Setting the Default Printer Programmatically in an MFC Application

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Overview

In a standard MFC application, the system wide default printer will be setup as default each time your application starts. This is done during your CWinApp objects initialization, when it calls the function CWinApp::UpdatePrinterSelection(). This sets up the m_hDevMode and m_hDevNames global handles (as in global memory handles used with GlobalLock/Unlock) which CWinApp uses to manage the selected printer.

I have provided a wrapper class for enumPrinters, which is used to gather information on the locally installed printers which is needed when switching printers. It can also set the printers when called by a function in your CWinApp derived class and passing through m_hDevMode and m_hDevNames as references, so they can be changed.

When switching printers programmatically, you need to know:

• The printer's name, e.g., HP Laserjet 4L
• The port the printer is installed on, e.g., LPT1:
• The spooler that will dump the printout to the printer, usually winspool

Details

The class CEnumPrinters encapsulates the required functionality needed to query for the locally setup printers. This list can then be read/used to select new printers and set them as the new default printer to be used by the application.

Restoring the Selected Printer

You can save the selected printer to the registry and restore it also. To do this, you need to place calls to CEnumPrinters::SavePrinterSelection() and CEnumPrinters::RestorePrinterSelection() in your application's ExitInstance and InitInstance procedures.

The information saved is:

• The printer name
• The spooling device
• The port name
• The page orientation (portrait or landscape)

Class Interface

The following functions are used in the class:

• int GetPrinterCount() ;
• CString GetPrinterName(int index) ;
• CString GetPrinterLocation(int index) ;
• CString GetPrinterShareName(int index) ;
• CString GetPrinterPortName(int index) ;
• void ReadLocalPrinters() ;

The above functions enumerate the list of locally installed printers - automatically called in class constructor.

• bool SetNewPrinter(HANDLE& hDevMode, HANDLE& hDevNames, const CString& PrinterName, const CString& PrinterSpooler, const CString& PrinterPort) ;

Use the function above when switching to a printer by Name, driver, port

• bool SetNewPrinter(HANDLE& hDevMode, HANDLE& hDevNames, int index) ;

Use the function above when switching to a printer in the local list by index

• bool SetPrintOrientation(HANDLE &hDevMode, int mode) ;

Use the above function to switch between portrait and landscape page orientations.

• bool SavePrinterSelection(HANDLE &hDevMode, HANDLE& hDevNames) ;
• bool RestorePrinterSelection(HANDLE &hDevMode, HANDLE& hDevNames) ;

These procedures save/restore the selected printer from the registry (key PrinterConfig)

Future Enhancements or Coding Projects

• Add functionality to query network printers
• Add functionality to add a new printer

Enjoy!

Revision History

• 12^th June, 2002 - Initial revision