Node Image

• Sep 20, 2019
• 7 minutes to read

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.

Select Image

Specify image source

The TreeList.SelectImageList 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.

Assign images to nodes

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

• the TreeList.ImageIndexFieldName property — specifies the name of the data field that contains image indexes. The property specifies the image index for both non-focused and focused states (you cannot use data source fields to specify two icons).

• the TreeListNode.ImageIndex and TreeListNode.SelectImageIndex properties — get or set the node’s image index in the non-focused and focused states, respectively. Images are automatically changed when a node gets / loses the focus.

  Note

  The SelectImageIndex and ImageIndex properties are not in effect if the TreeList obtains image indices from a data source field (ImageIndexFieldName).

  C#

  // Gets the select image index of the focused node.
  int selectImageIndex = treeList1.GetFocusedRowCellValue(treeList1.ImageIndexFieldName);
  

  VB.NET

  ' Gets the select image index of the focused node.
  Dim selectImageIndex As Integer = treeList1.GetFocusedRowCellValue(treeList1.ImageIndexFieldName)
  

• the TreeList.GetSelectImage 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.

Respond to clicks

The TreeList.RowSelectImageClick event fires when a select image is clicked.

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.

Node Image Location

Use the TreeList.OptionsView.RowImagesShowMode property to specify where to display node images:

• InIndent — images are displayed in the indent area.

  

  Note

  The TreeList control displays the placeholders (indents) for node images once you specified the SelectImageList and/or StateImageList properties (even if image collections are empty).

• InCell — images are displayed within cells.

  

Draw Node Images

The TreeList.CustomDrawNodeImages event provides access to a GDI+/DirectX drawing surface and allows you to draw node icons manually.

See Custom Draw Scenarios for more information on how to use a drawing surface.

Note

The CustomDrawNodeImages event does not occur if a node does not display the image(s) and the ViewStyle property is set to TreeListViewStyle.InCell.

The WXI skin activates the InCell (TreeView) style by default.

Examples

Example 1

The code below shows how to assign select and state images to nodes.

C#

using DevExpress.XtraTreeList.Nodes;

// Data source for select (left) images.
treeList1.SelectImageList = imageCollection1;
// Use the data source to assign select images to nodes.
// Data source fields do NOT allow you to specify
// two images that depend on the focus.
// This property has priority over the node's
// ImageIndex and SelectImageIndex properties.
treeList1.ImageIndexFieldName = "ImageIndex";
// Data source for state (right) images.
treeList1.StateImageList = imageCollection1;
// Use the Load event to assign images to nodes.
treeList1.Load += TreeList1_Load;

private void TreeList1_Load(object sender, EventArgs e) {
    foreach (TreeListNode node in treeList1.Nodes) {
        // The left image displayed when the node is NOT focused.
        node.ImageIndex = 0;
        // The left image displayed when the node is focused.
        node.SelectImageIndex = 1;
        // The right image that does not depend on the focus.
        node.StateImageIndex = 2;
    }
}

VB.NET

Imports DevExpress.XtraTreeList.Nodes

' Data source for select (left) images.
treeList1.SelectImageList = imageCollection1
' Use the data source to assign select images to nodes.
' Data source fields do NOT allow you to specify
' two images that depend on the focus.
' This property has priority over the node's
' ImageIndex and SelectImageIndex properties.
treeList1.ImageIndexFieldName = "ImageIndex"
' Data source for state (right) images.
treeList1.StateImageList = imageCollection1
' Use the Load event to assign images to nodes.
AddHandler treeList1.Load, AddressOf TreeList1_Load

Private Sub TreeList1_Load(ByVal sender As Object, ByVal e As EventArgs)
    For Each node As TreeListNode In treeList1.Nodes
        ' The left image displayed when the node is NOT focused.
        node.ImageIndex = 0
        ' The left image displayed when the node is focused.
        node.SelectImageIndex = 1
        ' The right image that does not depend on the focus.
        node.StateImageIndex = 2
    Next node
End Sub

Example 2

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.

Example 3

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

Example 4

This code below shows how to handle the TreeList.GetSelectImage event to assign select images to nodes depending on the focus state.

C#

using DevExpress.XtraTreeList;

treeList1.SelectImageList = imageCollection1;

private void treeList1_GetSelectImage(object sender, GetSelectImageEventArgs e) {
    if (e.FocusedNode)
        e.NodeImageIndex = 2;
    else
        e.NodeImageIndex = 0;
}

VB.NET

Imports DevExpress.XtraTreeList

treeList1.SelectImageList = imageCollection1

Private Sub TreeList1_GetSelectImage(ByVal sender As Object, _
ByVal e As GetSelectImageEventArgs) Handles TreeList1.GetSelectImage
    If e.FocusedNode Then
        e.NodeImageIndex = 2
    Else
        e.NodeImageIndex = 0
    End If
End Sub

Example 5

The code below shows how to fill the background with a custom color and then draw the image on top.

C#

private void TreeList_CustomDrawNodeImages(object sender, CustomDrawNodeImagesEventArgs e) {
    if (e.Node.Focused)
        e.Cache.FillRectangle(e.Cache.GetSolidBrush(Color.Orange), e.StateRect);
    e.DefaultDraw();
}

VB.NET

Private Sub treeList1_CustomDrawNodeImages(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawNodeImagesEventArgs) _
    Handles treeList1.CustomDrawNodeImages
    If e.Node.Focused Then
        e.Cache.FillRectangle(e.Cache.GetSolidBrush(Color.Orange), e.StateRect)
    End If
    e.DefaultDraw()
End Sub

Important

Do not change cell values, modify the control’s layout, or change the control’s object model in the events used for custom control painting. Actions that update the layout can cause the control to malfunction.