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The program declares a WithEvents variable of type MdiClient. When the MDI parent form loads, the program looks through its child controls looking for the MdiClient and saves a reference to that client in the WithEvents variable. The program then creates an MDI child form.
When the MdiClient receives a Paint or Resize event, it calls subroutine DrawPicture, passing it a Graphics object on which to draw. In this example, DrawPicture draws an ellipse with an X over it on the MdiClient control.
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Private WithEvents m_MdiClient As MdiClient
Private Sub Form1_Load(ByVal sender As Object, ByVal e As _
System.EventArgs) Handles MyBase.Load
' Get the MDIClient.
For Each ctl As Control In Me.Controls
If TypeOf ctl Is MdiClient Then
m_MdiClient = DirectCast(ctl, MdiClient)
Exit For
End If
Next ctl
' Display a child form.
Dim frm As New Form2
frm.Width = Me.Width \ 2
frm.Height = Me.Height \ 2
frm.MdiParent = Me
frm.Focus()
frm.Show()
End Sub
Private Sub m_MdiClient_Paint(ByVal sender As Object, ByVal _
e As System.Windows.Forms.PaintEventArgs) Handles _
m_MdiClient.Paint
DrawPicture(e.Graphics)
End Sub
Private Sub m_MdiClient_Resize(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles m_MdiClient.Resize
Dim gr As Graphics = m_MdiClient.CreateGraphics()
DrawPicture(gr)
End Sub
Private Sub DrawPicture(ByVal gr As Graphics)
gr.Clear(m_MdiClient.BackColor)
Dim thick_pen As New Pen(Color.Aquamarine, 10)
gr.DrawEllipse(thick_pen, 5, 5, _
m_MdiClient.ClientSize.Width - 6, _
m_MdiClient.ClientSize.Height - 6)
gr.DrawLine(Pens.Blue, 0, 0, _
m_MdiClient.ClientSize.Width, _
m_MdiClient.ClientSize.Height)
gr.DrawLine(Pens.Blue, m_MdiClient.ClientSize.Width, 0, _
_
0, m_MdiClient.ClientSize.Height)
End Sub
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