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/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.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;
class DrawableSurface;
/**
* 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 (potentially lazily computed) drawable reference to a surface.
virtual DrawableSurface Surface();
/// @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 actual number of bytes of memory this ISurfaceProvider is
/// using. May vary over the lifetime of the ISurfaceProvider. The default
/// implementation is appropriate for static ISurfaceProviders.
virtual void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
size_t& aHeapSizeOut,
size_t& aNonHeapSizeOut)
{
DrawableFrameRef ref = DrawableRef(/* aFrame = */ 0);
if (!ref) {
return;
}
ref->AddSizeOfExcludingThis(aMallocSizeOf, aHeapSizeOut, aNonHeapSizeOut);
}
/// @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 an eagerly computed drawable reference to a surface. For
/// dynamically generated animation surfaces, @aFrame specifies the 0-based
/// index of the desired frame.
virtual DrawableFrameRef DrawableRef(size_t aFrame) = 0;
/// @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;
friend class DrawableSurface;
AvailabilityState mAvailability;
};
/**
* A reference to a surface (stored in an imgFrame) that holds the surface in
* memory, guaranteeing that it can be drawn. If you have a DrawableSurface
* |surf| and |if (surf)| returns true, then calls to |surf->Draw()| and
* |surf->GetSourceSurface()| are guaranteed to succeed.
*
* Note that the surface may be computed lazily, so a DrawableSurface should not
* be dereferenced (i.e., operator->() should not be called) until you're
* sure that you want to draw it.
*/
class MOZ_STACK_CLASS DrawableSurface final
{
public:
DrawableSurface() : mHaveSurface(false) { }
explicit DrawableSurface(DrawableFrameRef&& aDrawableRef)
: mDrawableRef(Move(aDrawableRef))
, mHaveSurface(bool(mDrawableRef))
{ }
explicit DrawableSurface(NotNull<ISurfaceProvider*> aProvider)
: mProvider(aProvider)
, mHaveSurface(true)
{ }
DrawableSurface(DrawableSurface&& aOther)
: mDrawableRef(Move(aOther.mDrawableRef))
, mProvider(Move(aOther.mProvider))
, mHaveSurface(aOther.mHaveSurface)
{
aOther.mHaveSurface = false;
}
DrawableSurface& operator=(DrawableSurface&& aOther)
{
MOZ_ASSERT(this != &aOther, "Self-moves are prohibited");
mDrawableRef = Move(aOther.mDrawableRef);
mProvider = Move(aOther.mProvider);
mHaveSurface = aOther.mHaveSurface;
aOther.mHaveSurface = false;
return *this;
}
/**
* If this DrawableSurface is dynamically generated from an animation, attempt
* to seek to frame @aFrame, where @aFrame is a 0-based index into the frames
* of the animation. Otherwise, nothing will blow up at runtime, but we assert
* in debug builds, since calling this in an unexpected situation probably
* indicates a bug.
*
* @return a successful result if we could obtain frame @aFrame. Note that
* |mHaveSurface| being true means that we're guaranteed to have *some* frame,
* so the caller can dereference this DrawableSurface even if Seek() fails,
* but while nothing will blow up, the frame won't be the one they expect.
*/
nsresult Seek(size_t aFrame)
{
MOZ_ASSERT(mHaveSurface, "Trying to seek an empty DrawableSurface?");
if (!mProvider) {
MOZ_ASSERT_UNREACHABLE("Trying to seek a static DrawableSurface?");
return NS_ERROR_FAILURE;
}
mDrawableRef = mProvider->DrawableRef(aFrame);
return mDrawableRef ? NS_OK : NS_ERROR_FAILURE;
}
explicit operator bool() const { return mHaveSurface; }
imgFrame* operator->() { return DrawableRef().get(); }
private:
DrawableSurface(const DrawableSurface& aOther) = delete;
DrawableSurface& operator=(const DrawableSurface& aOther) = delete;
DrawableFrameRef& DrawableRef()
{
MOZ_ASSERT(mHaveSurface);
// If we weren't created with a DrawableFrameRef directly, we should've been
// created with an ISurfaceProvider which can give us one. Note that if
// Seek() has been called, we'll already have a DrawableFrameRef, so we
// won't need to get one here.
if (!mDrawableRef) {
MOZ_ASSERT(mProvider);
mDrawableRef = mProvider->DrawableRef(/* aFrame = */ 0);
}
MOZ_ASSERT(mDrawableRef);
return mDrawableRef;
}
DrawableFrameRef mDrawableRef;
RefPtr<ISurfaceProvider> mProvider;
bool mHaveSurface;
};
// Surface() is implemented here so that DrawableSurface's definition is
// visible. This default implementation eagerly obtains a DrawableFrameRef for
// the first frame and is intended for static ISurfaceProviders.
inline DrawableSurface
ISurfaceProvider::Surface()
{
return DrawableSurface(DrawableRef(/* aFrame = */ 0));
}
/**
* 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)
{ }
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:
DrawableFrameRef DrawableRef(size_t aFrame) override
{
MOZ_ASSERT(aFrame == 0,
"Requesting an animation frame from a SimpleSurfaceProvider?");
return mSurface->DrawableRef();
}
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