Clarify SkCodec::getFrameInfo comment re animation
Change-Id: I7f20b850baf39fd01d7d5f817c52179920121e09 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/478716 Auto-Submit: Nigel Tao <nigeltao@google.com> Reviewed-by: Leon Scroggins <scroggo@google.com> Reviewed-by: Derek Sollenberger <djsollen@google.com> Commit-Queue: Derek Sollenberger <djsollen@google.com>
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@ -684,9 +684,21 @@ public:
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/**
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* Return info about a single frame.
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*
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* Only supported by multi-frame images. Does not read through the stream,
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* so it should be called after getFrameCount() to parse any frames that
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* have not already been parsed.
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* Does not read through the stream, so it should be called after
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* getFrameCount() to parse any frames that have not already been parsed.
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*
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* Only supported by animated (multi-frame) codecs. Note that this is a
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* property of the codec (the SkCodec subclass), not the image.
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*
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* To elaborate, some codecs support animation (e.g. GIF). Others do not
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* (e.g. BMP). Animated codecs can still represent single frame images.
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* Calling getFrameInfo(0, etc) will return true for a single frame GIF
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* even if the overall image is not animated (in that the pixels on screen
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* do not change over time). When incrementally decoding a GIF image, we
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* might only know that there's a single frame *so far*.
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*
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* For non-animated SkCodec subclasses, it's sufficient but not necessary
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* for this method to always return false.
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*/
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bool getFrameInfo(int index, FrameInfo* info) const {
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if (index < 0) {
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@ -703,7 +715,8 @@ public:
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*
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* As such, future decoding calls may require a rewind.
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*
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* For still (non-animated) image codecs, this will return an empty vector.
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* This may return an empty vector for non-animated codecs. See the
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* getFrameInfo(int, FrameInfo*) comment.
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*/
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std::vector<FrameInfo> getFrameInfo();
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