制作椭圆形渐变形状

Question

我试图找出如何创建一个不是完美圆形的椭圆渐变。例如美式橄榄球/橄榄球/眼睛形状而不是圆形。

目前我已经创建了一个如下所示的CALayer子类，它创建了一个圆圈。我怎样才能将它变成椭圆形（如上所述）？

class CircleGradientLayer: CALayer {

var startRadius: CGFloat?
var startCenter: CGPoint?
var endCenter: CGPoint?
var endRadius: CGFloat?
var locations: [CGFloat]?
var colors: [UIColor]?

override func drawInContext(ctx: CGContext) {
    super.drawInContext(ctx)


    if let colors = self.colors, let locations = self.locations, let startRadius = self.startRadius, let startCenter = self.startCenter, let endCenter = self.endCenter, let endRadius = self.endRadius {
        var colorSpace: CGColorSpaceRef?

        var components = [CGFloat]()
        for i in 0 ..< colors.count {
            let colorRef = colors[i].CGColor
            let colorComponents = CGColorGetComponents(colorRef)
            let numComponents = CGColorGetNumberOfComponents(colorRef)
            if colorSpace == nil {
                colorSpace = CGColorGetColorSpace(colorRef)
            }
            for j in 0 ..< numComponents {
                let component = colorComponents[j]
                components.append(component)
            }
        }

        if let colorSpace = colorSpace {
            let gradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, locations.count)
            CGContextDrawRadialGradient(ctx, gradient, startCenter, startRadius, endCenter, endRadius, CGGradientDrawingOptions.DrawsAfterEndLocation)

        }
    } 
}
}

Answer 1

这样做的一种方法是通过将某个因子缩放X来设置图层的变换。例如：

layer.transform = CATransform3DMakeScale(1.5, 1.0)

不确定这是否是最佳解决方案，但它应该有效！