C++ AnimationState::FrameCount方法代码示例

RefreshResult
FrameAnimator::AdvanceFrame(AnimationState& aState, TimeStamp aTime)
{
  NS_ASSERTION(aTime <= TimeStamp::Now(),
               "Given time appears to be in the future");
  PROFILER_LABEL_FUNC(js::ProfileEntry::Category::GRAPHICS);

  RefreshResult ret;

  // Determine what the next frame is, taking into account looping.
  uint32_t currentFrameIndex = aState.mCurrentAnimationFrameIndex;
  uint32_t nextFrameIndex = currentFrameIndex + 1;

  // Check if we're at the end of the loop. (FrameCount() returns Nothing() if
  // we don't know the total count yet.)
  if (aState.FrameCount() == Some(nextFrameIndex)) {
    // If we are not looping forever, initialize the loop counter
    if (aState.mLoopRemainingCount < 0 && aState.LoopCount() >= 0) {
      aState.mLoopRemainingCount = aState.LoopCount();
    }

    // If animation mode is "loop once", or we're at end of loop counter,
    // it's time to stop animating.
    if (aState.mAnimationMode == imgIContainer::kLoopOnceAnimMode ||
        aState.mLoopRemainingCount == 0) {
      ret.mAnimationFinished = true;
    }

    nextFrameIndex = 0;

    if (aState.mLoopRemainingCount > 0) {
      aState.mLoopRemainingCount--;
    }

    // If we're done, exit early.
    if (ret.mAnimationFinished) {
      return ret;
    }
  }

  if (nextFrameIndex >= aState.KnownFrameCount()) {
    // We've already advanced to the last decoded frame, nothing more we can do.
    // We're blocked by network/decoding from displaying the animation at the
    // rate specified, so that means the frame we are displaying (the latest
    // available) is the frame we want to be displaying at this time. So we
    // update the current animation time. If we didn't update the current
    // animation time then it could lag behind, which would indicate that we are
    // behind in the animation and should try to catch up. When we are done
    // decoding (and thus can loop around back to the start of the animation) we
    // would then jump to a random point in the animation to try to catch up.
    // But we were never behind in the animation.
    aState.mCurrentAnimationFrameTime = aTime;
    return ret;
  }

  // There can be frames in the surface cache with index >= KnownFrameCount()
  // which GetRawFrame() can access because an async decoder has decoded them,
  // but which AnimationState doesn't know about yet because we haven't received
  // the appropriate notification on the main thread. Make sure we stay in sync
  // with AnimationState.
  MOZ_ASSERT(nextFrameIndex < aState.KnownFrameCount());
  RawAccessFrameRef nextFrame = GetRawFrame(nextFrameIndex);

  // We should always check to see if we have the next frame even if we have
  // previously finished decoding. If we needed to redecode (e.g. due to a draw
  // failure) we would have discarded all the old frames and may not yet have
  // the new ones.
  if (!nextFrame || !nextFrame->IsFinished()) {
    // Uh oh, the frame we want to show is currently being decoded (partial)
    // Wait until the next refresh driver tick and try again
    return ret;
  }

  if (GetTimeoutForFrame(nextFrameIndex) == FrameTimeout::Forever()) {
    ret.mAnimationFinished = true;
  }

  if (nextFrameIndex == 0) {
    ret.mDirtyRect = aState.FirstFrameRefreshArea();
  } else {
    MOZ_ASSERT(nextFrameIndex == currentFrameIndex + 1);

    // Change frame
    if (!DoBlend(&ret.mDirtyRect, currentFrameIndex, nextFrameIndex)) {
      // something went wrong, move on to next
      NS_WARNING("FrameAnimator::AdvanceFrame(): Compositing of frame failed");
      nextFrame->SetCompositingFailed(true);
      aState.mCurrentAnimationFrameTime = GetCurrentImgFrameEndTime(aState);
      aState.mCurrentAnimationFrameIndex = nextFrameIndex;

      return ret;
    }

    nextFrame->SetCompositingFailed(false);
  }

  aState.mCurrentAnimationFrameTime = GetCurrentImgFrameEndTime(aState);

  // If we can get closer to the current time by a multiple of the image's loop
  // time, we should. We can only do this if we're done decoding; otherwise, we
//.........这里部分代码省略.........