【发布时间】：2016-06-15 12:03:53
【问题描述】：
【问题讨论】：
标签： ios uiview core-graphics
【发布时间】：2016-06-15 12:03:53
【问题描述】：
实现此目的的一种方法是覆盖UIView 的draw(_:) 方法并在那里进行自定义绘图。
绘制对角线相当简单，您只需要：
从 0 到 width + height（沿着矩形的水平边缘，然后垂直向上），间隔 + 线宽，从对角线（45º）长度转换为平行于要绘制的矩形的边缘。
在每次迭代中，从该迭代的给定点到对边边缘上的点（45º）绘制一条线。我们通过简单地处理矩形的垂直边缘得到这一点，然后沿着水平）
这样的事情应该可以达到预期的效果：
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 属性以生成不同的结果。
【讨论】：
-
您有什么建议可以做出改变，以便能够以特定角度绘制线条吗？例如。 30 度而不是 45 度。
惊人的简单算法...
假设你有这些价值观：
let T: CGFloat = 15 // desired thickness of lines
let G: CGFloat = 30 // desired gap between lines
let W = rect.size.width
let H = rect.size.height
值得注意的是，就是这么简单……
var p = -(W > H ? W : H) - T
while p <= W {
c.move( to: CGPoint(x: p-T, y: -T) )
c.addLine( to: CGPoint(x: p+T+H, y: T+H) )
c.strokePath()
p += G + T + T
}
这是一个完整的 UIView 类：
class Ruled: UIView {
override func draw(_ rect: CGRect) {
let T: CGFloat = 15 // desired thickness of lines
let G: CGFloat = 30 // desired gap between lines
let W = rect.size.width
let H = rect.size.height
guard let c = UIGraphicsGetCurrentContext() else { return }
c.setStrokeColor(UIColor.orange.cgColor)
c.setLineWidth(T)
var p = -(W > H ? W : H) - T
while p <= W {
c.move( to: CGPoint(x: p-T, y: -T) )
c.addLine( to: CGPoint(x: p+T+H, y: T+H) )
c.strokePath()
p += G + T + T
}
}
}
就是这样！
整个基本算法：
1。从左上角开始，减去最长边
2。画对角线直到你走到右边
简单又好用！ :)
剪裁成矩形：
上面的类只是简单地画了一个 UIView 大小的“盒子”。
通常，您希望在一个视图中的不同位置绘制许多“框”。一个典型的例子是日历。
此示例将绘制一个框。为您需要绘制的每个框调用它：
此外，此示例显式绘制两条条纹，而不是在背景颜色上绘制一条条纹：
func simpleStripes(x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat) {
let stripeWidth: CGFloat = 20.0 // whatever you want
let m = stripeWidth / 2.0
guard let c = UIGraphicsGetCurrentContext() else { return }
c.setLineWidth(stripeWidth)
let r = CGRect(x: x, y: y, width: width, height: height)
let longerSide = width > height ? width : height
c.saveGState()
c.clip(to: r)
var p = x - longerSide
while p <= x + width {
c.setStrokeColor(pale blue)
c.move( to: CGPoint(x: p-m, y: y-m) )
c.addLine( to: CGPoint(x: p+m+height, y: y+m+height) )
c.strokePath()
p += stripeWidth
c.setStrokeColor(pale gray)
c.move( to: CGPoint(x: p-m, y: y-m) )
c.addLine( to: CGPoint(x: p+m+height, y: y+m+height) )
c.strokePath()
p += stripeWidth
}
c.restoreGState()
}
如果你想让它们移动...
1，要偏移，只需在启动时从指针中减去。令人惊讶的是，无需更改任何其他内容。
var p = x - longerSide - offset // animate offset from 0 to stripeWidth
2，细心的程序员更喜欢偏移等于斜接，以避免“尖尖的左上角”问题：
var p = x - longerSide - offset - m // for better-looking top-left corner
3，您可以使用任意数量的条纹各种颜色，实际上您可以使用不同的条纹宽度任意组合。令人惊讶的是，该算法仍然有效并且是安全的。 （如果你有多个宽度，只需将斜接m设置为最大宽度即可。）
【讨论】：
-
但是打开赏金并回答同样的问题@Fattie 有什么意义呢？
-
对，带来更好的新答案！
-
@Fattie 如何使用 45º angel？
最简单的画斜线代码：
import UIKit
@IBDesignable
class SlashPatternView: UIView {
@IBInspectable
var lineWidth: CGFloat = 1 { didSet { setNeedsLayout() } }
@IBInspectable
var squareSize: CGFloat = 1 { didSet { setNeedsLayout() } }
@IBInspectable
var lineColor: UIColor = .white { didSet { setNeedsLayout() }}
var slashes: UIImage {
let size = squareSize
let renderer = UIGraphicsImageRenderer(size: CGSize(width: size, height: size))
return renderer.image { context in
let cgcontext = context.cgContext
cgcontext.addLines(between: [CGPoint(x: 0, y: size/2), CGPoint(x: size/2, y: 0)])
cgcontext.addLines(between: [CGPoint(x: size/2, y: size), CGPoint(x: size, y: size/2)])
cgcontext.setStrokeColor(lineColor.cgColor)
cgcontext.setLineCap(.square)
cgcontext.setLineWidth(lineWidth)
cgcontext.strokePath()
}
}
override func layoutSubviews() {
super.layoutSubviews()
}
override func draw(_ rect: CGRect) {
backgroundColor?.setFill()
UIRectFill(rect)
slashes.drawAsPattern(in: rect)
}
}
【讨论】：
-
等等——那不是只画两条线吗？？