TreeList.CustomDrawNodeIndicator Event

Provides the ability to perform custom painting of indicator cells.

Namespace: DevExpress.XtraTreeList

Assembly: DevExpress.XtraTreeList.v23.2.dll

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

Declaration

C#

[DXCategory("CustomDraw")]
public event CustomDrawNodeIndicatorEventHandler CustomDrawNodeIndicator

VB.NET

<DXCategory("CustomDraw")>
Public Event CustomDrawNodeIndicator As CustomDrawNodeIndicatorEventHandler

Event Data

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

Property	Description
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.
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.
ImageIndex	Gets or sets the index of an image to be painted in the indicator cell.
IndicatorArgs	Gets an object containing information about the painted element.
IsNodeIndicator	Gets a value indicating whether the painted indicator cell corresponds to a node or to a row footer.
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.
DrawHtml(HtmlTemplate, DxHtmlPainterContext, Action<DxHtmlPainterArgs>)	Paints the required HTML template inside an element that raised this event. The context parameter allows you to assign an object that transfers mouse events to template elements. Inherited from CustomDrawEventArgs.
DrawHtml(HtmlTemplate, Action<DxHtmlPainterArgs>)	Paints the required HTML template inside an element that raised this event. Inherited from CustomDrawEventArgs.

Remarks

The Node Indicator Panel is used to navigate through nodes, expand/collapse nodes and display the node state. It is visible when the TreeListOptionsView.ShowIndicator option is enabled.

The event’s parameters provide you with all the information needed to perform indicator cell painting. Use the Node parameter property to identify the node to which the painted indicator cell corresponds.

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

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.

Example

The following sample code handles the TreeList.CustomDrawNodeIndicator event handler. It is used to perform custom painting of indicator panel cells.

The image below displays the result of sample code execution.

C#

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

private void treeList1_CustomDrawNodeIndicator(object sender, 
CustomDrawNodeIndicatorEventArgs e) {
    // Fill background with a linear gradient brush
    Brush backBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightSkyBlue,
      Color.Cyan, LinearGradientMode.Vertical);
    e.Cache.FillRectangle(backBrush, e.Bounds);
    // Paint borders
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds);

    // Calculate image position and painting it
    if (e.ImageIndex > -1)
    {
        Image indImage = (sender as TreeList).Painter.IndicatorImages.Images[e.ImageIndex];
        int imageLeft = e.Bounds.Left + (e.Bounds.Width - indImage.Width) / 2;
        int imageTop = e.Bounds.Top + (e.Bounds.Height - indImage.Height) / 2;
        e.Cache.DrawImage(indImage, new Point(imageLeft, imageTop));
    }

    // Prohibit default painting
    e.Handled = true;
}

VB.NET

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports DevExpress.XtraTreeList

Private Sub TreeList1_CustomDrawNodeIndicator(ByVal sender As Object, _
ByVal e As CustomDrawNodeIndicatorEventArgs) Handles TreeList1.CustomDrawNodeIndicator
    ' Fill background with a linear gradient brush
    Dim BackBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightSkyBlue,
                                             Color.Cyan, LinearGradientMode.Vertical)
    e.Cache.FillRectangle(BackBrush, e.Bounds)
    ' Paint borders
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds)

    ' Calculate image position and painting it
    If e.ImageIndex > -1 Then
        Dim IndImage As Image = sender.Painter.IndicatorImages.Images(e.ImageIndex)
        Dim ImageLeft As Integer = e.Bounds.Left + (e.Bounds.Width - IndImage.Width) / 2
        Dim ImageTop As Integer = e.Bounds.Top + (e.Bounds.Height - IndImage.Height) / 2
        e.Cache.DrawImage(IndImage, New Point(ImageLeft, ImageTop))
    End If

    ' Prohibit default painting
    e.Handled = True
End Sub