我正在使用Swift编程。我想使用CALayer和UIImage掩盖图像。我正在通过编程方式创建我的掩膜图像。当我单独查看掩膜图像时,它可以正常工作。但是当我将其用作掩膜时,整个屏幕变成了白色。我怀疑问题在于配置CALayer对象。感谢您的帮助!
class ViewController: UIViewController {
@IBOutlet weak var imageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
var maskImageSize = CGSizeMake(self.imageView.frame.width, self.imageView.frame.height)
UIGraphicsBeginImageContextWithOptions(maskImageSize, false, 0.0)
var color = UIColor(white: 1.0, alpha: 1.0)
color.setFill()
var rect = CGRectMake(0, 0, self.imageView.frame.width, self.imageView.frame.height)
UIRectFill(rect)
color = UIColor(white: 0.0, alpha: 1.0)
color.setFill()
rect = CGRectMake((self.imageView.frame.width/2)-100, (self.imageView.frame.height/2)-100, 200, 200)
UIRectFill(rect)
var maskImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
var maskLayer = CALayer()
maskLayer.contents = maskImage
maskLayer.contentsRect = CGRectMake(0, 0, self.imageView.bounds.width, self.imageView.bounds.height)
self.imageView.image = UIImage(named: "pictobemasked.png")
self.imageView.layer.mask = maskLayer;
}
}
fillWithBlendMode
会为你调用CGContextSetBlendMode
,所以你永远不需要获取当前的图形上下文 - 你可以使用 UIBezierPath(和 UIColor)完成整个过程。 - matt