ihealth_ios/Inhealth/IHRadialGradientLayer.swift

//
//  IHRadialGradientLayer.swift
//  Inhealth
//
//  Created by weclouds on 2020/4/17.
//  Copyright © 2020 weclouds. All rights reserved.
//

import UIKit

class IHRadialGradientLayer: CALayer {
    var center : CGPoint {
        return CGPoint(x: bounds.width / 2, y: bounds.height / 2)
    }
    
    var radius :CGFloat {
        return (bounds.width + bounds.height) / 2
    }
    
    var colors : [UIColor] = [UIColor.purple,UIColor.white]{
        didSet{
            setNeedsDisplay()
        }
    }
    var cgColors : [CGColor]  {
        return colors.map { (color) -> CGColor in
            return color.cgColor
        }
    }
    override init() {
        super.init()
        needsDisplayOnBoundsChange = false
    }
    
    
    required init?(coder: NSCoder) {
        super.init()
    }
    
    override func draw(in ctx: CGContext) {
        ctx.saveGState()
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let locations :[CGFloat] = [0.0,1.0]
        let gradient = CGGradient(colorsSpace: colorSpace, colors: cgColors as CFArray, locations: locations)
 
        ctx.drawRadialGradient(gradient!, startCenter: center, startRadius: 0.0, endCenter: center, endRadius: radius, options: CGGradientDrawingOptions(rawValue: 0))
    }
}