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| 1 /* | |
| 2 * Copyright 2013 Google Inc. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license that can be | |
| 5 * found in the LICENSE file. | |
| 6 */ | |
| 7 | |
| 8 #ifndef SkImageCache_DEFINED | |
| 9 #define SkImageCache_DEFINED | |
| 10 | |
| 11 #include "SkRefCnt.h" | |
| 12 #include "SkTypes.h" | |
| 13 | |
| 14 /** | |
| 15 * Interface for a cache that manages pixel memory. | |
| 16 */ | |
| 17 class SkImageCache : public SkRefCnt { | |
| 18 | |
| 19 public: | |
| 20 SK_DECLARE_INST_COUNT(SkImageCache) | |
| 21 | |
| 22 typedef intptr_t ID; | |
| 23 | |
| 24 /** | |
| 25 * Allocate memory whose lifetime is managed by the cache. On success, MUST
be balanced with a | |
| 26 * call to releaseCache and a call to throwAwayCache. | |
| 27 * @param bytes Number of bytes needed. | |
| 28 * @param ID Output parameter which must not be NULL. On success, ID will b
e set to a value | |
| 29 * associated with that memory which can be used as a parameter to the
other functions | |
| 30 * in SkImageCache. On failure, ID is unchanged. | |
| 31 * @return Pointer to the newly allocated memory, or NULL. This memory is s
afe to use until | |
| 32 * releaseCache is called with ID. | |
| 33 */ | |
| 34 virtual void* allocAndPinCache(size_t bytes, ID*) = 0; | |
| 35 | |
| 36 /** | |
| 37 * Output parameter for pinCache, stating whether the memory still contains
the data it held | |
| 38 * when releaseCache was last called for the same ID. | |
| 39 */ | |
| 40 enum DataStatus { | |
| 41 /** | |
| 42 * The data has been purged, and therefore needs to be rewritten to the
returned memory. | |
| 43 */ | |
| 44 kUninitialized_DataStatus, | |
| 45 | |
| 46 /** | |
| 47 * The memory still contains the data it held when releaseCache was las
t called with the | |
| 48 * same ID. | |
| 49 */ | |
| 50 kRetained_DataStatus, | |
| 51 }; | |
| 52 | |
| 53 /** | |
| 54 * Re-request the memory associated with ID and pin it so that it will not
be reclaimed until | |
| 55 * the next call to releaseCache with the same ID. | |
| 56 * @param ID Unique ID for the memory block. | |
| 57 * @param status Output parameter which must not be NULL. On success (i.e.
the return value is | |
| 58 * not NULL), status will be set to one of two states representing the
cached memory. If | |
| 59 * status is set to kRetained_DataStatus, the memory contains the same
data it did | |
| 60 * before releaseCache was called with this ID. If status is set to | |
| 61 * kUninitialized_DataStatus, the memory is still pinned, but the previ
ous data is no | |
| 62 * longer available. If the return value is NULL, status is unchanged. | |
| 63 * @return Pointer: If non-NULL, points to the previously allocated memory,
in which case | |
| 64 * this call must be balanced with a call to releaseCache. If NULL, the
memory | |
| 65 * has been reclaimed, and throwAwayCache MUST NOT be called. | |
| 66 */ | |
| 67 virtual void* pinCache(ID, DataStatus* status) = 0; | |
| 68 | |
| 69 /** | |
| 70 * Inform the cache that it is safe to free the block of memory correspondi
ng to ID. After | |
| 71 * calling this function, the pointer returned by allocAndPinCache or pinCa
che must not be | |
| 72 * used again. In order to access the same memory after this, pinCache must
be called with | |
| 73 * the same ID. | |
| 74 * @param ID Unique ID for the memory block which is now safe to age out of
the cache. | |
| 75 */ | |
| 76 virtual void releaseCache(ID) = 0; | |
| 77 | |
| 78 /** | |
| 79 * Inform the cache that the block of memory associated with ID will not be
asked for again. | |
| 80 * After this call, ID is no longer valid. Must not be called while the ass
ociated memory is | |
| 81 * pinned. Must be called to balance a successful allocAndPinCache. | |
| 82 */ | |
| 83 virtual void throwAwayCache(ID) = 0; | |
| 84 | |
| 85 /** | |
| 86 * ID which does not correspond to any valid cache. | |
| 87 */ | |
| 88 static const ID UNINITIALIZED_ID = 0; | |
| 89 | |
| 90 #ifdef SK_DEBUG | |
| 91 /** | |
| 92 * Debug only status of a memory block. | |
| 93 */ | |
| 94 enum MemoryStatus { | |
| 95 /** | |
| 96 * It is safe to use the pointer returned by the most recent of allocAn
dPinCache(ID) or | |
| 97 * pinCache(ID) with the same ID. | |
| 98 */ | |
| 99 kPinned_MemoryStatus, | |
| 100 | |
| 101 /** | |
| 102 * The pointer returned by the most recent call to allocAndPinCache(ID)
or pinCache(ID) has | |
| 103 * since been released by releaseCache(ID). In order to reuse it, pinCa
che(ID) must be | |
| 104 * called again. Note that after calling releaseCache(ID), the status o
f that particular | |
| 105 * ID may not be kUnpinned_MemoryStatus, depending on the implementatio
n, but it will not | |
| 106 * be kPinned_MemoryStatus. | |
| 107 */ | |
| 108 kUnpinned_MemoryStatus, | |
| 109 | |
| 110 /** | |
| 111 * The memory associated with ID has been thrown away. No calls should
be made using the | |
| 112 * same ID. | |
| 113 */ | |
| 114 kFreed_MemoryStatus, | |
| 115 }; | |
| 116 | |
| 117 /** | |
| 118 * Debug only function to get the status of a particular block of memory. S
afe to call after | |
| 119 * throwAwayCache has been called with this ID. | |
| 120 */ | |
| 121 virtual MemoryStatus getMemoryStatus(intptr_t ID) const = 0; | |
| 122 | |
| 123 /** | |
| 124 * Debug only function to clear all unpinned caches. | |
| 125 */ | |
| 126 virtual void purgeAllUnpinnedCaches() = 0; | |
| 127 #endif | |
| 128 | |
| 129 private: | |
| 130 typedef SkRefCnt INHERITED; | |
| 131 }; | |
| 132 #endif // SkImageCache_DEFINED | |
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Chromium Code Reviews
Issue 103033002:
Big Cleanup: SkBitmapFactory, SkLazyPixelRef, SkImageCache (Closed)
Base URL: https://skia.googlecode.com/svn/trunk