在 Xamarin iOS C# 中将 Swift 图形代码转换为 UIKit

Question

我需要在我的 Xamarin 应用程序中将图像裁剪成圆形。这是依赖于平台的，所以它必须使用 UIKit。

我找到了以下 Swift 代码（来源）：

extension UIImage {
    var isPortrait:  Bool    { size.height > size.width }
    var isLandscape: Bool    { size.width > size.height }
    var breadth:     CGFloat { min(size.width, size.height) }
    var breadthSize: CGSize  { .init(width: breadth, height: breadth) }
    var breadthRect: CGRect  { .init(origin: .zero, size: breadthSize) }
    var circleMasked: UIImage? {
        guard let cgImage = cgImage?
            .cropping(to: .init(origin: .init(x: isLandscape ? ((size.width-size.height)/2).rounded(.down) : 0,
                                              y: isPortrait  ? ((size.height-size.width)/2).rounded(.down) : 0),
                                size: breadthSize)) else { return nil }
        let format = imageRendererFormat
        format.opaque = false
        return UIGraphicsImageRenderer(size: breadthSize, format: format).image { _ in
            UIBezierPath(ovalIn: breadthRect).addClip()
            UIImage(cgImage: cgImage, scale: format.scale, orientation: imageOrientation)
            .draw(in: .init(origin: .zero, size: breadthSize))
        }
    }
}

你能帮我把它转换成 UIKit C# 吗？
谢谢！

P.S。没有相关回复，所以我尽我所能整理了一个可用的版本。见下文。

Answer 1

对于圆形图片我推荐使用 - FFImageLoading

否则通过 xaml:

<Image Source="Image">
          <Image.Clip>
                <EllipseGeometry Center="30,30">
                    <EllipseGeometry.RadiusX>
                        <OnPlatform x:TypeArguments="x:Double"
                                    iOS="30"
                                    Android="0"/>
                    </EllipseGeometry.RadiusX>
                    <EllipseGeometry.RadiusY>
                        <OnPlatform x:TypeArguments="x:Double"
                                    iOS="30"
                                    Android="0"/>
                    </EllipseGeometry.RadiusY>
                </EllipseGeometry>
          </Image.Clip>
</Image>

Answer 2

没有相关回复，所以我尽我所能整理了一个有效的版本：

public UIImage cropToCircle(UIImage inimg) {
     if(null == inimg) return null;

     // step 1. crop to a square:
     var length = Math.Min(inimg.Size.Width, inimg.Size.Height); 
     var x = inimg.Size.Width/2 - length/2;
     var y = inimg.Size.Height/2 - length/2;
     var cropRect = new CGRect(x, y, length, length);

     UIGraphics.BeginImageContextWithOptions(cropRect.Size, false, 0);
     var context = UIGraphics.GetCurrentContext();

     context.TranslateCTM(0.0f, (float)length);
     context.ScaleCTM(1.0f, -1.0f);
     context.DrawImage(new RectangleF(0, 0,
            (float)length, (float)length), inimg.CGImage);
     context.ClipToRect(cropRect);

     var croppedImage = UIGraphics.GetImageFromCurrentImageContext();
            UIGraphics.EndImageContext();

     // step 2. crop to a circle 
     UIImageView imageView = new UIImageView(croppedImage);
     var layer = imageView.Layer;
     layer.MasksToBounds = true;
     layer.CornerRadius = 
          (nfloat)(Math.Min(imageView.Frame.Height, imageView.Frame.Width)) / 2;
     UIGraphics.BeginImageContext(imageView.Bounds.Size);
     layer.RenderInContext(UIGraphics.GetCurrentContext());
     var circleImg = UIGraphics.GetImageFromCurrentImageContext();
     UIGraphics.EndImageContext();

     return circleImg;
}

（我使用图层进行循环裁剪的原因是我不知道如何将 UIBezierPath 附加到上下文）。

在 Xamarin iOS C# 中将 Swift 图形代码转换为 UIKit

Convert Swift graphics code to UIKit in Xamarin iOS C#

c#

uikit

ios

xamarin

swift