How does WPF expand all Treeview Tree nodes?

Generally, the treeviewitem in the Treeview can be generated in two ways:

1. directly use the treeviewitem label in XAML (use C # code to do the same, in short, explicitly use treeviewitem)

2. Data Binding, such as binding to XML or arrays.

 

Solution to the first situation:

Add the expandall () method to the Treeview.

Public static class extensionmethods
{
Public static void expandall (this system. Windows. Controls. Treeview)
{
Expandallitems (Treeview );
}

Private Static void expandallitems (itemscontrol Control)
{
If (control = NULL)
{
Return;
}

Foreach (Object item in control. Items)
{

System. Windows. Controls. treeviewitem treeitem = control. itemcontainergenerator. containerfromitem (item) as treeviewitem;

If (treeitem = NULL |! Treeitem. hasitems)
{
Continue;
}

Treeitem. isexpanded = true;
Expandallitems (treeitem as itemscontrol );
}
}
}

Pay attention to the Red Line. This can be used when the item is not treeviewitem.

Then add the following method in the window. contentrendered event processing method:

Void mainwindow_contentrendered (Object sender, eventargs E)
{
This. Treeview. expandall ();
}

 

Solution to the second situation:

First, combine the methods in the first case, and then add the following code in the XAML code:

<Window. Resources>
<Style targettype = "treeviewitem">
<Setter property = "isexpanded"
Value = "{binding isexpanded,
Mode = oneway,
Relativesource = {relativesource findancestor, ancestortype = {X: Type treeviewitem }}"/>
</Style>
</Window. Resources>

This will solve the problem caused by data binding:

1. Items in Treeview is not treeviewitem

2. itemcontainergenerator. containerfromitem (item) can only be used at the first level of the Treeview itself. For deeper calls, itemcontainergenerator. _ status is notstarted.