michael@0: 
michael@0: /*
michael@0:  * Copyright 2010 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #include "SkBitmapCache.h"
michael@0: 
michael@0: struct SkBitmapCache::Entry {
michael@0:     Entry*      fPrev;
michael@0:     Entry*      fNext;
michael@0: 
michael@0:     void*       fBuffer;
michael@0:     size_t      fSize;
michael@0:     SkBitmap    fBitmap;
michael@0: 
michael@0:     Entry(const void* buffer, size_t size, const SkBitmap& bm)
michael@0:             : fPrev(NULL),
michael@0:               fNext(NULL),
michael@0:               fBitmap(bm) {
michael@0:         fBuffer = sk_malloc_throw(size);
michael@0:         fSize = size;
michael@0:         memcpy(fBuffer, buffer, size);
michael@0:     }
michael@0: 
michael@0:     ~Entry() { sk_free(fBuffer); }
michael@0: 
michael@0:     bool equals(const void* buffer, size_t size) const {
michael@0:         return (fSize == size) && !memcmp(fBuffer, buffer, size);
michael@0:     }
michael@0: };
michael@0: 
michael@0: SkBitmapCache::SkBitmapCache(int max) : fMaxEntries(max) {
michael@0:     fEntryCount = 0;
michael@0:     fHead = fTail = NULL;
michael@0: 
michael@0:     this->validate();
michael@0: }
michael@0: 
michael@0: SkBitmapCache::~SkBitmapCache() {
michael@0:     this->validate();
michael@0: 
michael@0:     Entry* entry = fHead;
michael@0:     while (entry) {
michael@0:         Entry* next = entry->fNext;
michael@0:         delete entry;
michael@0:         entry = next;
michael@0:     }
michael@0: }
michael@0: 
michael@0: SkBitmapCache::Entry* SkBitmapCache::detach(Entry* entry) const {
michael@0:     if (entry->fPrev) {
michael@0:         SkASSERT(fHead != entry);
michael@0:         entry->fPrev->fNext = entry->fNext;
michael@0:     } else {
michael@0:         SkASSERT(fHead == entry);
michael@0:         fHead = entry->fNext;
michael@0:     }
michael@0:     if (entry->fNext) {
michael@0:         SkASSERT(fTail != entry);
michael@0:         entry->fNext->fPrev = entry->fPrev;
michael@0:     } else {
michael@0:         SkASSERT(fTail == entry);
michael@0:         fTail = entry->fPrev;
michael@0:     }
michael@0:     return entry;
michael@0: }
michael@0: 
michael@0: void SkBitmapCache::attachToHead(Entry* entry) const {
michael@0:     entry->fPrev = NULL;
michael@0:     entry->fNext = fHead;
michael@0:     if (fHead) {
michael@0:         fHead->fPrev = entry;
michael@0:     } else {
michael@0:         fTail = entry;
michael@0:     }
michael@0:     fHead = entry;
michael@0: }
michael@0: 
michael@0: bool SkBitmapCache::find(const void* buffer, size_t size, SkBitmap* bm) const {
michael@0:     AutoValidate av(this);
michael@0: 
michael@0:     Entry* entry = fHead;
michael@0:     while (entry) {
michael@0:         if (entry->equals(buffer, size)) {
michael@0:             if (bm) {
michael@0:                 *bm = entry->fBitmap;
michael@0:             }
michael@0:             // move to the head of our list, so we purge it last
michael@0:             this->detach(entry);
michael@0:             this->attachToHead(entry);
michael@0:             return true;
michael@0:         }
michael@0:         entry = entry->fNext;
michael@0:     }
michael@0:     return false;
michael@0: }
michael@0: 
michael@0: void SkBitmapCache::add(const void* buffer, size_t len, const SkBitmap& bm) {
michael@0:     AutoValidate av(this);
michael@0: 
michael@0:     if (fEntryCount == fMaxEntries) {
michael@0:         SkASSERT(fTail);
michael@0:         delete this->detach(fTail);
michael@0:         fEntryCount -= 1;
michael@0:     }
michael@0: 
michael@0:     Entry* entry = SkNEW_ARGS(Entry, (buffer, len, bm));
michael@0:     this->attachToHead(entry);
michael@0:     fEntryCount += 1;
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0: 
michael@0: void SkBitmapCache::validate() const {
michael@0:     SkASSERT(fEntryCount >= 0 && fEntryCount <= fMaxEntries);
michael@0: 
michael@0:     if (fEntryCount > 0) {
michael@0:         SkASSERT(NULL == fHead->fPrev);
michael@0:         SkASSERT(NULL == fTail->fNext);
michael@0: 
michael@0:         if (fEntryCount == 1) {
michael@0:             SkASSERT(fHead == fTail);
michael@0:         } else {
michael@0:             SkASSERT(fHead != fTail);
michael@0:         }
michael@0: 
michael@0:         Entry* entry = fHead;
michael@0:         int count = 0;
michael@0:         while (entry) {
michael@0:             count += 1;
michael@0:             entry = entry->fNext;
michael@0:         }
michael@0:         SkASSERT(count == fEntryCount);
michael@0: 
michael@0:         entry = fTail;
michael@0:         while (entry) {
michael@0:             count -= 1;
michael@0:             entry = entry->fPrev;
michael@0:         }
michael@0:         SkASSERT(0 == count);
michael@0:     } else {
michael@0:         SkASSERT(NULL == fHead);
michael@0:         SkASSERT(NULL == fTail);
michael@0:     }
michael@0: }
michael@0: 
michael@0: #endif