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