Error with HitTestScrollBar

[punker76]

Original author: mitchell...@gmail.com (April 07, 2011 11:48:11)

There is an issue with the HitTestScrollBar code.

You current have the line:

hit.VisualHit.GetVisualAncestor<System.Windows.Controls.Primitives.ScrollBar>() != null;

This checks to see if the visual ancestor of the hit item is the a scroll bar. However what it doesn't check for is if its visible or not.

I've changed the version in my branch to be:

static bool HitTestScrollBar(object sender, MouseButtonEventArgs e)
{
    HitTestResult hit = VisualTreeHelper.HitTest((Visual)sender, e.GetPosition((IInputElement)sender));

    if (hit == null)
        return false;
    else
    {
        var scrollBar = hit.VisualHit.GetVisualAncestor<System.Windows.Controls.Primitives.ScrollBar>();
        return scrollBar != null && scrollBar.Visibility == Visibility.Visible;
    }
}

Without the extra visibility check the scroll bar is reporting it is being hit when it isn't visible, and therefore stops the user from dragging the item.

Original issue: http://code.google.com/p/gong-wpf-dragdrop/issues/detail?id=34

[punker76]

From rdingw...@gmail.com on January 05, 2013 15:16:07
Thanks this fix was just what I needed. (Please ignore deleted comment about GridViews)