Question

Ok this is really making me crazy and I need some help.

I have a listview with an itemssource that has several gridviewcolumns. When the ItemsSource gets set, the columns size to fit the contents.

Whenever I increase the width by grabbing the column it makes the listview grow, but when I decrease the width it does not shrink. According to this post this is per WPF layout process.

I subclassed the ListView to override this behavior and can’t get it to work right.

I have overridden the MeasureOverride function like so:

    protected override Size MeasureOverride(Size constraint)
    {
            var size = base.MeasureOverride(constraint);

            var gv = this.View as GridView;

            if (gv != null)
            {
                var width = gv.Columns.Select(a => a.ActualWidth).ToArray();
                size.Width = gv.Columns.Sum(a => a.ActualWidth) ;
                if (scroll.ScrollableHeight > 0)
                    size.Width += SystemParameters.ScrollWidth;
            }

            return size;
    }

Which does cause the listview to shrink as desired, but if the listview has a vertical scrollbar it disappears.
I can’t figure out how to get the scrollbar to come back programmatically.

Now if I then increase the width beyond the original width the scrollbar comes back(but this is through the UI not code. I just have been playing with this for longer than I care to admit and I’m lost.

Anyone have any idea what I should do besides quit trying?

Answer 1

The reason this is even a problem is because of the very nature of a ScrollViewer, it keeps the size of it’s content, so when the ListView shrinks via a MeasureOverride, it’s content still remains the same. The solution below is not perfect, but it is the best I could find. If there is a better one please let me know.

The solution I arrived at was to keep the MeasureOverride function as above and also overriding ArrangeOverride and set the width of the ScrollViewer to be the final width of the ListView like so:

public Size ArrangeOverride(Size arrangeBounds)
{
  var size = base.ArrangeOverride(arrangeBounds);
  var scroll = GetScrollViewer();
  scroll.Width = size.Width;
  return size;
}