在UIImage中按坐标截出新的UIImage的完美代码（网上绝大部分都有问题！）

最新推荐文章于 2020-12-19 11:20:37 发布

转载最新推荐文章于 2020-12-19 11:20:37 发布 · 455 阅读

本文介绍了一个裁剪并根据原始图像的方向调整裁剪区域的方法。通过使用CGAffineTransform转换，该方法可以处理不同方向的UIImage，并创建一个新的裁剪后的UIImage。文章详细展示了如何根据图像的方向调整裁剪矩形的位置。

- (UIImage *)cropImage:(UIImage*)image toRect:(CGRect)rect {

CGFloat (^rad)(CGFloat) = ^CGFloat(CGFloat deg) {

return deg / 180.0f * (CGFloat) M_PI;

};

// determine the orientation of the image and apply a transformation to the crop rectangle to shift it to the correct position

CGAffineTransform rectTransform;

switch (image.imageOrientation) {

case UIImageOrientationLeft:

rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(90)), 0, -image.size.height);

break;

case UIImageOrientationRight:

rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(-90)), -image.size.width, 0);

break;

case UIImageOrientationDown:

rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(-180)), -image.size.width, -image.size.height);

break;

default:

rectTransform = CGAffineTransformIdentity;

};

// adjust the transformation scale based on the image scale

rectTransform = CGAffineTransformScale(rectTransform, image.scale, image.scale);

// apply the transformation to the rect to create a new, shifted rect

CGRect transformedCropSquare = CGRectApplyAffineTransform(rect, rectTransform);

// use the rect to crop the image

CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, transformedCropSquare);

// create a new UIImage and set the scale and orientation appropriately

UIImage *result = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation];

// memory cleanup

CGImageRelease(imageRef);

return result;

}