用对角线绘制UIView？ [英] Fill a UIView with diagonally drawn lines?

问题描述

如何像这样填充 UIView （带有一些对角线绘制的白线）。

How to fill a UIView like this (with some diagonally drawn white lines).

PS：我的意图是关于填充而不是边界。

PS: My intentions is about the fill not the border.

任何帮助？

推荐答案

实现这一目标的一种方法是覆盖绘制（_：） UIView 的方法并在那里进行自定义绘图。

One way of achieving this would be to override the draw(_:) method of UIView and do your custom drawing there.

绘制对角线很简单，你只需要：

Drawing diagonal lines is fairly simple, you just need to:

• 从0到宽度+高度（沿着水平边缘）直线，然后向上垂直），由间隙+线宽，从对角线（45º）长度转换为平行于矩形边缘进行绘制。

• Stride from 0 to width + height (along the horizontal edge of the rect, then up the vertical), by the gap + line width, converted from being a diagonal (at 45º) length to being parallel to the edge of the rect to draw in.

在每次迭代中，从该迭代的给定点绘制一条直线到该点相对的边缘（45º）。我们通过简单地处理矩形的垂直边缘来获得这一点，然后沿着水平方向）

At each iteration, draw a line from the given point for that iteration to the point on the edge opposite (at 45º). We get this point by simply working up the vertical edge of the rect, then along the horizontal)

这样的事情应该达到预期的效果：

Something like this should achieve the desired result:

class StripeyView : UIView {

    let lineGap: CGFloat = 7
    let lineWidth: CGFloat = 3
    let lineColor = UIColor.white

    override func draw(_ rect: CGRect) {

        let ctx = UIGraphicsGetCurrentContext()!

        // flip y-axis of context, so (0,0) is the bottom left of the context
        ctx.scaleBy(x: 1, y: -1)
        ctx.translateBy(x: 0, y: -bounds.size.height)

        // generate a slightly larger rect than the view,
        // to allow the lines to appear seamless
        let renderRect = bounds.insetBy(dx: -lineWidth * 0.5, dy: -lineWidth * 0.5)

        // the total distance to travel when looping (each line starts at a point that
        // starts at (0,0) and ends up at (width, height)).
        let totalDistance = renderRect.size.width + renderRect.size.height

        // loop through distances in the range 0 ... totalDistance
        for distance in stride(from: 0, through: totalDistance,
                               // divide by cos(45º) to convert from diagonal length
                               by: (lineGap + lineWidth) / cos(.pi / 4)) {

            // the start of one of the stripes
            ctx.move(to: CGPoint(
                // x-coordinate based on whether the distance is less than the width of the
                // rect (it should be fixed if it is above, and moving if it is below)
                x: distance < renderRect.width ?
                    renderRect.origin.x + distance :
                    renderRect.origin.x + renderRect.width,

                // y-coordinate based on whether the distance is less than the width of the
                // rect (it should be moving if it is above, and fixed if below)
                y: distance < renderRect.width ?
                    renderRect.origin.y :
                    distance - (renderRect.width - renderRect.origin.x)
            ))

            // the end of one of the stripes
            ctx.addLine(to: CGPoint(
                // x-coordinate based on whether the distance is less than the height of
                // the rect (it should be moving if it is above, and fixed if it is below)
                x: distance < renderRect.height ?
                    renderRect.origin.x :
                    distance - (renderRect.height - renderRect.origin.y),

                // y-coordinate based on whether the distance is less than the height of
                // the rect (it should be fixed if it is above, and moving if it is below)
                y: distance < renderRect.height ?
                    renderRect.origin.y + distance :
                    renderRect.origin.y + renderRect.height
            ))
        }

        // stroke all of the lines added
        ctx.setStrokeColor(lineColor.cgColor)
        ctx.setLineWidth(lineWidth)
        ctx.strokePath()
    }
}

输出：

（假设视图有红色 backgroundColor ）

您可以调整 lineGap 和 lineWidth 产生不同结果的属性。

You can adjust the lineGap and lineWidth properties to generate varying results.

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