IOS平台生成图片缩略图的两种方案

来源：互联网发布：哪里卖淘宝号的编辑：程序博客网时间：2024/05/17 03:40

1.自动缩放到指定大小

+ (UIImage *)thumbnailWithImage:(UIImage *)image size:(CGSize)asize{UIImage *newimage;if (nil == image) {newimage = nil;}else{UIGraphicsBeginImageContext(asize);[image drawInRect:CGRectMake(0, 0, asize.width, asize.height)];newimage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();}return newimage;}

2.保持原来的长宽比，生成一个缩略图

+ (UIImage *)thumbnailWithImageWithoutScale:(UIImage *)image size:(CGSize)asize{UIImage *newimage;if (nil == image) {newimage = nil;}else{CGSize oldsize = image.size;CGRect rect;if (asize.width/asize.height > oldsize.width/oldsize.height) {rect.size.width = asize.height*oldsize.width/oldsize.height;rect.size.height = asize.height;rect.origin.x = (asize.width - rect.size.width)/2;rect.origin.y = 0;}else{rect.size.width = asize.width;rect.size.height = asize.width*oldsize.height/oldsize.width;rect.origin.x = 0;rect.origin.y = (asize.height - rect.size.height)/2;}UIGraphicsBeginImageContext(asize);CGContextRef context = UIGraphicsGetCurrentContext();CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);UIRectFill(CGRectMake(0, 0, asize.width, asize.height));//clear background[image drawInRect:rect];newimage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();}return newimage;}

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