feat(reader): replace MP4 transcoding with CADisplayLink-driven animated image player#623
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feat(reader): replace MP4 transcoding with CADisplayLink-driven animated image player#623
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…ted image player Animated GIF/WebP pages in the DIVINA reader were transcoded to MP4 via AVAssetWriter before playback, which was slow. Replace the entire transcode pipeline with a CADisplayLink-driven frame decoder that reads frames lazily from CGImageSource, eliminating the conversion step entirely. New files: - AnimatedImageFrameDecoder: parses GIF/WebP frame durations, decodes individual frames on demand - AnimatedImagePlayerController: drives playback via CADisplayLink with a ring buffer of ~5 pre-decoded frames and automatic eviction - AnimatedImagePlayerView: SwiftUI wrapper (UIViewRepresentable on iOS, NSViewRepresentable on macOS, disabled on tvOS) Removed: - AnimatedImageVideoTranscoder (MP4 transcode pipeline) - LoopingVideoPlayerView (AVQueuePlayer-based playback) Simplified ReaderViewModel, ReaderViewItemImageView, and NativeImagePageViewController by removing all transcoder references, progress tracking, and preparation task management.
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Problem
The DIVINA reader transcodes animated GIF/WebP images to MP4 via
AVAssetWriter(frame-by-frame decode → CVPixelBuffer → H.264) before playback withAVQueuePlayer. This transcode step is slow and adds visible loading time with a progress indicator before animated pages can play.Approach
Replace the entire transcode-then-play pipeline with a
CADisplayLink-driven approach that decodes frames lazily fromCGImageSource:AnimatedImageFrameDecoderowns aCGImageSourceand provides frame count, per-frame duration (reusing the exact GIF/WebP unclamped/clamped delay logic), and on-demand single-frame decodingAnimatedImagePlayerControllerdrives aCADisplayLink, maintains a ring buffer of ~5 pre-decodedCGImageframes, advances frames based on accumulated elapsed time, and setsCALayer.contentsdirectlyCADisplayLink(target:selector:)on iOS,NSScreen.displayLink(target:selector:)on macOSScope
AnimatedImageFrameDecoder,AnimatedImagePlayerController,AnimatedImagePlayerViewReaderViewModel(removed transcoder state, preparation tasks, progress tracking),ReaderViewItemImageView(removed progress overlay and monitoring loop),NativeImagePageViewController(replaced AVPlayer stack with controller)AnimatedImageVideoTranscoder,LoopingVideoPlayerViewValidation
make buildpasses on all three platforms (iOS, macOS, tvOS)