中央剪切图片

中央剪切图片后上传可极大的减小上传图片的大小:

-(UIImage ) imageCompressForSize:(UIImage )sourceImage targetSize:(CGSize)size{

UIImage *newImage = nil;

CGSize imageSize = sourceImage.size;

CGFloat width = imageSize.width;

CGFloat height = imageSize.height;

CGFloat targetWidth = size.width;

CGFloat targetHeight = size.height;

CGFloat scaleFactor = 0.0;

CGFloat scaledWidth = targetWidth;

CGFloat scaledHeight = targetHeight;

CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);

if(CGSizeEqualToSize(imageSize, size) == NO){

CGFloat widthFactor = targetWidth / width;

CGFloat heightFactor = targetHeight / height;

if(widthFactor > heightFactor){

scaleFactor = widthFactor;

}

else{

scaleFactor = heightFactor;

}

scaledWidth = width * scaleFactor;

scaledHeight = height * scaleFactor;

if(widthFactor > heightFactor){

thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;

}else if(widthFactor < heightFactor){

thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;

}

}

UIGraphicsBeginImageContext(size);

CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();

if(newImage == nil){
NSLog(@"scale image fail");
}

UIGraphicsEndImageContext();

return newImage;

}