使用Swift保存带圆角和边框的UIImage

Question

我正在使用imagePickerController从用户的库中选择图片。 我需要将图片以圆角和边框的形式保存在应用程序中。 当我保存图像时，它保存未经修改的图像。 我认为我只是修改了视图而不是图像本身。 有没有办法将图片保存为视图中所见的样子？

@IBOutlet var imageViewer: UIImageView!

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
    var imagePicked = info[UIImagePickerControllerOriginalImage] as UIImage
    imageViewer.layer.cornerRadius = 10.0
    imageViewer.clipsToBounds = true
    imageViewer.layer.frame = CGRectInset(imageViewer.layer.frame, 20, 20)
    imageViewer.layer.borderColor = UIColor.purpleColor().CGColor
    imageViewer.layer.borderWidth = 2.0
    imageViewer.image = imagePicked

感谢您的帮助！

- seekerOfTruth

Answer 1

您需要执行的基本操作包括：

• Clip the drawing area to draw your image into without the corners
• Draw the image
• Configure the stroke colour etc

• Then stroke the path used for clipping

  func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
    let borderWidth: CGFloat = 2.0
    let imagePicked = info[UIImagePickerControllerOriginalImage] as UIImage
  
    UIGraphicsBeginImageContextWithOptions(imageViewer.frame.size, false, 0)
  
    let path = UIBezierPath(roundedRect: CGRectInset(imageViewer.bounds, borderWidth / 2, borderWidth / 2), cornerRadius: 10.0)
    let context = UIGraphicsGetCurrentContext()
  
    CGContextSaveGState(context)
    // Clip the drawing area to the path
    path.addClip()
  
    // Draw the image into the context
    imagePicked.drawInRect(imageViewer.bounds)
    CGContextRestoreGState(context)
  
    // Configure the stroke
    UIColor.purpleColor().setStroke()
    path.lineWidth = borderWidth
  
    // Stroke the border
    path.stroke()
  
    roundedImage = UIGraphicsGetImageFromCurrentImageContext();
  
    UIGraphicsEndImageContext();
  
    view.addSubview(UIImageView(image: roundedImage))
  
    picker.dismissViewControllerAnimated(true, completion: nil)
  }
  

在上面的代码中，我将路径缩小半个描边宽度，因为描边沿着路径的中心绘制，这意味着一个像素会落在路径之外。

- Paul.s

Answer 2

带边框的圆形UIImage：

extension UIImage {
    
    func roundedWithStroke(width: CGFloat = 3) -> UIImage {
        let imageLayer = CALayer()
        let targetSize = CGSize(width: 29, height: 29)

        imageLayer.frame = CGRect(x: 0, y: 0, width: targetSize.width, height: targetSize.height)
        imageLayer.contents = cgImage
        imageLayer.masksToBounds = true
        imageLayer.cornerRadius = targetSize.width / 2
        imageLayer.borderWidth = width
        imageLayer.borderColor = UIColor.mainAccent.cgColor
        
        UIGraphicsBeginImageContextWithOptions(targetSize, false, scale)
        imageLayer.render(in: UIGraphicsGetCurrentContext()!)
        let roundedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        return roundedImage ?? UIImage()
    }
    
}

你可以修改扩展方法以传递所需的参数。

- Arthur Stepanov

Answer 3

Paul.s的回答很完美（⬆️），但是它只捕捉了UIImage相对于UIImageView的大小，可能会降低图像质量。假设您希望图像在框架内保持其纵横比，并且希望边框直接位于其边缘上，则可以执行以下操作以保持完整图像的大小以进行保存：

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {

    let imagePicked = info[UIImagePickerControllerOriginalImage] as UIImage

    let borderWidth: CGFloat = 2.0
    let cornerRadius:CGFloat = 10.0

    // Create a multiplier to scale up the corner radius and border
    // width you decided on relative to the imageViewer frame such
    // that the corner radius and border width can be converted to
    // the UIImage's scale.
    let multiplier:CGFloat = imagePicked.size.height/imageViewer.frame.size.height > imagePicked.size.width/imageViewer.frame.size.width ?
       imagePicked.size.height/imageViewer.frame.size.height :
       imagePicked.size.width/imageViewer.frame.size.width

    let borderWidthMultiplied:CGFloat = borderWidth * multiplier
    let cornerRadiusMultiplied:CGFloat = cornerRadius * multiplier

    UIGraphicsBeginImageContextWithOptions(imagePicked.size, false, 0)

    let path = UIBezierPath(roundedRect: CGRectInset(CGRectMake(0, 0, imagePicked.size.width, imagePicked.size.height),
       borderWidthMultiplied / 2, borderWidthMultiplied / 2), cornerRadius: cornerRadiusMultiplied)

    let context = UIGraphicsGetCurrentContext()

    CGContextSaveGState(context)
    // Clip the drawing area to the path
    path.addClip()

    // Draw the image into the context
    imagePicked.drawInRect(CGRectMake(0, 0, imagePicked.size.width, imagePicked.size.height))
    CGContextRestoreGState(context)

    // Configure the stroke
    UIColor.blackColor().setStroke()
    path.lineWidth = borderWidthMultiplied

    // Stroke the border
    path.stroke()

    imageViewer.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    picker.dismissViewControllerAnimated(true, completion: nil)


}

- Lyndsey Scott

Answer 4

你目前所做的是更改图像呈现方式，而不是更改图像本身。你需要创建一个位图上下文（参见UIGraphicsBeginImageContextWithOptions）；设置圆角矩形剪切区域（CGContextEOClip）；将图像绘制到上下文中；最后，从上下文获取UIImage（UIGraphicsGetImageFromCurrentImageContext）。

- David Berry

Answer 5

Swift 3：

     func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        if let image = info[UIImagePickerControllerEditedImage] as? UIImage {
            let borderWidth: CGFloat = 2.0
               UIGraphicsBeginImageContextWithOptions(myImageButton.frame.size, false, 0)
                let path = UIBezierPath(roundedRect: myImageButton.bounds.insetBy(dx: borderWidth / 2, dy: borderWidth / 2), cornerRadius: 40.0)
                let context = UIGraphicsGetCurrentContext()
                context!.saveGState()
                path.addClip()
                image.draw(in: myImageButton.bounds)
                UIColor.gray.setStroke()
                path.lineWidth = borderWidth
                path.stroke()
                let roundedImage = UIGraphicsGetImageFromCurrentImageContext()
                UIGraphicsEndImageContext()

                myImageButton.setImage(roundedImage, for: .normal)
}
}

- JP Aquino