windowsforms-devexpress-dot-xtratreelist-dot-treelist-2c2a8590.md
Allows you to custom paint preview sections.
Namespace : DevExpress.XtraTreeList
Assembly : DevExpress.XtraTreeList.v25.2.dll
NuGet Packages : DevExpress.Win.Navigation, DevExpress.Win.TreeList
[DXCategory("CustomDraw")]
public event CustomDrawNodePreviewEventHandler CustomDrawNodePreview
<DXCategory("CustomDraw")>
Public Event CustomDrawNodePreview As CustomDrawNodePreviewEventHandler
The CustomDrawNodePreview event's data class is CustomDrawNodePreviewEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| Appearance | Gets the painted element’s appearance settings. |
| 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. |
| 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. |
| PreviewText | Gets or sets the painted preview section’s text. |
| PreviewTextBounds | Gets the content bounds of the preview section. |
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. |
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.
The following sample code handles the TreeList.CustomDrawNodePreview event. It is used to perform custom painting of preview sections.
The image below displays the result of sample code execution.
using System.Drawing;
using System.Drawing.Drawing2D;
using DevExpress.XtraTreeList
private void treeList1_CustomDrawNodePreview(object sender, CustomDrawNodePreviewEventArgs e) {
// filling background with a linear gradient brush
Brush backBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightGoldenrodYellow, Color.Cornsilk, LinearGradientMode.Vertical);
e.Cache.FillRectangle(backBrush, e.Bounds);
// painting the preview string
e.Appearance.FontStyleDelta = FontStyle.Italic;
e.Cache.DrawString(e.PreviewText, e.Appearance.Font, Brushes.Maroon, e.Bounds, e.Appearance.GetStringFormat());
// prohibiting default painting
e.Handled = true;
}
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports DevExpress.XtraTreeList
Private Sub TreeList1_CustomDrawNodePreview(sender As Object, e As DevExpress.XtraTreeList.CustomDrawNodePreviewEventArgs) Handles TreeList1.CustomDrawNodePreview
' filling background with a linear gradient brush
Dim backBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightGoldenrodYellow, Color.Cornsilk, LinearGradientMode.Vertical)
e.Cache.FillRectangle(backBrush, e.Bounds)
' painting the preview string
e.Appearance.FontStyleDelta = FontStyle.Italic
e.Cache.DrawString(e.PreviewText, e.Appearance.Font, Brushes.Maroon, e.Bounds, e.Appearance.GetStringFormat())
' prohibiting default painting
e.Handled = True
End Sub
See Also