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我正在使用以下代码翻转（旋转 180 度）一个NSImage. 但是新图像在保存到磁盘时是原始图像的两倍大小（MB，而不是尺寸）。我希望它与原版大致相同。我怎样才能做到这一点？

NSBitmapImageRep *imageRep = [NSBitmapImageRep imageRepWithData:[[_imageView image] TIFFRepresentation]];
NSImage *img = [[NSImage alloc] initWithSize:NSMakeSize(imageRep.pixelsWide, imageRep.pixelsHigh)];
[img lockFocus];
NSAffineTransform *rotator = [NSAffineTransform transform];
[rotator translateXBy:imageRep.pixelsWide yBy:imageRep.pixelsHigh];
[rotator scaleXBy:-1 yBy:-1];
[rotator concat];
[imageRep drawInRect:NSMakeRect(0, 0, imageRep.pixelsWide, imageRep.pixelsHigh)];
[img unlockFocus];

我用来将图像保存到磁盘的代码：

[[NSFileManager defaultManager] createFileAtPath:path contents:[img TIFFRepresentation] attributes:nil];

提前致谢！

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1 回答 1

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我仍然不知道造成这种情况的根本原因，但一种解决方法是保存为 JPEG 表示而不是 TIFF。我写的方法如下：

- (void)CompressAndSaveImg:(NSImage *)img ToDiskAt:(NSString *)path WithCompressionFactor:(float)value{
    NSData *imgData = [img TIFFRepresentation];
    NSBitmapImageRep *imgRep = [NSBitmapImageRep imageRepWithData:imgData];
    NSNumber *compressionFactor = [NSNumber numberWithFloat:value];
    NSDictionary *imageProps = [NSDictionary dictionaryWithObject:compressionFactor forKey:NSImageCompressionFactor];
    imgData = [imgRep representationUsingType:NSJPEGFileType properties:imageProps];
    [imgData writeToFile:path atomically:YES];
}

您可以使用WithCompressionFactor:(float)value参数玩转，但0.75对我来说效果很好。

于 2015-01-28T18:53:43.463 回答