So I have a very large canvas, which I'm using in virtual mode. This allows me to draw very long graphs, and have the user scroll left and right using the thumb of the virtual canvas horizontal scroll bar.

But I need to be able to retrieve the value of that scroll thumb - i.e., I need to know to which point in the graph they've scrolled.

How can I read that value out?


Here is the code that demonstrates what I'm talking about :

Uses "UI"

Begin ControlID
End ControlID

Function TBMain() As Long
  Local hDlg    As DWord   '---Used to store window handle of main dialog

  hDlg = Dialog_New Pixels, 0, "ABC ", -1, -1, 1200, 775,
                                                  %WS_DLGFRAME  | 
                                                  %DS_CENTER    | 
                                                  %WS_CAPTION   | 
                                                  %WS_SYSMENU   | 

  Dialog Show Modal hDlg, Call cbDialog
End Function 

CallBack Function cbDialog() As Long
  Select Case CBMSG
      Control Add Canvas, CBHNDL, %ID_Canvas, "", 200,  10,1000, 400, %WS_BORDER | %WS_CHILD | %WS_VISIBLE                              
      Canvas_Attach(CBHNDL, %ID_Canvas, %FALSE)
      Canvas_SetVirtual(100000, 380)
  End Select
End Function