windowsforms-devexpress-dot-xtratreelist-dot-treelist-c89781ca.md
Enables you to custom paint a Tree List’s empty area.
Namespace : DevExpress.XtraTreeList
Assembly : DevExpress.XtraTreeList.v25.2.dll
NuGet Packages : DevExpress.Win.Navigation, DevExpress.Win.TreeList
[DXCategory("CustomDraw")]
public event CustomDrawEmptyAreaEventHandler CustomDrawEmptyArea
<DXCategory("CustomDraw")>
Public Event CustomDrawEmptyArea As CustomDrawEmptyAreaEventHandler
The CustomDrawEmptyArea event's data class is CustomDrawEmptyAreaEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| Appearance | Gets the painted element’s appearance settings. Inherited from CustomDrawEventArgs. |
| BehindColumn | Gets the blank column’s bounding rectangle. |
| 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. |
| EmptyAreaRegion | Use the EmptyRectangles property to get the region occupied by the empty area. |
| EmptyRectangles | Gets the array of rectangles that specify the empty area. |
| EmptyRows | Gets the bounding rectangle occupied by the empty rows. |
| 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. |
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. |
Handle the CustomDrawEmptyArea event to custom paint the control’s empty area(the area where Tree List nodes are going to be displayed).
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 code handles the TreeList.CustomDrawEmptyArea event to manually paint the control’s empty area when no nodes are displayed.
The image below shows the result.
using DevExpress.XtraTreeList;
private void treeList1_CustomDrawEmptyArea(object sender, CustomDrawEmptyAreaEventArgs e) {
if (treeList1.Nodes.Count > 1) return;
string s = "No Records Available";
e.Appearance.FontStyleDelta = FontStyle.Bold;
e.Appearance.FontSizeDelta = 2;
e.Cache.DrawString(s, e.Appearance.Font, e.Cache.GetSolidBrush(Color.Black), e.Bounds);
e.Handled = true;
}
Imports DevExpress.XtraTreeList
Private Sub TreeList1_CustomDrawEmptyArea(sender As Object, e As DevExpress.XtraTreeList.CustomDrawEmptyAreaEventArgs) Handles TreeList1.CustomDrawEmptyArea
If TreeList1.Nodes.Count > 1 Then Return
Dim s As String = "No Records Available"
e.Appearance.FontStyleDelta = FontStyle.Bold
e.Appearance.FontSizeDelta = 2
e.Cache.DrawString(s, e.Appearance.Font, e.Cache.GetSolidBrush(Color.Black), e.Bounds)
e.Handled = True
End Sub
The following code snippet (auto-collected from DevExpress Examples) contains a reference to the CustomDrawEmptyArea 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.
tree.CustomColumnDisplayText += Tree_CustomColumnDisplayText;
tree.CustomDrawEmptyArea += Tree_CustomDrawEmptyArea;
tree.OptionsView.FocusRectStyle = DrawFocusRectStyle.RowFullFocus;
AddHandler tree.CustomColumnDisplayText, AddressOf Tree_CustomColumnDisplayText
AddHandler tree.CustomDrawEmptyArea, AddressOf Tree_CustomDrawEmptyArea
tree.OptionsView.FocusRectStyle = DrawFocusRectStyle.RowFullFocus
See Also