如何制作Scrollview所有内容的屏幕截图？

Question

我想创建一个截图,UIScrollView其中应包含滚动视图的整个内容,甚至包含当前用户不可见的内容.为此,我尝试了以下两种方法:

func snapShot(view:UIView) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, true, 0);

    view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true);

    let image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;
}

func snapShotScrollView(scrollView:UIScrollView) -> UIImage {
    let bounds = scrollView.bounds;

    scrollView.bounds.size = scrollView.contentSize;

    let image = snapShot(scrollView);

    scrollView.bounds = bounds;

    return image;
}

但是生成的图像仍然只显示滚动视图中当前对用户可见的那些视图元素.但我希望看到所有观点.

我怎样才能做到这一点？

编辑

我也尝试过:

func snapshot() -> UIImage? {
    var image: UIImage?

    UIGraphicsBeginImageContext(scrollView.contentSize)

    let savedContentOffset = scrollView.contentOffset
    let savedFrame = scrollView.frame;

    scrollView.contentOffset = CGPoint.zero;
    scrollView.frame = CGRect(x: 0, y: 0, width: scrollView.contentSize.width, height: scrollView.contentSize.height);

    scrollView.layer.render(in: UIGraphicsGetCurrentContext()!)
    image = UIGraphicsGetImageFromCurrentImageContext();

    scrollView.contentOffset = savedContentOffset;
    scrollView.frame = savedFrame;

    UIGraphicsEndImageContext();

    return image
}

编辑2

我UIScrollView被安置在一个内部UIView并确实包含一个UIStackView.View被设计为一个弹出窗口视图,因此它看起来像是一个弹出对话框.我第一次编辑的代码示例是在一个空白处UIViewController,只有一个UIScrollView但不在提到的星座中.

Answer 1

要从Swift中回答这个问题,添加一个测试ViewController:

class ScreenShotTestViewController: UIViewController {

    var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()
        scrollView = UIScrollView(frame: CGRect(origin: CGPoint.zero, size: view.frame.size))
        scrollView.contentSize = CGSize(width: view.frame.size.width, height: view.frame.size.height * 2)
        scrollView.backgroundColor = UIColor.yellow
        view.addSubview(scrollView)

        let label = UILabel(frame: CGRect(x: 0.0, y: view.frame.size.height * 1.5, width: view.frame.size.width, height: 44.0))
        label.text = "Hello World!"
        scrollView.addSubview(label)

        let screenShot = snapshot()
    }

    func snapshot() -> UIImage?
    {      
        UIGraphicsBeginImageContext(scrollView.contentSize)

        let savedContentOffset = scrollView.contentOffset
        let savedFrame = scrollView.frame

        scrollView.contentOffset = CGPoint.zero
        scrollView.frame = CGRect(x: 0, y: 0, width: scrollView.contentSize.width, height: scrollView.contentSize.height)

        scrollView.layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()

        scrollView.contentOffset = savedContentOffset
        scrollView.frame = savedFrame

        UIGraphicsEndImageContext()

        return image
    }
}

生成完整内容的图像,包括子视图: