Three Questions

1. List item

Hi.Now I have three questions like this:

1. About MulticolumnTreeView.I want to set SelectItem of MulticolumnTreeView is null,but I can't. In ListView,it's OK.

2. About Chart.In your example project,I find these code as follow: <ms:Chart Title="Marked stripe grid"> <ms:Chart.BackgroundElements> <ms:MarkedStripeGrid> <ms:MarkedStripeGrid.MarkedStripes> <ms:MarkedStripe Value="5" Background="#F4D3D3" /> <ms:MarkedStripe Value="15" Background="#FEF0CD" /> <ms:MarkedStripe Value="30" Background="#E7F1D2" /> </ms:MarkedStripeGrid.MarkedStripes> </ms:MarkedStripeGrid> </ms:Chart.BackgroundElements> </ms:Chart>

   These codes set backgroud to different colors along the Y axis.Now I want to set backgroud of chart to different colors along the X axis. How to do it?

3. About MulticolumnTreeView.In my project,I need to change ItemsSource of MulticolumnTreeView per 2500 milliseconds to refresh MulticolumnTreeView .I use Timer to realize. After changing DataSource,My code is like this:MulticolumnTreeView.ItemsSource=null;MulticolumnTreeView.ItemsSource=DataSource;The depth of tree is 2.ItemsCount is about 1000.I find it's too slow.How to improve the speed of refreshing MulticolumnTreeView ？

Hello and thanks for the feedback. We will get back to you very shortly.

Jason Fauchelle

Hello

1) The MulticolumnTreeView extends the WPF TreeView class which means the SelectedItem property is readonly. One way you could get around this is to traverse the tree and use the ItemContainerGenerator to look for the MultiColumnTreeViewItem for the selected item. If found, you then set its IsSelected property to false which is effectively the same as setting the SelectedItem property to null. Here is some code that can find the MulticolumnTreeViewItem (which extends TreeViewItem) for a given data object:

private static TreeViewItem ContainerFromItem(TreeView treeView, object item)
{
  TreeViewItem container = treeView.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;
  if (container != null)
  {
    return container;
  }
  else
  {
    return ContainerFromItem(treeView.ItemContainerGenerator, treeView.Items, item);
  }
}

private static TreeViewItem ContainerFromItem(ItemContainerGenerator itemContainerGenerator, ItemCollection items, object item)
{
  foreach (object child in items)
  {
    TreeViewItem parentContainer = (TreeViewItem)itemContainerGenerator.ContainerFromItem(child);
    TreeViewItem container = (TreeViewItem)parentContainer.ItemContainerGenerator.ContainerFromItem(item);
    if (container != null)
    {
      return container;
    }
    container = ContainerFromItem(parentContainer.ItemContainerGenerator, parentContainer.Items, item);
    if (container != null)
    {
      return container;
    }
  }
  return null;
}

This is a little bit brute-force for items that are not in the root level, though you could probably improve this by traversing your own model structure first to select the correct child items to traverse. You would use the above methods like this:

TreeViewItem item = ContainerFromItem(mctv, mctv.SelectedItem);
if (item != null)
{
  item.IsSelected = false;
}

Where mctv is the MultiColumnTreeView.

2) In the next nightly build The MarkedStripeGrid class will have an Orientation property. By default, this will be Horizontal. You can set this to Vertical to make the stripes change to different colors along the X axis. This will be available for download at around 1200 GMT.

3) For this there are 2 options. Firstly, you could try see if you can make smaller changes at one time to the items source. After 2500 milliseconds, if only a few items were added or deleted, then only change these in the items source rather than refreshing the whole collection. If this is not possible for your data, then I would recommend using the DataGrid instead of the MulticolumnTreeView. We have recently added hierarchical data support for the data grid which can be used in the same way as the MultiColumnTreeView. (Set the ItemTemplate of the DataGrid to be a HierarchicalDataTemplate). The DataGrid uses UI virtualization making it much faster than the MulticolumnTreeView. Also, If you do decide to use DataGrid, then issue 1 will no longer be a problem because you can set the SelectedItem property of the DataGrid to null.

Let us know if you have further questions about these.

Jason Fauchelle