UIBezierPath 和曲线指向但只有一个 CGPoint 而不是两个

Question

这是我的代码：

private func bezierPathForSmile(fractionOfMaxSmile : Double) -> UIBezierPath
    {
        let mouthWidth = faceRadius / Scaling.FaceRadiusToMouthWidthRatio
        let mouthHeight = faceRadius / Scaling.FaceRadiusToMouthHeightRatio
        let mouthVerticalOffset = faceRadius / Scaling.FaceRadiusToMouthOffsetRatio

        let smileHeight = CGFloat(max(min(fractionOfMaxSmile, 1), -1)) * mouthHeight    //an einai pio megalo tou 1 krata to 1 an einai pio megalo apo -1 krata to pio megalo

        let start = CGPoint(x: faceCenter.x - mouthWidth / 2, y: faceCenter.y + mouthVerticalOffset)
        let end = CGPoint(x: start.x + mouthWidth, y: start.y)
        let cp1 = CGPoint(x: start.x + mouthWidth / 3, y: start.y + smileHeight)
        let cp2 = CGPoint(x: end.x - mouthWidth / 3, y: cp1.y)

        let path = UIBezierPath()
        path.moveToPoint(start)
        path.addCurveToPoint(end, controlPoint1: cp1, controlPoint2: cp2)
        path.lineWidth = lineWidth
        return path
    }

我想问一下是否有一种方法可以通过仅指定 (start.x + end.x) /2 及其 y 轴与 start.y 或 end.y 的偏差，而不是使用：

path.addCurveToPoint(end, controlPoint1: cp1, controlPoint2: cp2)

有两个控制点。换句话说，我想通过仅指定中心的 GCPoint 来实现上述确切的事情。(start + end)/2 谢谢。

Answer 1

addCurveToPoint使用两个控制点，而addQuadCurveToPoint只使用一个控制点。

图片来自Drawing and Printing Guide for iOS.

UIBezierPath 和曲线指向但只有一个 CGPoint 而不是两个

UIBezierPath and curve to point but only with one CGPoint instead of two

cgpoint

ios

swift