在bezierPath上绘制CAShapeLayer时上下文无效
在bezierPath上绘制CAShapeLayer时上下文无效
提问于 2019-09-27 07:57:40
因此，在运行我的代码时，我会得到以下错误：
CGContextSetStrokeColorWithColor: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSetLineWidth: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSetLineJoin: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSetLineCap: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSetMiterLimit: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextSetFlatness: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextAddPath: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextDrawPath: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
CGContextRestoreGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.当我设置CG_CONTEXT_SHOW_BACKTRACE环境变量时，错误指向我的func bezierPath(dentInMM value: Float) -> CGPath函数。下面是组成控制器这一部分的代码片段：
var shape = CAShapeLayer()
func someFunc() {
self.dentView.layer.addSublayer(self.shape)
let color: UIColor = .systemGreen
self.shape.fillColor = color.withAlphaComponent(0.3).cgColor
self.shape.strokeColor = color.cgColor
self.shape.lineWidth = 6
self.shape.path = self.bezierPath(dentInMM: 0)
}
func bezierPath(dentInMM value: Float) -> CGPath {
self.shape.frame = self.dentView.bounds
let x000 = Int(self.shape.frame.minX)
let x050 = Int(self.shape.frame.midX)
let x100 = Int(self.shape.frame.maxX)
let x010 = x100 / 10
let x040 = x050 - x010
let x060 = x050 + x010
let yOffSet = Int(self.shape.frame.minY)
let indentation = Int(value * self.dentDisplayMultiplier)
let bezierPath = UIBezierPath()
bezierPath.move(to: CGPoint(x: x000, y: yOffSet))
bezierPath.addCurve(to: CGPoint(x: x050, y: indentation), controlPoint1: CGPoint(x: x050, y: yOffSet), controlPoint2: CGPoint(x: x040, y: indentation))
bezierPath.addCurve(to: CGPoint(x: x100, y: yOffSet), controlPoint1: CGPoint(x: x060, y: indentation), controlPoint2: CGPoint(x: x050, y: yOffSet))
UIColor.label.setStroke()
bezierPath.stroke()
return bezierPath.cgPath
}我需要在某个地方指定上下文吗？我的印象是CAShapeLayer提供了.
回答 2
Stack Overflow用户
回答已采纳
发布于 2019-09-27 09:16:17
不必调用绘图方法
bezierPath.stroke()
CAShapeLayer将在dentView中绘制自己
你真的需要
UIColor.label.setStroke()
因为您已经在someFunc()中设置了someFunc()
以下是没有错误的工作原理：
class ThirdViewController: UIViewController {
let dentDisplayMultiplier : Float = 6
var shape = CAShapeLayer()
@IBOutlet weak var dentView: UIView!
func someFunc() {
self.dentView.layer.addSublayer(self.shape)
let color: UIColor = .systemGreen
self.shape.fillColor = color.withAlphaComponent(0.3).cgColor
self.shape.strokeColor = color.cgColor
self.shape.lineWidth = 6
self.shape.path = self.bezierPath(dentInMM: 3)
}
func bezierPath(dentInMM value: Float) -> CGPath {
self.shape.frame = self.dentView.bounds
let x000 = Int(self.shape.frame.minX)
let x050 = Int(self.shape.frame.midX)
let x100 = Int(self.shape.frame.maxX)
let x010 = x100 / 10
let x040 = x050 - x010
let x060 = x050 + x010
let yOffSet = Int(self.shape.frame.minY)
let indentation = Int(value * self.dentDisplayMultiplier)
let bezierPath = UIBezierPath()
bezierPath.move(to: CGPoint(x: x000, y: yOffSet))
bezierPath.addCurve(to: CGPoint(x: x050, y: indentation), controlPoint1: CGPoint(x: x050, y: yOffSet), controlPoint2: CGPoint(x: x040, y: indentation))
bezierPath.addCurve(to: CGPoint(x: x100, y: yOffSet), controlPoint1: CGPoint(x: x060, y: indentation), controlPoint2: CGPoint(x: x050, y: yOffSet))
return bezierPath.cgPath
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
someFunc()
}
}Stack Overflow用户
发布于 2019-09-27 08:27:15
尝尝这个
let bezierPath = UIBezierPath()
UIGraphicsBeginImageContextWithOptions(self.shape.frame.size, false, 0)
bezierPath.move(to: CGPoint(x: x000, y: yOffSet))
bezierPath.addCurve(to: CGPoint(x: x050, y: indentation), controlPoint1: CGPoint(x: x050, y: yOffSet), controlPoint2: CGPoint(x: x040, y: indentation))
bezierPath.addCurve(to: CGPoint(x: x100, y: yOffSet), controlPoint1: CGPoint(x: x060, y: indentation), controlPoint2: CGPoint(x: x050, y: yOffSet))
UIColor.label.setStroke()
bezierPath.stroke()
UIGraphicsEndImageContext()页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/58130232
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