From 83ad6fa97739374eb89743d7b19ee0baf03fa53d Mon Sep 17 00:00:00 2001
From: flexih <flexih@gmail.com>
Date: Thu, 23 Oct 2014 12:14:43 +0800
Subject: [PATCH] Decoding webp, depends on source image data alpha status.

---
 SDWebImage/UIImage+WebP.m | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/SDWebImage/UIImage+WebP.m b/SDWebImage/UIImage+WebP.m
index e6e84645..95c95a8f 100644
--- a/SDWebImage/UIImage+WebP.m
+++ b/SDWebImage/UIImage+WebP.m
@@ -24,7 +24,11 @@ static void FreeImageData(void *info, const void *data, size_t size)
         return nil;
     }
 
-    config.output.colorspace = MODE_rgbA;
+    if (WebPGetFeatures(data.bytes, data.length, &config.input) != VP8_STATUS_OK) {
+        return nil;
+    }
+
+    config.output.colorspace = config.input.has_alpha ? MODE_rgbA : MODE_RGB;
     config.options.use_threads = 1;
 
     // Decode the WebP image data into a RGBA value array.
@@ -43,9 +47,10 @@ static void FreeImageData(void *info, const void *data, size_t size)
     CGDataProviderRef provider =
     CGDataProviderCreateWithData(NULL, config.output.u.RGBA.rgba, config.output.u.RGBA.size, FreeImageData);
     CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
-    CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast;
+    CGBitmapInfo bitmapInfo = config.input.has_alpha ? kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast : 0;
+    size_t components = config.input.has_alpha ? 4 : 3;
     CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
-    CGImageRef imageRef = CGImageCreate(width, height, 8, 32, 4 * width, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
+    CGImageRef imageRef = CGImageCreate(width, height, 8, components * 8, components * width, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
 
     CGColorSpaceRelease(colorSpaceRef);
     CGDataProviderRelease(provider);