ios - 如何使用 Graphics Context 清除具有关闭路径的任何 imageView 的图像

Question

当用户在屏幕上拖动触摸时，我正在使用此代码清除图像的一部分。我有多个图像相互覆盖。现在清楚到最顶层工作正常，所以下部图像的一部分是可见的。现在我想要实现的是用户选择一条关闭路径，并且所选关闭路径的区域应该是清晰的。 用户可以选择多个图层并选择要剪切的任何部分。例如，如果有 8 张图像并且用户选择了第 6 层到第 8 层，那么可见部分将来自第 5 层，用户可以通过触摸清除该层。

func drawBrushOnLayer(fromPoint: CGPoint, toPoint: CGPoint , selected:[Int]) {               

            UIGraphicsBeginImageContext(DrawImage.frame.size)

     var context = UIGraphicsGetCurrentContext()
            DrawImage.image?.draw(in: CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height - 50))

            context?.move(to: fromPoint)

            context?.addLine(to: toPoint)

            context?.setLineCap(.butt)

            context?.setLineWidth(BrushSize)

            context?.setBlendMode(.clear)

            context?.setShouldAntialias(false)

            UIColor.clear.set()

            context?.strokePath()

           DrawImage.image = UIGraphicsGetImageFromCurrentImageContext()!

            UIGraphicsEndImageContext()

}

现在我在图像上绘制白色，但我需要清除选择的区域，以便可以看到较低的图像。

 func drawFill(point : CGPoint) {

        autoreleasepool{

            UIGraphicsBeginImageContext(CGSize(width: self.view.frame.size.width, height: self.view.frame.size.height - 50))

            DrawImage .draw(in: CGRect(x: 0, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height - 50))

            UIColor.white.set()

            BezierPath.addLine(to: point)

             BezierPath.lineWidth = 2.0

             BezierPath .close()

            BezierPath.fill()

            let context = UIGraphicsGetCurrentContext()

            context?.addPath(lassoBezier.cgPath)

            newImage = UIGraphicsGetImageFromCurrentImageContext()!

           DrawImage.image = newImage

                UIGraphicsEndImageContext()

        }

 }

Answer 1

func drawFill(point : CGPoint) {

    autoreleasepool{

        UIGraphicsBeginImageContext(CGSize(width: self.view.frame.size.width, height: self.view.frame.size.height - 50))

        DrawImage .draw(in: CGRect(x: 0, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height - 50))

        BezierPath.addLine(to: point)

         BezierPath .close()

        let context = UIGraphicsGetCurrentContext()
         UIColor.clear.set()
        context?.addPath(lassoBezier.cgPath)
        context?.setLineCap(.square)
        context?.setBlendMode(.clear)
        context?.setShouldAntialias(false)
        context?.fillPath()
        newImage = UIGraphicsGetImageFromCurrentImageContext()!

       DrawImage.image = newImage

            UIGraphicsEndImageContext()

    }