CODEWITHSUNDEEP
c#scrollviewxamarin.forms
Brend
Brend

Reputation: 13

Xamarin.Forms: Can't dinamically Add layouts to content of a scrollView

Basically I'm trying to dinamically add layouts to the content of a scrollView. I did an example code but it only works at the second click, for some reason it doesn't render the first layout added!!! Am I doing something wrong?

public class PageExperiment
{
    ScrollView _page;

    public PageExperiment()
    {
        _page = new ScrollView { Orientation = ScrollOrientation.Vertical,
                                 Content = new RelativeLayout { BackgroundColor = Color.White} };

        var button = new Button { Text="Add Button"};
        button.Clicked += OnButtonClicked;
        ((RelativeLayout)_page.Content).Children.Add(button,xConstraint:null);
    }

    public ScrollView getPage()
    {
        return _page;
    } 
    void OnButtonClicked(object sender, EventArgs e)
    {
        var relative = AddLayout();
        var content = (RelativeLayout)_page.Content;
        var v = content.Children[content.Children.Count - 1];
        Constraint xConstraint = Constraint.Constant(0);
        Constraint yConstraint = Constraint.RelativeToView(v, (parent, sibling) => {
            return sibling.Y + sibling.Height;
        });            

        ((RelativeLayout)_page.Content).Children.Add((View)relative, xConstraint, yConstraint);        

    }

    public VisualElement AddLayout()
    {
        var root = new RelativeLayout();

        root.BackgroundColor = Color.Red;
        var a = new Label { Text = "Button Added!!!!", BackgroundColor = Color.Purple};
        a.FontSize = 30;
        root.Children.Add(a, xConstraint:null);

        return root;
    }
}

Here is the main:

public class App : Application
{
    public App()
    {
        var root = new PageExperiment();
        MainPage = new ContentPage
        {
            Content = root.getPage()
        };

    }
}

Upvotes: 0

Views: 1151

Answers (1)

David
David

Reputation: 1196

Add 

((RelativeLayout)_page.Content).ForceLayout ();

to the end of your OnButtonClicked(object sender, EventArgs e)

Looks like this is a bug in the relative Layout rendering. It doesn't appear to be an issue with the scroll view. I see you've already placed a Bug Report with Xamarin that's likely all the more that can be done to "fix" this. As I noted on the bug report. The bugs not just for layouts within layouts its any visual element added into a relative layout on the first click. Adding a call to ForceLayout should make your app functional though there might be a performance hit.

Upvotes: 1

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