Merge changes Iecccb09c,If5ee9fd2,I3e181ce4 into 0.3.0

* changes:
  dwebp: warn when decoding animated webp's
  Decode: return more meaningful error for animation
  WebPBitstreamFeatures: add has_animation field

examples/dwebp.c

@@ -460,6 +460,13 @@ int main(int argc, const char *argv[]) {
       goto end;
     }
 
+    if (bitstream->has_animation) {
+      fprintf(stderr,
+              "Error! Decoding of an animated WebP file is not supported.\n"
+              "       Use webpmux to extract the individual frames or\n"
+              "       vwebp to view this image.\n");
+    }
+
     switch (format) {
       case PNG:
 #ifdef HAVE_WINCODEC_H

src/dec/webp.c

@@ -276,6 +276,7 @@ static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
                                           int* const width,
                                           int* const height,
                                           int* const has_alpha,
+                                          int* const has_animation,
                                           WebPHeaderStructure* const headers) {
   int found_riff = 0;
   int found_vp8x = 0;
@@ -309,6 +310,7 @@ static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
       return VP8_STATUS_BITSTREAM_ERROR;
     }
     if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
+    if (has_animation != NULL) *has_animation = !!(flags & ANIMATION_FLAG);
     if (found_vp8x && headers == NULL) {
       return VP8_STATUS_OK;  // Return features from VP8X header.
     }
@@ -370,10 +372,19 @@ static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
 }
 
 VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
+  VP8StatusCode status;
+  int has_animation = 0;
   assert(headers != NULL);
   // fill out headers, ignore width/height/has_alpha.
-  return ParseHeadersInternal(headers->data, headers->data_size,
+  status = ParseHeadersInternal(headers->data, headers->data_size,
-                              NULL, NULL, NULL, headers);
+                                NULL, NULL, NULL, &has_animation, headers);
+  if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
+    // TODO(jzern): full support of animation frames will require API additions.
+    if (has_animation) {
+      status = VP8_STATUS_UNSUPPORTED_FEATURE;
+    }
+  }
+  return status;
 }
 
 //------------------------------------------------------------------------------
@@ -625,10 +636,11 @@ static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
   }
   DefaultFeatures(features);
 
-  // Only parse enough of the data to retrieve width/height/has_alpha.
+  // Only parse enough of the data to retrieve the features.
   return ParseHeadersInternal(data, data_size,
                               &features->width, &features->height,
-                              &features->has_alpha, NULL);
+                              &features->has_alpha, &features->has_animation,
+                              NULL);
 }
 
 //------------------------------------------------------------------------------

src/webp/decode.h

@@ -392,9 +392,10 @@ WEBP_EXTERN(const WebPDecBuffer*) WebPIDecodedArea(
 
 // Features gathered from the bitstream
 struct WebPBitstreamFeatures {
-  int width;        // Width in pixels, as read from the bitstream.
+  int width;          // Width in pixels, as read from the bitstream.
-  int height;       // Height in pixels, as read from the bitstream.
+  int height;         // Height in pixels, as read from the bitstream.
-  int has_alpha;    // True if the bitstream contains an alpha channel.
+  int has_alpha;      // True if the bitstream contains an alpha channel.
+  int has_animation;  // True if the bitstream is an animation.
 
   // Unused for now:
   int bitstream_version;        // should be 0 for now. TODO(later)
@@ -402,7 +403,7 @@ struct WebPBitstreamFeatures {
                                 // recommended.
   int rotate;                   // TODO(later)
   int uv_sampling;              // should be 0 for now. TODO(later)
-  uint32_t pad[3];              // padding for later use
+  uint32_t pad[2];              // padding for later use
 };
 
 // Internal, version-checked, entry point