Visual Basic

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Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown<br />
        Dim oGP As GraphicsPath<br />
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        ' Loop through the collection of lines to see if we clicked on one.<br />
        For Each oGP In LineCollection<br />
            ' The following IF returns true if the line was clicked on, the trigonometry is done for you :)<br />
            If oGP.IsOutlineVisible(e.X, e.Y, New Pen(Color.Black)) Then<br />
                oGP.Reset() ' Should remove the line from the collection or do something different here!<br />
                Me.Invalidate()<br />
                Exit Sub<br />
            End If<br />
        Next<br />
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        Drawing = True<br />
        GP = New GraphicsPath ' Create a new GP object to hold the line. <br />
        pt1 = New Point(e.X, e.Y) ' Set the start point of the line.<br />
        LineCollection.Add(GP) ' Add this graphics path object to the collection<br />
End Sub<br />
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Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseUp<br />
        Drawing = False ' Not drawing a line anymore<br />
End Sub<br />
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Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseMove<br />
        If Drawing = True Then<br />
            GP.Reset() ' Clear the current graphics path object.<br />
            GP.AddLine(pt1.X, pt1.Y, e.X, e.Y) ' Add the line<br />
            Me.Invalidate() ' Force paint<br />
        End If<br />
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End Sub<br />