Plotting Graph

[tigger]

Hi there,
I seem to face some problems with multiple click event. When i click plotButton, it should plot a cross. For example if user select 250Hz, it will plot a cross at 250Hz. x and y are the pixel values to draw the cross. When the user select a different frequency (eg. 500Hz) and click plotButton again, the cross for the 250Hz will disappear. So how do i make it stay? I think it has got something to do with the plotButton click event.

Private Sub Audiogram_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
  If BIEMaskingMachine.freqTrackBar.Value = 250 Then
    If BIEMaskingMachine.count = -10 Then
      x = 80
      y = 50
      G.DrawLine(Bluepen, (x - 5), (y - 5), (x + 5), (y + 5)) 'drawing 'x'
      G.DrawLine(Bluepen, (x + 5), (y - 5), (x - 5), (y + 5))
      xpoints(0) = G
    End If
 
    If BIEMaskingMachine.freqTrackBar.Value = 500 Then
      If BIEMaskingMachine.toneLabel.Text = "-10dB" Then
        x = 120
        y = 50
        H.DrawLine(Bluepen, (x - 5), (y - 5), (x + 5), (y + 5)) 'drawing 'x'
        H.DrawLine(Bluepen, (x + 5), (y - 5), (x - 5), (y + 5))
        xplotted500 = H
      End If
End Sub

The plotButton is in a different form. This is the code for the plotButton.

Private Sub plotButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles plotButton.Click
 
  'Audiogram.ShowDialog()
  Audiogram.Show()
 
End Sub

[Killer42]

Hi tigger.

I haven't even tried to follow the code yet (assuming I could, since I'm a VB6 developer, not VB.Net). But after tidying up the indenting (sorry, I just like it nice and symmetrical), I have to ask - does the VB.Net compiler really allow you to get away with wildly unbalanced IF...End If structures like that? If so, frankly I'm appalled.

And I suspect that may be the source of any problems. For instance, the test for freqTrackBar.Value = 500 is dependent on the truth of freqTrackBar.Value = 250. Unless I've just missed something in between which changes the value, the second test can never be true.

[tigger]

Hi tigger.

I haven't even tried to follow the code yet (assuming I could, since I'm a VB6 developer, not VB.Net). But after tidying up the indenting (sorry, I just like it nice and symmetrical), I have to ask - does the VB.Net compiler really allow you to get away with wildly unbalanced IF...End If structures like that? If so, frankly I'm appalled.

And I suspect that may be the source of any problems. For instance, the test for freqTrackBar.Value = 500 is dependent on the truth of freqTrackBar.Value = 250. Unless I've just missed something in between which changes the value, the second test can never be true.

Sorry i actually posted only part of the codes. If not, it's quite long.

Private Sub Audiogram_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
  If BIEMaskingMachine.freqTrackBar.Value = 250 Then
    If BIEMaskingMachine.count = -10 Then
      x = 80
      y = 50
      G.DrawLine(Bluepen, (x - 5), (y - 5), (x + 5), (y + 5)) 'drawing 'x'
      G.DrawLine(Bluepen, (x + 5), (y - 5), (x - 5), (y + 5))
      xpoints(0) = G
    End If
End If
 
    If BIEMaskingMachine.freqTrackBar.Value = 500 Then
      If BIEMaskingMachine.toneLabel.Text = "-10dB" Then
        x = 120
        y = 50
        H.DrawLine(Bluepen, (x - 5), (y - 5), (x + 5), (y + 5)) 'drawing 'x'
        H.DrawLine(Bluepen, (x + 5), (y - 5), (x - 5), (y + 5))
        xplotted500 = H
      End If
End If
End Sub

[Killer42]

I'd be more inclined to suspect the AutoRedraw setting, or whatever the equivalent is in VB.Net.

Not too sure about VB.Net, but I believe the general way that painting a window (a "window" can be a control such as a picturebox) works is that Windows (or VB) either stores a permanent copy to be thrown back on screen whenever the control needs to be repainted, or it leaves it up to the code in the Paint event procedure to draw it.

So if Windows is calling this Paint code of yours each time the window (control) needs to be repainted, then I guess you're only going to get whatever your routine says to paint.

Perhaps you ought to have a look on the web for a tutorial covering how to produce graphics in VB.Net. VB does make things relatively simple, but sometimes it's not quite as simple as it seems.