From 0d8e05880c01cc0339a1f1531baa11f031dc6c26 Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Tue, 24 Jan 2017 23:37:36 -0800
Subject: [PATCH] img2webp: treat -loop as a no-op w/single images

or in cases where duplicates have been reduced to one

Change-Id: I145cd61b6792b021617f1234f0ba36e2a3128d84
---
 examples/img2webp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/examples/img2webp.c b/examples/img2webp.c
index 799a64cc..d9012cc4 100644
--- a/examples/img2webp.c
+++ b/examples/img2webp.c
@@ -85,10 +85,15 @@ static int ReadImage(const char filename[], WebPPicture* const pic) {
 static int SetLoopCount(int loop_count, WebPData* const webp_data) {
   int ok = 1;
   WebPMuxError err;
+  uint32_t features;
   WebPMuxAnimParams new_params;
   WebPMux* const mux = WebPMuxCreate(webp_data, 1);
   if (mux == NULL) return 0;
 
+  err = WebPMuxGetFeatures(mux, &features);
+  ok = (err == WEBP_MUX_OK);
+  if (!ok || !(features & ANIMATION_FLAG)) goto End;
+
   err = WebPMuxGetAnimationParams(mux, &new_params);
   ok = (err == WEBP_MUX_OK);
   if (ok) {
@@ -101,6 +106,8 @@ static int SetLoopCount(int loop_count, WebPData* const webp_data) {
     err = WebPMuxAssemble(mux, webp_data);
     ok = (err == WEBP_MUX_OK);
   }
+
+ End:
   WebPMuxDelete(mux);
   if (!ok) {
     fprintf(stderr, "Error during loop-count setting\n");