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Only store an image with unknown format as PNG if it has an alpha channel.

This commit is contained in:
Dan Dofter 2015-04-02 17:50:20 -07:00
parent 7e50d78c80
commit 38a6edb02a
2 changed files with 8 additions and 4 deletions
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10
SDWebImage/SDImageCache.m
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@ -175,9 +175,13 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
// The first eight bytes of a PNG file always contain the following (decimal) values:
// 137 80 78 71 13 10 26 10
// We assume the image is PNG, in case the imageData is nil (i.e. if trying to save a UIImage directly),
// we will consider it PNG to avoid loosing the transparency
BOOL imageIsPng = YES;
// If the imageData is nil (i.e. if trying to save a UIImage directly or the image was transformed on download)
// and the image has an alpha channel, we will consider it PNG to avoid losing the transparency
int alphaInfo = CGImageGetAlphaInfo(image.CGImage);
BOOL hasAlpha = !(alphaInfo == kCGImageAlphaNone ||
alphaInfo == kCGImageAlphaNoneSkipFirst ||
alphaInfo == kCGImageAlphaNoneSkipLast);
BOOL imageIsPng = hasAlpha;
// But if we have an image data, we will look at the preffix
if ([imageData length] >= [kPNGSignatureData length]) {

2
SDWebImage/SDWebImageManager.m
View File

@ -210,7 +210,7 @@
if (transformedImage && finished) {
BOOL imageWasTransformed = ![transformedImage isEqual:downloadedImage];
[self.imageCache storeImage:transformedImage recalculateFromImage:imageWasTransformed imageData:imageWasTransformed ? nil : data forKey:key toDisk:cacheOnDisk];
[self.imageCache storeImage:transformedImage recalculateFromImage:imageWasTransformed imageData:(imageWasTransformed ? nil : data) forKey:key toDisk:cacheOnDisk];
}
dispatch_main_sync_safe(^{