image/FrameAnimator.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   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 #ifndef mozilla_image_FrameAnimator_h
   8 #define mozilla_image_FrameAnimator_h
   9
  10 #include "mozilla/Maybe.h"
  11 #include "mozilla/StaticPrefs_image.h"
  12 #include "mozilla/TimeStamp.h"
  13 #include "gfxTypes.h"
  14 #include "imgFrame.h"
  15 #include "nsCOMPtr.h"
  16 #include "nsRect.h"
  17 #include "SurfaceCache.h"
  18
  19 namespace mozilla {
  20 namespace image {
  21
  22 class RasterImage;
  23 class DrawableSurface;
  24
  25 class AnimationState {
  26  public:
  27   explicit AnimationState(uint16_t aAnimationMode)
  28       : mFrameCount(0),
  29         mCurrentAnimationFrameIndex(0),
  30         mLoopRemainingCount(-1),
  31         mLoopCount(-1),
  32         mFirstFrameTimeout(FrameTimeout::FromRawMilliseconds(0)),
  33         mAnimationMode(aAnimationMode),
  34         mHasBeenDecoded(false),
  35         mHasRequestedDecode(false),
  36         mIsCurrentlyDecoded(false),
  37         mCompositedFrameInvalid(false),
  38         mCompositedFrameRequested(false),
  39         mDiscarded(false) {}
  40
  41   /**
  42    * Call this whenever a decode completes, a decode starts, or the image is
  43    * discarded. It will update the internal state. Specifically mDiscarded,
  44    * mCompositedFrameInvalid, and mIsCurrentlyDecoded. If aAllowInvalidation
  45    * is true then returns a rect to invalidate.
  46    */
  47   const gfx::IntRect UpdateState(RasterImage* aImage, const gfx::IntSize& aSize,
  48                                  bool aAllowInvalidation = true);
  49
  50  private:
  51   const gfx::IntRect UpdateStateInternal(LookupResult& aResult,
  52                                          const gfx::IntSize& aSize,
  53                                          bool aAllowInvalidation = true);
  54
  55  public:
  56   /**
  57    * Call when a decode of this image has been completed.
  58    */
  59   void NotifyDecodeComplete();
  60
  61   /**
  62    * Returns true if this image has been fully decoded before.
  63    */
  64   bool GetHasBeenDecoded() { return mHasBeenDecoded; }
  65
  66   /**
  67    * Returns true if this image has ever requested a decode before.
  68    */
  69   bool GetHasRequestedDecode() { return mHasRequestedDecode; }
  70
  71   /**
  72    * Returns true if this image has been discarded and a decoded has not yet
  73    * been created to redecode it.
  74    */
  75   bool IsDiscarded() { return mDiscarded; }
  76
  77   /**
  78    * Sets the composited frame as valid or invalid.
  79    */
  80   void SetCompositedFrameInvalid(bool aInvalid) {
  81     MOZ_ASSERT(!aInvalid ||
  82                StaticPrefs::image_mem_animated_discardable_AtStartup());
  83     mCompositedFrameInvalid = aInvalid;
  84   }
  85
  86   /**
  87    * Returns whether the composited frame is valid to draw to the screen.
  88    */
  89   bool GetCompositedFrameInvalid() { return mCompositedFrameInvalid; }
  90
  91   /**
  92    * Returns whether the image is currently full decoded..
  93    */
  94   bool GetIsCurrentlyDecoded() { return mIsCurrentlyDecoded; }
  95
  96   /**
  97    * Call when you need to re-start animating. Ensures we start from the first
  98    * frame.
  99    */
 100   void ResetAnimation();
 101
 102   /**
 103    * The animation mode of the image.
 104    *
 105    * Constants defined in imgIContainer.idl.
 106    */
 107   void SetAnimationMode(uint16_t aAnimationMode);
 108
 109   /// Update the number of frames of animation this image is known to have.
 110   void UpdateKnownFrameCount(uint32_t aFrameCount);
 111
 112   /// @return the number of frames of animation we know about so far.
 113   uint32_t KnownFrameCount() const { return mFrameCount; }
 114
 115   /// @return the number of frames this animation has, if we know for sure.
 116   /// (In other words, if decoding is finished.) Otherwise, returns Nothing().
 117   Maybe<uint32_t> FrameCount() const;
 118
 119   /**
 120    * Get or set the area of the image to invalidate when we loop around to the
 121    * first frame.
 122    */
 123   void SetFirstFrameRefreshArea(const gfx::IntRect& aRefreshArea);
 124   gfx::IntRect FirstFrameRefreshArea() const { return mFirstFrameRefreshArea; }
 125
 126   /**
 127    * If the animation frame time has not yet been set, set it to
 128    * TimeStamp::Now().
