这是我必须创建一个渐变三角形的代码(该三角形不是平坦的颜色,而是具有颜色渐变的三角形):
extension UIImage {
struct GradientPoint {
var location: CGFloat
var color: UIColor
}
static func gradiatedTriangle(side: CGFloat)->UIImage {
UIGraphicsBeginImageContextWithOptions(CGSize(width: side, height: side), false, 0)
let ctx = UIGraphicsGetCurrentContext()!
ctx.saveGState()
//create gradient and draw it
let gradientPoints = [UIImage.GradientPoint(location: 0, color: UIColor.from(rgb: 0xff0000)), UIImage.GradientPoint(location: 1, color: UIColor.from(rgb: 0xd0d0d0))]
let gradient = CGGradient(colorSpace: CGColorSpaceCreateDeviceRGB(), colorComponents: gradientPoints.flatMap{$0.color.cgColor.components}.flatMap{$0}, locations: gradientPoints.map{$0.location}, count: gradientPoints.count)!
ctx.drawLinearGradient(gradient, start: CGPoint.zero, end: CGPoint(x: 0, y: side), options: CGGradientDrawingOptions())
//draw triangle
ctx.beginPath()
ctx.move(to: CGPoint(x: side / 2, y: side))
ctx.addLine(to: CGPoint(x: 0, y: 0))
ctx.addLine(to: CGPoint(x: side, y: 0))
ctx.closePath()
ctx.drawPath(using: .fill)
ctx.restoreGState()
let img = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return img
}
}
但是,返回的图像在背景中具有正方形渐变,在其顶部具有黑色三角形。我可以使填充变得清晰,但是我不知道如何修剪路径周围的渐变层,以便仅保留三角形。如何修剪掉绘制路径之外的渐变层?
用此代码替换代码,首先需要添加路径,然后ctx.clip()
剪切上下文,然后绘制渐变
import UIKit
extension UIImage {
struct GradientPoint {
var location: CGFloat
var color: UIColor
}
static func gradiatedTriangle(side: CGFloat)->UIImage {
UIGraphicsBeginImageContextWithOptions(CGSize(width: side, height: side), false, 0)
let ctx = UIGraphicsGetCurrentContext()!
//draw triangle
ctx.beginPath()
ctx.move(to: CGPoint(x: side / 2, y: side))
ctx.addLine(to: CGPoint(x: 0, y: 0))
ctx.addLine(to: CGPoint(x: side, y: 0))
ctx.closePath()
ctx.clip()
//create gradient and draw it
let gradientPoints = [UIImage.GradientPoint(location: 0, color: UIColor.red), UIImage.GradientPoint(location: 1, color: UIColor.blue)]
let gradient = CGGradient(colorSpace: CGColorSpaceCreateDeviceRGB(), colorComponents: gradientPoints.flatMap{$0.color.cgColor.components}.flatMap{$0}, locations: gradientPoints.map{$0.location}, count: gradientPoints.count)!
ctx.drawLinearGradient(gradient, start: CGPoint.zero, end: CGPoint(x: 0, y: side), options: CGGradientDrawingOptions())
let img = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return img
}
}
希望这对您有帮助,最好的问候
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