image/AnimationFrameBuffer.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef mozilla_image_AnimationFrameBuffer_h
   7 #define mozilla_image_AnimationFrameBuffer_h
   8
   9 #include "ISurfaceProvider.h"
  10 #include <deque>
  11
  12 namespace mozilla {
  13 namespace image {
  14
  15 /**
  16  * An AnimationFrameBuffer owns the frames outputted by an animated image
  17  * decoder as well as directing its owner on how to drive the decoder,
  18  * whether to produce more or to stop.
  19  *
  20  * This should be subclassed by the different types of queues, depending on
  21  * what behaviour is desired.
  22  */
  23 class AnimationFrameBuffer {
  24  public:
  25   enum class InsertStatus : uint8_t {
  26     YIELD,            // No more frames required at this time.
  27     CONTINUE,         // Continue decoding more frames.
  28     DISCARD_YIELD,    // Crossed threshold, switch to discarding structure
  29                       // and stop decoding more frames.
  30     DISCARD_CONTINUE  // Crossed threshold, switch to discarding structure
  31                       // and continue decoding more frames.
  32   };
  33
  34   /**
  35    * @param aBatch      Number of frames we request to be decoded each time it
  36    *                    decides we need more.
  37    *
  38    * @param aStartFrame The starting frame for the animation. The frame buffer
  39    *                    will auto-advance (and thus keep the decoding pipeline
  40    *                    going) until it has reached this frame. Useful when the
  41    *                    animation was progressing, but the surface was
  42    *                    discarded, and we had to redecode.
  43    */
  44   AnimationFrameBuffer(size_t aBatch, size_t aStartFrame)
  45       : mSize(0),
  46         mBatch(aBatch),
  47         mGetIndex(0),
  48         mAdvance(aStartFrame),
  49         mPending(0),
  50         mSizeKnown(false),
  51         mMayDiscard(false),
  52         mRedecodeError(false),
  53         mRecycling(false) {
  54     if (mBatch > SIZE_MAX / 4) {
  55       // Batch size is so big, we will just end up decoding the whole animation.
  56       mBatch = SIZE_MAX / 4;
  57     } else if (mBatch < 1) {
  58       // Never permit a batch size smaller than 1. We always want to be asking
  59       // for at least one frame to start.
  60       mBatch = 1;
  61     }
  62   }
  63
  64   AnimationFrameBuffer(const AnimationFrameBuffer& aOther)
  65       : mSize(aOther.mSize),
  66         mBatch(aOther.mBatch),
  67         mGetIndex(aOther.mGetIndex),
  68         mAdvance(aOther.mAdvance),
  69         mPending(aOther.mPending),
  70         mSizeKnown(aOther.mSizeKnown),
  71         mMayDiscard(aOther.mMayDiscard),
  72         mRedecodeError(aOther.mRedecodeError),
  73         mRecycling(aOther.mRecycling) {}
  74
  75   virtual ~AnimationFrameBuffer() {}
  76
  77   /**
  78    * @returns True if frames post-advance may be discarded and redecoded on
  79    *          demand, else false.
  80    */
  81   bool MayDiscard() const { return mMayDiscard; }
  82
  83   /**
  84    * @returns True if frames post-advance may be reused after displaying, else
  85    *          false. Implies MayDiscard().
  86    */
  87   bool IsRecycling() const {
  88     MOZ_ASSERT_IF(mRecycling, mMayDiscard);
  89     return mRecycling;
  90   }
  91
  92   /**
  93    * @returns True if the frame buffer was ever marked as complete. This implies
  94    *          that the total number of frames is known and may be gotten from
  95    *          Frames().Length().
  96    */
  97   bool SizeKnown() const { return mSizeKnown; }
  98
  99   /**
 100    * @returns The total number of frames in the animation. If SizeKnown() is
 101    *          true, then this is a constant, else it is just the total number of
 102    *          frames we have decoded thus far.
 103    */
 104   size_t Size() const { return mSize; }
 105
 106   /**
 107    * @returns True if encountered an error during redecode which should cause
 108    *          the caller to stop inserting frames.
 109    */
 110   bool HasRedecodeError() const { return mRedecodeError; }
 111
 112   /**
 113    * @returns The current frame index we have advanced to.
 114    */
 115   size_t Displayed() const { return mGetIndex; }
 116
 117   /**
 118    * @returns Outstanding frames desired from the decoder.
 119    */
 120   size_t PendingDecode() const { return mPending; }
 121
 122   /**
 123    * @returns Outstanding frames to advance internally.
 124    */
 125   size_t PendingAdvance() const { return mAdvance; }
 126
 127   /**
 128    * @returns Number of frames we request to be decoded each time it decides we
 129    *          need more.
