GridView.CustomDrawRowPreview Event

Enables you to paint preview sections manually.

Namespace: DevExpress.XtraGrid.Views.Grid

Assembly: DevExpress.XtraGrid.v23.2.dll

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

Declaration

C#

[DXCategory("CustomDraw")]
public event RowObjectCustomDrawEventHandler CustomDrawRowPreview

VB.NET

<DXCategory("CustomDraw")>
Public Event CustomDrawRowPreview As RowObjectCustomDrawEventHandler

Event Data

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

Property	Description
Appearance	Gets the painted element’s appearance settings. Inherited from CustomDrawEventArgs.
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 containing information about the painted element. Inherited from CustomDrawObjectEventArgs.
Painter	Gets the painter object that provides the default element painting mechanism. Inherited from CustomDrawObjectEventArgs.
RowHandle	Gets the handle of the row whose corresponding element is being painted.

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 CustomDrawRowPreview event is raised each time a preview section needs to be repainted. The preview section’s row is identified by the event’s RowObjectCustomDrawEventArgs.RowHandle parameter.

See the Custom Painting Basics and Custom Painting Scenarios topics for information on using custom draw events.

To provide custom text for preview sections, handle the GridView.CalcPreviewText event instead of the CustomDrawRowPreview event.

The preview section’s height is specified by the GridView.PreviewLineCount property value and the GridOptionsView.AutoCalcPreviewLineCount property value. When the CustomDrawRowPreview event is raised, the preview section’s height is calculated and cannot be changed. Please refer to the Row Preview Sections topic for details.

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 example demonstrates how to manually redraw the Grid preview section. You can test this sample in the Custom painting - CustomDrawRowPreview demo.

C#

using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraGrid.Views.Base;

 private void Form3_Load1(object sender, EventArgs e) {
     CustomDrawRowPreview(gridControl1, gridView1);
 }

 public static void CustomDrawRowPreview(GridControl gridControl, GridView gridView) {
     gridView.Columns["Notes"].Visible = false;
     gridView.PreviewFieldName = "Notes";
     gridView.PreviewLineCount = 2;
     gridView.OptionsView.ShowPreview = true;

     // Handle this event to paint row previews manually
     gridView.CustomDrawRowPreview += (s, e) => {
         if (e.RowHandle == 2) {
             GridView view = s as GridView;
             int dx = 5;
             // A rectangle for displaying text.
             Rectangle r = e.Bounds;
             r.X += e.Bounds.Height + dx * 2;
             r.Width -= (e.Bounds.Height + dx * 3);
             e.Cache.FillRectangle(Color.Coral, new Rectangle(e.Bounds.X + dx, e.Bounds.Y, e.Bounds.Height, e.Bounds.Height));
             e.Appearance.ForeColor = Color.Green;
             e.Appearance.DrawString(e.Cache, view.GetRowPreviewDisplayText(e.RowHandle), r);
             e.Handled = true;
         }
     };
 }

VB.NET

Imports DevExpress.XtraGrid.Views.Grid
Imports DevExpress.XtraGrid.Views.Base

 Private Sub Form3_Load1(ByVal sender As Object, ByVal e As EventArgs)
     CustomDrawRowPreview(gridControl1, gridView1)
 End Sub

 Public Shared Sub CustomDrawRowPreview(ByVal gridControl As GridControl, ByVal gridView As GridView)
     gridView.Columns("Notes").Visible = False
     gridView.PreviewFieldName = "Notes"
     gridView.PreviewLineCount = 2
     gridView.OptionsView.ShowPreview = True

     ' Handle this event to paint row previews manually
     AddHandler gridView.CustomDrawRowPreview, Sub(s, e)
         If e.RowHandle = 2 Then
             Dim view As GridView = TryCast(s, GridView)
             Dim dx As Integer = 5
             ' A rectangle for displaying text.
             Dim r As Rectangle = e.Bounds
             r.X += e.Bounds.Height + dx * 2
             r.Width -= (e.Bounds.Height + dx * 3)
             e.Cache.FillRectangle(Color.Coral, New Rectangle(e.Bounds.X + dx, e.Bounds.Y, e.Bounds.Height, e.Bounds.Height))
             e.Appearance.ForeColor = Color.Green
             e.Appearance.DrawString(e.Cache, view.GetRowPreviewDisplayText(e.RowHandle), r)
             e.Handled = True
         End If
     End Sub
 End Sub