 129    */
 130   void InitAnimationFrameTimeIfNecessary();
 131
 132   /**
 133    * Set the animation frame time to @aTime.
 134    */
 135   void SetAnimationFrameTime(const TimeStamp& aTime);
 136
 137   /**
 138    * Set the animation frame time to @aTime if we are configured to stop the
 139    * animation when not visible and aTime is later than the current time.
 140    * Returns true if the time was updated, else false.
 141    */
 142   bool MaybeAdvanceAnimationFrameTime(const TimeStamp& aTime);
 143
 144   /**
 145    * The current frame we're on, from 0 to (numFrames - 1).
 146    */
 147   uint32_t GetCurrentAnimationFrameIndex() const;
 148
 149   /*
 150    * Set number of times to loop the image.
 151    * @note -1 means loop forever.
 152    */
 153   void SetLoopCount(int32_t aLoopCount) { mLoopCount = aLoopCount; }
 154   int32_t LoopCount() const { return mLoopCount; }
 155
 156   /// Set the @aLength of a single loop through this image.
 157   void SetLoopLength(FrameTimeout aLength) { mLoopLength = Some(aLength); }
 158
 159   /**
 160    * @return the length of a single loop of this image. If this image is not
 161    * finished decoding, is not animated, or it is animated but does not loop,
 162    * returns FrameTimeout::Forever().
 163    */
 164   FrameTimeout LoopLength() const;
 165
 166   /*
 167    * Get or set the timeout for the first frame. This is used to allow animation
 168    * scheduling even before a full decode runs for this image.
 169    */
 170   void SetFirstFrameTimeout(FrameTimeout aTimeout) {
 171     mFirstFrameTimeout = aTimeout;
 172   }
 173   FrameTimeout FirstFrameTimeout() const { return mFirstFrameTimeout; }
 174
 175  private:
 176   friend class FrameAnimator;
 177
 178   //! Area of the first frame that needs to be redrawn on subsequent loops.
 179   gfx::IntRect mFirstFrameRefreshArea;
 180
 181   //! the time that the animation advanced to the current frame
 182   TimeStamp mCurrentAnimationFrameTime;
 183
 184   //! The number of frames of animation this image has.
 185   uint32_t mFrameCount;
 186
 187   //! The current frame index we're on, in the range [0, mFrameCount).
 188   uint32_t mCurrentAnimationFrameIndex;
 189
 190   //! number of loops remaining before animation stops (-1 no stop)
 191   int32_t mLoopRemainingCount;
 192
 193   //! The total number of loops for the image.
 194   int32_t mLoopCount;
 195
 196   //! The length of a single loop through this image.
 197   Maybe<FrameTimeout> mLoopLength;
 198
 199   //! The timeout for the first frame of this image.
 200   FrameTimeout mFirstFrameTimeout;
 201
 202   //! The animation mode of this image. Constants defined in imgIContainer.
 203   uint16_t mAnimationMode;
 204
 205   /**
 206    * The following four bools (mHasBeenDecoded, mIsCurrentlyDecoded,
 207    * mCompositedFrameInvalid, mDiscarded) track the state of the image with
 208    * regards to decoding. They all start out false, including mDiscarded,
 209    * because we want to treat being discarded differently from "not yet decoded
 210    * for the first time".
 211    *
 212    * (When we are decoding the image for the first time we want to show the
 213    * image at the speed of data coming in from the network or the speed
 214    * specified in the image file, whichever is slower. But when redecoding we
 215    * want to show nothing until the frame for the current time has been
 216    * decoded. The prevents the user from seeing the image "fast forward"
 217    * to the expected spot.)
 218    *
 219    * When the image is decoded for the first time mHasBeenDecoded and
 220    * mIsCurrentlyDecoded get set to true. When the image is discarded
 221    * mIsCurrentlyDecoded gets set to false, and mCompositedFrameInvalid
 222    * & mDiscarded get set to true. When we create a decoder to redecode the
 223    * image mDiscarded gets set to false. mCompositedFrameInvalid gets set to
 224    * false when we are able to advance to the frame that should be showing
 225    * for the current time. mIsCurrentlyDecoded gets set to true when the
 226    * redecode finishes.
 227    */
 228
 229   //! Whether this image has been decoded at least once.
 230   bool mHasBeenDecoded;
 231
 232   //! Whether this image has ever requested a decode.
 233   bool mHasRequestedDecode;
 234
 235   //! Whether this image is currently fully decoded.
