ios - 多个 UIBezierPath 的渐变

Question

我应该创建这个。

我确实搜索了 google、youtube 和 StackOverflow，下面的代码是我的研究结果。

     @IBDesignable class TriangleView2: UIView {
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    let gradient = CAGradientLayer()
    override func draw(_ rect: CGRect) {
 
        //draw the line of UIBezierPath
        
        let path1 = UIBezierPath()
        path1.move(to: CGPoint(x: rect.minX - 100, y: rect.maxY - 80))
        path1.addLine(to: CGPoint(x: rect.maxX, y: rect.maxY))
        path1.addLine(to: CGPoint(x: (rect.maxX + 90  ), y: rect.minY/2 ))
        path1.close()

        // add clipping path. this draws an imaginary line (to create bounds) from the
        //ends of the UIBezierPath line down to the bottom of the screen
        let clippingPath = path1.copy() as! UIBezierPath
        clippingPath.move(to: CGPoint(x: rect.minX - 100, y: rect.maxY - 80))
        clippingPath.addLine(to: CGPoint(x: rect.maxX, y: rect.maxY))
        clippingPath.addLine(to: CGPoint(x: (rect.maxX + 90  ), y: rect.minY/2 ))
        clippingPath.close()
        
        clippingPath.addClip()
        
        // create and add the gradient
        let colors = [theme.current.profile_start_view1.cgColor, theme.current.profile_end_view1.cgColor]
        
        let colorSpace = CGColorSpaceCreateDeviceRGB()        
        let colorLocations:[CGFloat] = [0.0, 1.0]        
        let gradient = CGGradient(colorsSpace: colorSpace,
                                  colors: colors as CFArray,
                                  locations: colorLocations)
        
        let context = UIGraphicsGetCurrentContext()
        let startPoint = CGPoint(x: 1, y: 1)
        let endPoint = CGPoint(x: 1, y: bounds.maxY)
        // and lastly, draw the gradient.
        context!.drawLinearGradient(gradient!, start: startPoint, end: 
      endPoint, options: CGGradientDrawingOptions.drawsAfterEndLocation)
        }
    }

对吧，我有 2 个 View (如果我能完成的话，将会是 3 个)，但存在一些差异。

结果是这样的。

这两个 View 没有相同的颜色，但正如您所看到的，两个 View 具有相同方向的相同渐变。

有人有什么建议吗？

Answer 1

这有点类似于 Codo 的答案，但你只需要 4 分。

class FourGradientsView: UIView {
    override func draw(_ rect: CGRect) {
        let ctx = UIGraphicsGetCurrentContext()!

        // Points of area to draw - adjust these 4 variables as needed
        let tl = CGPoint(x: 0, y: 0)
        let tr = CGPoint(x: bounds.width * 1.3, y: 0)
        let bl = CGPoint(x: -bounds.width * 1.8, y: bounds.height * 1.4)
        let br = CGPoint(x: bounds.width * 1.3, y: bounds.height * 2)

        // Find the intersection of the two crossing diagonals
        let s1x = br.x - tl.x
        let s1y = br.y - tl.y
        let s2x = tr.x - bl.x
        let s2y = tr.y - bl.y
        //let s = (-s1y * (tl.x - bl.x) + s1x * (tl.y - bl.y)) / (-s2x * s1y + s1x * s2y)
        let t = ( s2x * (tl.y - bl.y) - s2y * (tl.x - bl.x)) / (-s2x * s1y + s1x * s2y)
        let center = CGPoint(x: tl.x + (t * s1x), y: tl.y + (t * s1y))

        // Create clipping region to avoid drawing where we don't want any gradients
        ctx.saveGState()
        let clip = CGPoint(x: 0, y: bounds.height * 0.7)
        let clipPath = UIBezierPath()
        clipPath.move(to: CGPoint(x: 0, y: 0))
        clipPath.addLine(to: clip)
        clipPath.addLine(to: CGPoint(x: bounds.width, y: bounds.height))
        clipPath.addLine(to: CGPoint(x: bounds.width, y: 0))
        clipPath.close()
        clipPath.addClip()

        // Use these two colors for all 4 gradients (adjust as needed)
        let colors = [
            UIColor(hue: 120/360, saturation: 1, brightness: 0.85, alpha: 1).cgColor,
            UIColor(hue: 120/360, saturation: 1, brightness: 0.3, alpha: 1).cgColor
        ] as CFArray

        // The common gradient
        let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: colors, locations: nil)!

        // Top gradient
        ctx.saveGState()
        let pathTop = UIBezierPath()
        pathTop.move(to: tl)
        pathTop.addLine(to: tr)
        pathTop.addLine(to: center)
        pathTop.close()
        pathTop.addClip()

        ctx.drawLinearGradient(gradient, start: CGPoint(x: bounds.width, y: 0), end: CGPoint(x: 0, y: 0), options: [])
        ctx.restoreGState()

        // Right gradient
        ctx.saveGState()
        let pathRight = UIBezierPath()
        pathRight.move(to: tr)
        pathRight.addLine(to: br)
        pathRight.addLine(to: center)
        pathRight.close()
        pathRight.addClip()

        ctx.drawLinearGradient(gradient, start: CGPoint(x: bounds.width, y: bounds.height), end: CGPoint(x: bounds.width, y: 0), options: [])
        ctx.restoreGState()

        // Bottom gradient
        ctx.saveGState()
        let pathBottom = UIBezierPath()
        pathBottom.move(to: br)
        pathBottom.addLine(to: bl)
        pathBottom.addLine(to: center)
        pathBottom.close()
        pathBottom.addClip()

        ctx.drawLinearGradient(gradient, start: CGPoint(x: 0, y: bounds.height), end: CGPoint(x: bounds.width, y: bounds.height), options: [])
        ctx.restoreGState()

        // Left gradient
        ctx.saveGState()
        let pathLeft = UIBezierPath()
        pathLeft.move(to: tl)
        pathLeft.addLine(to: bl)
        pathLeft.addLine(to: center)
        pathLeft.close()
        pathLeft.addClip()

        ctx.drawLinearGradient(gradient, start: CGPoint(x: 0, y: 0), end: CGPoint(x: 0, y: bounds.height), options: [])
        ctx.restoreGState()

        ctx.restoreGState()
    }
}

let grView = FourGradientsView(frame: CGRect(x: 0, y: 0, width: 320, height: 320))
grView.backgroundColor = .black