/** *从图片中按指定的位置大小截取图片的一部分 * UIImage image 原始的图片 * CGRect rect 要截取的区域 */ - (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect { CGImageRef sourceImageRef = [image CGImage]; CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect); UIImage *newImage = [UIImage imageWithCGImage:newImageRef]; return newImage; } - (UIImage *)reSizeImage:(UIImage *)image toSize:(CGSize)reSize { UIGraphicsBeginImageContext(CGSizeMake(reSize.width, reSize.height)); [image drawInRect:CGRectMake(0, 0, reSize.width, reSize.height)]; UIImage *reSizeImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return reSizeImage; } - (UIImage *)squareImageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize { double ratio; double delta; CGPoint offset; //make a new square size, that is the resized imaged width CGSize sz = CGSizeMake(newSize.width, newSize.width); //figure out if the picture is landscape or portrait, then //calculate scale factor and offset if (image.size.width > image.size.height) { ratio = newSize.width / image.size.width; delta = (ratio*image.size.width - ratio*image.size.height); offset = CGPointMake(delta/2, 0); } else { ratio = newSize.width / image.size.height; delta = (ratio*image.size.height - ratio*image.size.width); offset = CGPointMake(0, delta/2); } //make the final clipping rect based on the calculated values CGRect clipRect = CGRectMake(-offset.x, -offset.y, (ratio * image.size.width) + delta, (ratio * image.size.height) + delta); //start a new context, with scale factor 0.0 so retina displays get //high quality image if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) { UIGraphicsBeginImageContextWithOptions(sz, YES, 0.0); } else { UIGraphicsBeginImageContext(sz); } UIRectClip(clipRect); [image drawInRect:clipRect]; UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage; } |
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