michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "CanvasImageCache.h"
michael@0: #include "nsIImageLoadingContent.h"
michael@0: #include "nsExpirationTracker.h"
michael@0: #include "imgIRequest.h"
michael@0: #include "mozilla/dom/Element.h"
michael@0: #include "nsTHashtable.h"
michael@0: #include "mozilla/dom/HTMLCanvasElement.h"
michael@0: #include "nsContentUtils.h"
michael@0: #include "mozilla/Preferences.h"
michael@0: #include "mozilla/gfx/2D.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: using namespace dom;
michael@0: using namespace gfx;
michael@0: 
michael@0: struct ImageCacheKey {
michael@0:   ImageCacheKey(Element* aImage, HTMLCanvasElement* aCanvas)
michael@0:     : mImage(aImage), mCanvas(aCanvas) {}
michael@0:   Element* mImage;
michael@0:   HTMLCanvasElement* mCanvas;
michael@0: };
michael@0: 
michael@0: struct ImageCacheEntryData {
michael@0:   ImageCacheEntryData(const ImageCacheEntryData& aOther)
michael@0:     : mImage(aOther.mImage)
michael@0:     , mILC(aOther.mILC)
michael@0:     , mCanvas(aOther.mCanvas)
michael@0:     , mRequest(aOther.mRequest)
michael@0:     , mSourceSurface(aOther.mSourceSurface)
michael@0:     , mSize(aOther.mSize)
michael@0:   {}
michael@0:   ImageCacheEntryData(const ImageCacheKey& aKey)
michael@0:     : mImage(aKey.mImage)
michael@0:     , mILC(nullptr)
michael@0:     , mCanvas(aKey.mCanvas)
michael@0:   {}
michael@0: 
michael@0:   nsExpirationState* GetExpirationState() { return &mState; }
michael@0: 
michael@0:   size_t SizeInBytes() { return mSize.width * mSize.height * 4; }
michael@0: 
michael@0:   // Key
michael@0:   nsRefPtr<Element> mImage;
michael@0:   nsIImageLoadingContent* mILC;
michael@0:   nsRefPtr<HTMLCanvasElement> mCanvas;
michael@0:   // Value
michael@0:   nsCOMPtr<imgIRequest> mRequest;
michael@0:   RefPtr<SourceSurface> mSourceSurface;
michael@0:   gfxIntSize mSize;
michael@0:   nsExpirationState mState;
michael@0: };
michael@0: 
michael@0: class ImageCacheEntry : public PLDHashEntryHdr {
michael@0: public:
michael@0:   typedef ImageCacheKey KeyType;
michael@0:   typedef const ImageCacheKey* KeyTypePointer;
michael@0: 
michael@0:   ImageCacheEntry(const KeyType *key) :
michael@0:       mData(new ImageCacheEntryData(*key)) {}
michael@0:   ImageCacheEntry(const ImageCacheEntry &toCopy) :
michael@0:       mData(new ImageCacheEntryData(*toCopy.mData)) {}
michael@0:   ~ImageCacheEntry() {}
michael@0: 
michael@0:   bool KeyEquals(KeyTypePointer key) const
michael@0:   {
michael@0:     return mData->mImage == key->mImage && mData->mCanvas == key->mCanvas;
michael@0:   }
michael@0: 
michael@0:   static KeyTypePointer KeyToPointer(KeyType& key) { return &key; }
michael@0:   static PLDHashNumber HashKey(KeyTypePointer key)
michael@0:   {
michael@0:     return HashGeneric(key->mImage, key->mCanvas);
michael@0:   }
michael@0:   enum { ALLOW_MEMMOVE = true };
michael@0: 
michael@0:   nsAutoPtr<ImageCacheEntryData> mData;
michael@0: };
michael@0: 
michael@0: static bool sPrefsInitialized = false;
michael@0: static int32_t sCanvasImageCacheLimit = 0;
michael@0: 
michael@0: class ImageCache MOZ_FINAL : public nsExpirationTracker<ImageCacheEntryData,4> {
michael@0: public:
michael@0:   // We use 3 generations of 1 second each to get a 2-3 seconds timeout.
