The Tor Browser: gfx/skia/trunk/src/core/SkScaledImageCache.h@97036ab72558 (annotated)

gfx/skia/trunk/src/core/SkScaledImageCache.h@97036ab72558 (annotated)

gfx/skia/trunk/src/core/SkScaledImageCache.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkScaledImageCache_DEFINED
 #define SkScaledImageCache_DEFINED
 #include "SkBitmap.h"
 class SkDiscardableMemory;
 class SkMipMap;
 /**
  *  Cache object for bitmaps (with possible scale in X Y as part of the key).
  *
  *  Multiple caches can be instantiated, but each instance is not implicitly
  *  thread-safe, so if a given instance is to be shared across threads, the
  *  caller must manage the access itself (e.g. via a mutex).
  *
  *  As a convenience, a global instance is also defined, which can be safely
  *  access across threads via the static methods (e.g. FindAndLock, etc.).
  */
 class SkScaledImageCache {
 public:
     struct ID;
     /**
      *  Returns a locked/pinned SkDiscardableMemory instance for the specified
      *  number of bytes, or NULL on failure.
      */
     typedef SkDiscardableMemory* (*DiscardableFactory)(size_t bytes);
     /*
      *  The following static methods are thread-safe wrappers around a global
      *  instance of this cache.
      */
     static ID* FindAndLock(uint32_t pixelGenerationID,
                            int32_t width,
                            int32_t height,
                            SkBitmap* returnedBitmap);
     static ID* FindAndLock(const SkBitmap& original, SkScalar scaleX,
                            SkScalar scaleY, SkBitmap* returnedBitmap);
     static ID* FindAndLockMip(const SkBitmap& original,
                               SkMipMap const** returnedMipMap);
     static ID* AddAndLock(uint32_t pixelGenerationID,
                           int32_t width,
                           int32_t height,
                           const SkBitmap& bitmap);
     static ID* AddAndLock(const SkBitmap& original, SkScalar scaleX,
                           SkScalar scaleY, const SkBitmap& bitmap);
     static ID* AddAndLockMip(const SkBitmap& original, const SkMipMap* mipMap);
     static void Unlock(ID*);
     static size_t GetBytesUsed();
     static size_t GetByteLimit();
     static size_t SetByteLimit(size_t newLimit);
     static SkBitmap::Allocator* GetAllocator();
     /**
      *  Call SkDebugf() with diagnostic information about the state of the cache
      */
     static void Dump();
     ///////////////////////////////////////////////////////////////////////////
     /**
      *  Construct the cache to call DiscardableFactory when it
      *  allocates memory for the pixels. In this mode, the cache has
      *  not explicit budget, and so methods like getBytesUsed() and
      *  getByteLimit() will return 0, and setByteLimit will ignore its argument
      *  and return 0.
      */
     SkScaledImageCache(DiscardableFactory);
     /**
      *  Construct the cache, allocating memory with malloc, and respect the
      *  byteLimit, purging automatically when a new image is added to the cache
      *  that pushes the total bytesUsed over the limit. Note: The limit can be
      *  changed at runtime with setByteLimit.
      */
     SkScaledImageCache(size_t byteLimit);
     ~SkScaledImageCache();
     /**
      *  Search the cache for a matching bitmap (using generationID,
      *  width, and height as a search key). If found, return it in
      *  returnedBitmap, and return its ID pointer. Use the returned
      *  ptr to unlock the cache when you are done using
      *  returnedBitmap.
      *
      *  If a match is not found, returnedBitmap will be unmodifed, and
      *  NULL will be returned.
      *
      *  This is used if there is no scaling or subsetting, for example
      *  by SkLazyPixelRef.
      */
     ID* findAndLock(uint32_t pixelGenerationID, int32_t width, int32_t height,
                     SkBitmap* returnedBitmap);
     /**
      *  Search the cache for a scaled version of original. If found,
      *  return it in returnedBitmap, and return its ID pointer. Use
      *  the returned ptr to unlock the cache when you are done using
      *  returnedBitmap.
      *
      *  If a match is not found, returnedBitmap will be unmodifed, and
      *  NULL will be returned.
      */
     ID* findAndLock(const SkBitmap& original, SkScalar scaleX,
                     SkScalar scaleY, SkBitmap* returnedBitmap);
     ID* findAndLockMip(const SkBitmap& original,
                        SkMipMap const** returnedMipMap);
     /**
      *  To add a new bitmap (or mipMap) to the cache, call
      *  AddAndLock. Use the returned ptr to unlock the cache when you
      *  are done using scaled.
      *
      *  Use (generationID, width, and height) or (original, scaleX,
      *  scaleY) or (original) as a search key
      */
     ID* addAndLock(uint32_t pixelGenerationID, int32_t width, int32_t height,
                    const SkBitmap& bitmap);
     ID* addAndLock(const SkBitmap& original, SkScalar scaleX,
                    SkScalar scaleY, const SkBitmap& bitmap);
     ID* addAndLockMip(const SkBitmap& original, const SkMipMap* mipMap);
     /**
      *  Given a non-null ID ptr returned by either findAndLock or addAndLock,
      *  this releases the associated resources to be available to be purged
      *  if needed. After this, the cached bitmap should no longer be
      *  referenced by the caller.
      */
     void unlock(ID*);
     size_t getBytesUsed() const { return fBytesUsed; }
     size_t getByteLimit() const { return fByteLimit; }
     /**
      *  Set the maximum number of bytes available to this cache. If the current
      *  cache exceeds this new value, it will be purged to try to fit within
      *  this new limit.
      */
     size_t setByteLimit(size_t newLimit);
     SkBitmap::Allocator* allocator() const { return fAllocator; };
     /**
      *  Call SkDebugf() with diagnostic information about the state of the cache
      */
     void dump() const;
 public:
     struct Rec;
     struct Key;
 private:
     Rec*    fHead;
     Rec*    fTail;
     class Hash;
     Hash*   fHash;
     DiscardableFactory  fDiscardableFactory;
     // the allocator is NULL or one that matches discardables
     SkBitmap::Allocator* fAllocator;
     size_t  fBytesUsed;
     size_t  fByteLimit;
     int     fCount;
     Rec* findAndLock(uint32_t generationID, SkScalar sx, SkScalar sy,
                      const SkIRect& bounds);
     Rec* findAndLock(const Key& key);
     ID* addAndLock(Rec* rec);
     void purgeRec(Rec*);
     void purgeAsNeeded();
     // linklist management
     void moveToHead(Rec*);
     void addToHead(Rec*);
     void detach(Rec*);
     void init();    // called by constructors
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif

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gfx/skia/trunk/src/core/SkScaledImageCache.h@97036ab72558 (annotated)

gfx/skia/trunk/src/core/SkScaledImageCache.h