gecko-dev/image/ISurfaceProvider.h

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/* -*- Mode: C++; tab-width: 2; 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/. */
/**
* An interface for objects which can either store a surface or dynamically
* generate one, and various implementations.
*/
#ifndef mozilla_image_ISurfaceProvider_h
#define mozilla_image_ISurfaceProvider_h
#include "mozilla/Maybe.h"
#include "mozilla/NotNull.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/Variant.h"
#include "mozilla/gfx/2D.h"
#include "imgFrame.h"
#include "SurfaceCache.h"
namespace mozilla {
namespace image {
class CachedSurface;
/**
* An interface for objects which can either store a surface or dynamically
* generate one.
*/
class ISurfaceProvider
{
public:
// Subclasses may or may not be XPCOM classes, so we just require that they
// implement AddRef and Release.
NS_IMETHOD_(MozExternalRefCountType) AddRef() = 0;
NS_IMETHOD_(MozExternalRefCountType) Release() = 0;
/// @return a drawable reference to a surface.
virtual DrawableFrameRef DrawableRef() = 0;
/// @return true if DrawableRef() will return a completely decoded surface.
virtual bool IsFinished() const = 0;
/// @return the number of bytes of memory this ISurfaceProvider is expected to
/// require. Optimizations may result in lower real memory usage. Trivial
/// overhead is ignored.
virtual size_t LogicalSizeInBytes() const = 0;
/// @return the availability state of this ISurfaceProvider, which indicates
/// whether DrawableRef() could successfully return a surface. Should only be
/// called from SurfaceCache code as it relies on SurfaceCache for
/// synchronization.
AvailabilityState& Availability() { return mAvailability; }
const AvailabilityState& Availability() const { return mAvailability; }
protected:
explicit ISurfaceProvider(AvailabilityState aAvailability)
: mAvailability(aAvailability)
{ }
virtual ~ISurfaceProvider() { }
/// @return true if this ISurfaceProvider is locked. (@see SetLocked())
/// Should only be called from SurfaceCache code as it relies on SurfaceCache
/// for synchronization.
virtual bool IsLocked() const = 0;
/// If @aLocked is true, hint that this ISurfaceProvider is in use and it
/// should avoid releasing its resources. Should only be called from
/// SurfaceCache code as it relies on SurfaceCache for synchronization.
virtual void SetLocked(bool aLocked) = 0;
private:
friend class CachedSurface;
AvailabilityState mAvailability;
};
/**
* An ISurfaceProvider that stores a single surface.
*/
class SimpleSurfaceProvider final : public ISurfaceProvider
{
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SimpleSurfaceProvider, override)
explicit SimpleSurfaceProvider(NotNull<imgFrame*> aSurface)
: ISurfaceProvider(AvailabilityState::StartAvailable())
, mSurface(aSurface)
{ }
DrawableFrameRef DrawableRef() override { return mSurface->DrawableRef(); }
bool IsFinished() const override { return mSurface->IsFinished(); }
size_t LogicalSizeInBytes() const override
{
gfx::IntSize size = mSurface->GetSize();
return size.width * size.height * mSurface->GetBytesPerPixel();
}
protected:
bool IsLocked() const override { return bool(mLockRef); }
void SetLocked(bool aLocked) override
{
if (aLocked == IsLocked()) {
return; // Nothing changed.
}
// If we're locked, hold a DrawableFrameRef to |mSurface|, which will keep
// any volatile buffer it owns in memory.
mLockRef = aLocked ? mSurface->DrawableRef()
: DrawableFrameRef();
}
private:
virtual ~SimpleSurfaceProvider() { }
NotNull<RefPtr<imgFrame>> mSurface;
DrawableFrameRef mLockRef;
};
} // namespace image
} // namespace mozilla
#endif // mozilla_image_ISurfaceProvider_h