diff -r 000000000000 -r 6474c204b198 image/src/FrameAnimator.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/image/src/FrameAnimator.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,174 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+#ifndef mozilla_imagelib_FrameAnimator_h_
+#define mozilla_imagelib_FrameAnimator_h_
+
+#include "mozilla/TimeStamp.h"
+#include "nsRect.h"
+
+namespace mozilla {
+namespace image {
+
+class FrameBlender;
+
+class FrameAnimator
+{
+public:
+  FrameAnimator(FrameBlender& aBlender, uint16_t aAnimationMode);
+
+  /**
+   * Return value from RequestRefresh. Tells callers what happened in that call
+   * to RequestRefresh.
+   */
+  struct RefreshResult
+  {
+    // The dirty rectangle to be re-drawn after this RequestRefresh().
+    nsIntRect dirtyRect;
+
+    // Whether any frame changed, and hence the dirty rect was set.
+    bool frameAdvanced : 1;
+
+    // Whether the animation has finished playing.
+    bool animationFinished : 1;
+
+    // Whether an error has occurred when trying to advance a frame. Note that
+    // errors do not, on their own, end the animation.
+    bool error : 1;
+
+    RefreshResult()
+      : frameAdvanced(false)
+      , animationFinished(false)
+      , error(false)
+    {}
+
+    void Accumulate(const RefreshResult& other)
+    {
+      frameAdvanced = frameAdvanced || other.frameAdvanced;
+      animationFinished = animationFinished || other.animationFinished;
+      error = error || other.error;
+      dirtyRect = dirtyRect.Union(other.dirtyRect);
+    }
+  };
+
+  /**
+   * Re-evaluate what frame we're supposed to be on, and do whatever blending
+   * is necessary to get us to that frame.
+   *
+   * Returns the result of that blending, including whether the current frame
+   * changed and what the resulting dirty rectangle is.
+   */
+  RefreshResult RequestRefresh(const mozilla::TimeStamp& aTime);
+
+  /**
+   * Call when this image is finished decoding so we know that there aren't any
+   * more frames coming.
+   */
+  void SetDoneDecoding(bool aDone);
+
+  /**
+   * Call when you need to re-start animating. Ensures we start from the first
+   * frame.
+   */
+  void ResetAnimation();
+
+  /**
+   * The animation mode of the image.
+   *
+   * Constants defined in imgIContainer.idl.
+   */
+  void SetAnimationMode(uint16_t aAnimationMode);
+
+  /**
+   * Set the area to refresh when we loop around to the first frame.
+   */
+  void SetFirstFrameRefreshArea(const nsIntRect& aRect);
+
+  /**
+   * Union the area to refresh when we loop around to the first frame with this
+   * rect.
+   */
+  void UnionFirstFrameRefreshArea(const nsIntRect& aRect);
+
+  /**
+   * If the animation frame time has not yet been set, set it to
+   * TimeStamp::Now().
+   */
+  void InitAnimationFrameTimeIfNecessary();
+
+  /**
+   * Set the animation frame time to @aTime.
+   */
+  void SetAnimationFrameTime(const TimeStamp& aTime);
+
+  /**
+   * The current frame we're on, from 0 to (numFrames - 1).
+   */
+  uint32_t GetCurrentAnimationFrameIndex() const;
+
+  /**
+   * Get the area we refresh when we loop around to the first frame.
+   */
+  nsIntRect GetFirstFrameRefreshArea() const;
+
+private: // methods
+  /**
+   * Gets the length of a single loop of this image, in milliseconds.
+   *
+   * If this image is not finished decoding, is not animated, or it is animated
+   * but does not loop, returns -1. Can return 0 in the case of an animated image
+   * that has a 0ms delay between its frames and does not loop.
+   */
+  int32_t GetSingleLoopTime() const;
+
+  /**
+   * Advances the animation. Typically, this will advance a single frame, but it
+   * may advance multiple frames. This may happen if we have infrequently
+   * "ticking" refresh drivers (e.g. in background tabs), or extremely short-
+   * lived animation frames.
+   *
+   * @param aTime the time that the animation should advance to. This will
+   *              typically be <= TimeStamp::Now().
+   *
+   * @returns a RefreshResult that shows whether the frame was successfully
+   *          advanced, and its resulting dirty rect.
+   */
+  RefreshResult AdvanceFrame(mozilla::TimeStamp aTime);
+
+  /**
+   * Get the time the frame we're currently displaying is supposed to end.
+   *
+   * In the error case, returns an "infinity" timestamp.
+   */
+  mozilla::TimeStamp GetCurrentImgFrameEndTime() const;
+
+private: // data
+  //! Area of the first frame that needs to be redrawn on subsequent loops.
+  nsIntRect mFirstFrameRefreshArea;
+
+  //! the time that the animation advanced to the current frame
+  TimeStamp mCurrentAnimationFrameTime;
+
+  //! The current frame index we're on. 0 to (numFrames - 1).
+  uint32_t mCurrentAnimationFrameIndex;
+
+  //! number of loops remaining before animation stops (-1 no stop)
+  int32_t mLoopCounter;
+
+  //! All the frames of the image, shared with our owner
+  FrameBlender& mFrameBlender;
+
+  //! The animation mode of this image. Constants defined in imgIContainer.
+  uint16_t mAnimationMode;
+
+  //! Whether this image is done being decoded.
+  bool mDoneDecoding;
+};
+
+} // namespace image
+} // namespace mozilla
+
+#endif /* mozilla_imagelib_FrameAnimator_h_ */