From 1bf9668d975279d808959b804307a2ffba268d24 Mon Sep 17 00:00:00 2001
From: Nacho Soto <ignaciosoto90@gmail.com>
Date: Wed, 10 Oct 2012 16:36:53 -0700
Subject: [PATCH] Keeping original image alpha info when decoding
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This fixes issue #26 and #55, after the change introduced in commit c32f9c03f816dac58a8cac25d6189310272ca9c1
---
 SDWebImage/SDWebImageDecoder.m | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/SDWebImage/SDWebImageDecoder.m b/SDWebImage/SDWebImageDecoder.m
index 9b6e50c..34af4e4 100644
--- a/SDWebImage/SDWebImageDecoder.m
+++ b/SDWebImage/SDWebImageDecoder.m
@@ -98,6 +98,7 @@ static SDWebImageDecoder *sharedInstance;
 {
     CGImageRef imageRef = image.CGImage;
     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
+    CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);
     CGContextRef context = CGBitmapContextCreate(NULL,
                                                  CGImageGetWidth(imageRef),
                                                  CGImageGetHeight(imageRef),
@@ -107,10 +108,7 @@ static SDWebImageDecoder *sharedInstance;
                                                  // System only supports RGB, set explicitly
                                                  colorSpace,
                                                  // Makes system don't need to do extra conversion when displayed.
-                                                 // NOTE: here we remove the alpha channel for performance. Most of the time, images loaded
-                                                 //       from the network are jpeg with no alpha channel. As a TODO, finding a way to detect
-                                                 //       if alpha channel is necessary would be nice.
-                                                 kCGImageAlphaNoneSkipLast | kCGBitmapByteOrder32Little);
+                                                 alphaInfo | kCGBitmapByteOrder32Little);
     CGColorSpaceRelease(colorSpace);
     if (!context) return nil;