NSBezierPath:如何使用LineDashStyle控制段数?

时间:2016-04-26 06:46:51

标签: xcode swift macos nsbezierpath

我想用NSBezierPath绘制一个正方形。广场的边框必须停止,所以我使用dashStyle,但我不能控制创建的段数。

在Apple文档中,解释有点模糊。他们说"设置线条划线图案时,指定每个连续的实心或透明样本的宽度(以磅为单位)"。   所以我想,我需要一种方法来获得弯曲贝塞尔的长度。

有没有人知道我怎么能做到这一点?

1 个答案:

答案 0 :(得分:0)

extension NSBezierPath {

    var lenght:Double {
        get{
            let flattenedPath =  self.bezierPathByFlatteningPath
            let segments = flattenedPath.elementCount
            var lastPoint:NSPoint = NSZeroPoint
            var point:NSPoint = NSZeroPoint
            var size :Double = 0

            for i in 0...segments - 1 {
                let e:NSBezierPathElement = flattenedPath.elementAtIndex(i, associatedPoints: &point)
                if e == .MoveToBezierPathElement {
                    lastPoint = point
                } else {
                    let distance:Double = sqrt(pow(Double(point.x - lastPoint.x) , 2) + pow(Double(point.y - lastPoint.y) , 2))
                   size += distance
                    lastPoint = point
                }
            }

            return size
        }
    }
}

通过此扩展,我获得了bezier的“近似”长度。在那之后,一切都很简单:

let myPath = NSBezierPath(roundedRect:myRect, xRadius:50, yRadius:50)
let pattern = myPath.length / (numbersOfSegments * 2) // we divide the length to double of segments we need.
myPath.setLineDash([CGFloat(pattern),CGFloat(pattern)], countL:2 , phase: 0)
myPath.stroke()