TreeList.GetStateImage Event

Allows you to assign state images to nodes.

Namespace: DevExpress.XtraTreeList

Assembly: DevExpress.XtraTreeList.v23.2.dll

NuGet Packages: DevExpress.Win.Navigation, DevExpress.Win.TreeList

Declaration

C#

public event GetStateImageEventHandler GetStateImage

VB.NET

Public Event GetStateImage As GetStateImageEventHandler

Event Data

The GetStateImage event's data class is GetStateImageEventArgs. The following properties provide information specific to this event:

Property	Description
Node	Gets the current Tree List node. Inherited from NodeEventArgs.
NodeImageIndex	Gets or sets the index of the node’s image in a source image list. When handling the TreeList.GetStateImage event, the source of images is specified by the TreeList.StateImageList property. When handling the TreeList.GetSelectImage event, the source of images is specified by the TreeList.SelectImageList property.

Remarks

Nodes can display the following icons:

• Select Image - two icons that automatically switch when a node gets / loses the focus.
• State Image - any custom icon.

State Image

State image: Specify image source

The TreeList.StateImageList property specifies an ordered (indexed) collection that stores images. You can use the following image collections:

• ImageList — manages a collection of Image objects.
• ImageCollection — provides additional functionality compared to the ImageList class.
• SharedImageCollection — shares images between multiple controls and forms.
• SvgImageCollection — stores vector images.

State image: Assign images to nodes

To specify the index of the image displayed in a particular node, use the following properties and events:

• the TreeListNode.StateImageIndex property — gets or sets the image index.

• the TreeList.GetStateImage event — fires before a node is displayed and allows you to specify (override) the image index for the processed node.

If the index is out of range, no image is displayed.

State image: Respond to clicks

The TreeList.RowStateImageClick event fires when a state image is clicked.

Examples

The code below shows how to display state images depending on data field values.

C#

using DevExpress.XtraTreeList;

string currentGroupName;
private void treeList1_GetStateImage(object sender, GetStateImageEventArgs e) {
    if(treeList.IsAutoFilterNode(e.Node))
        return;
    string[] groupNames = new string[] { "Administration", "Inventory", "Manufacturing", "Quality", "Research", "Sales" };
    currentGroupName = (string)e.Node.GetValue("GroupName");
    e.NodeImageIndex = Array.FindIndex(groupNames, new Predicate<string>(IsCurrentGroupName));
}
private bool IsCurrentGroupName(string groupName) {
    if(currentGroupName != null)
        return currentGroupName.Contains(groupName);
    return false;
}

VB.NET

Imports DevExpress.XtraTreeList

Private currentGroupName As String
Private Sub treeList1_GetStateImage(ByVal sender As Object, ByVal e As GetStateImageEventArgs) Handles treeList.GetStateImage
    If treeList.IsAutoFilterNode(e.Node) Then
        Return
    End If
    Dim groupNames() As String = { "Administration", "Inventory", "Manufacturing", "Quality", "Research", "Sales" }
    currentGroupName = DirectCast(e.Node.GetValue("GroupName"), String)
    e.NodeImageIndex = Array.FindIndex(groupNames, New Predicate(Of String)(AddressOf IsCurrentGroupName))
End Sub
Private Function IsCurrentGroupName(ByVal groupName As String) As Boolean
    If currentGroupName IsNot Nothing Then
        Return currentGroupName.Contains(groupName)
    End If
    Return False
End Function

Note

Run the XtraTreeList demo for the complete example.

The code below shows how to display state images depending on the node check state.

C#

using DevExpress.XtraTreeList;

ImageCollection collection = new ImageCollection();
collection.Images.AddRange(new Image[] { img, img2 });
treeList1.StateImageList = collection;
treeList1.GetStateImage += treeList1_GetStateImage;

private void treeList1_GetStateImage(object sender, GetStateImageEventArgs e) {
    if (e.Node.Checked)
        e.NodeImageIndex = 1;
    else
        e.NodeImageIndex = 0;
}

VB.NET

Imports DevExpress.XtraTreeList

Private collection As New ImageCollection()
collection.Images.AddRange(New Image() { img, img2 })
treeList1.StateImageList = collection
AddHandler treeList1.GetStateImage, AddressOf treeList1_GetStateImage

private void treeList1_GetStateImage(Object sender, GetStateImageEventArgs e)
    If e.Node.Checked Then
        e.NodeImageIndex = 1
    Else
        e.NodeImageIndex = 0
    End If