---
title: "Overriding the OnPaint Method"
ms.date: "03/30/2017"
dev_langs: 
  - "csharp"
  - "vb"
helpviewer_keywords: 
  - "Paint event [Windows Forms], handling in Windows Forms custom control"
  - "OnPaint method [Windows Forms], overriding in Windows Forms custom controls"
ms.assetid: e9ca2723-0107-4540-bb21-4f5ffb4a9906
---
# Overriding the OnPaint Method

The basic steps for overriding any event defined in the .NET Framework are identical and are summarized in the following list.  
  
#### To override an inherited event  
  
1. Override the protected `On`*EventName* method.  
  
2. Call the `On`*EventName* method of the base class from the overridden `On`*EventName* method, so that registered delegates receive the event.  
  
 The <xref:System.Windows.Forms.Control.Paint> event is discussed in detail here because every Windows Forms control must override the <xref:System.Windows.Forms.Control.Paint> event that it inherits from <xref:System.Windows.Forms.Control>. The base <xref:System.Windows.Forms.Control> class does not know how a derived control needs to be drawn and does not provide any painting logic in the <xref:System.Windows.Forms.Control.OnPaint%2A> method. The <xref:System.Windows.Forms.Control.OnPaint%2A> method of <xref:System.Windows.Forms.Control> simply dispatches the <xref:System.Windows.Forms.Control.Paint> event to registered event receivers.  
  
 If you worked through the sample in [How to: Develop a Simple Windows Forms Control](how-to-develop-a-simple-windows-forms-control.md), you have seen an example of overriding the <xref:System.Windows.Forms.Control.OnPaint%2A> method. The following code fragment is taken from that sample.  
  
```vb  
Public Class FirstControl  
   Inherits Control  
  
   Public Sub New()  
   End Sub  
  
   Protected Overrides Sub OnPaint(e As PaintEventArgs)  
      ' Call the OnPaint method of the base class.  
      MyBase.OnPaint(e)  
      ' Call methods of the System.Drawing.Graphics object.  
      e.Graphics.DrawString(Text, Font, New SolidBrush(ForeColor), RectangleF.op_Implicit(ClientRectangle))  
   End Sub  
End Class
```  
  
```csharp  
public class FirstControl : Control {  
   public FirstControl() {}  
   protected override void OnPaint(PaintEventArgs e) {  
      // Call the OnPaint method of the base class.  
      base.OnPaint(e);  
      // Call methods of the System.Drawing.Graphics object.  
      e.Graphics.DrawString(Text, Font, new SolidBrush(ForeColor), ClientRectangle);  
   }
}
```  
  
 The <xref:System.Windows.Forms.PaintEventArgs> class contains data for the <xref:System.Windows.Forms.Control.Paint> event. It has two properties, as shown in the following code.  
  
```vb  
Public Class PaintEventArgs  
   Inherits EventArgs  
   ...  
   Public ReadOnly Property ClipRectangle() As System.Drawing.Rectangle  
      ...  
   End Property  
  
   Public ReadOnly Property Graphics() As System.Drawing.Graphics  
      ...  
   End Property
   ...  
End Class  
```  
  
```csharp  
public class PaintEventArgs : EventArgs {  
...  
    public System.Drawing.Rectangle ClipRectangle {}  
    public System.Drawing.Graphics Graphics {}  
...  
}  
```  
  
 <xref:System.Windows.Forms.PaintEventArgs.ClipRectangle%2A> is the rectangle to be painted, and the <xref:System.Windows.Forms.PaintEventArgs.Graphics%2A> property refers to a <xref:System.Drawing.Graphics> object. The classes in the <xref:System.Drawing?displayProperty=nameWithType> namespace are managed classes that provide access to the functionality of GDI+, the new Windows graphics library. The <xref:System.Drawing.Graphics> object has methods to draw points, strings, lines, arcs, ellipses, and many other shapes.  
  
 A control invokes its <xref:System.Windows.Forms.Control.OnPaint%2A> method whenever it needs to change its visual display. This method in turn raises the <xref:System.Windows.Forms.Control.Paint> event.  
  
## See also

- [Events](/dotnet/standard/events/index)
- [Rendering a Windows Forms Control](rendering-a-windows-forms-control.md)
- [Defining an Event](defining-an-event-in-windows-forms-controls.md)