1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/thebes/gfxReusableSurfaceWrapper.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,89 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.6 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#ifndef GFXCOWSURFACEWRAPPER
1.9 +#define GFXCOWSURFACEWRAPPER
1.10 +
1.11 +#include "gfxImageSurface.h"
1.12 +#include "nsISupportsImpl.h"
1.13 +#include "nsAutoPtr.h"
1.14 +
1.15 +
1.16 +/**
1.17 + * Provides an interface to implement a cross thread/process wrapper for a
1.18 + * gfxImageSurface that has copy-on-write semantics.
1.19 + *
1.20 + * Only the owner thread can write to the surface and acquire
1.21 + * read locks. Destroying a gfxReusableSurfaceWrapper releases
1.22 + * a read lock.
1.23 + *
1.24 + * OMTC Usage:
1.25 + * 1) Content creates a writable copy of this surface
1.26 + * wrapper which will be optimized to the same wrapper if there
1.27 + * are no readers.
1.28 + * 2) The surface is sent from content to the compositor once
1.29 + * or potentially many times, each increasing a read lock.
1.30 + * 3) When the compositor receives the surface, it adopts the
1.31 + * read lock.
1.32 + * 4) Once the compositor has processed the surface and uploaded
1.33 + * the content, it then releases the read lock by dereferencing
1.34 + * its wrapper.
1.35 + */
1.36 +class gfxReusableSurfaceWrapper {
1.37 + NS_INLINE_DECL_THREADSAFE_REFCOUNTING(gfxReusableSurfaceWrapper)
1.38 +public:
1.39 +
1.40 + /**
1.41 + * Returns a read-only pointer to the image data.
1.42 + */
1.43 + virtual const unsigned char* GetReadOnlyData() const = 0;
1.44 +
1.45 + /**
1.46 + * Returns the image surface format.
1.47 + */
1.48 + virtual gfxImageFormat Format() = 0;
1.49 +
1.50 + /**
1.51 + * Returns a writable copy of the image.
1.52 + * If necessary this will copy the wrapper. If there are no contention
1.53 + * the same wrapper will be returned. A ReadLock must be held when
1.54 + * calling this function, and calling it will give up this lock.
1.55 + */
1.56 + virtual gfxReusableSurfaceWrapper* GetWritable(gfxImageSurface** aSurface) = 0;
1.57 +
1.58 + /**
1.59 + * A read only lock count is recorded, any attempts to
1.60 + * call GetWritable() while this count is greater than one will
1.61 + * create a new surface/wrapper pair.
1.62 + *
1.63 + * When a surface's read count falls to zero, its memory will be
1.64 + * deallocated. It is the responsibility of the user to make sure
1.65 + * that all locks are matched with an equal number of unlocks.
1.66 + */
1.67 + virtual void ReadLock() = 0;
1.68 + virtual void ReadUnlock() = 0;
1.69 +
1.70 + /**
1.71 + * Types for each implementation of gfxReusableSurfaceWrapper.
1.72 + */
1.73 + enum Type {
1.74 + TYPE_SHARED_IMAGE,
1.75 + TYPE_IMAGE,
1.76 +
1.77 + TYPE_MAX
1.78 + };
1.79 +
1.80 + /**
1.81 + * Returns a unique ID for each implementation of gfxReusableSurfaceWrapper.
1.82 + */
1.83 + virtual Type GetType() = 0;
1.84 +
1.85 +protected:
1.86 + // Protected destructor, to discourage deletion outside of Release():
1.87 + virtual ~gfxReusableSurfaceWrapper() {}
1.88 +
1.89 + NS_DECL_OWNINGTHREAD
1.90 +};
1.91 +
1.92 +#endif // GFXCOWSURFACEWRAPPER