 130    */
 131   size_t Batch() const { return mBatch; }
 132
 133   /**
 134    * Resets the currently displayed frame of the frame buffer to the beginning.
 135    *
 136    * @returns True if the caller should restart the decoder.
 137    */
 138   bool Reset() {
 139     mGetIndex = 0;
 140     mAdvance = 0;
 141     return ResetInternal();
 142   }
 143
 144   /**
 145    * Advance the currently displayed frame of the frame buffer. If it reaches
 146    * the end, it will loop back to the beginning. It should not be called unless
 147    * a call to Get has returned a valid frame for the next frame index.
 148    *
 149    * As we advance, the number of frames we have buffered ahead of the current
 150    * will shrink. Once that becomes too few, we will request a batch-sized set
 151    * of frames to be decoded from the decoder.
 152    *
 153    * @param aExpectedFrame  The frame we expect to have advanced to. This is
 154    *                        used for confirmation purposes (e.g. asserts).
 155    *
 156    * @returns True if the caller should restart the decoder.
 157    */
 158   bool AdvanceTo(size_t aExpectedFrame) {
 159     MOZ_ASSERT(mAdvance == 0);
 160
 161     if (++mGetIndex == mSize && mSizeKnown) {
 162       mGetIndex = 0;
 163     }
 164     MOZ_ASSERT(mGetIndex == aExpectedFrame);
 165
 166     bool hasPending = mPending > 0;
 167     AdvanceInternal();
 168     // Restart the decoder if we transitioned from no pending frames being
 169     // decoded, to some pending frames to be decoded.
 170     return !hasPending && mPending > 0;
 171   }
 172
 173   /**
 174    * Inserts a frame into the frame buffer.
 175    *
 176    * Once we have a sufficient number of frames buffered relative to the
 177    * currently displayed frame, it will return YIELD to indicate the caller
 178    * should stop decoding. Otherwise it will return CONTINUE.
 179    *
 180    * If we cross the threshold, it will return DISCARD_YIELD or DISCARD_CONTINUE
 181    * to indicate that the caller should switch to a new queue type.
 182    *
 183    * @param aFrame      The frame to insert into the buffer.
 184    *
 185    * @returns True if the decoder should decode another frame.
 186    */
 187   InsertStatus Insert(RefPtr<imgFrame>&& aFrame) {
 188     MOZ_ASSERT(mPending > 0);
 189     MOZ_ASSERT(aFrame);
 190
 191     --mPending;
 192     bool retain = InsertInternal(std::move(aFrame));
 193
 194     if (mAdvance > 0 && mSize > 1) {
 195       --mAdvance;
 196       ++mGetIndex;
 197       AdvanceInternal();
 198     }
 199
 200     if (!retain) {
 201       return mPending > 0 ? InsertStatus::DISCARD_CONTINUE
 202                           : InsertStatus::DISCARD_YIELD;
 203     }
 204
 205     return mPending > 0 ? InsertStatus::CONTINUE : InsertStatus::YIELD;
 206   }
 207
 208   /**
 209    * Access a specific frame from the frame buffer. It should generally access
 210    * frames in sequential order, increasing in tandem with AdvanceTo calls. The
 211    * first frame may be accessed at any time. The access order should start with
 212    * the same value as that given in Initialize (aStartFrame).
 213    *
 214    * @param aFrame      The frame index to access.
 215    *
 216    * @returns The frame, if available.
 217    */
 218   virtual imgFrame* Get(size_t aFrame, bool aForDisplay) = 0;
 219
 220   /**
 221    * @returns True if the first frame of the animation (not of the queue) is
 222    *          available/finished, else false.
 223    */
 224   virtual bool IsFirstFrameFinished() const = 0;
 225
 226   /**
 227    * @returns True if the last inserted frame matches the given frame, else
 228    *          false.
 229    */
 230   virtual bool IsLastInsertedFrame(imgFrame* aFrame) const = 0;
 231
 232   /**
 233    * This should be called after the last frame has been inserted. If the buffer
 234    * is discarding old frames, it may request more frames to be decoded. In this
 235    * case that means the decoder should start again from the beginning. This
 236    * return value should be used in preference to that of the Insert call.
 237    *
 238    * @returns True if the decoder should decode another frame.
 239    */
 240   virtual bool MarkComplete(const gfx::IntRect& aFirstFrameRefreshArea) = 0;
 241
 242   typedef ISurfaceProvider::AddSizeOfCbData AddSizeOfCbData;
 243   typedef ISurfaceProvider::AddSizeOfCb AddSizeOfCb;
 244
 245   /**
 246    * Accumulate the total cost of all the frames in the buffer.
 247    */
 248   virtual void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
 249                                       const AddSizeOfCb& aCallback) = 0;
 250
 251   /**
 252    * Request a recycled frame buffer, and if available, set aRecycleRect to be
 253    * the dirty rect between the contents of the recycled frame, and the restore
 254    * frame (e.g. what we composite on top of) for the next frame to be created.
