How to: Customize Display Information via Custom Draw Events

• Nov 13, 2018
• 2 minutes to read

To customize the NavBarControl appearance, you can use two approaches:

• Completely repaint a visual element

  For example, use the NavBarControl.CustomDrawBackground event to draw a string at the bottom. The CustomDrawObjectEventArgs.Handled event parameter should be set to true to disable the default paint algorithm.

• Customize paint parameters

  For example, use the NavBarControl.CustomDrawLink event to display in bold hot-tracked links.

C#

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

private void navBarControl1_CustomDrawBackground(object sender, CustomDrawObjectEventArgs e) {
    Rectangle rect = e.RealBounds;
    Graphics gr = e.ObjectInfo.Graphics;

    // Create a new font for the string.
    Font stringFont = new Font("Verdana", 8);
    // Create a brush used to draw the string.
    LinearGradientBrush stringBrush = new LinearGradientBrush(rect, Color.Blue,
      Color.Red, LinearGradientMode.Horizontal);
    // Calculate string rectangle.
    int stringHeight = Convert.ToInt16(gr.MeasureString("www.devexpress.com",
      stringFont).Height);
    Rectangle stringRect = new Rectangle(rect.Left, rect.Bottom - stringHeight,
      rect.Width, stringHeight);
    // Format string output.
    StringFormat outStringFormat = new StringFormat();
    outStringFormat.Alignment = StringAlignment.Center;

    // Draw the string.
    gr.DrawString("www.devexpress.com", stringFont, stringBrush, stringRect, outStringFormat);

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

private void navBarControl1_CustomDrawLink(object sender, CustomDrawNavBarElementEventArgs e) {
    // If a link is not hot tracked or pressed it is drawn in the normal way.
    if (e.ObjectInfo.State == ObjectState.Hot || e.ObjectInfo.State == ObjectState.Pressed) {
        NavLinkInfoArgs linkInfo = e.ObjectInfo as NavLinkInfoArgs;
        // Customize the font style.
        e.Appearance.FontStyleDelta = FontStyle.Bold;
    }
}

VB.NET

Private Sub navBarControl1_CustomDrawBackground(ByVal sender As Object, ByVal e As _
CustomDrawObjectEventArgs) Handles navBarControl1.CustomDrawBackground

    Dim rect As Rectangle = e.RealBounds
    Dim gr As Graphics = e.ObjectInfo.Graphics

    ' Create a new font for the string.
    Dim stringFont As New Font("Verdana", 8)

    ' Create a brush used to draw the string.
    Dim stringBrush As New LinearGradientBrush(rect, Color.Blue, Color.Red, _
        LinearGradientMode.Horizontal)

    ' Calculate string rectangle.
    Dim stringHeight As Integer = Convert.ToInt16(gr.MeasureString("www.devexpress.com", _
        stringFont).Height)
    Dim stringRect As New Rectangle(rect.Left, rect.Bottom - stringHeight, rect.Width, _
        stringHeight)

    ' Format string output.
    Dim outStringFormat As New StringFormat()
    outStringFormat.Alignment = StringAlignment.Center

    ' Draw the string.
    gr.DrawString("www.devexpress.com", stringFont, stringBrush, stringRect, outStringFormat)

    ' Prohibit default background painting
    e.Handled = True

End Sub


Private Sub navBarControl1_CustomDrawLink(ByVal sender As Object, ByVal e As _
CustomDrawNavBarElementEventArgs) Handles navBarControl1.CustomDrawLink

    ' If a link is not hot tracked or pressed it is drawn in the normal way.
    If e.ObjectInfo.State = ObjectState.Hot OrElse e.ObjectInfo.State = ObjectState.Pressed Then
        Dim linkInfo As NavLinkInfoArgs = TryCast(e.ObjectInfo, NavLinkInfoArgs)
        ' Customize the font style.
        e.Appearance.FontStyleDelta = FontStyle.Bold;
    End If

End Sub