裁剪 UIImage 的中心正方形

Question

所以这就是我到目前为止所做的。 我正在使用从相机捕获的 UIImage 并且可以在横向时裁剪中心正方形。 出于某种原因，这不会按预期转换为纵向模式。 我将发布我的代码和日志仅供参考。

代码：

CGRect squareRect = CGRectMake(offsetX, offsetY, newWidth, newHeight);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], squareRect);
image = [UIImage imageWithCGImage:imageRef scale:1 orientation:image.imageOrientation];

纵向结果（非方形）：

original image size: {1536, 2048}, with orientation: 3
squareRect: {{0, 256}, {1536, 1536}}
new image size: {1280, 1536}, with orientation: 3 <--- not expected

景观结果（正方形）：

original image size: {2048, 1536}, with orientation: 1
squareRect: {{256, 0}, {1536, 1536}}
new image size: {1536, 1536}, with orientation: 1

这是 CGImageCreateWithImageInRect() 中的错误还是我在这里遗漏了什么？

Answer 1

我认为这将是完美的解决方案！
根据toSize的大小裁剪图像不是一个好主意。 当图像分辨率（尺寸）非常大时，它看起来会很奇怪。
以下代码将根据toSize的比例裁剪图像。
改进了@BlackRider的回答。

- (UIImage *)imageByCroppingImage:(UIImage *)image toSize:(CGSize)size
{
    double newCropWidth, newCropHeight;

    //=== To crop more efficently =====//
    if(image.size.width < image.size.height){
         if (image.size.width < size.width) {
                 newCropWidth = size.width;
          }
          else {
                 newCropWidth = image.size.width;
          }
          newCropHeight = (newCropWidth * size.height)/size.width;
    } else {
          if (image.size.height < size.height) {
                newCropHeight = size.height;
          }
          else {
                newCropHeight = image.size.height;
          }
          newCropWidth = (newCropHeight * size.width)/size.height;
    }
    //==============================//

    double x = image.size.width/2.0 - newCropWidth/2.0;
    double y = image.size.height/2.0 - newCropHeight/2.0;

    CGRect cropRect = CGRectMake(x, y, newCropWidth, newCropHeight);
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect);

    UIImage *cropped = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return cropped;
}

Answer 2

这适用于不同的方向。 纵向和横向都可以正常工作。

- (UIImage *)imageByCroppingImage:(UIImage *)image toSize:(CGSize)size
{
    // not equivalent to image.size (which depends on the imageOrientation)!
    double refWidth = CGImageGetWidth(image.CGImage);
    double refHeight = CGImageGetHeight(image.CGImage);

    double x = (refWidth - size.width) / 2.0;
    double y = (refHeight - size.height) / 2.0;

    CGRect cropRect = CGRectMake(x, y, size.height, size.width);
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect);

    UIImage *cropped = [UIImage imageWithCGImage:imageRef scale:0.0 orientation:self.imageOrientation];
    CGImageRelease(imageRef);

    return cropped;
}

Answer 3

根据 Elmundo 的检查答案和 Imbrue 的 swift 版本，这里是自动计算图像中心大小（考虑方向）并考虑错误的相同解决方案：

func cropImageToSquare(image: UIImage) -> UIImage? {
    var imageHeight = image.size.height
    var imageWidth = image.size.width

    if imageHeight > imageWidth {
        imageHeight = imageWidth
    }
    else {
        imageWidth = imageHeight
    }

    let size = CGSize(width: imageWidth, height: imageHeight)

    let refWidth : CGFloat = CGFloat(CGImageGetWidth(image.CGImage))
    let refHeight : CGFloat = CGFloat(CGImageGetHeight(image.CGImage))

    let x = (refWidth - size.width) / 2
    let y = (refHeight - size.height) / 2

    let cropRect = CGRectMake(x, y, size.height, size.width)
    if let imageRef = CGImageCreateWithImageInRect(image.CGImage, cropRect) {
        return UIImage(CGImage: imageRef, scale: 0, orientation: image.imageOrientation)
    }

   return nil
}

---

斯威夫特 3版本

func cropImageToSquare(image: UIImage) -> UIImage? {
    var imageHeight = image.size.height
    var imageWidth = image.size.width

    if imageHeight > imageWidth {
        imageHeight = imageWidth
    }
    else {
        imageWidth = imageHeight
    }

    let size = CGSize(width: imageWidth, height: imageHeight)

    let refWidth : CGFloat = CGFloat(image.cgImage!.width)
    let refHeight : CGFloat = CGFloat(image.cgImage!.height)

    let x = (refWidth - size.width) / 2
    let y = (refHeight - size.height) / 2

    let cropRect = CGRect(x: x, y: y, width: size.height, height: size.width)
    if let imageRef = image.cgImage!.cropping(to: cropRect) {
        return UIImage(cgImage: imageRef, scale: 0, orientation: image.imageOrientation)
    }

    return nil
}

Answer 4

尝试这样的事情：

- (UIImage *)imageByCroppingImage:(UIImage *)image toSize:(CGSize)size
{
    double x = (image.size.width - size.width) / 2.0;
    double y = (image.size.height - size.height) / 2.0;

