PrintDlg (handles,dc)

[mark smit]

Hello all

I'm using PrintDlg to get a printer DC. The question is do I have to free the global memory handles(hDevMode,hDevNames) and delete the DC myself or does this some how get resolved internaly?



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Cheers

[Semen Matusovski]

Mark --

In MSDN samples always

DeleteDC pd.hDC
If pd.hDevMode Then GlobalFree pd.hDevMode
If pd.hDevNames Then GlobalFree pd.hDevNames

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E-MAIL: [email protected]

[mark smit]

Thanks Semen!

I thought that would be the case. Funny enough I have never seen an example about it. I guess the MSDN is a bit too big!

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Cheers

[Semen Matusovski]

For example, http://msdn.microsoft.com/library/bo.../chpt06-10.htm

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E-MAIL: [email protected]

[Edwin Knoppert]

The save_ variables are very handy during the app lifetime.
At the end the memory will be freed anyway.

Why should i release it?


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[Semen Matusovski]

Edwin --
With the same success you can do not delete memory bitmaps and so on.
Imagine that you execute PrintDlg many times.


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E-MAIL: [email protected]

[Edwin Knoppert]

Well, it becomes a serious question now

No, I can't imagne..

My printdlg USES the old save_.. each time.

Afaik the handle is simply reused each time, or not?
Only on app end, "i should" destroy the handles.
But i don't care much for those small memory blocks.

Can you explain where i'm wrong?

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[Semen Matusovski]

Memory leaks are small - agree (on my PC under Win2000 - about 20-30K per time).
There is no "re-using"

   #Compile Exe
   #Dim All
   #Register None
   #Include "Win32Api.Inc"
   #Include "Comdlg32.Inc"

  Sub PrintFile (hWnd As Long, FileBuf As Asciiz)
     Dim di As DOCINFO
     Dim nError As Integer, pd As PRINTDLGAPI

     ' // Initialize the PRINTDLG structure.
     pd.lStructSize = SizeOf (pd)
     pd.hwndOwner = hWnd
     pd.hInstance = GetModuleHandle(ByVal 0&)
     pd.Flags = %PD_RETURNDC Or %PD_USEDEVMODECOPIES Or %PD_COLLATE Or %PD_NOSELECTION Or %PD_PRINTSETUP

     '// Print a test Page If successful.
     If PrintDlg (pd) Then
        ' // Fill out the DOCINFO structure.
        di.cbSize = SizeOf (di)
        Dim aa As String
        aa = "Printing Test"
        di.lpszDocName = StrPtr(aa)
        StartDoc pd.hDC, di

        nError = StartPage (pd.hDC)
        If (nError <= 0) Then
           MessageBox hWnd, "Error in StartPage.", ByVal %Null, %MB_OK
        Else
           ' // Print the text.
           TextOut pd.hDC, 5, 5, FileBuf, Len (FileBuf)
           nError = EndPage (pd.hDC)
           If (nError <= 0) Then
               MessageBox hWnd, "Error in EndPage.", ByVal 0&, %MB_OK
               AbortDoc pd.hDC
           Else
               ' // The document has ended.
               nError = EndDoc (pd.hDC)
               If (nError <= 0) Then
                  MessageBox hWnd, "Error in EndDoc.", ByVal 0&, %MB_OK
               End If
           End If
        End If
        MsgBox Hex$(pd.hDC) + "  " + Hex$(pd.hDevMode)
        'DeleteDC pd.hDC
        'If pd.hDevMode Then GlobalFree pd.hDevMode
        'If pd.hDevNames Then GlobalFree pd.hDevNames
     Else
        MsgBox "Error"
     End If
  End Sub

  CallBack Function PrnProc
    PrintFile CbHndl, "Test"
  End Function

  Function PbMain
     Dim hDlg As Long
     Dialog New 0, "Print", , , 200, 200 To hDlg
     Control Add Button, hDlg, 101, "Print", 10, 10, 100, 15 Call PrnProc
     Dialog Show Modal hDlg
  End Function

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E-MAIL: [email protected]

[Edwin Knoppert]

But you didn't delete the DC, maybe this is the problem.

