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重画视图时,绘图中uibezierpath上的阴影集(矩形:)被删除

core-graphics uiview swift ios

Obi Anachebe · 技术社区 · 7 年前

我实现了一个可折叠的标题视图,它有一个弯曲的底部边框和一个位于滚动视图上方的渐变层。标题具有在其draw(rect:)函数中绘制的阴影。阴影为底部边界提供了辉光效果。一切看起来都很好,但当在标题上调用setNeedsDisplay()或重新绘制视图时,阴影消失了。

重画视图时,如何使投影保持不变?

override func draw(_ rect: CGRect) {
    super.draw(rect)

    let p1 = CGPoint(x: 0, y: self.frame.height * 0.8)
    let p2 = CGPoint(x: self.frame.width / 2, y: self.frame.height * 1.06)
    let p3 = CGPoint(x: self.frame.width, y: self.frame.height * 0.8)
    let p4 = CGPoint(x: self.frame.width, y: 0)
    let p5 = CGPoint(x: 0, y: 0)

    let path = UIBezierPath()

    path.move(to: p1)
    path.addQuadCurve(to: p3, controlPoint: p2)
    path.addLine(to: p4)
    path.addLine(to: p5)
    path.addLine(to: p1)
    path.close()

    self.shapeLayer.path = path.cgPath
    self.layer.mask = self.shapeLayer

    if !self.didSetGradient {

        self.gradient = CustomColors.blueGreenBackgroundGradient(frame: path.bounds)

        self.gradient.mask = shapeLayer
        self.gradient.masksToBounds = true
        self.gradient.removeFromSuperlayer()

        self.layer.insertSublayer(self.gradient, at: 0)

        self.didSetGradient = true
    }

    let context = UIGraphicsGetCurrentContext()

    context?.saveGState()
    context?.setShadow(offset: CGSize(width: 0, height: 2.5), blur: 15, color: CustomColors.green.cgColor)
    CustomColors.blueGreen.setStroke()
    UIColor.clear.setFill()
    path.lineWidth = 5
    path.stroke()
    context?.restoreGState()        
}

1 回复 | 直到 7 年前

Obi Anachebe 7 年前

艾希特能够解决这个问题。重新绘制视图时,贝塞尔路径阴影被隐藏,因为层掩码被设置为shapeLayer。我的解决方案是使用层的 shadowPath 属性并插入 shapeLayer 作为子层,而不是掩蔽层。确保添加 形状层 在添加渐变之前,使渐变显示在这个 didSetGradient

override func draw(_ rect: CGRect) {
    super.draw(rect)

    let p1 = CGPoint(x: 0, y: self.frame.height * 0.8)
    let p2 = CGPoint(x: self.frame.width / 2, y: self.frame.height * 1.06)
    let p3 = CGPoint(x: self.frame.width, y: self.frame.height * 0.8)
    let p4 = CGPoint(x: self.frame.width, y: 0)
    let p5 = CGPoint(x: 0, y: 0)

    let path = UIBezierPath()

    path.move(to: p1)
    path.addQuadCurve(to: p3, controlPoint: p2)
    path.addLine(to: p4)
    path.addLine(to: p5)
    path.addLine(to: p1)
    path.close()

    self.shapeLayer.path = path.cgPath

    if !self.didSetGradient {
            self.layer.insertSublayer(shapeLayer, at: 0)

        self.gradient = CustomColors.blueGreenBackgroundGradient(frame: path.bounds)
        self.gradient.mask = shapeLayer
        self.gradient.masksToBounds = true
        self.layer.insertSublayer(self.gradient, at: 0)

        self.didSetGradient = true
    }       

    self.layer.shadowPath = startPath.cgPath
    self.layer.shadowColor = CustomColors.blueGreen.cgColor
    self.layer.shadowOpacity = 0.5
    self.layer.shadowRadius = 8
    self.layer.shadowOffset = CGSize(width: 0, height: 7)
    self.layer.masksToBounds = false
    self.clipsToBounds = false
}