 255    *
 256    * @returns The frame to be recycled, if available.
 257    */
 258   virtual RawAccessFrameRef RecycleFrame(gfx::IntRect& aRecycleRect) {
 259     MOZ_ASSERT(!mRecycling);
 260     return RawAccessFrameRef();
 261   }
 262
 263  protected:
 264   /**
 265    * Perform the actual insertion of the given frame into the underlying buffer
 266    * representation. mGetIndex shall be the index of the frame we are inserting,
 267    * and mSize and mPending have already been adjusted as needed.
 268    *
 269    * @returns True if the caller should continue as normal, false if the discard
 270    *          threshold was crossed and we should change queue types.
 271    */
 272   virtual bool InsertInternal(RefPtr<imgFrame>&& aFrame) = 0;
 273
 274   /**
 275    * Advance from the current frame to the immediately adjacent next frame.
 276    * mGetIndex shall be the the index of the new current frame after advancing.
 277    * mPending may be adjusted to request more frames.
 278    */
 279   virtual void AdvanceInternal() = 0;
 280
 281   /**
 282    * Discard any frames as necessary for the reset. mPending may be adjusted to
 283    * request more frames.
 284    *
 285    * @returns True if the caller should resume decoding new frames, else false.
 286    */
 287   virtual bool ResetInternal() = 0;
 288
 289   // The total number of frames in the animation. If mSizeKnown is true, it is
 290   // the actual total regardless of how many frames are available, otherwise it
 291   // is the total number of inserted frames.
 292   size_t mSize;
 293
 294   // The minimum number of frames that we want buffered ahead of the display.
 295   size_t mBatch;
 296
 297   // The sequential index of the frame we have advanced to.
 298   size_t mGetIndex;
 299
 300   // The number of frames we need to auto-advance to synchronize with the
 301   // caller.
 302   size_t mAdvance;
 303
 304   // The number of frames to decode before we stop.
 305   size_t mPending;
 306
 307   // True if the total number of frames for the animation is known.
 308   bool mSizeKnown;
 309
 310   // True if this buffer may discard frames.
 311   bool mMayDiscard;
 312
 313   // True if we encountered an error while redecoding.
 314   bool mRedecodeError;
 315
 316   // True if this buffer is recycling frames.
 317   bool mRecycling;
 318 };
 319
 320 /**
 321  * An AnimationFrameRetainedBuffer will retain all of the frames inserted into
 322  * it. Once it crosses its maximum number of frames, it will recommend
 323  * conversion to a discarding queue.
 324  */
 325 class AnimationFrameRetainedBuffer final : public AnimationFrameBuffer {
 326  public:
 327   /**
 328    * @param aThreshold  Maximum number of frames that may be stored in the frame
 329    *                    buffer before it may discard already displayed frames.
 330    *                    Once exceeded, it will discard the previous frame to the
 331    *                    current frame whenever Advance is called. It always
 332    *                    retains the first frame.
 333    *
 334    * @param aBatch      See AnimationFrameBuffer::AnimationFrameBuffer.
 335    *
 336    * @param aStartFrame See AnimationFrameBuffer::AnimationFrameBuffer.
 337    */
 338   AnimationFrameRetainedBuffer(size_t aThreshold, size_t aBatch,
 339                                size_t aCurrentFrame);
 340
 341   /**
 342    * @returns Maximum number of frames before we start discarding previous
 343    *          frames post-advance.
 344    */
 345   size_t Threshold() const { return mThreshold; }
 346
 347   /**
 348    * @returns The frames of this animation, in order. Each element will always
 349    *          contain a valid frame.
 350    */
 351   const nsTArray<RefPtr<imgFrame>>& Frames() const { return mFrames; }
 352
 353   imgFrame* Get(size_t aFrame, bool aForDisplay) override;
 354   bool IsFirstFrameFinished() const override;
 355   bool IsLastInsertedFrame(imgFrame* aFrame) const override;
 356   bool MarkComplete(const gfx::IntRect& aFirstFrameRefreshArea) override;
 357   void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
 358                               const AddSizeOfCb& aCallback) override;
 359
 360  private:
 361   friend class AnimationFrameDiscardingQueue;
 362   friend class AnimationFrameRecyclingQueue;
 363
 364   bool InsertInternal(RefPtr<imgFrame>&& aFrame) override;
 365   void AdvanceInternal() override;
 366   bool ResetInternal() override;
 367
 368   // The frames of this animation, in order.
 369   nsTArray<RefPtr<imgFrame>> mFrames;
 370
 371   // The maximum number of frames we can have before discarding.