    CGRect cropRect = CGRectMake(x, y, size.height, size.width);
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect);

    UIImage *cropped = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return cropped;
}

如您所见，我没有在调用UIImage imageWithCGImage:指定方向。 我想知道这是否是您代码中的问题。

Answer 5

检查的解决方案有 swift 版本：

private func imageByCroppingImage(image : UIImage, size : CGSize) -> UIImage{
        var refWidth : CGFloat = CGFloat(CGImageGetWidth(image.CGImage))
        var refHeight : CGFloat = CGFloat(CGImageGetHeight(image.CGImage))

        var x = (refWidth - size.width) / 2
        var y = (refHeight - size.height) / 2

        let cropRect = CGRectMake(x, y, size.height, size.width)
        let imageRef = CGImageCreateWithImageInRect(image.CGImage, cropRect)

        let cropped : UIImage = UIImage(CGImage: imageRef, scale: 0, orientation: image.imageOrientation)!


        return cropped
    }

Answer 6

从@Elmundo 的回答中改进

+(UIImage *)getCenterMaxSquareImageByCroppingImage:(UIImage *)image withOrientation:(UIImageOrientation)imageOrientation

{
    CGSize centerSquareSize;
    double oriImgWid = CGImageGetWidth(image.CGImage);
    double oriImgHgt = CGImageGetHeight(image.CGImage);
    NSLog(@"oriImgWid==[%.1f], oriImgHgt==[%.1f]", oriImgWid, oriImgHgt);
    if(oriImgHgt <= oriImgWid) {
        centerSquareSize.width = oriImgHgt;
        centerSquareSize.height = oriImgHgt;
    }else {
        centerSquareSize.width = oriImgWid;
        centerSquareSize.height = oriImgWid;
    }

    NSLog(@"squareWid==[%.1f], squareHgt==[%.1f]", centerSquareSize.width, centerSquareSize.height);

    double x = (oriImgWid - centerSquareSize.width) / 2.0;
    double y = (oriImgHgt - centerSquareSize.height) / 2.0;
    NSLog(@"x==[%.1f], x==[%.1f]", x, y);

    CGRect cropRect = CGRectMake(x, y, centerSquareSize.height, centerSquareSize.width);
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect);

    UIImage *cropped = [UIImage imageWithCGImage:imageRef scale:0.0 orientation:imageOrientation];
    CGImageRelease(imageRef);


    return cropped;
}

Answer 7

这是一个老问题，但没有一个答案是真正正确的（即使是公认的答案）。 需要理解的重要一点是UIImageOrientation ( image.imageOrientation ) 实际上是正确的，但它对UP的定义和我们对UP的定义不同。 对我们来说， UP是设备的顶部（电源按钮所在的位置）。 对于UIImageOrientation ，向上是音量控制按钮的对面。 因此，如果设备在音量控制降低的情况下UIImageOrientationUp ，则为UIImageOrientationUp 。 如果您以纵向模式（按下主页按钮） UIImageOrientationLeft ，这是UIImageOrientationLeft 。

所以你可以计算纵向的中心，然后你可以对图像应用以下变换，使裁剪在正确的位置。

- (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;
}

此代码移动裁剪方块，使其处于正确的相对位置。

Answer 8

Swift 2 使用 UIImage 扩展

extension UIImage
{    
    func imageByCroppingImage(size : CGSize) -> UIImage
    {
        let refWidth : CGFloat = CGFloat(CGImageGetWidth(self.CGImage))
        let refHeight : CGFloat = CGFloat(CGImageGetHeight(self.CGImage))

        let x = (refWidth - size.width) / 2
        let y = (refHeight - size.height) / 2

        let cropRect = CGRectMake(x, y, size.width, size.height)
        let imageRef = CGImageCreateWithImageInRect(self.CGImage, cropRect)

