How to: Send Data to the Active MDI Child

Often, within the context of Multiple-Document Interface (MDI) Applications, you will need to send data to the active child window, such as when the user pastes data from the Clipboard into an MDI application.

To send data to the active MDI child window from the Clipboard

• Within a method, copy the text on the Clipboard to the active control of the active child form.

  Note

  This example assumes there is an MDI parent form (Form1) that has one or more MDI child windows containing a RichTextBox control. For more information, see Creating MDI Parent Forms.

  Public Sub mniPaste_Click(ByVal sender As Object, _
     ByVal e As System.EventArgs) Handles mniPaste.Click
  
     ' Determine the active child form.
     Dim activeChild As Form = Me.ParentForm.ActiveMDIChild
  
     ' If there is an active child form, find the active control, which
     ' in this example should be a RichTextBox.
     If (Not activeChild Is Nothing) Then
        Try
           Dim theBox As RichTextBox = Ctype(activeChild.ActiveControl, RichTextBox)
           If (Not theBox Is Nothing) Then
              ' Create a new instance of the DataObject interface.
              Dim data As IDataObject = Clipboard.GetDataObject()
              ' If the data is text, then set the text of the 
              ' RichTextBox to the text in the clipboard.
              If (data.GetDataPresent(DataFormats.Text)) Then
                 theBox.SelectedText = data.GetData(DataFormats.Text).ToString()
              End If
           End If
        Catch
           MessageBox.Show("You need to select a RichTextBox.")
        End Try
     End If
  End Sub
  

  protected void mniPaste_Click (object sender, System.EventArgs e)
  {
    // Determine the active child form.
     Form activeChild = this.ParentForm.ActiveMdiChild;
  
     // If there is an active child form, find the active control, which
     // in this example should be a RichTextBox.
     if (activeChild != null)
     {
        try 
        {
           RichTextBox theBox = (RichTextBox)activeChild.ActiveControl;
           if (theBox != null)
           {
              // Create a new instance of the DataObject interface.
              IDataObject data = Clipboard.GetDataObject();
              // If the data is text, then set the text of the 
              // RichTextBox to the text in the clipboard.
              if (data.GetDataPresent(DataFormats.Text))
              {
                 theBox.SelectedText = data.GetData(DataFormats.Text).ToString();               
              }
           }
        }
        catch 
        {
           MessageBox.Show("You need to select a RichTextBox.");
        }
     }
  }
  

  private void mniPaste_Click(System.Object sender, System.EventArgs e) 
  {
     // Determine the active child form.
     Form activeChild = this.get_ActiveMdiChild();
  
     // If there is an active child form, find the active control, which
     // in this example should be a RichTextBox.
     if ( activeChild  != null  ) 
     {
        try 
        {
           RichTextBox theBox = ((RichTextBox)(activeChild.get_ActiveControl()));
           if ( theBox  != null  ) 
           {
              // Put the selected text on the Clipboard.
              Clipboard.SetDataObject(theBox.get_SelectedText());
           }
        } 
        catch(System.Exception exp)
        {
           MessageBox.Show("You need to select a RichTextBox.");
        }
     }
  }
  

See Also

Tasks

How to: Create MDI Parent Forms

How to: Create MDI Child Forms

How to: Determine the Active MDI Child

How to: Arrange MDI Child Forms

Other Resources

Multiple-Document Interface (MDI) Applications