这是我创建一个渐变三角形的代码(一个三角形,而不是一个平面颜色,其中有一个颜色渐变):
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有一个方形渐变,在它上面有一个黑色三角形。我可以使填充清晰,但我不知道如何修剪路径周围的渐变层,以便只保留一个三角形。如何修剪掉我绘制的路径之外的渐变层?
答案 0 :(得分:3)
将此代码替换为此代码,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
}
}
希望这能帮到你,祝你好运