Expanders in Grid

Question

This is going to be straight forward no doubt, but for what ever reason, my mind is drawing a blank on it.

I\'ve got a small, non-resizeable window (325x450) which has 3

Answer 1

If you don't mind a little code-behind, you could probably hook into the Expanded/Collapsed events, find the parent Grid, get the RowDefinition for the expander, and set the value equal to * if its expanded, or Auto if not.

For example,

Expander ex = sender as Expander;
Grid parent = FindAncestor(ex);
int rowIndex = Grid.GetRow(ex);

if (parent.RowDefinitions.Count > rowIndex && rowIndex >= 0)
    parent.RowDefinitions[rowIndex].Height = 
        (ex.IsExpanded ? new GridLength(1, GridUnitType.Star) : GridLength.Auto);

And the FindAncestor method is defined as this:

public static T FindAncestor(DependencyObject current)
where T : DependencyObject
{
    // Need this call to avoid returning current object if it is the 
    // same type as parent we are looking for
    current = VisualTreeHelper.GetParent(current);

    while (current != null)
    {
        if (current is T)
        {
            return (T)current;
        }
        current = VisualTreeHelper.GetParent(current);
    };
    return null;
}