michael@0:   enum { GENERATION_MS = 1000 };
michael@0:   ImageCache()
michael@0:     : nsExpirationTracker<ImageCacheEntryData,4>(GENERATION_MS)
michael@0:     , mTotal(0)
michael@0:   {
michael@0:     if (!sPrefsInitialized) {
michael@0:       sPrefsInitialized = true;
michael@0:       Preferences::AddIntVarCache(&sCanvasImageCacheLimit, "canvas.image.cache.limit", 0);
michael@0:     }
michael@0:   }
michael@0:   ~ImageCache() {
michael@0:     AgeAllGenerations();
michael@0:   }
michael@0: 
michael@0:   virtual void NotifyExpired(ImageCacheEntryData* aObject)
michael@0:   {
michael@0:     mTotal -= aObject->SizeInBytes();
michael@0:     RemoveObject(aObject);
michael@0:     // Deleting the entry will delete aObject since the entry owns aObject
michael@0:     mCache.RemoveEntry(ImageCacheKey(aObject->mImage, aObject->mCanvas));
michael@0:   }
michael@0: 
michael@0:   nsTHashtable<ImageCacheEntry> mCache;
michael@0:   size_t mTotal;
michael@0: };
michael@0: 
michael@0: static ImageCache* gImageCache = nullptr;
michael@0: 
michael@0: class CanvasImageCacheShutdownObserver MOZ_FINAL : public nsIObserver
michael@0: {
michael@0: public:
michael@0:   NS_DECL_ISUPPORTS
michael@0:   NS_DECL_NSIOBSERVER
michael@0: };
michael@0: 
michael@0: void
michael@0: CanvasImageCache::NotifyDrawImage(Element* aImage,
michael@0:                                   HTMLCanvasElement* aCanvas,
michael@0:                                   imgIRequest* aRequest,
michael@0:                                   SourceSurface* aSource,
michael@0:                                   const gfxIntSize& aSize)
michael@0: {
michael@0:   if (!gImageCache) {
michael@0:     gImageCache = new ImageCache();
michael@0:     nsContentUtils::RegisterShutdownObserver(new CanvasImageCacheShutdownObserver());
michael@0:   }
michael@0: 
michael@0:   ImageCacheEntry* entry = gImageCache->mCache.PutEntry(ImageCacheKey(aImage, aCanvas));
michael@0:   if (entry) {
michael@0:     if (entry->mData->mSourceSurface) {
michael@0:       // We are overwriting an existing entry.
michael@0:       gImageCache->mTotal -= entry->mData->SizeInBytes();
michael@0:       gImageCache->RemoveObject(entry->mData);
michael@0:     }
michael@0:     gImageCache->AddObject(entry->mData);
michael@0: 
michael@0:     nsCOMPtr<nsIImageLoadingContent> ilc = do_QueryInterface(aImage);
michael@0:     if (ilc) {
michael@0:       ilc->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
michael@0:                       getter_AddRefs(entry->mData->mRequest));
michael@0:     }
michael@0:     entry->mData->mILC = ilc;
michael@0:     entry->mData->mSourceSurface = aSource;
michael@0:     entry->mData->mSize = aSize;
michael@0: 
michael@0:     gImageCache->mTotal += entry->mData->SizeInBytes();
michael@0:   }
michael@0: 
michael@0:   if (!sCanvasImageCacheLimit)
michael@0:     return;
michael@0: 
michael@0:   // Expire the image cache early if its larger than we want it to be.
michael@0:   while (gImageCache->mTotal > size_t(sCanvasImageCacheLimit))
michael@0:     gImageCache->AgeOneGeneration();
michael@0: }
michael@0: 
michael@0: SourceSurface*
michael@0: CanvasImageCache::Lookup(Element* aImage,
michael@0:                          HTMLCanvasElement* aCanvas,
michael@0:                          gfxIntSize* aSize)
michael@0: {
michael@0:   if (!gImageCache)
michael@0:     return nullptr;
michael@0: 
michael@0:   ImageCacheEntry* entry = gImageCache->mCache.GetEntry(ImageCacheKey(aImage, aCanvas));
michael@0:   if (!entry || !entry->mData->mILC)
michael@0:     return nullptr;
michael@0: 
michael@0:   nsCOMPtr<imgIRequest> request;
michael@0:   entry->mData->mILC->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST, getter_AddRefs(request));
michael@0:   if (request != entry->mData->mRequest)
michael@0:     return nullptr;
michael@0: 
michael@0:   gImageCache->MarkUsed(entry->mData);
michael@0: 
michael@0:   *aSize = entry->mData->mSize;
michael@0:   return entry->mData->mSourceSurface;
michael@0: }
michael@0: 
michael@0: NS_IMPL_ISUPPORTS(CanvasImageCacheShutdownObserver, nsIObserver)
michael@0: 
michael@0: NS_IMETHODIMP
michael@0: CanvasImageCacheShutdownObserver::Observe(nsISupports *aSubject,
michael@0:                                           const char *aTopic,
michael@0:                                           const char16_t *aData)
michael@0: {
michael@0:   if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
michael@0:     delete gImageCache;
michael@0:     gImageCache = nullptr;
michael@0: 
michael@0:     nsContentUtils::UnregisterShutdownObserver(this);
michael@0:   }
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: } // namespace mozilla