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comparison: gfx/thebes/gfxReusableSurfaceWrapper.h
gfx/thebes/gfxReusableSurfaceWrapper.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:e82e24888991 |
|---|---|
| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 3 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 #ifndef GFXCOWSURFACEWRAPPER | |
| 6 #define GFXCOWSURFACEWRAPPER | |
| 7 | |
| 8 #include "gfxImageSurface.h" | |
| 9 #include "nsISupportsImpl.h" | |
| 10 #include "nsAutoPtr.h" | |
| 11 | |
| 12 | |
| 13 /** | |
| 14 * Provides an interface to implement a cross thread/process wrapper for a | |
| 15 * gfxImageSurface that has copy-on-write semantics. | |
| 16 * | |
| 17 * Only the owner thread can write to the surface and acquire | |
| 18 * read locks. Destroying a gfxReusableSurfaceWrapper releases | |
| 19 * a read lock. | |
| 20 * | |
| 21 * OMTC Usage: | |
| 22 * 1) Content creates a writable copy of this surface | |
| 23 * wrapper which will be optimized to the same wrapper if there | |
| 24 * are no readers. | |
| 25 * 2) The surface is sent from content to the compositor once | |
| 26 * or potentially many times, each increasing a read lock. | |
| 27 * 3) When the compositor receives the surface, it adopts the | |
| 28 * read lock. | |
| 29 * 4) Once the compositor has processed the surface and uploaded | |
| 30 * the content, it then releases the read lock by dereferencing | |
| 31 * its wrapper. | |
| 32 */ | |
| 33 class gfxReusableSurfaceWrapper { | |
| 34 NS_INLINE_DECL_THREADSAFE_REFCOUNTING(gfxReusableSurfaceWrapper) | |
| 35 public: | |
| 36 | |
| 37 /** | |
| 38 * Returns a read-only pointer to the image data. | |
| 39 */ | |
| 40 virtual const unsigned char* GetReadOnlyData() const = 0; | |
| 41 | |
| 42 /** | |
| 43 * Returns the image surface format. | |
| 44 */ | |
| 45 virtual gfxImageFormat Format() = 0; | |
| 46 | |
| 47 /** | |
| 48 * Returns a writable copy of the image. | |
| 49 * If necessary this will copy the wrapper. If there are no contention | |
| 50 * the same wrapper will be returned. A ReadLock must be held when | |
| 51 * calling this function, and calling it will give up this lock. | |
| 52 */ | |
| 53 virtual gfxReusableSurfaceWrapper* GetWritable(gfxImageSurface** aSurface) = 0; | |
| 54 | |
| 55 /** | |
| 56 * A read only lock count is recorded, any attempts to | |
| 57 * call GetWritable() while this count is greater than one will | |
| 58 * create a new surface/wrapper pair. | |
| 59 * | |
| 60 * When a surface's read count falls to zero, its memory will be | |
| 61 * deallocated. It is the responsibility of the user to make sure | |
| 62 * that all locks are matched with an equal number of unlocks. | |
| 63 */ | |
| 64 virtual void ReadLock() = 0; | |
| 65 virtual void ReadUnlock() = 0; | |
| 66 | |
| 67 /** | |
| 68 * Types for each implementation of gfxReusableSurfaceWrapper. | |
| 69 */ | |
| 70 enum Type { | |
| 71 TYPE_SHARED_IMAGE, | |
| 72 TYPE_IMAGE, | |
| 73 | |
| 74 TYPE_MAX | |
| 75 }; | |
| 76 | |
| 77 /** | |
| 78 * Returns a unique ID for each implementation of gfxReusableSurfaceWrapper. | |
| 79 */ | |
| 80 virtual Type GetType() = 0; | |
| 81 | |
| 82 protected: | |
| 83 // Protected destructor, to discourage deletion outside of Release(): | |
| 84 virtual ~gfxReusableSurfaceWrapper() {} | |
| 85 | |
| 86 NS_DECL_OWNINGTHREAD | |
| 87 }; | |
| 88 | |
| 89 #endif // GFXCOWSURFACEWRAPPER |
