NavBarControl.CustomDrawGroupClientBackground Event

Provides the ability to perform custom painting of group client areas.

Namespace: DevExpress.XtraNavBar

Assembly: DevExpress.XtraNavBar.v23.2.dll

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

Declaration

C#

public event CustomDrawObjectEventHandler CustomDrawGroupClientBackground

VB.NET

Public Event CustomDrawGroupClientBackground As CustomDrawObjectEventHandler

Event Data

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

Property	Description
Appearance	Gets the painted element’s appearance settings.
Cache	Gets an object which specifies the storage for the most used pens, fonts and brushes.
Graphics	Gets an object used to paint the object.
Handled	Gets or sets a value specifying whether the control must perform default painting after an event handler has been executed.
ObjectInfo	Gets an object providing information on the element being painted.
RealBounds	Gets the bounding rectangle of the painted object.

Remarks

Write a CustomDrawGroupClientBackground event handler to perform custom painting of group client areas. Set the CustomDrawObjectEventArgs.Handled property of the event parameter to true to disable default painting. Other properties of the event parameter allow you to identify the group whose client area is painted and provide all necessary information to paint it.

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 NavBarControl.CustomDrawGroupClientBackground event to fill the top and bottom portions of a group’s client background with linear gradient brushes of opposing color.

The image below shows the result.

C#

using System.Drawing.Drawing2D;
using DevExpress.XtraNavBar.ViewInfo;

private void navBarControl1_CustomDrawGroupClientBackground(object sender, DevExpress.XtraNavBar.ViewInfo.CustomDrawObjectEventArgs e) {
    // calculate the top and bottom part rectangles
    Rectangle rect = e.RealBounds;
    int halfHeight = rect.Height / 2;
    Rectangle topRect = new Rectangle(rect.Left, rect.Top, rect.Width, halfHeight);
    Rectangle bottomRect = new Rectangle(rect.Left, rect.Top + halfHeight,
        rect.Width, halfHeight);

    // create brushes for the top and bottom parts
    Color outerColor = Color.White;
    Color innerColor = Color.LightSkyBlue;
    LinearGradientBrush topBrush = new LinearGradientBrush(topRect, outerColor, innerColor,
        LinearGradientMode.Vertical);
    LinearGradientBrush bottomBrush = new LinearGradientBrush(bottomRect, innerColor,
        outerColor, LinearGradientMode.Vertical);
    // fill the top and bottom rectangles with the created brushes
    e.Cache.FillRectangle(topBrush, topRect);
    e.Cache.FillRectangle(bottomBrush, bottomRect);

    topBrush.Dispose();
    bottomBrush.Dispose();

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

VB.NET

Imports System.Drawing.Drawing2D
Imports DevExpress.XtraNavBar.ViewInfo

Private Sub NavBarControl1_CustomDrawGroupClientBackground(sender As Object, e As CustomDrawObjectEventArgs) Handles NavBarControl1.CustomDrawGroupClientBackground
    ' calculate the top and bottom part rectangles
    Dim Rect As Rectangle = e.RealBounds
    Dim HalfHeight = Rect.Height / 2
    Dim TopRect As New Rectangle(Rect.Left, Rect.Top, Rect.Width, HalfHeight)
    Dim BottomRect As New Rectangle(Rect.Left, Rect.Top + HalfHeight, Rect.Width, HalfHeight)

    ' create brushes for the top and bottom parts
    Dim OuterColor As Color = Color.White
    Dim InnerColor As Color = Color.LightSkyBlue
    Dim TopBrush As New LinearGradientBrush(TopRect, OuterColor, InnerColor,
        LinearGradientMode.Vertical)
    Dim BottomBrush As New LinearGradientBrush(BottomRect, InnerColor, OuterColor,
        LinearGradientMode.Vertical)

    ' fill the top and bottom rectangles with the created brushes
    e.Cache.FillRectangle(TopBrush, TopRect)
    e.Cache.FillRectangle(BottomBrush, BottomRect)

    TopBrush.Dispose()
    BottomBrush.Dispose()

    ' prohibit default painting     
    e.Handled = True
End Sub