namespace mozilla {
namespace layers {
class CopyableCanvasLayer;
/**
* 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:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProvider)
virtual ~PersistentBufferProvider() { }
virtual LayersBackend GetType() { return LayersBackend::LAYERS_NONE; }
/**
* 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
* ReturnAndUseDT.
*/
virtual already_AddRefed<gfx::DrawTarget> GetDT(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 ReturnAndUseDT(already_AddRefed<gfx::DrawTarget> aDT) = 0;
virtual already_AddRefed<gfx::SourceSurface> GetSnapshot() = 0;
protected:
};
class PersistentBufferProviderBasic : public PersistentBufferProvider
{
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PersistentBufferProviderBasic)
PersistentBufferProviderBasic(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
gfx::BackendType aBackend);
explicit PersistentBufferProviderBasic(gfx::DrawTarget* aTarget) : mDrawTarget(aTarget) {}
bool IsValid() { return !!mDrawTarget; }
virtual LayersBackend GetType() { return LayersBackend::LAYERS_BASIC; }
already_AddRefed<gfx::DrawTarget> GetDT(const gfx::IntRect& aPersistedRect) {
RefPtr<gfx::DrawTarget> dt(mDrawTarget);
return dt.forget();
}
bool ReturnAndUseDT(already_AddRefed<gfx::DrawTarget> aDT) {
RefPtr<gfx::DrawTarget> dt(aDT);
MOZ_ASSERT(mDrawTarget == dt);
return true;
}
virtual already_AddRefed<gfx::SourceSurface> GetSnapshot() { return mDrawTarget->Snapshot(); }
private:
RefPtr<gfx::DrawTarget> mDrawTarget;
};
} // namespace layers
} // namespace mozilla
#endif