WebPDemuxGetI: add doc details around WebPFormatFeature
@@ -115,20 +115,25 @@ WEBP_EXTERN void WebPDemuxDelete(WebPDemuxer* dmux);
// Data/information extraction.
typedef enum WebPFormatFeature {
- WEBP_FF_FORMAT_FLAGS, // Extended format flags present in the 'VP8X' chunk.
+ WEBP_FF_FORMAT_FLAGS, // bit-wise combination of WebPFeatureFlags
+ // corresponding to the 'VP8X' chunk (if present).
WEBP_FF_CANVAS_WIDTH,
WEBP_FF_CANVAS_HEIGHT,
- WEBP_FF_LOOP_COUNT,
- WEBP_FF_BACKGROUND_COLOR,
+ WEBP_FF_LOOP_COUNT, // only relevant for animated file
+ WEBP_FF_BACKGROUND_COLOR, // idem.
WEBP_FF_FRAME_COUNT // Number of frames present in the demux object.
- // In case of a partial demux, this is the number of
- // frames seen so far, with the last frame possibly
- // being partial.
+ // In case of a partial demux, this is the number
+ // of frames seen so far, with the last frame
+ // possibly being partial.
} WebPFormatFeature;
// Get the 'feature' value from the 'dmux'.
// NOTE: values are only valid if WebPDemux() was used or WebPDemuxPartial()
// returned a state > WEBP_DEMUX_PARSING_HEADER.
+// If 'feature' is WEBP_FF_FORMAT_FLAGS, the returned value is a bit-wise
+// combination of WebPFeatureFlags values.
+// If 'feature' is WEBP_FF_LOOP_COUNT, WEBP_FF_BACKGROUND_COLOR, the returned
+// value is only meaningful if the bitstream is animated.
WEBP_EXTERN uint32_t WebPDemuxGetI(
const WebPDemuxer* dmux, WebPFormatFeature feature);