        let cropped : UIImage = UIImage(CGImage: imageRef!, scale: 0, orientation: self.imageOrientation)


        return cropped
    }
}

Answer 9

斯威夫特 3

    let refWidth : CGFloat = CGFloat(image.cgImage!.width)
    let refHeight : CGFloat = CGFloat(image.cgImage!.height)

    let x = (refWidth - size.width) / 2
    let y = (refHeight - size.height) / 2

    let cropRect = CGRect(x: x, y: y, width: size.width, height: size.height)
    let imageRef = image.cgImage!.cropping(to: cropRect)

    let cropped : UIImage = UIImage(cgImage: imageRef!, scale: 0, orientation: image.imageOrientation)


    return cropped

Answer 10

这是基于@Alonzo's Swift 3 answer 以上，代码经过简化和精简，使其更易于理解和简洁。 如果图像已经是方形的，它也会退出。

extension UIImage {
    func square() -> UIImage? {
        if size.width == size.height {
            return self
        }

        let cropWidth = min(size.width, size.height)

        let cropRect = CGRect(
            x: (size.width - cropWidth) * scale / 2.0,
            y: (size.height - cropWidth) * scale / 2.0,
            width: cropWidth * scale,
            height: cropWidth * scale
        )

        guard let imageRef = cgImage?.cropping(to: cropRect) else {
            return nil
        }

        return UIImage(cgImage: imageRef, scale: scale, orientation: imageOrientation)
    }
}

Answer 11

从 UIImageView 获得帮助怎么样

+ (UIImage *)laodSquareImage:(UIImage *)image withDiameter:(CGFloat)diameter  
{
    CGRect frame = CGRectMake(0.0f, 0.0f, diameter, diameter);
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:frame];
    imageView.contentMode = UIViewContentModeScaleAspectFill;
    imageView.clipsToBounds = YES;
    imageView.image = image;
    CALayer *layer = imageView.layer;


    layer.masksToBounds = YES;
    UIGraphicsBeginImageContextWithOptions(imageView.bounds.size,NO, [UIScreen mainScreen].scale);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [layer renderInContext:context];


    UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return roundedImage;
}

您还可以通过添加一条线来制作图像圆圈。

layer.cornerRadius =MAX( imageView.frame.size.height,imageView.frame.size.width)/2;

Answer 12

已经有很多解决方案，但我想发布我的：

  extension UIImage {

    var cgImageWidth: Int { return cgImage?.width ?? 0 }
    var cgImageheight: Int { return cgImage?.height ?? 0 }
    var blance: CGFloat { return min(size.width, size.height)}
    var blanceSize: CGSize { return CGSize(width: blance, height: blance) }
    var blanceRect: CGRect { return CGRect(origin: .zero, size: blanceSize) }

    var roundedImage: UIImage? {
        UIGraphicsBeginImageContextWithOptions(blanceSize, false, scale)
        defer { UIGraphicsEndImageContext() }
        guard let cgImage = cgImage?.cropping(to: CGRect(origin: CGPoint(x: max(0, CGFloat(cgImageWidth) - blance)/2.0, y: max(0, CGFloat(cgImageheight) - blance)/2.0), size: blanceSize)) else { return nil }
        UIBezierPath(ovalIn: blanceRect).addClip()

        UIImage(cgImage: cgImage, scale: 1.0, orientation: self.imageOrientation).draw(in: blanceRect)
        return UIGraphicsGetImageFromCurrentImageContext()
    }

}

Answer 13

沙马林：

UIImage ImageByCroppingImage(UIImage image, CGSize size)
{
    double newCropWidth, newCropHeight;

    if (image.Size.Width < image.Size.Height)
    {
        newCropWidth = image.Size.Width < size.Width ? size.Width : image.Size.Width;
        newCropHeight = (newCropWidth * size.Height) / size.Width;
    }
    else
    {
        newCropHeight = image.Size.Height < size.Height ? size.Height : image.Size.Height;
        newCropWidth = (newCropHeight * size.Width) / size.Height;
    }

    double x = image.Size.Width / 2.0 - newCropWidth / 2.0;
    double y = image.Size.Height / 2.0 - newCropHeight / 2.0;

    CGRect cropRect = new CGRect(x, y, newCropWidth, newCropHeight);
    var imageRef = image.CGImage.WithImageInRect(cropRect);

    var cropped = new UIImage(imageRef);

    return cropped;
}

Answer 14

Swift 5 最干净的版本。

func cropImage() -> UIImage? {
    let size = min(self.size.width, self.size.height)
    UIGraphicsBeginImageContextWithOptions(CGSize(width: size, height: size), true, 1.0)
    defer { UIGraphicsEndImageContext() }
    self.draw(in: CGRect(x: (size - self.size.width) / 2.0,
                          y: (size - self.size.height) / 2.0,
                          width: self.size.width,
                          height: self.size.height))
    return UIGraphicsGetImageFromCurrentImageContext()
}

