如何在Swift中裁剪一张3:4的图片？

Question

我试图在互联网上查找答案，但没有找到，可能是我在互联网上输入的查询有误。

你能告诉我如何裁剪一张3:4的照片吗？我找不到裁剪功能。请分享一下吗？

- user19726662

Answer 1

您可以使用此函数以任何纵横比（例如3:4）裁剪您的图像。您需要将您的Image和所需的AspectRatio作为参数传递给该函数，它将返回您裁剪后的图像。

func crop(image: UIImage, to aspectRatio: CGFloat) -> UIImage {

    let originalAspectRatio = image.size.height/image.size.width

    var newImagesize = image.size

    if originalAspectRatio > aspectRatio {
        newImagesize.height = image.size.width * aspectRatio
    } else if originalAspectRatio < aspectRatio {
        newImagesize.width = image.size.height / aspectRatio
    } else {
        return image
    }

    let center = CGPoint(x: image.size.width/2, y: image.size.height/2)
    let origin = CGPoint(x: center.x - newImagesize.width/2, y: center.y - newImagesize.height/2)

    let cgCroppedImage = image.cgImage!.cropping(to: CGRect(origin: origin, size: CGSize(width: newImagesize.width, height: newImagesize.height)))!
    let croppedImage = UIImage(cgImage: cgCroppedImage, scale: image.scale, orientation: image.imageOrientation)

    return croppedImage
}

使用方法：

 let croppedImage = crop(image: "ImageName", to: 3/4)

- Ali Hamza

Answer 2

请使用以下函数。如需更多详细信息，请阅读this。

func cropImage(_ inputImage: UIImage, toRect cropRect: CGRect, viewWidth: CGFloat, viewHeight: CGFloat) -> UIImage? 
{    
    let imageViewScale = max(inputImage.size.width / viewWidth,
                             inputImage.size.height / viewHeight)

    // Scale cropRect to handle images larger than shown-on-screen size
    let cropZone = CGRect(x:cropRect.origin.x * imageViewScale,
                          y:cropRect.origin.y * imageViewScale,
                          width:cropRect.size.width * imageViewScale,
                          height:cropRect.size.height * imageViewScale)

    // Perform cropping in Core Graphics
    guard let cutImageRef: CGImage = inputImage.cgImage?.cropping(to:cropZone)
    else {
        return nil
    }

    // Return image to UIImage
    let croppedImage: UIImage = UIImage(cgImage: cutImageRef)
    return croppedImage
}

- udi