将UIImage剪切到UIBezierPath(不屏蔽) [英] Clip UIImage to UIBezierPath (not masking)

问题描述

我正在尝试基于给定的UIBezierPath裁剪UIImage，但是生成的图像保留了原始形状和大小.我希望形状和大小类似于路径，即新图像的可见内容.

I'm trying to clip a UIImage based on a given UIBezierPath, but the resulting image retains the original shape and size. I want the shape and size to resemble the path, i.e. the visible content of the new image.

看看下面的例子:

以下是我用来屏蔽给定路径的图像的代码:

The following is the code I am using to mask an image given a path:

func imageByApplyingClippingBezierPath(_ path: UIBezierPath) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(CGSize(
        width: size.width,
        height: size.height
    ), false, 0.0)
    let context = UIGraphicsGetCurrentContext()!
    context.saveGState()

    path.addClip()
    draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))

    let newImage = UIGraphicsGetImageFromCurrentImageContext()!

    context.restoreGState()
    UIGraphicsEndImageContext()

    return newImage
}

一种解决方案是在蒙版后裁剪图像，但理想情况下，我希望一次完成尽可能简单有效的操作.

One solution would be to crop the image after masking it, but ideally I want this to be done as simple and efficiently as possible in one go.

任何解决方案/技巧都将不胜感激.

Any solution/ tips would be appreciated.

推荐答案

感谢 Rob 我能够实现一个解决方案使用CGImage的cropping(to:)方法.

Thanks to Rob I was able to implement a solution using the cropping(to:) method of CGImage.

这是一个分为两个步骤的过程，首先我使用给定的路径遮罩图像，然后使用路径的边界裁剪结果.

This is a two step process where first I mask the image using the given path, and then crop the result using the bounds of the path.

以下是用于实现剪切 UIBezierPath UIImage扩展名的最终工作源代码:

The following is my final working source code for implementing a clipping UIBezierPath UIImage extension:

extension UIImage {

    func imageByApplyingClippingBezierPath(_ path: UIBezierPath) -> UIImage {
        // Mask image using path
        let maskedImage = imageByApplyingMaskingBezierPath(path)

        // Crop image to frame of path
        let croppedImage = UIImage(cgImage: maskedImage.cgImage!.cropping(to: path.bounds)!)
        return croppedImage
    }

    func imageByApplyingMaskingBezierPath(_ path: UIBezierPath) -> UIImage {
        // Define graphic context (canvas) to paint on
        UIGraphicsBeginImageContext(size)
        let context = UIGraphicsGetCurrentContext()!
        context.saveGState()

        // Set the clipping mask
        path.addClip()
        draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))

        let maskedImage = UIGraphicsGetImageFromCurrentImageContext()!

        // Restore previous drawing context
        context.restoreGState()
        UIGraphicsEndImageContext()

        return maskedImage
    }

}

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