I'll check out your code this day..




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[Edwin Knoppert]

Semen, i modified your example.
It works the same as the PB procedures in comdlg32.inc (WICH I RECOMMEND)
No loss in GDI or user.

I can actually see that it succeeds because every 2nd prindlg() the old devmode handle is reused by winapi.
This can only be if the handle was released somehow.
(I mean, the same value for the new memory is used)

If you see my point differently please let me know.
I was just finishing a print method for the compagny.
I also heard of using ResetDC in between pages.
Maybe we can gather good tips for printing.

1) Like sideways printing is not allways supported.
2) Switching orientation in between pages might not be allways succesful.
3) Drivers and ports like USB
4) Would like to know more..

I think printing is rather problematic.
The printerdrivers are not allways the best, i mostly replace them for internal drivers from windows itself.
We still make 16bit VB3 software, USB is somehow NOT supported, we don't know if this will be a problem for 32bit in the near future.

#Compile Exe
 
   #Dim All
   #Register None
   #include "Win32Api.Inc"
   #include "Comdlg32.Inc"
 
  Sub PrintFile (hWnd As Long, FileBuf As Asciiz)
     Dim di As DOCINFO
     Dim nError As Integer, pd As PRINTDLGAPI
 
     ' // Initialize the PRINTDLG structure.
     pd.lStructSize = SizeOf (pd)
     pd.hwndOwner = hWnd
     pd.hInstance = GetModuleHandle(ByVal 0&)
     pd.Flags = %PD_RETURNDC Or %PD_USEDEVMODECOPIES Or %PD_COLLATE Or %PD_NOSELECTION Or %PD_PRINTSETUP
 
'//////////////////////////////////////////////////////////////////////// 
'// This is how i use it
    pd.hDevMode    = save_hDevMode
    pd.hDevNames   = save_hDevNames
'//////////////////////////////////////////////////////////////////////// 
 
     '// Print a test Page If successful.
     If PrintDlg (pd) Then
 
        ' // Fill out the DOCINFO structure.
        di.cbSize = SizeOf (di)
 
        Dim aa As String
 
        aa = "Printing Test"
 
        di.lpszDocName = StrPtr(aa)
        StartDoc pd.hDC, di
 
        nError = StartPage (pd.hDC)
        If (nError <= 0) Then
           MessageBox hWnd, "Error in StartPage.", ByVal %Null, %MB_OK
        Else
           ' // Print the text.
           TextOut pd.hDC, 5, 5, FileBuf, Len (FileBuf)
           nError = EndPage (pd.hDC)
           If (nError <= 0) Then
               MessageBox hWnd, "Error in EndPage.", ByVal 0&, %MB_OK
               AbortDoc pd.hDC
           Else
               ' // The document has ended.
               nError = EndDoc (pd.hDC)
               If (nError <= 0) Then
                  MessageBox hWnd, "Error in EndDoc.", ByVal 0&, %MB_OK
               End If
           End If
        End If

'//////////////////////////////////////////////////////////////////////// 
        MsgBox Str$( pd.hDC) + "  " + Str$( pd.hDevMode)
        DeleteDC pd.hDC
'//////////////////////////////////////////////////////////////////////// 

        'If pd.hDevMode Then GlobalFree pd.hDevMode
        'If pd.hDevNames Then GlobalFree pd.hDevNames
 
 
'//////////////////////////////////////////////////////////////////////// 
        '// Store the devmode etc..
            save_hDevMode = pd.hDevMode
            save_hDevNames = pd.hDevNames
'//////////////////////////////////////////////////////////////////////// 
 
     Else
        MsgBox "Error"
     End If
  End Sub
 
  CallBack Function PrnProc
    PrintFile CbHndl, "Test"
  End Function
 
  Function PbMain
     Dim hDlg As Long
     Dialog New 0, "Print", , , 200, 200 To hDlg
     Control Add Button, hDlg, 101, "Print", 10, 10, 100, 15 Call PrnProc
     Dialog Show Modal hDlg
  End Function

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