BandedGridView.CustomDrawBandHeader Event

Enables you to custom paint band headers.

Namespace: DevExpress.XtraGrid.Views.BandedGrid

Assembly: DevExpress.XtraGrid.v19.2.dll

Declaration

C#

[DXCategory("CustomDraw")]
public event BandHeaderCustomDrawEventHandler CustomDrawBandHeader

VB.NET

<DXCategory("CustomDraw")>
Public Event CustomDrawBandHeader As BandHeaderCustomDrawEventHandler

Event Data

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

Property	Description
Appearance	Gets the painted element’s appearance settings. Inherited from CustomDrawEventArgs.
Band	Gets the band whose header is to be painted. Returns null if an “empty band header” is currently being painted.
Bounds	Returns a value specifying limits for the drawing area. Inherited from CustomDrawEventArgs.
Cache	Provides methods to paint on drawing surfaces in GDI+ and DirectX modes. See DirectX hardware acceleration to learn more. Inherited from CustomDrawEventArgs.
Graphics	A GDI+ drawing surface. Use the CustomDrawEventArgs.Cache property instead if you enable the DirectX hardware acceleration. 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.
Info	Gets an object providing View information for the band header being painted.
Painter	Gets the painter object that provides the default element painting mechanism. Inherited from CustomDrawObjectEventArgs.

The event data class exposes the following methods:

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

Remarks

The CustomDrawBandHeader event fires when a band header is about to be painted. See the Custom Painting Basics and Custom Painting Scenarios topics for information on using custom draw events.

Important

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.

Example

The following code handles the BandedGridView.CustomDrawBandHeader event to paint band headers with a 3D effect in the pressed state.

C#

private void bandedGridView1_CustomDrawBandHeader(object sender, DevExpress.XtraGrid.Views.BandedGrid.BandHeaderCustomDrawEventArgs e) {
    if (e.Band == null) return;
    if (e.Info.State != ObjectState.Pressed) return;
    using (Brush brushPressed = new LinearGradientBrush(e.Bounds, Color.WhiteSmoke, Color.Gray, LinearGradientMode.ForwardDiagonal)) {
        Rectangle r = e.Bounds;
        Draw3DBorder(e.Cache, r);
        r.Inflate(-1, -1);
        //Fill the background
        e.Cache.FillRectangle(brushPressed, r);

        //Draw a band glyph
        foreach (DrawElementInfo info in e.Info.InnerElements) {
            if (!info.Visible) continue;
            GlyphElementInfoArgs glyphInfoArgs = info.ElementInfo as GlyphElementInfoArgs;
            if (glyphInfoArgs == null) continue;
            info.ElementInfo.OffsetContent(1, 1);
            ObjectPainter.DrawObject(e.Cache, info.ElementPainter, info.ElementInfo);
            info.ElementInfo.OffsetContent(-1, -1);
            break;
        }

        //Draw the band's caption with a shadowed effect
        Rectangle textRect = e.Info.CaptionRect;
        textRect.Offset(2, 2);
        e.Appearance.DrawString(e.Cache, e.Info.Caption, textRect, Brushes.White);
        textRect.Offset(-1, -1);
        e.Appearance.DrawString(e.Cache, e.Info.Caption, textRect, Brushes.Black);

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

private void Draw3DBorder(GraphicsCache cache, Rectangle rect) {
    //Draw a 3D border
    BorderPainter painter = BorderHelper.GetPainter(DevExpress.XtraEditors.Controls.BorderStyles.Style3D);
    AppearanceObject borderAppearance = new AppearanceObject();
    borderAppearance.BorderColor = Color.DarkGray;
    painter.DrawObject(new BorderObjectInfoArgs(cache, borderAppearance, rect));
}

VB.NET

Imports DevExpress.XtraGrid.Views.BandedGrid
Imports System.Drawing.Drawing2D
Imports DevExpress.Utils.Drawing

Private Sub BandedGridView1_CustomDrawBandHeader(sender As Object, e As DevExpress.XtraGrid.Views.BandedGrid.BandHeaderCustomDrawEventArgs) Handles BandedGridView1.CustomDrawBandHeader
    If e.Band Is Nothing Then
        Return
    End If
    If e.Info.State <> ObjectState.Pressed Then
        Return
    End If
    Using brushPressed As Brush = New LinearGradientBrush(e.Bounds, Color.WhiteSmoke, Color.Gray, LinearGradientMode.ForwardDiagonal)
        Dim r As Rectangle = e.Bounds
        Draw3DBorder(e.Cache, r)
        r.Inflate(-1, -1)
        'Fill the background
        e.Cache.FillRectangle(brushPressed, r)

        'Draw a band glyph
        For Each info As DrawElementInfo In e.Info.InnerElements
            If (Not info.Visible) Then
                Continue For
            End If
            Dim glyphInfoArgs As GlyphElementInfoArgs = TryCast(info.ElementInfo, GlyphElementInfoArgs)
            If glyphInfoArgs Is Nothing Then
                Continue For
            End If
            info.ElementInfo.OffsetContent(1, 1)
            ObjectPainter.DrawObject(e.Cache, info.ElementPainter, info.ElementInfo)
            info.ElementInfo.OffsetContent(-1, -1)
            Exit For
        Next info

        'Draw the band's caption with a shadowed effect
        Dim textRect As Rectangle = e.Info.CaptionRect
        textRect.Offset(2, 2)
        e.Appearance.DrawString(e.Cache, e.Info.Caption, textRect, Brushes.White)
        textRect.Offset(-1, -1)
        e.Appearance.DrawString(e.Cache, e.Info.Caption, textRect, Brushes.Black)

        'Prevent default painting
        e.Handled = True
    End Using
End Sub

Private Sub Draw3DBorder(ByVal cache As GraphicsCache, ByVal rect As Rectangle)
    Dim painter As BorderPainter = BorderHelper.GetPainter(DevExpress.XtraEditors.Controls.BorderStyles.Style3D)
    Dim borderAppearance As AppearanceObject = New AppearanceObject()
    borderAppearance.BorderColor = Color.DarkGray
    painter.DrawObject(New BorderObjectInfoArgs(cache, borderAppearance, rect))
End Sub

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the CustomDrawBandHeader event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

VB.NET

how-to-create-a-custom-view-allowing-collapsing-of-band-headers-e2433/VB/BandedViewBandDefaultColumn/BandedViewBandDefaultColumn/MyBandedGridView.vb#L22

MyBase.New()
AddHandler Me.CustomDrawBandHeader, AddressOf OnCustomDrawBandHeader
AddHandler Me.MouseMove, AddressOf OnMouseMove

bandedgridview-how-to-hide-particular-bands-e3175/VB/BandedGridViewHideBands/MyPaintHelper.vb#L34

AddHandler _View.GridControl.PaintEx, AddressOf GridControl_PaintEx
AddHandler _View.CustomDrawBandHeader, AddressOf _View_CustomDrawBandHeader
AddHandler _View.MouseDown, AddressOf _View_MouseDown

C#

bandedgridview-how-to-hide-particular-bands-e3175/CS/BandedGridViewHideBands/MyPaintHelper.cs#L32

_View.GridControl.PaintEx += GridControl_PaintEx;
_View.CustomDrawBandHeader += new BandHeaderCustomDrawEventHandler(_View_CustomDrawBandHeader);
_View.MouseDown += _View_MouseDown;