WPF ListView columns dont update thair width in time [duplicate] - wpf

Question

I have a ListView WPF control with a GridView. I'd like to resize the GridView columns when the content of the columns changes.
I have several distinct data sets but when I change from one to another, the size of each columns fits the previous data. I'd like to update dynamically. How can I do that?

Answer 1

Finally, some results on this one. I've found a way to do the same auto-sizing that is done initially and when the gripper on a column header is double clicked.
public void AutoSizeColumns()
{
GridView gv = listView1.View as GridView;
if (gv != null)
{
foreach (var c in gv.Columns)
{
// Code below was found in GridViewColumnHeader.OnGripperDoubleClicked() event handler (using Reflector)
// i.e. it is the same code that is executed when the gripper is double clicked
if (double.IsNaN(c.Width))
{
c.Width = c.ActualWidth;
}
c.Width = double.NaN;
}
}
}

Answer 2

Building on top of Oskars answer, here is a blend behavior to automatically size the columns when the content changes.
/// <summary>
/// A <see cref="Behavior{T}"/> implementation which will automatically resize the automatic columns of a <see cref="ListView">ListViews</see> <see cref="GridView"/> to the new content.
/// </summary>
public class GridViewColumnResizeBehaviour : Behavior<ListView>
{
/// <summary>
/// Listens for when the <see cref="ItemsControl.Items"/> collection changes.
/// </summary>
protected override void OnAttached()
{
base.OnAttached();
var listView = AssociatedObject;
if (listView == null)
return;
AddHandler(listView.Items);
}
private void AddHandler(INotifyCollectionChanged sourceCollection)
{
Contract.Requires(sourceCollection != null);
sourceCollection.CollectionChanged += OnListViewItemsCollectionChanged;
}
private void RemoveHandler(INotifyCollectionChanged sourceCollection)
{
Contract.Requires(sourceCollection != null);
sourceCollection.CollectionChanged -= OnListViewItemsCollectionChanged;
}
private void OnListViewItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs notifyCollectionChangedEventArgs)
{
var listView = AssociatedObject;
if (listView == null)
return;
var gridView = listView.View as GridView;
if (gridView == null)
return;
// If the column is automatically sized, change the column width to re-apply automatic width
foreach (var column in gridView.Columns.Where(column => Double.IsNaN(column.Width)))
{
Contract.Assume(column != null);
column.Width = column.ActualWidth;
column.Width = Double.NaN;
}
}
/// <summary>
/// Stops listening for when the <see cref="ItemsControl.Items"/> collection changes.
/// </summary>
protected override void OnDetaching()
{
var listView = AssociatedObject;
if (listView != null)
RemoveHandler(listView.Items);
base.OnDetaching();
}
}

Answer 3

If like me you are old and prefer VB.NET then here's Oskars code:
Public Sub AutoSizeColumns()
Dim gv As GridView = TryCast(Me.listview1.View, GridView)
If gv IsNot Nothing Then
For Each c As GridViewColumn In gv.Columns
If Double.IsNaN(c.Width) Then
c.Width = c.ActualWidth
End If
c.Width = Double.NaN
Next
End If
End Sub
This works great in WPF, finally someone has worked this out. Thanks Oskar.

Answer 4

Isn't there a way to bind to the ActualWidth of the column? Something like :
<GridViewColumn x:Name="column1" Width="{Binding ElementName=column1, Path=ActualWidth}" />
I have tried this and it works only the first time, it seems. No binding error.

Answer 5

You could measure the longest string in pixels and then adjust the column widths accordingly:
Graphics graphics = this.CreateGraphics();
SizeF textSize = graphics.MeasureString("How long am I?", this.Font);
If you create an algorithm for sizing each column as a ratio of these lengths, you should get a good result.