c75764ed44
Review URL: https://codereview.chromium.org/12398021 git-svn-id: http://skia.googlecode.com/svn/trunk@7973 2bbb7eff-a529-9590-31e7-b0007b416f81
77 lines
2.7 KiB
C++
77 lines
2.7 KiB
C++
/*
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* Copyright 2013 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkImageCache_DEFINED
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#define SkImageCache_DEFINED
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#include "SkRefCnt.h"
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#include "SkTypes.h"
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/**
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* Interface for a cache that manages pixel memory.
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*/
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class SkImageCache : public SkRefCnt {
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public:
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/**
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* Allocate memory whose lifetime is managed by the cache. On success, MUST be balanced with a
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* call to releaseCache and a call to throwAwayCache.
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* @param bytes Number of bytes needed.
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* @param ID Output parameter which must not be NULL. On success, ID will be set to a value
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* associated with that memory which can be used as a parameter to the other functions
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* in SkImageCache. On failure, ID is unchanged.
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* @return Pointer to the newly allocated memory, or NULL. This memory is safe to use until
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* releaseCache is called with ID.
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*/
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virtual void* allocAndPinCache(size_t bytes, intptr_t* ID) = 0;
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/**
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* Re-request the memory associated with ID.
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* @param ID Unique ID for the memory block.
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* @return Pointer: If non-NULL, points to the previously allocated memory, in which case
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* this call must be balanced with a call to releaseCache. If NULL, the memory
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* has been reclaimed, so allocAndPinCache must be called again with a pointer to
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* the same ID.
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*/
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virtual void* pinCache(intptr_t ID) = 0;
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/**
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* Inform the cache that it is safe to free the block of memory corresponding to ID. After
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* calling this function, the pointer returned by allocAndPinCache or pinCache must not be
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* used again. In order to access the same memory after this, pinCache must be called with
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* the same ID.
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* @param ID Unique ID for the memory block which is now safe to age out of the cache.
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*/
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virtual void releaseCache(intptr_t ID) = 0;
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/**
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* Inform the cache that the block of memory associated with ID will not be asked for again.
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* After this call, ID is no longer valid. Must not be called while the associated memory is
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* pinned. Must be called to balance a successful allocAndPinCache.
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*/
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virtual void throwAwayCache(intptr_t ID) = 0;
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/**
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* ID which does not correspond to any valid cache.
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*/
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static const intptr_t UNINITIALIZED_ID = 0;
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#ifdef SK_DEBUG
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enum CacheStatus {
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kPinned_CacheStatus,
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kUnpinned_CacheStatus,
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kThrownAway_CacheStatus,
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};
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/**
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* Debug only function to get the status of a particular block of memory.
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*/
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virtual CacheStatus getCacheStatus(intptr_t ID) const = 0;
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#endif
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};
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#endif // SkImageCache_DEFINED
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