ios iOS中来自CALayer的UIImage
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UIImage from CALayer in iOS
提问by Brett
In my application, I have created a CALayer(with a few sublayers - the CALayer is composed of shapes added as sublayers).
在我的应用程序中，我创建了一个CALayer（带有几个子层 - CALayer 由添加为子层的形状组成）。
I am trying to create a UIImagethat I will be able to upload to a server (I have the code for this).
However, I can't figure out how to add the CALayerto a UIImage.
我正在尝试创建一个UIImage我可以上传到服务器的文件（我有这个代码）。然而，我无法弄清楚如何将添加CALayer到UIImage。
Is this possible?
这可能吗？
回答by Todd Yandell
Sounds like you want to render your layer into a UIImage. In that case, the method below should do the trick. Just add this to your view or controller class, or create a category on CALayer.
听起来您想将图层渲染为 UIImage。在这种情况下，下面的方法应该可以解决问题。只需将此添加到您的视图或控制器类，或在 CALayer 上创建一个类别。
Obj-C
对象-C
- (UIImage *)imageFromLayer:(CALayer *)layer
{
UIGraphicsBeginImageContextWithOptions(layer.frame.size, NO, 0);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return outputImage;
}
Swift
迅速
func imageFromLayer(layer:CALayer) -> UIImage {
UIGraphicsBeginImageContextWithOptions(layer.frame.size, layer.isOpaque, 0)
layer.render(in: UIGraphicsGetCurrentContext()!)
let outputImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return outputImage!
}
回答by ?mer Faruk Gül
Todd's answer is correct, however for retina screens there should be a little difference:
托德的回答是正确的，但是对于视网膜屏幕应该有一点区别：
- (UIImage *)imageFromLayer:(CALayer *)layer
{
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
UIGraphicsBeginImageContextWithOptions([layer frame].size, NO, [UIScreen mainScreen].scale);
else
UIGraphicsBeginImageContext([layer frame].size);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return outputImage;
}
回答by Heberti Almeida
I have created a Swift extension based for this:
我已经创建了基于这个迅捷的扩展：
extension UIImage {
class func imageWithLayer(layer: CALayer) -> UIImage {
UIGraphicsBeginImageContextWithOptions(layer.bounds.size, layer.opaque, 0.0)
layer.renderInContext(UIGraphicsGetCurrentContext()!)
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img
}
}
The usage:
用法：
var gradient = CAGradientLayer()
gradient.colors = [UIColor.redColor().CGColor, UIColor.blueColor().CGColor]
gradient.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
let image = UIImage.imageWithLayer(gradient)
回答by Justin Wright
Swift 3 version with a little bit of error checking for context.
Swift 3 版本，对上下文进行了一些错误检查。
extension UIImage {
class func image(from layer: CALayer) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(layer.bounds.size,
layer.isOpaque, UIScreen.main.scale)
defer { UIGraphicsEndImageContext() }
// Don't proceed unless we have context
guard let context = UIGraphicsGetCurrentContext() else {
return nil
}
layer.render(in: context)
return UIGraphicsGetImageFromCurrentImageContext()
}
}
