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TreeList.CustomDrawNodeButton Event

Gives you the ability to perform custom painting of expand buttons.

Namespace: DevExpress.XtraTreeList

Assembly: DevExpress.XtraTreeList.v19.1.dll


public event CustomDrawNodeButtonEventHandler CustomDrawNodeButton

Event Data

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

Property Description
AllowDrawBackground Gets or sets whether to draw a background that detaches the button from the tree hierarchy lines.
Appearance Gets the painted element’s appearance settings. Inherited from CustomDrawEventArgs.
Bounds Gets the painted element’s bounding rectangle. Inherited from CustomDrawEventArgs.
Cache Gets an object specifying the storage for the most used pens, fonts and brushes. Inherited from CustomDrawEventArgs.
Expanded Gets a value indicating whether the painted button’s corresponding node is expanded.
Graphics Gets an object used to paint. Inherited from CustomDrawEventArgs.
Handled Gets or sets a value specifying whether an event was handled and that the default element painting is therefore not required. Inherited from CustomDrawEventArgs.
IsRightToLeft Gets a value indicating whether the TreeList’s elements are aligned to support locales using right-to-left fonts. Inherited from CustomDrawEventArgs.
ObjectArgs Gets an object containing information about the painted element. Inherited from CustomDrawEventArgs.
Painter Gets the painter object that provides the default element’s painting mechanism. Inherited from CustomDrawEventArgs.

The event data class exposes the following methods:

Method Description
DefaultDraw() Performs default painting of an element. Inherited from CustomDrawEventArgs.


Expand buttons are used to expand/collapse nodes which have child nodes. Handle the CustomDrawNodeButton event to custom paint expand buttons.

The event’s parameters provide all the information needed to perform node button painting. The CustomDrawNodeButtonEventArgs.Expanded property allows you to determine whether the painted button corresponds to the expanded or collapsed state of a node.

See the Custom Draw Scenarios topic for information on using custom draw events.


Never change cell values or modify the control’s layout on this event, or any other event designed to tune the control’s appearance. Any action that causes a layout update can cause the control to malfunction.


The following sample code handles the TreeList.CustomDrawNodeButton event. It is used to perform custom painting of buttons used to expand/collapse nodes.

The image below displays the result of sample code execution.

CustomDraw - NodeButton

using System.Drawing;
using System.Drawing.Drawing2D;
using DevExpress.XtraTreeList;

private void treeList1_CustomDrawNodeButton(object sender, CustomDrawNodeButtonEventArgs e) {
    Rectangle rect = Rectangle.Inflate(e.Bounds, 0, -2);

    // painting background
    Brush backBrush = e.Cache.GetGradientBrush(rect, Color.Blue, Color.LightSkyBlue,

    e.Cache.FillRectangle(backBrush, rect);
    // painting borders
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), rect);

    // determining the character to display
    string displayCharacter = e.Expanded ? "-" : "+";
    // formatting the output character
    StringFormat outCharacterFormat = e.Appearance.GetStringFormat();
    outCharacterFormat.Alignment = StringAlignment.Center;
    outCharacterFormat.LineAlignment = StringAlignment.Center;

    // painting the character
    e.Appearance.FontSizeDelta = -2;
    e.Appearance.FontStyleDelta = FontStyle.Bold;
    e.Cache.DrawString(displayCharacter, e.Appearance.Font, 
        e.Cache.GetSolidBrush(Color.White), rect, outCharacterFormat);

    // prohibiting default painting
    e.Handled = true;
See Also