iOS 给UIImage添加边框(直接加在UIImage上)

水深无声 2022-06-05 12:15 533阅读 0赞

先上代码。后面附上解释：

class func imageWith(radius: CGFloat, borderWidth: CGFloat, borderColor: UIColor, image: UIImage, resultImageSize: CGSize = CGSize.zero, centerIconSize: CGSize) -> UIImage? {
            var size = CGSize.zero
            if resultImageSize == CGSize.zero {
                size = CGSize(width: image.size.width+2*borderWidth, height: image.size.height+2*borderWidth)
            }else {
                size = CGSize(width: resultImageSize.width+2*borderWidth, height: resultImageSize.height+2*borderWidth)
            }
            UIGraphicsBeginImageContextWithOptions(size, false, 0)
            let path = UIBezierPath(roundedRect: CGRect(origin: CGPoint.zero, size: size), cornerRadius: radius+borderWidth/2)
            borderColor.set()
            path.addClip()
            path.stroke()
            let clipPath = UIBezierPath(roundedRect: CGRect(x: borderWidth, y: borderWidth, width: size.width-2*borderWidth, height: size.height-2*borderWidth), cornerRadius: radius)
            clipPath.addClip()
            image.draw(in: CGRect(origin: CGPoint(x: borderWidth+(size.width-2*borderWidth-centerIconSize.width)/2, y: borderWidth+(size.height-2*borderWidth-centerIconSize.height)/2), size: centerIconSize))
            let newImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return newImage
        }

具体实现思路:  
  
1.假设边框宽度为borderWidth  
  
2.开启的图片上下文的尺寸就应该是原始图片的宽高分别加上两倍的borderWidth,这样开启的目的是为了不让原始图片变形.  
  
3.在上下文上面添加一个圆形填充路径.位置从0,0点开始,宽高和上下文尺寸一样大.设置颜色为要设置的边框颜色.  
  
4.继续在上下文上面添加一个圆形路径,这个路径为裁剪路径.  
  
  它的x,y分别从borderWidth这个点开始.宽度和高度分别和原始图片的宽高一样大.  
  
  将绘制的这个路径设为裁剪区域.  
  
5.把原始路径绘制到上下文当中.绘制的位置和是裁剪区域的位置相同,x,y分别从border开始绘制.  
  
6.从上下文状态当中取出图片.  
  
7.关闭上下文状态.