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Fixed CGBitmapContextCreate warnings for invalid alpha properties

This commit is contained in:
Martin Conte Mac Donell 2013-01-17 01:16:41 -03:00
parent 815d1c5eae
commit 12196f4de6
1 changed files with 34 additions and 3 deletions
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37
SDWebImage/SDWebImageDecoder.m
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@ -13,13 +13,44 @@
@implementation UIImage (ForceDecode)
+ (UIImage *)decodedImageWithImage:(UIImage *)image
{
{
CGImageRef imageRef = image.CGImage;
CGSize imageSize = CGSizeMake(CGImageGetWidth(imageRef), CGImageGetHeight(imageRef));
CGRect imageRect = (CGRect){.origin = CGPointZero, .size = imageSize};
CGColorSpaceRef colorSpace = CGImageGetColorSpace(imageRef);
CGContextRef context = CGBitmapContextCreate(NULL, imageSize.width, imageSize.height, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpace, CGImageGetBitmapInfo(imageRef));
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
// CGBitmapContextCreate doesn't support kCGImageAlphaNone with RGB.
// https://developer.apple.com/library/mac/#qa/qa1037/_index.html
if ((bitmapInfo & kCGBitmapAlphaInfoMask) == kCGImageAlphaNone && CGColorSpaceGetNumberOfComponents(colorSpace) > 1)
{
// Unset the old alpha info.
bitmapInfo &= ~kCGBitmapAlphaInfoMask;
// Set noneSkipFirst.
bitmapInfo |= kCGImageAlphaNoneSkipFirst;
}
// Some PNGs tell us they have alpha but only 3 components. Odd.
else if (((bitmapInfo & kCGBitmapAlphaInfoMask) & (kCGImageAlphaFirst | kCGImageAlphaLast)) != 0
&& CGColorSpaceGetNumberOfComponents(colorSpace) == 3)
{
// Unset the old alpha info.
bitmapInfo &= ~kCGBitmapAlphaInfoMask;
// Set noneSkipFirst.
bitmapInfo |= kCGImageAlphaPremultipliedFirst;
}
// It calculates the bytes-per-row based on the bitsPerComponent and width arguments.
CGContextRef context = CGBitmapContextCreate(NULL,
imageSize.width,
imageSize.height,
CGImageGetBitsPerComponent(imageRef),
0,
colorSpace,
bitmapInfo);
CGColorSpaceRelease(colorSpace);
// If failed, return undecompressed image
if (!context) return image;