 372   size_t mThreshold;
 373 };
 374
 375 /**
 376  * An AnimationFrameDiscardingQueue will only retain up to mBatch * 2 frames.
 377  * When the animation advances, it will discard the old current frame.
 378  */
 379 class AnimationFrameDiscardingQueue : public AnimationFrameBuffer {
 380  public:
 381   explicit AnimationFrameDiscardingQueue(AnimationFrameRetainedBuffer&& aQueue);
 382
 383   imgFrame* Get(size_t aFrame, bool aForDisplay) final;
 384   bool IsFirstFrameFinished() const final;
 385   bool IsLastInsertedFrame(imgFrame* aFrame) const final;
 386   bool MarkComplete(const gfx::IntRect& aFirstFrameRefreshArea) override;
 387   void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
 388                               const AddSizeOfCb& aCallback) override;
 389
 390   const std::deque<RefPtr<imgFrame>>& Display() const { return mDisplay; }
 391   const imgFrame* FirstFrame() const { return mFirstFrame; }
 392   size_t PendingInsert() const { return mInsertIndex; }
 393
 394  protected:
 395   bool InsertInternal(RefPtr<imgFrame>&& aFrame) override;
 396   void AdvanceInternal() override;
 397   bool ResetInternal() override;
 398
 399   /// The sequential index of the frame we inserting next.
 400   size_t mInsertIndex;
 401
 402   /// Queue storing frames to be displayed by the animator. The first frame in
 403   /// the queue is the currently displayed frame.
 404   std::deque<RefPtr<imgFrame>> mDisplay;
 405
 406   /// The first frame which is never discarded, and preferentially reused.
 407   RefPtr<imgFrame> mFirstFrame;
 408 };
 409
 410 /**
 411  * An AnimationFrameRecyclingQueue will only retain up to mBatch * 2 frames.
 412  * When the animation advances, it will place the old current frame into a
 413  * recycling queue to be reused for a future allocation. This only works for
 414  * animated images where we decoded full sized frames into their own buffers,
 415  * so that the buffers are all identically sized and contain the complete frame
 416  * data.
 417  */
 418 class AnimationFrameRecyclingQueue final
 419     : public AnimationFrameDiscardingQueue {
 420  public:
 421   explicit AnimationFrameRecyclingQueue(AnimationFrameRetainedBuffer&& aQueue);
 422
 423   bool MarkComplete(const gfx::IntRect& aFirstFrameRefreshArea) override;
 424   void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
 425                               const AddSizeOfCb& aCallback) override;
 426
 427   RawAccessFrameRef RecycleFrame(gfx::IntRect& aRecycleRect) override;
 428
 429   struct RecycleEntry {
 430     explicit RecycleEntry(const gfx::IntRect& aDirtyRect)
 431         : mDirtyRect(aDirtyRect) {}
 432
 433     RecycleEntry(RecycleEntry&& aOther)
 434         : mFrame(std::move(aOther.mFrame)), mDirtyRect(aOther.mDirtyRect) {}
 435
 436     RecycleEntry& operator=(RecycleEntry&& aOther) {
 437       mFrame = std::move(aOther.mFrame);
 438       mDirtyRect = aOther.mDirtyRect;
 439       return *this;
 440     }
 441
 442     RecycleEntry(const RecycleEntry& aOther) = delete;
 443     RecycleEntry& operator=(const RecycleEntry& aOther) = delete;
 444
 445     RefPtr<imgFrame> mFrame;  // The frame containing the buffer to recycle.
 446     gfx::IntRect mDirtyRect;  // The dirty rect of the frame itself.
 447   };
 448
 449   const std::deque<RecycleEntry>& Recycle() const { return mRecycle; }
 450   const gfx::IntRect& FirstFrameRefreshArea() const {
 451     return mFirstFrameRefreshArea;
 452   }
 453
 454  protected:
 455   void AdvanceInternal() override;
 456   bool ResetInternal() override;
 457
 458   /// Queue storing frames to be recycled by the decoder to produce its future
 459   /// frames. May contain up to mBatch frames, where the last frame in the queue
 460   /// is adjacent to the first frame in the mDisplay queue.
 461   std::deque<RecycleEntry> mRecycle;
 462
 463   /// The first frame refresh area. This is used instead of the dirty rect for
 464   /// the last frame when transitioning back to the first frame.
 465   gfx::IntRect mFirstFrameRefreshArea;
 466
 467   /// Force recycled frames to use the first frame refresh area as their dirty
 468   /// rect. This is used when we are recycling frames from the end of an
 469   /// animation to produce frames at the beginning of an animation.
 470   bool mForceUseFirstFrameRefreshArea;
 471 };
 472
 473 }  // namespace image
 474 }  // namespace mozilla
 475
 476 #endif  // mozilla_image_AnimationFrameBuffer_h