How to check if a scroll is currently visible in W

问题:

How to check if a scroll (vertical or horizontal) is currently shown in WPF DataGrid? HorizontalScrollBarVisibility and VerticalScrollBarVisibility are used to set the behaviour and they are set to Auto.

回答1:

ScrollViewer scrollview = FindVisualChild<ScrollViewer>(dataGrid);
Visibility verticalVisibility = scrollview.ComputedVerticalScrollBarVisibility;
Visibility horizontalVisibility = scrollview.ComputedHorizontalScrollBarVisibility;

回答2:

Here's an implementation of FindVisualChild:

private childItem FindVisualChild<childItem>(DependencyObject obj)
    where childItem : DependencyObject
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
    {
        DependencyObject child = VisualTreeHelper.GetChild(obj, i);
        if (child != null && child is childItem)
            return (childItem)child;
        else
        {
            childItem childOfChild = FindVisualChild<childItem>(child);
            if (childOfChild != null)
                return childOfChild;
        }
    }
    return null;
}

回答3:

Private Function FindVisualChild(Of childItem As DependencyObject)(ByVal obj As DependencyObject) As childItem
        For i As Integer = 0 To VisualTreeHelper.GetChildrenCount(obj) - 1
            Dim child As DependencyObject = VisualTreeHelper.GetChild(obj, i)
            If child IsNot Nothing AndAlso TypeOf child Is childItem Then
                Return CType(child, childItem)
            Else
                Dim childOfChild As childItem = FindVisualChild(Of childItem)(child)
                If childOfChild IsNot Nothing Then
                    Return childOfChild
                End If
            End If
        Next i
        Return Nothing
    End Function