docs-desktop/dotnet-desktop-guide/framework/winforms/controls/determine-when-formatting-attributes-change-wf-richtextbox-control.md

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title	ms.date	dev_langs	helpviewer_keywords	ms.assetid
Determine When Formatting Attributes Change in RichTextBox Control	03/30/2017	csharp vb cpp	examples [Windows Forms], text boxes RichTextBox control [Windows Forms], determining font changes text boxes [Windows Forms], determining font changes SelChange event	bdfed015-f77a-41e5-b38f-f8629b2fa166

How to: Determine When Formatting Attributes Change in the Windows Forms RichTextBox Control

A common use of the Windows Forms xref:System.Windows.Forms.RichTextBox control is formatting text with attributes such as font options or paragraph styles. Your application may need to keep track of any changes in text formatting for the purpose of displaying a toolbar, as in many word-processing applications.

To respond to changes in formatting attributes

1. Write code in the xref:System.Windows.Forms.RichTextBox.SelectionChanged event handler to perform an appropriate action depending on the value of the attribute. The following example changes the appearance of a toolbar button depending on the value of the xref:System.Windows.Forms.RichTextBox.SelectionBullet%2A property. The toolbar button will only be updated when the insertion point is moved in the control.

   The example below assumes a form with a xref:System.Windows.Forms.RichTextBox control and a xref:System.Windows.Forms.ToolBar control that contains a toolbar button. For more information about toolbars and toolbar buttons, see How to: Add Buttons to a ToolBar Control.

   ' The following code assumes the existence of a toolbar control  
   ' with at least one toolbar button.  
   Private Sub RichTextBox1_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles RichTextBox1.SelectionChanged  
      If RichTextBox1.SelectionBullet = True Then  
         ' Bullet button on toolbar should appear pressed  
         ToolBarButton1.Pushed = True  
      Else  
          ' Bullet button on toolbar should appear unpressed  
          ToolBarButton1.Pushed = False  
      End If  
   End Sub  
   

   // The following code assumes the existence of a toolbar control  
   // with at least one toolbar button.  
   private void richTextBox1_SelectionChanged(object sender,  
   System.EventArgs e)  
   {  
      if (richTextBox1.SelectionBullet == true)
      {  
         // Bullet button on toolbar should appear pressed  
         toolBarButton1.Pushed = true;  
      }  
      else
      {  
         // Bullet button on toolbar should appear unpressed  
         toolBarButton1.Pushed = false;  
      }  
   }  
   

   // The following code assumes the existence of a toolbar control  
   // with at least one toolbar button.  
   private:  
      System::Void richTextBox1_SelectionChanged(  
         System::Object ^  sender, System::EventArgs ^  e)  
      {  
         if (richTextBox1->SelectionBullet == true)  
         {  
            // Bullet button on toolbar should appear pressed  
            toolBarButton1->Pushed = true;  
         }  
         else  
         {  
            // Bullet button on toolbar should appear unpressed  
            toolBarButton1->Pushed = false;  
         }  
      }  
   

See also

• xref:System.Windows.Forms.RichTextBox.SelectionChanged
• xref:System.Windows.Forms.RichTextBox
• RichTextBox Control
• Controls to Use on Windows Forms