在子类值中使用 uislider 更改线宽

Question

我的代码试图使用幻灯片值来更改线条的宽度。现在它不起作用。我只希望不希望在值更改之前绘制的线条仅在 class Canvas 中的增值税编号为 changed.Look 之后的新行生效。 Struct ColoredLine 控制线条的颜色。


    struct ColoredLine {
    var color = UIColor.black
    var points = [CGPoint]()
}


class ViewController: UIViewController {

    @objc func hhh() {
        canvas.number = Int(justinBiber.value)
    }

    var justinBiber = UISlider()
}

class Canvas: UIView {

       var strokeColor = UIColor.green
       var number = 5
        func undo() {
            _ = lines.popLast()
            setNeedsDisplay()
        }

        func clear() {
            lines.removeAll()
            setNeedsDisplay()
        }

        var lines = [ColoredLine]()

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

            guard let context = UIGraphicsGetCurrentContext() else { return }

            context.setLineWidth(number)
            context.setLineCap(.butt)

            lines.forEach { (line) in
                for (i, p) in line.points.enumerated() {
                    if i == 0 {
                        context.move(to: p)
                    } else {
                        context.addLine(to: p)
                    }
                }

                context.setStrokeColor(line.color.cgColor)
                context.strokePath()
                context.beginPath()
            }


        }

        override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
            var coloredLine = ColoredLine()
            coloredLine.color = strokeColor
            lines.append(coloredLine)
        }

        override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
            guard let point = touches.first?.location(in: self) else { return }
            guard var lastLine = lines.popLast() else { return }
            lastLine.points.append(point)
            lines.append(lastLine)
            setNeedsDisplay()
        }

    }

Answer 1

线宽只是你线的另一个属性。将属性添加到 ColoredLine struct:

struct ColoredLine {
    var color = UIColor.black
    var width = 5
    var points = [CGPoint]()
}

将 strokeWidth 属性添加到您的 Canvas class 并在滑块值更改时更新它：

class Canvas : UIView {
    var strokeWidth = 5

    ....
}

在touchesBegan()中，将strokeWidth的当前值添加到coloredLine实例中：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    var coloredLine = ColoredLine()
    coloredLine.color = strokeColor
    coloredLine.width = strokeWidth
    lines.append(coloredLine)
}

然后在draw(rect:)画线前设置context的strokeWidth：

lines.forEach { (line) in
    for (i, p) in line.points.enumerated() {
        if i == 0 {
            context.move(to: p)
        } else {
            context.addLine(to: p)
        }
    }

    context.setStrokeColor(line.color.cgColor)
    context.setLineWidth(line.width)
    context.strokePath()
    context.beginPath()
}

在子类值中使用 uislider 更改线宽

Change line width with uislider in a subclass value

subclass

uislider

cgpoint

uigraphicscontext

swift