我希望用户在我的应用程序中使用
Swift中的编程按钮按下应用程序的屏幕截图.我知道UIGraphicsGetImageFromCurrentImageContext()需要截图,但我不想要整个屏幕的图片.我希望弹出一个矩形(有点像裁剪工具),用户可以拖动矩形并调整其大小,只截取屏幕的某个部分.我希望矩形遍历WKWebView并裁剪网页视图的图片.
解决方法
标准快照技术是drawViewHierarchyInRect.要获取图像的一部分,可以使用CGImageCreateWithImageInRect.
因此,在Swift 2中：
extension UIView {
/// Create snapshot
///
/// - parameter rect: The `CGRect` of the portion of the view to return. If `nil` (or omitted),/// return snapshot of the whole view.
///
/// - returns: Returns `UIImage` of the specified portion of the view.
func snapshot(of rect: CGRect? = nil) -> UIImage? {
// snapshot entire view
UIGraphicsBeginImageContextWithOptions(bounds.size,opaque,0)
drawViewHierarchyInRect(bounds,afterScreenUpdates: true)
let wholeImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
// if no `rect` provided,return image of whole view
guard let rect = rect,let image = wholeImage else { return wholeImage }
// otherwise,grab specified `rect` of image
let scale = image.scale
let scaledRect = CGRect(x: rect.origin.x * scale,y: rect.origin.y * scale,width: rect.size.width * scale,height: rect.size.height * scale)
guard let cgImage = CGImageCreateWithImageInRect(image.CGImage!,scaledRect) else { return nil }
return UIImage(CGImage: cgImage,scale: scale,orientation: .Up)
}
}
在Swift 3中：
extension UIView {
/// Create snapshot
///
/// - parameter rect: The `CGRect` of the portion of the view to return. If `nil` (or omitted),isOpaque,0)
drawHierarchy(in: bounds,return image of whole view
guard let image = wholeImage,let rect = rect else { return wholeImage }
// otherwise,height: rect.size.height * scale)
guard let cgImage = image.cgImage?.cropping(to: scaledRect) else { return nil }
return UIImage(cgImage: cgImage,orientation: .up)
}
}
要使用它,您可以：
if let image = webView.snapshot(of: rect) {
// do something with `image` here
}
