layers?

[Guest]

I'm writing a program to communicate with the Millenium 3 from Crouzet. Communication works and I can send and receive data. I now want to progam a trending. My intention is to see a kind of oscilloscope sreen on the computer screen, a green rectangle with square divisions in black. At the utmost right side of the scope a point is set at a height corresponding to the amplitude of the Millenium signal. Then it's my intention to copy the trending already written and to move it one pixel to the left. Afterwards a new point is set at the right side, and so on. But when I do this, the background moves also what is obviously not the intention. How can I move only the signal line without changing the scope screen view itself and without unquiet display? Using bitmaps? Layers would be usefull but I doubt this is possible with Powerbasic. Is there a good handbook of Powerbasic 9 in which this topic is mentioned? Thanks.

[Dave Biggs]

Here's some rough code that does something similar to what you're describing. Create a grid on your 'scope', draw onto a memory bitmap, copy the bitmap to the appropriate location on your 'scope' and redraw the grid.. repeat.

#PBForms CREATED V1.51
#Compile Exe
#Dim All
 
#PBForms BEGIN INCLUDES
#If Not %Def(%WINAPI)
  #Include "WIN32API.INC"
#EndIf
#If Not %Def(%COMMCTRL_INC)
  #Include "COMMCTRL.INC"
#EndIf
#Include "PBForms.INC"
#PBForms END INCLUDES
 
#PBForms BEGIN CONSTANTS
%IDD_DIALOG1 =  101
%GFX_Scope   = 1001
%BTN_Start   = 1002
%BTN_Exit    = 1003
#PBForms END CONSTANTS
 
Declare CallBack Function ShowDIALOG1Proc()
Declare Function ShowDIALOG1(ByVal hParent As Dword) As Long
#PBForms DECLARATIONS
'------------------/
 
Function PBMain()
  PBFormsInitComCtls (%ICC_WIN95_CLASSES Or %ICC_DATE_CLASSES Or %ICC_INTERNET_CLASSES)
 
  ShowDIALOG1 %HWND_Desktop
End Function
'------------------/
 
Sub DrawGrid(ByVal hWin As Dword, ByVal nID As Long, ByVal x As Long, ByVal y As Long)
 Local Clx, Cly, n As Long 
 
  Graphic Attach hWin, nID
  Graphic Attach hWin, nID, ReDraw
  Graphic Get Client To Clx, Cly
  x = Clx \ x : y = Cly \ y
  n = 1
  Do Until n*x > Clx
    Graphic Line (n*x, 0) - (n*x, Cly), %rgb_LightGray
    Incr n
  Loop
 
  n = 1
  Do Until n*y > Cly
    Graphic Line (0, n*y) - (Clx, n*y), %rgb_LightGray
    Incr n
  Loop
  Graphic Redraw
 
End Sub
'------------------/
 
Sub PlotPoints (hWin As Dword, nID As Long)
 Local hBmp As Dword
 Local x, y As Long, hzRadDeg, Pi As Double
 
  Pi     = 4 * Atn(1)                         ' Calculate Pi
  hzRadDeg = Pi / 180
 
  Graphic Bitmap New 300, 300 To hBmp         ' create memory bitmap
  Graphic Attach hBmp, 0
  Graphic Clear %RGB_PALEGREEN
  Graphic Set Pos (0, 150)
    For x = 0 To 360                          ' draw on it
        y = Sin(hzRadDeg * x) * 148
        Graphic Line Step - (x, 150 + y)
    Next
    Graphic Attach hWin, nID
    For x = 0 To 300                          ' copy it to the graphic control
      Graphic Copy hBmp, 0 To (300 -x, 0)
      Sleep 50
      DrawGrid hWin, nID, 10, 10              ' redraw the grid
    Next
 
End Sub
'------------------/
 
CallBack Function ShowDIALOG1Proc()
 
  Select Case As Long CbMsg
    Case %WM_InitDialog
      Graphic Attach CbHndl, %GFX_Scope
      Graphic Clear %RGB_PALEGREEN
      DrawGrid Cb.Hndl, %GFX_Scope, 10, 10
 
    Case %WM_NCActivate
      Static hWndSaveFocus As Dword
      If IsFalse CbWParam Then
        hWndSaveFocus = GetFocus()
      ElseIf hWndSaveFocus Then
        SetFocus(hWndSaveFocus)
        hWndSaveFocus = 0
      End If
 
    Case %WM_Command
      Select Case As Long CbCtl
        Case %GFX_Scope
 
        Case %BTN_Start
          If CbCtlMsg = %BN_Clicked Or CbCtlMsg = 1 Then
            PlotPoints Cb.Hndl, %GFX_Scope
            DrawGrid Cb.Hndl, %GFX_Scope, 10, 10
          End If
 
        Case %BTN_Exit
          If CbCtlMsg = %BN_Clicked Or CbCtlMsg = 1 Then
            Dialog End CbHndl
          End If
 
      End Select
  End Select
End Function
'------------------/
 
Function ShowDIALOG1(ByVal hParent As Dword) As Long
  Local lRslt As Long
 
#PBForms BEGIN DIALOG %IDD_DIALOG1->->
  Local hDlg  As Dword
 
  Dialog New Pixels, hParent, "Test", 105, 114, 390, 390, To hDlg
  Control Add Graphic, hDlg, %GFX_Scope, "", 45, 16, 302, 302, %WS_Child Or %WS_Visible Or %WS_Border
  Control Add Button,  hDlg, %BTN_Start, "Start", 90, 333, 75, 25
  Control Add Button,  hDlg, %BTN_Exit, "Exit", 210, 333, 75, 25
#PBForms END DIALOG
 
  Dialog Show Modal hDlg, Call ShowDIALOG1Proc To lRslt
 
#PBForms BEGIN CLEANUP %IDD_DIALOG1
#PBForms END CLEANUP
 
  Function = lRslt
End Function
'------------------/