UIElement.OnRender Method (DrawingContext)

.NET Framework (current version)

When overridden in a derived class, participates in rendering operations that are directed by the layout system. The rendering instructions for this element are not used directly when this method is invoked, and are instead preserved for later asynchronous use by layout and drawing.

Namespace: System.Windows
Assembly: PresentationCore (in PresentationCore.dll)

Syntax

C++

Protected Overridable Sub OnRender (
	drawingContext As DrawingContext
)

Parameters

drawingContext: Type: System.Windows.Media.DrawingContext
The drawing instructions for a specific element. This context is provided to the layout system.

Remarks

This method has no default implementation in the UIElement class.

Notes to Inheritors:

The OnRender method can be overridden to add further graphical elements (not previously defined in a logical tree) to a rendered element, such as effects or adorners. A DrawingContext object is passed as an argument, which provides methods for drawing shapes, text, images or videos.

Examples

The following code example shows a possible implementation for a panel derived class.

' Override the OnRender call to add a Background and Border to the OffSetPanel
Protected Overrides Sub OnRender(ByVal dc As DrawingContext)
	Dim mySolidColorBrush As New SolidColorBrush()
	mySolidColorBrush.Color = Colors.LimeGreen
	Dim myPen As New Pen(Brushes.Blue, 10)
	Dim myRect As New Rect(0, 0, 500, 500)
	dc.DrawRectangle(mySolidColorBrush, myPen, myRect)
End Sub

Version Information

.NET Framework
Available since 3.0