 236   bool mIsCurrentlyDecoded;
 237
 238   //! Whether the composited frame is valid to draw to the screen, note that
 239   //! the composited frame can exist and be filled with image data but not
 240   //! valid to draw to the screen.
 241   bool mCompositedFrameInvalid;
 242
 243   //! Whether the composited frame was requested from the animator since the
 244   //! last time we advanced the animation.
 245   bool mCompositedFrameRequested;
 246
 247   //! Whether this image is currently discarded. Only set to true after the
 248   //! image has been decoded at least once.
 249   bool mDiscarded;
 250 };
 251
 252 /**
 253  * RefreshResult is used to let callers know how the state of the animation
 254  * changed during a call to FrameAnimator::RequestRefresh().
 255  */
 256 struct RefreshResult {
 257   RefreshResult() : mFrameAdvanced(false), mAnimationFinished(false) {}
 258
 259   /// Merges another RefreshResult's changes into this RefreshResult.
 260   void Accumulate(const RefreshResult& aOther) {
 261     mFrameAdvanced = mFrameAdvanced || aOther.mFrameAdvanced;
 262     mAnimationFinished = mAnimationFinished || aOther.mAnimationFinished;
 263     mDirtyRect = mDirtyRect.Union(aOther.mDirtyRect);
 264   }
 265
 266   // The region of the image that has changed.
 267   gfx::IntRect mDirtyRect;
 268
 269   // If true, we changed frames at least once. Note that, due to looping, we
 270   // could still have ended up on the same frame!
 271   bool mFrameAdvanced : 1;
 272
 273   // Whether the animation has finished playing.
 274   bool mAnimationFinished : 1;
 275 };
 276
 277 class FrameAnimator {
 278  public:
 279   FrameAnimator(RasterImage* aImage, const gfx::IntSize& aSize)
 280       : mImage(aImage), mSize(aSize) {
 281     MOZ_COUNT_CTOR(FrameAnimator);
 282   }
 283
 284   MOZ_COUNTED_DTOR(FrameAnimator)
 285
 286   /**
 287    * Call when you need to re-start animating. Ensures we start from the first
 288    * frame.
 289    */
 290   void ResetAnimation(AnimationState& aState);
 291
 292   /**
 293    * Re-evaluate what frame we're supposed to be on, and do whatever blending
 294    * is necessary to get us to that frame.
 295    *
 296    * Returns the result of that blending, including whether the current frame
 297    * changed and what the resulting dirty rectangle is.
 298    */
 299   RefreshResult RequestRefresh(AnimationState& aState, const TimeStamp& aTime);
 300
 301   /**
 302    * Get the full frame for the current frame of the animation (it may or may
 303    * not have required compositing). It may not be available because it hasn't
 304    * been decoded yet, in which case we return an empty LookupResult.
 305    */
 306   LookupResult GetCompositedFrame(AnimationState& aState, bool aMarkUsed);
 307
 308  private:  // methods
 309   /**
 310    * Advances the animation. Typically, this will advance a single frame, but it
 311    * may advance multiple frames. This may happen if we have infrequently
 312    * "ticking" refresh drivers (e.g. in background tabs), or extremely short-
 313    * lived animation frames.
 314    *
 315    * @param aTime the time that the animation should advance to. This will
 316    *              typically be <= TimeStamp::Now().
 317    *
 318    * @param aCurrentFrame the currently displayed frame of the animation. If
 319    *                      we advance, it will replace aCurrentFrame with the
 320    *                      new current frame we advanced to.
 321    *
 322    * @returns a RefreshResult that shows whether the frame was successfully
 323    *          advanced, and its resulting dirty rect.
 324    */
 325   RefreshResult AdvanceFrame(AnimationState& aState, DrawableSurface& aFrames,
 326                              RefPtr<imgFrame>& aCurrentFrame, TimeStamp aTime);
 327
 328   /**
 329    * Get the time the frame we're currently displaying is supposed to end.
 330    *
 331    * In the error case (like if the requested frame is not currently
 332    * decoded), returns None().
 333    */
 334   TimeStamp GetCurrentImgFrameEndTime(AnimationState& aState,
 335                                       FrameTimeout aCurrentTimeout) const;
 336
 337  private:  // data
 338   //! A weak pointer to our owning image.
 339   RasterImage* mImage;
 340
 341   //! The intrinsic size of the image.
 342   gfx::IntSize mSize;
 343 };
 344
 345 }  // namespace image
 346 }  // namespace mozilla
 347
 348 #endif  // mozilla_image_FrameAnimator_h