1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ 3 /* This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 /* table of images used in a document, for batch locking/unlocking and 8 * animating */ 9 10 #ifndef mozilla_dom_ImageTracker 11 #define mozilla_dom_ImageTracker 12 13 #include "nsDataHashtable.h" 14 #include "nsHashKeys.h" 15 16 class imgIRequest; 17 18 namespace mozilla { 19 namespace dom { 20 21 /* 22 * Image Tracking 23 * 24 * Style and content images register their imgIRequests with their document's 25 * image tracker, so that we can efficiently tell all descendant images when 26 * they are and are not visible. When an image is on-screen, we want to call 27 * LockImage() on it so that it doesn't do things like discarding frame data 28 * to save memory. The PresShell informs its document's image tracker whether 29 * its images should be locked or not via SetLockingState(). 30 * 31 * See bug 512260. 32 */ 33 class ImageTracker 34 { 35 public: 36 ImageTracker(); 37 ImageTracker(const ImageTracker&) = delete; 38 ImageTracker& operator=(const ImageTracker&) = delete; 39 40 NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageTracker) 41 42 nsresult Add(imgIRequest* aImage); 43 44 enum { REQUEST_DISCARD = 0x1 }; 45 nsresult Remove(imgIRequest* aImage, uint32_t aFlags = 0); 46 47 // Makes the images on this document locked/unlocked. By default, the locking 48 // state is unlocked/false. 49 nsresult SetLockingState(bool aLocked); 50 51 // Makes the images on this document capable of having their animation 52 // active or suspended. An Image will animate as long as at least one of its 53 // owning Documents needs it to animate; otherwise it can suspend. 54 void SetAnimatingState(bool aAnimating); 55 56 void RequestDiscardAll(); 57 58 private: 59 ~ImageTracker(); 60 61 nsDataHashtable<nsPtrHashKey<imgIRequest>, uint32_t> mImages; 62 bool mLocking; 63 bool mAnimating; 64 }; 65 66 } // namespace dom 67 } // namespace mozilla 68 69 #endif // mozilla_dom_ImageTracker 70