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Replace the background decode core function CGImageCreateDecoded with UIGraphicsRenderer, this one should use the perferred format

This commit is contained in:
DreamPiggy 2019-12-15 20:44:32 +08:00
parent 1e778f0fe6
commit 3929f2cd2a
1 changed files with 20 additions and 15 deletions
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35
SDWebImage/Core/SDImageCoderHelper.m
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@ -12,6 +12,7 @@
#import "NSData+ImageContentType.h"
#import "SDAnimatedImageRep.h"
#import "UIImage+ForceDecode.h"
#import "SDGraphicsImageRenderer.h"
#import "SDAssociatedObject.h"
#if SD_UIKIT || SD_WATCH
@ -257,22 +258,26 @@ static const CGFloat kDestSeemOverlap = 2.0f; // the numbers of pixels to over
}
BOOL hasAlpha = [self CGImageContainsAlpha:cgImage];
// iOS prefer BGRA8888 (premultiplied) or BGRX8888 bitmapInfo for screen rendering, which is same as `UIGraphicsBeginImageContext()` or `- [CALayer drawInContext:]`
// Though you can use any supported bitmapInfo (see: https://developer.apple.com/library/content/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_context/dq_context.html#//apple_ref/doc/uid/TP30001066-CH203-BCIBHHBB ) and let Core Graphics reorder it when you call `CGContextDrawImage`
// But since our build-in coders use this bitmapInfo, this can have a little performance benefit
CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host;
bitmapInfo |= hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNoneSkipFirst;
CGContextRef context = CGBitmapContextCreate(NULL, newWidth, newHeight, 8, 0, [self colorSpaceGetDeviceRGB], bitmapInfo);
if (!context) {
return NULL;
}
// Apply transform
CGAffineTransform transform = SDCGContextTransformFromOrientation(orientation, CGSizeMake(newWidth, newHeight));
CGContextConcatCTM(context, transform);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), cgImage); // The rect is bounding box of CGImage, don't swap width & height
CGImageRef newImageRef = CGBitmapContextCreateImage(context);
CGContextRelease(context);
// Using UIGraphicsRenderer on supported platforms, and use the main screeen's perferred format (like Wide Color)
SDGraphicsImageRendererFormat *format = [SDGraphicsImageRendererFormat preferredFormat];
format.scale = 1; // use pixel instead of point
format.opaque = !hasAlpha;
SDGraphicsImageRenderer *renderer = [[SDGraphicsImageRenderer alloc] initWithSize:CGSizeMake(newWidth, newHeight) format:format];
UIImage *newImage = [renderer imageWithActions:^(CGContextRef _Nonnull context) {
// Apply transform
CGAffineTransform transform = SDCGContextTransformFromOrientation(orientation, CGSizeMake(newWidth, newHeight));
CGContextConcatCTM(context, transform);
#if SD_MAC
UIImage *drawImage = [[UIImage alloc] initWithCGImage:cgImage scale:1 orientation:kCGImagePropertyOrientationUp];
#else
UIImage *drawImage = [[UIImage alloc] initWithCGImage:cgImage scale:1 orientation:UIImageOrientationUp];
#endif
[drawImage drawInRect:CGRectMake(0, 0, width, height)]; // The rect is bounding box of CGImage, don't swap width & height
}];
CGImageRef newImageRef = newImage.CGImage;
// Retain the CGImage because this temp `newImage` will release after function return
CGImageRetain(newImageRef);
return newImageRef;
}