Enabling Drag and Drop
Here we have a simple tutorial to demonstrate the drag and drop functionality of the TreeView control. In this example we have 2 folders containing 5 files. When using the Liquid TreeView if you wish to use the drag and drop feature you must be using icons for your nodes you wish to drag. This is essential as to drag a node you do so by clicking the node icon and drag the node to it's destination.
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Here is the XAML for this demonstration:
<UserControl x:Class="TreeViewDragAndDrop.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:liquid="clr-namespace:Liquid;assembly=Liquid"
Width="400" Height="300">
<Grid x:Name="LayoutRoot" Background="White" VerticalAlignment="Top" HorizontalAlignment="Left">
<liquid:Tree x:Name="tree" EnableDragAndDrop="true" Drop="Tree_Drop" Width="300" Height="151" Margin="4">
<liquid:Tree.Nodes>
<liquid:Node ID="0" Title="Root" Icon="images/folder.png" IconExpanded="images/folderOpen.png">
<liquid:Node.Nodes>
<liquid:Node ID="1" Title="Folder 1" Icon="images/folder.png" IconExpanded="images/folderOpen.png">
<liquid:Node.Nodes>
<liquid:Node ID="10" Title="File 1.doc" Icon="images/doc.png" />
<liquid:Node ID="11" Title="File 2.doc" Icon="images/doc.png" />
</liquid:Node.Nodes>
</liquid:Node>
<liquid:Node ID="2" Title="Folder 2" Icon="images/folder.png" IconExpanded="images/folderOpen.png">
<liquid:Node.Nodes>
<liquid:Node ID="20" Title="File 3.doc" Icon="images/doc.png" />
<liquid:Node ID="21" Title="File 4.doc" Icon="images/doc.png" />
<liquid:Node ID="21" Title="File 5.doc" Icon="images/doc.png" />
</liquid:Node.Nodes>
</liquid:Node>
</liquid:Node.Nodes>
</liquid:Node>
</liquid:Tree.Nodes>
</liquid:Tree>
</Grid>
</UserControl>
In the XAML we define 2 folder nodes which contain several child document nodes. The important attributes in the XAML are EnableDragAndDrop="true" and Drop="Tree_Drop". The first ensures dragging and dropping is enabled and the second is the name of an event handler we have declared in the C# code behind file which allows you specify where the node is positioned or whether the Drop operation should be cancelled.
using System.Windows.Controls;
using Liquid;
namespace TreeViewDragAndDrop
{
public partial class Page : UserControl
{
public Page()
{
InitializeComponent();
}
private void Tree_Drop(object sender, TreeEventArgs e)
{
e.DropAction = Tree.DropActions.InsertAfter;
}
}
}
In this event handler you can instruct the TreeView to insert the node before or after the node under the cursor. Or if you like the node can be appended as a child of the node under the cursor, either as the first or last child. It is also possible to cancel the drop operation by setting e.Cancel = true, this allows for a lot of flexibility in your Silverlight apps.
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