TreeNode.ImageIndex Property

Definition

Gets or sets the image list index value of the image displayed when the tree node is in the unselected state.

C#
public int ImageIndex { get; set; }
C#
[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.TreeViewImageIndexConverter))]
[System.Windows.Forms.RelatedImageList("TreeView.ImageList")]
public int ImageIndex { get; set; }

Property Value

A zero-based index value that represents the image position in the assigned ImageList.

Attributes

Exceptions

.NET 5 and later: value is less than -2.

Examples

The following code example creates and assigns an ImageList to a TreeView control and fills the TreeView control with TreeNode objects. The tree nodes are assigned images from the ImageList that is displayed when the tree node is in a selected or unselected state. This example requires that you have a Form that contains a TreeView, and an ArrayList that contains Customer objects that each contain Order objects. It also requires that the Customer and Order objects are defined.

C#

public class Customer
{
   public ArrayList CustomerOrders;
   public string CustomerName;
   public Customer(string myName)
   {
      CustomerName = myName;
      CustomerOrders = new ArrayList(); 
   }
}
public class Order
{
   public string OrderID;
   public Order(string myOrderID )
   {
      this.OrderID = myOrderID;
   }
}

private void FillTreeView()
{
    // Load the images in an ImageList.
    ImageList myImageList = new ImageList();
    myImageList.Images.Add(Image.FromFile("Default.gif"));
    myImageList.Images.Add(Image.FromFile("SelectedDefault.gif"));
    myImageList.Images.Add(Image.FromFile("Root.gif"));
    myImageList.Images.Add(Image.FromFile("UnselectedCustomer.gif"));
    myImageList.Images.Add(Image.FromFile("SelectedCustomer.gif"));
    myImageList.Images.Add(Image.FromFile("UnselectedOrder.gif"));
    myImageList.Images.Add(Image.FromFile("SelectedOrder.gif"));
    
    // Assign the ImageList to the TreeView.
    myTreeView.ImageList = myImageList;
    
    // Set the TreeView control's default image and selected image indexes.
    myTreeView.ImageIndex = 0;
    myTreeView.SelectedImageIndex = 1;

    /* Set the index of image from the 
    ImageList for selected and unselected tree nodes.*/
    this.rootImageIndex = 2;
    this.selectedCustomerImageIndex = 3;
    this.unselectedCustomerImageIndex = 4;
    this.selectedOrderImageIndex = 5;
    this.unselectedOrderImageIndex = 6;
    
    // Create the root tree node.
    TreeNode rootNode = new TreeNode("CustomerList");
    rootNode.ImageIndex = rootImageIndex;
    rootNode.SelectedImageIndex = rootImageIndex;
      
    // Add a main root tree node.
    myTreeView.Nodes.Add(rootNode);

    // Add a root tree node for each Customer object in the ArrayList.
    foreach(Customer myCustomer in customerArray)
    {
        // Add a child tree node for each Order object.
        int countIndex=0;
        TreeNode[] myTreeNodeArray = new TreeNode[myCustomer.CustomerOrders.Count];
        foreach(Order myOrder in myCustomer.CustomerOrders)
        {
            // Add the Order tree node to the array.
            myTreeNodeArray[countIndex] = new TreeNode(myOrder.OrderID,
              unselectedOrderImageIndex, selectedOrderImageIndex);
            countIndex++;
        }
        // Add the Customer tree node.
        TreeNode customerNode = new TreeNode(myCustomer.CustomerName,
            unselectedCustomerImageIndex, selectedCustomerImageIndex, myTreeNodeArray);
        myTreeView.Nodes[0].Nodes.Add(customerNode);
    }
}

Remarks

The ImageIndex value is the index value of an Image stored in the ImageList assigned to the TreeView.ImageList property.

Note

The default value of the ImageIndex property is the same as the ImageIndex property of the TreeView control that the TreeNode is assigned to.

ImageKey and ImageIndex are mutually exclusive, meaning if one is set, the other is set to an invalid value and ignored. If you set the ImageKey property, the ImageIndex property is automatically set to -1. Alternatively, if you set the ImageIndex property, the ImageKey is automatically set to an empty string ("").

.NET 5 and later versions: If the associated ImageList property value is changed to null, the ImageIndex property returns its default value, -1. However, the assigned ImageIndex value is retained internally and used when another ImageList object is assigned to the ImageList property. If the new ImageList assigned to the ImageList property has an ImageList.ImageCollection.Count property value that is less than or equal to the value assigned to the ImageIndex property minus one (to account for the collection being a zero-based index), the ImageIndex property value is adjusted to one less than the Count property value. For example, consider a button control whose ImageList has three images and whose ImageIndex property is set to 2. If a new ImageList that has only two images is assigned to the button, the ImageIndex value changes to 1.

Applies to

Product Versions
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
Windows Desktop 3.0, 3.1, 5, 6, 7, 8, 9

See also