Answer 15

斯威夫特 5

extension UIImage {

    var squared: UIImage? {
        guard let cgImage = cgImage else {
            return nil
        }

        let length = min(cgImage.width, cgImage.height)

        let x = cgImage.width / 2 - length / 2
        let y = cgImage.height / 2 - length / 2
        let cropRect = CGRect(x: x, y: y, width: length, height: length)

        guard let croppedCGImage = cgImage.cropping(to: cropRect) else {
            return nil
        }

        return UIImage(cgImage: croppedCGImage, scale: scale, orientation: imageOrientation)
    }
}

Answer 16

基于 Swift 2 扩展的解决方案。 由@Geoffrey 和@Nirav Dangi 即兴创作。 请注意，当 newCropWidth 和 newCropHeight 小于给定的宽度或高度时，我们将它们设置为图像的宽度或高度。

extension UIImage {
    func imageByCroppingImage(size: CGSize) -> UIImage {
        let newCropWidth, newCropHeight : CGFloat;

        if(self.size.width < self.size.height) {
            if (self.size.width < size.width) {
                newCropWidth = self.size.width;
            }
            else {
                newCropWidth = size.width;
            }
            newCropHeight = (newCropWidth * size.height)/size.width;
        } else {
            if (self.size.height < size.height) {
                newCropHeight = self.size.height;
            }
            else {
                newCropHeight = size.height;
            }
            newCropWidth = (newCropHeight * size.width)/size.height;
        }

        let x = self.size.width / 2 - newCropWidth / 2;
        let y = self.size.height / 2 - newCropHeight / 2;

        let cropRect = CGRectMake(x, y, newCropWidth, newCropHeight);
        let imageRef = CGImageCreateWithImageInRect(self.CGImage, cropRect);

        let croppedImage : UIImage = UIImage(CGImage: imageRef!, scale: 0, orientation: self.imageOrientation);

        return croppedImage;
    }
}

Answer 17

我正在处理以下问题

    extension UIImage {

    var cgImageWidth: Int { return cgImage?.width ?? 0 }
    var cgImageheight: Int { return cgImage?.height ?? 0 }
    var blance: CGFloat { return min(size.width, size.height)}
    var blanceSize: CGSize { return CGSize(width: blance, height: blance) }
    var blanceRect: CGRect { return CGRect(origin: .zero, size: blanceSize) }

    var roundedImage: UIImage? {
        UIGraphicsBeginImageContextWithOptions(blanceSize, false, scale)
        defer { UIGraphicsEndImageContext() }
        guard let cgImage = cgImage?.cropping(to: CGRect(origin: CGPoint(x: max(0, CGFloat(cgImageWidth) - blance)/2.0, y: max(0, CGFloat(cgImageheight) - blance)/2.0), size: blanceSize)) else { return nil }
        UIBezierPath(ovalIn: blanceRect).addClip()

        UIImage(cgImage: cgImage, scale: 1.0, orientation: self.imageOrientation).draw(in: blanceRect)
        return UIGraphicsGetImageFromCurrentImageContext()
    }

}

Answer 18

这是根据给定大小从中心裁剪图像的 Swift 5 版本。

extension UIImage {

     func imageByCroppingImage(size : CGSize) -> UIImage{
        let refWidth : CGFloat = CGFloat(self.cgImage!.width)
        let refHeight : CGFloat = CGFloat(self.cgImage!.height)
        let x = (refWidth - size.width) / 2
        let y = (refHeight - size.height) / 2
        let cropRect = CGRect(x: x, y: y, width: size.width, height: size.height)
        let imageRef = self.cgImage!.cropping(to: cropRect)
        let cropped : UIImage = UIImage(cgImage: imageRef!, scale: 0, orientation: self.imageOrientation)
        return cropped
    }
    }

Answer 19

我能够用这样的东西来完成它：

   UIImage *thisImage = [[UIImage alloc] initWithContentsOfFile:imagePath];
                double x = (thisImage.size.width )/2.0;
                double y = (thisImage.size.height)/2.0;
                mediaImage = [self imageByCropping:thisImage toRect:CGRectMake(x, y, 60, 60)];
                [thisImage release];