当尝试执行UI
Image的中心裁剪时,我得到以下结果(左边是640 * 1136处的原始图像,右边是适合320 * 320的正方形UIImageView的裁剪图像)：
转向：
我对比率元素进行了相当多的修改,以便能够正确地检测要修剪的数量：使用图像的较短边,构建基于short_side / width_of_desired_rect的比率,但在这种情况下似乎不起作用.帮助赞赏！
- (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);
//for retina consideration
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;
}
解决方法
试试这个：
- (UIImage *)squareImageFromImage:(UIImage *)image scaledToSize:(CGFloat)newSize {
CGAffineTransform scaleTransform;
CGPoint origin;
if (image.size.width > image.size.height) {
CGFloat scaleRatio = newSize / image.size.height;
scaleTransform = CGAffineTransformMakeScale(scaleRatio,scaleRatio);
origin = CGPointMake(-(image.size.width - image.size.height) / 2.0f,0);
} else {
CGFloat scaleRatio = newSize / image.size.width;
scaleTransform = CGAffineTransformMakeScale(scaleRatio,scaleRatio);
origin = CGPointMake(0,-(image.size.height - image.size.width) / 2.0f);
}
CGSize size = CGSizeMake(newSize,newSize);
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(size,0);
} else {
UIGraphicsBeginImageContext(size);
}
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextConcatCTM(context,scaleTransform);
[image drawAtPoint:origin];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
