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Optimize the decoder to avoid of unwanted blended layer

This commit is contained in:
yebw 2016-04-12 17:27:33 +08:00
parent 0da78a4ce6
commit 32787175ac
1 changed files with 29 additions and 15 deletions
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44
SDWebImage/SDWebImageDecoder.m
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@ -19,14 +19,16 @@
// when there are memory warning.
// on iOS7, do not forget to call
// [[SDImageCache sharedImageCache] clearMemory];
if (image == nil) { // Prevent "CGBitmapContextCreateImage: invalid context 0x0" error
return nil;
}
@autoreleasepool{
// do not decode animated images
if (image.images) { return image; }
if (image.images != nil) {
return image;
}
CGImageRef imageRef = image.CGImage;
@ -35,43 +37,55 @@
alpha == kCGImageAlphaLast ||
alpha == kCGImageAlphaPremultipliedFirst ||
alpha == kCGImageAlphaPremultipliedLast);
if (anyAlpha) { return image; }
if (anyAlpha) {
return image;
}
// current
CGColorSpaceModel imageColorSpaceModel = CGColorSpaceGetModel(CGImageGetColorSpace(imageRef));
CGColorSpaceRef colorspaceRef = CGImageGetColorSpace(imageRef);
bool unsupportedColorSpace = (imageColorSpaceModel == 0 || imageColorSpaceModel == -1 || imageColorSpaceModel == kCGColorSpaceModelCMYK || imageColorSpaceModel == kCGColorSpaceModelIndexed);
if (unsupportedColorSpace)
BOOL unsupportedColorSpace = (imageColorSpaceModel == kCGColorSpaceModelUnknown ||
imageColorSpaceModel == kCGColorSpaceModelMonochrome ||
imageColorSpaceModel == kCGColorSpaceModelCMYK ||
imageColorSpaceModel == kCGColorSpaceModelIndexed);
if (unsupportedColorSpace) {
colorspaceRef = CGColorSpaceCreateDeviceRGB();
}
size_t width = CGImageGetWidth(imageRef);
size_t height = CGImageGetHeight(imageRef);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
// kCGImageAlphaNone is not supported in CGBitmapContextCreate.
// Since the original image here has no alpha info, use kCGImageAlphaNoneSkipLast
// to create bitmap graphics contexts without alpha info.
CGContextRef context = CGBitmapContextCreate(NULL,
width,
height,
bitsPerComponent,
bytesPerRow,
colorspaceRef,
kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
kCGBitmapByteOrderDefault|kCGImageAlphaNoneSkipLast);
// Draw the image into the context and retrieve the new image, which will now have an alpha layer
// Draw the image into the context and retrieve the new bitmap image without alpha
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGImageRef imageRefWithAlpha = CGBitmapContextCreateImage(context);
UIImage *imageWithAlpha = [UIImage imageWithCGImage:imageRefWithAlpha scale:image.scale orientation:image.imageOrientation];
CGImageRef imageRefWithoutAlpha = CGBitmapContextCreateImage(context);
UIImage *imageWithoutAlpha = [UIImage imageWithCGImage:imageRefWithoutAlpha
scale:image.scale
orientation:image.imageOrientation];
if (unsupportedColorSpace)
if (unsupportedColorSpace) {
CGColorSpaceRelease(colorspaceRef);
}
CGContextRelease(context);
CGImageRelease(imageRefWithAlpha);
CGImageRelease(imageRefWithoutAlpha);
return imageWithAlpha;
return imageWithoutAlpha;
}
}