我需要在边框中创建带渐变的圆角UIButton。我在Core Graphics代码中错过了什么?
我用面具创建了CAGradientLayer。
layer.cornerRadius = 43
let gradient = CAGradientLayer()
gradient.frame = bounds
gradient.colors = [UIColor(red: 0.99, green: 0.89, blue: 0.54, alpha: 1).cgColor, UIColor(red: 0.95, green: 0.51, blue: 0.51, alpha: 1).cgColor]
gradient.locations = [0, 1]
gradient.startPoint = CGPoint(x: 1.83, y: -0.68)
gradient.endPoint = CGPoint(x: 0.13, y: 0.82)
gradient.cornerRadius = 43
let shape = CAShapeLayer()
shape.lineWidth = 6
shape.path = UIBezierPath(roundedRect: gradient.frame, cornerRadius: 43).cgPath
shape.strokeColor = UIColor.black.cgColor
shape.fillColor = UIColor.clear.cgColor
gradient.mask = shape
layer.addSublayer(gradient)
setTitleColor(.red, for: .normal)
titleLabel?.font = Theme.shared.font.bold(ofSize: 25.0)
clipsToBounds = true
我期待不是生涩的渐变,被面具均匀地修剪。
第一个问题是路径的边框以帧的边缘为中心,因此您需要将路径插入线宽的1/2。
第二个问题是设置图层的.cornerRadius
不会给出与圆形rect bezier路径相同的曲线(奇数,但情况就是这样)。因此,您需要创建另一个蒙版以应用于按钮的图层。它可能会在边缘产生伪影,因此将其插入0.5点。
试试这个修改后的代码
// create gradient layer
let gradient = CAGradientLayer()
gradient.frame = bounds
gradient.colors = [UIColor(red: 0.99, green: 0.89, blue: 0.54, alpha: 1).cgColor, UIColor(red: 0.95, green: 0.51, blue: 0.51, alpha: 1).cgColor]
gradient.locations = [0, 1]
gradient.startPoint = CGPoint(x: 1.83, y: -0.68)
gradient.endPoint = CGPoint(x: 0.13, y: 0.82)
// create shape for gradient layer mask
let gradientShape = CAShapeLayer()
// edge / line width of 6
gradientShape.lineWidth = 6
// border is centered on the edge, so we want to inset the rect by 1/2 of the border width
var r = bounds.insetBy(dx: 3, dy: 3)
// create rounded rect path
gradientShape.path = UIBezierPath(roundedRect: r, cornerRadius: 43).cgPath
// black stroke, clear fill
gradientShape.strokeColor = UIColor.black.cgColor
gradientShape.fillColor = UIColor.clear.cgColor
// assign the shape as the gradient layer's mask
gradient.mask = gradientShape
// create a new shape for the button's layer
let layerShape = CAShapeLayer()
// inset by 0.5, to avoid artifacts on the edges
r = bounds.insetBy(dx: 0.5, dy: 0.5)
// create rounded rect path
layerShape.path = UIBezierPath(roundedRect: r, cornerRadius: 43).cgPath
// black fill (no stroke)
layerShape.fillColor = UIColor.black.cgColor
// assign the shape as the layer's mask
layer.mask = layerShape
// add gradient layer as a sublayer
layer.addSublayer(gradient)
setTitleColor(.red, for: .normal)
titleLabel?.font = Theme.shared.font.bold(ofSize: 25.0)
clipsToBounds = true