From 98f020f610181a18bd48d11361460cddbbb39160 Mon Sep 17 00:00:00 2001
From: DreamPiggy <lizhuoli1126@126.com>
Date: Sun, 5 Nov 2017 06:40:35 +0800
Subject: [PATCH] Fix WebP progressive decoding may do extra calculate because
 that libwebp will output last_y to zero, which means current image data is
 not enough to decode first stride

---
 SDWebImage/SDWebImageWebPCoder.m | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/SDWebImage/SDWebImageWebPCoder.m b/SDWebImage/SDWebImageWebPCoder.m
index 7dbe1afa..48a1ff2b 100644
--- a/SDWebImage/SDWebImageWebPCoder.m
+++ b/SDWebImage/SDWebImageWebPCoder.m
@@ -166,7 +166,8 @@
     int last_y = 0;
     int stride = 0;
     uint8_t *rgba = WebPIDecGetRGB(_idec, &last_y, &width, &height, &stride);
-    if (width + height > 0 && height >= last_y) {
+    // last_y may be 0, means no enough bitmap data to decode, ignore this
+    if (width + height > 0 && last_y > 0 && height >= last_y) {
         // Construct a UIImage from the decoded RGBA value array
         CGDataProviderRef provider =
         CGDataProviderCreateWithData(NULL, rgba, 0, NULL);