为 CGMutablePath 绘制阴影，不是闭合的，只是一条线

Question

我有函数 Track.getShadowPath() 返回 CGMutablePath。

函数返回 CGMutablePath

static func getShadowPath() -> CGMutablePath{

    let trackPath = CGMutablePath()

    let initPoint = Track.tracks.first?.initPoint


    let heigthShift = CGPoint(x: 0, y: 100)
    trackPath.move(to: initPoint! - heigthShift)

    var yShift = CGPoint(x: 0, y: 0)

    for track:Track in Track.tracks{

        let q = track.getQuadrant()
        if(q == 2 || q == 5){
            yShift.y = yShift.y + track.endPoint.y - track.initPoint.y
        }
        else {
            trackPath.addLine(to: track.endPoint - heigthShift - yShift)
        }
    }

    return trackPath
}

然后将此路径添加到 CAShapeLayer，并将图层作为子图层添加到我的视图中。我希望这条路有影子方面。但是当它呈现时，它会产生一个阴影，就好像路径是封闭的一样。我怎样才能达到我的目的？

NSView

class DemoView: NSView {
    var trackShape:CAShapeLayer!
    var trackShadowShape:CAShapeLayer!

override init(frame: CGRect){
    super.init(frame: frame)

    trackShape = CAShapeLayer()

    trackShape.strokeColor = NSColor.black.cgColor
    trackShape.lineWidth = 3
    trackShape.lineJoin = kCALineJoinBevel
    trackShape.lineCap = kCALineCapRound
    trackShape.fillColor = nil

    trackShadowShape = CAShapeLayer()

    trackShadowShape.lineWidth = 14
    trackShadowShape.lineJoin = kCALineJoinBevel
    trackShadowShape.lineCap = kCALineCapRound
    trackShadowShape.fillColor = nil
    trackShadowShape.shadowColor = NSColor.blue.cgColor
    trackShadowShape.shadowRadius = 10

    self.layer?.addSublayer(trackShadowShape)
    self.layer?.addSublayer(trackShape)
 }

func redrawTrack(){
    trackShape.path = Track.getCompletePath()
    trackShadowShape.shadowPath = Track.getShadowPath()
    trackShadowShape.shadowRadius = 20
    trackShadowShape.shadowOpacity = 1
    trackShadowShape.fillColor = NSColor.clear.cgColor
    trackShadowShape.lineWidth = 10

 }
}

非预期结果

Answer 1

我使用以下方法解决了这个问题：

copy(strokingWithWidth lineWidth: CGFloat, lineCap: CGLineCap, lineJoin: CGLineJoin, miterLimit: CGFloat, transform: CGAffineTransform = default)

根据文档

Returns a new path equivalent to the results of drawing the path with a solid stroke.

所以基本上它创建了一个新的 CGPath 这是你提供的路径的笔划轮廓，具有所需的宽度、上限等...我制作了我的 getShadowPath 函数 return 这个新的计算路径：

return trackPath.copy(strokingWithWidth: 6, lineCap: CGLineCap.round, lineJoin: CGLineJoin.round, miterLimit: 10) as! CGMutablePath

然后我将该路径用作图层的 shadowPath。结果现在是预期的结果：

可以在 Objective-c 中找到类似的答案

为 CGMutablePath 绘制阴影，不是闭合的，只是一条线

Drawing a shadow for a CGMutablePath, not closed, just a line

macos

calayer

nsview

shadow