libwebp/demux: add WebPDemuxGetI

Enables queries for format flag, canvas width/height.

Change-Id: I1d97a633712141e42dfc86c95492eb6da5cefa01

src/mux/demux.c

@@ -650,6 +650,21 @@ void WebPDemuxDelete(WebPDemuxer* const dmux) {
   free(dmux);
 }
 
+// -----------------------------------------------------------------------------
+
+uint32_t WebPDemuxGetI(const WebPDemuxer* const dmux,
+                       WebPFormatFeature feature) {
+  if (dmux == NULL) return 0;
+
+  switch (feature) {
+    case WEBP_FF_FORMAT_FLAGS:  return dmux->feature_flags_;
+    case WEBP_FF_CANVAS_WIDTH:  return (uint32_t)dmux->canvas_width_;
+    case WEBP_FF_CANVAS_HEIGHT: return (uint32_t)dmux->canvas_height_;
+    case WEBP_FF_LOOP_COUNT:    return (uint32_t)dmux->loop_count_;
+  }
+  return 0;
+}
+
 #if defined(__cplusplus) || defined(c_plusplus)
 }  // extern "C"
 #endif

src/webp/mux.h

@@ -502,6 +502,22 @@ static WEBP_INLINE WebPDemuxer* WebPDemuxPartial(
 // Frees memory associated with 'dmux'.
 WEBP_EXTERN(void) WebPDemuxDelete(WebPDemuxer* const dmux);
 
+//------------------------------------------------------------------------------
+// Data/information extraction.
+
+typedef enum {
+  WEBP_FF_FORMAT_FLAGS,  // Extended format flags present in the 'VP8X' chunk.
+  WEBP_FF_CANVAS_WIDTH,
+  WEBP_FF_CANVAS_HEIGHT,
+  WEBP_FF_LOOP_COUNT
+} 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.
+WEBP_EXTERN(uint32_t) WebPDemuxGetI(
+    const WebPDemuxer* const dmux, WebPFormatFeature feature);
+
 //------------------------------------------------------------------------------
 
 #if defined(__cplusplus) || defined(c_plusplus)