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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* table of images used in a document, for batch locking/unlocking and
* animating */
#ifndef mozilla_dom_ImageTracker
#define mozilla_dom_ImageTracker
#include "imgIRequest.h"
#include "nsDataHashtable.h"
#include "nsHashKeys.h"
class imgIRequest;
namespace mozilla {
namespace dom {
/*
* Image Tracking
*
* Style and content images register their imgIRequests with their document's
* image tracker, so that we can efficiently tell all descendant images when
* they are and are not visible. When an image is on-screen, we want to call
* LockImage() on it so that it doesn't do things like discarding frame data
* to save memory. The PresShell informs its document's image tracker whether
* its images should be locked or not via SetLockingState().
*
* See bug 512260.
*/
class ImageTracker
{
public:
ImageTracker();
ImageTracker(const ImageTracker&) = delete;
ImageTracker& operator=(const ImageTracker&) = delete;
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageTracker)
nsresult Add(imgIRequest* aImage);
enum { REQUEST_DISCARD = 0x1 };
nsresult Remove(imgIRequest* aImage, uint32_t aFlags = 0);
// Makes the images on this document locked/unlocked. By default, the locking
// state is unlocked/false.
nsresult SetLockingState(bool aLocked);
// Makes the images on this document capable of having their animation
// active or suspended. An Image will animate as long as at least one of its
// owning Documents needs it to animate; otherwise it can suspend.
void SetAnimatingState(bool aAnimating);
void RequestDiscardAll();
private:
~ImageTracker();
nsDataHashtable<nsPtrHashKey<imgIRequest>, uint32_t> mImages;
bool mLocking;
bool mAnimating;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_ImageTracker
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