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OnPaint Method

Syntax

C#
VB
C++
protected override void OnPaint( 
   PaintEventArgs e 
) 
  
Protected Overrides Sub OnPaint( _ 
   ByVal e As PaintEventArgs _ 
)  
protected: 
void OnPaint(  
   PaintEventArgs^ e 
) override  

Parameters

e
A System.Windows.Forms.PaintEventArgs that contains information about the control to paint.

Remarks

Raising an event invokes the event handler through a delegate.

The OnPaint method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors When overriding OnPaint in a derived class, be sure to call the base class's OnPaint method so that registered delegates receive the event.

Example

This example overrides the virtual events of the RasterImagePanViewer class.

C#
VB
using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
 
public class MyRasterImagePanViewer : RasterImagePanViewer 
{ 
   //. 
   //. 
   //. 
   protected override void OnViewerChanged(EventArgs e) 
   { 
      base.OnViewerChanged(e); 
 
      Console.WriteLine("OnViewerChanged is called"); 
   } 
 
   protected override void OnRectangleColorChanged(EventArgs e) 
   { 
      base.OnRectangleColorChanged(e); 
 
      Console.WriteLine("OnRectangleColorChanged is called"); 
   } 
 
   protected override void OnImageColorChanged(EventArgs e) 
   { 
      base.OnImageColorChanged(e); 
 
      Console.WriteLine("OnImageColorChanged is called"); 
   } 
 
   protected override void OnClipCursorChanged(EventArgs e) 
   { 
      base.OnClipCursorChanged(e); 
 
      Console.WriteLine("OnClipCursorChanged is called"); 
   } 
 
   protected override void OnPaint(PaintEventArgs e) 
   { 
      base.OnPaint(e); 
 
      Console.WriteLine("OnPaint is called"); 
   } 
 
   protected override void OnMouseDown(MouseEventArgs e) 
   { 
      base.OnMouseDown(e); 
 
      Console.WriteLine("OnMouseDown is called"); 
   } 
 
   protected override void OnMouseMove(MouseEventArgs e) 
   { 
      base.OnMouseMove(e); 
 
      Console.WriteLine("OnMouseMove is called"); 
   } 
 
   protected override void OnMouseUp(MouseEventArgs e) 
   { 
      base.OnMouseUp(e); 
 
      Console.WriteLine("OnMouseUp is called"); 
   } 
 
   protected override void OnLostFocus(EventArgs e) 
   { 
      base.OnLostFocus(e); 
 
      Console.WriteLine("OnLostFocus is called"); 
   } 
 
   protected override void OnSizeChanged(EventArgs e) 
   { 
      base.OnSizeChanged(e); 
 
      Console.WriteLine("OnSizeChanged is called"); 
   } 
} 
Imports Leadtools.WinForms 
Imports Leadtools 
Imports Leadtools.Codecs 
 
Public Class MyRasterImagePanViewer 
   Inherits RasterImagePanViewer 
   '. 
   '. 
   '. 
   Protected Overrides Sub OnViewerChanged(ByVal e As EventArgs) 
      MyBase.OnViewerChanged(e) 
 
      Console.WriteLine("OnViewerChanged is called") 
   End Sub 
 
   Protected Overrides Sub OnRectangleColorChanged(ByVal e As EventArgs) 
      MyBase.OnRectangleColorChanged(e) 
 
      Console.WriteLine("OnRectangleColorChanged is called") 
   End Sub 
 
   Protected Overrides Sub OnImageColorChanged(ByVal e As EventArgs) 
      MyBase.OnImageColorChanged(e) 
 
      Console.WriteLine("OnImageColorChanged is called") 
   End Sub 
 
   Protected Overrides Sub OnClipCursorChanged(ByVal e As EventArgs) 
      MyBase.OnClipCursorChanged(e) 
 
      Console.WriteLine("OnClipCursorChanged is called") 
   End Sub 
 
   Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) 
      MyBase.OnPaint(e) 
 
      Console.WriteLine("OnPaint is called") 
   End Sub 
 
   Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs) 
      MyBase.OnMouseDown(e) 
 
      Console.WriteLine("OnMouseDown is called") 
   End Sub 
 
   Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs) 
      MyBase.OnMouseMove(e) 
 
      Console.WriteLine("OnMouseMove is called") 
   End Sub 
 
   Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs) 
      MyBase.OnMouseUp(e) 
 
      Console.WriteLine("OnMouseUp is called") 
   End Sub 
 
   Protected Overrides Sub OnLostFocus(ByVal e As EventArgs) 
      MyBase.OnLostFocus(e) 
 
      Console.WriteLine("OnLostFocus is called") 
   End Sub 
 
   Protected Overrides Sub OnSizeChanged(ByVal e As EventArgs) 
      MyBase.OnSizeChanged(e) 
 
      Console.WriteLine("OnSizeChanged is called") 
   End Sub 
End Class 

Requirements

Target Platforms

Help Version 19.0.2017.10.27
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