How To Localize Application Resources with Foundation Classes

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Summary

Microsoft Foundation Class Library Technical Note 23 explains how to customize standard framework resources, such as the buttons on a print preview dialog bar. However, this technical note does not provide a good solution for developers who are producing an application localized into more than one language, and there is a problem with the method described.

When localizing an application for several languages, it is most convenient to place all of the application's resources into a dynamic link library (DLL). To localize the application into a new language, clone the DLL and translate the resources into the appropriate language. After testing, you can ship the application code with the appropriate language-specific DLL to address each market.

The remainder of this article outlines the general steps required to localize an application by moving the resources into a DLL.

More information

To place all application resources into a DLL project, open the .rc file in App Studio. Choose Save As from the File menu to store the resources into another directory (created for this purpose). Then open the original .rc file, and remove all resources visible in the App Studio Resource Browser. Finally, choose Set Includes from the App Studio File menu. Delete the #include statements for Afxprint.rc and for Afxres.rc from the Compile-Time Directives list and choose OK.

Use the Visual Workbench to create a new Windows DLL project for the resources. Set the project type to Windows dynamic-link library, and clear the "Use Microsoft Foundation Classes" check box. Add the .rc file to the project. Then create the following files in your DLL directory, and add them to the project.

Mylocal.cpp

#include <windows.h>

int CALLBACK LibMain(HINSTANCE hinst, WORD wDataSeg, WORD cbHeap,
      LPSTR lpszCmdLine )
{
   return 1;
}
				

Mylocal.def

LIBRARY      MYLOCAL
DESCRIPTION  'Localized resources for MFC application'
EXETYPE      WINDOWS

CODE         PRELOAD MOVEABLE DISCARDABLE
DATA         PRELOAD MOVEABLE SINGLE

SEGMENTS
   WEP_TEXT FIXED PRELOAD

EXPORTS
   WEP @1 RESIDENTNAME ; required WEP entry point
                       ; (uses library WEP routine)
				
Copy the standard framework resources into the .rc file for your DLL so you can modify them. Technical Note 23 outlines a procedure to do this. To copy all resources from Afxprint.rc and Afxres.rc into the .rc file for your DLL, select the resources in each source file. Then press and hold the CTRL key and drag the resources into the new .rc file. Edit the Compile- Time Directives list box in App Studio to remove the #include files.

There are two problems with this procedure. Perform the following two steps to work around these problems before compiling your DLL:

NOTE: In MFC version 2.5 and later, step 1 is no longer necessary.

  1. The AFX_IDC_MAGNIFY cursor, used by print preview, is loaded using the AfxGetInstanceHandle() function rather than the AfxGetResourceHandle() function. This error occurs on line 904 of the Viewprev.cpp file in the Microsoft Foundation Class Library source directory (by default, C:\Msvc\Mfc\Src). If you wish, you can modify the source code and recompile the libraries. However, a reasonable method to work around this problem involves copying the AFX_IDC_MAGNIFY resource into your application's .rc file. Only this resource would be common to all languages.
  2. The Afxprint.rc file (located by default in the C:\Msvc\Mfc\Include directory) declares AFX_IDD_PREVIEW_TOOLBAR, the standard framework resource for the print preview CDialogBar, with the following resource style:
          STYLE WS_CHILD | CBRS_TOP
    						
    The problem is that the CBRS_TOP style is specific to the Microsoft Foundation Class Library; App Studio does not copy this style when you follow the procedure in Technical Note 23. Use a text editor to open the .rc file as a text file. (Note that you may need to change an option in the Editor Options dialog box in Visual Workbench.) Add the vertical bar (the OR symbol) and CBRS_TOP to the STYLE statement. Otherwise, the print preview dialog bar does not appear.
AppWizard creates the .rc2 file in the DLL Res directory to contain version information for the application. Edit this information as appropriate for your DLL.

Build the DLL project and copy it into your application's directory.

To use the localized resources in the DLL from your application, add the following code to your application and rebuild it:

  1. Modify the main application class (for example, CMyApp) to add an HINSTANCE member variable to contain the DLL instance handle, as follows:
       HINSTANCE m_hInstDLL;
    						
  2. In CMyApp::InitInstance(), insert the following code before the first line of code generated by ClassWizard:
       if ((m_hInstDLL = ::LoadLibrary("mylocal.dll")) < HINSTANCE_ERROR)
       {
          return FALSE; // failed to load the localized resources
       }
       else
       {
          AfxSetResourceHandle(m_hInstDLL); // get resources from the DLL
       }
    						
  3. Modify the CMyApp::ExitInstance() function to free the library before the application exits. Modify the function as follows:
       int CMyApp::ExitInstance()
       {
          FreeLibrary(m_hInstDLL);
          return CWinApp::ExitInstance();
       }
    						
WARNING: You might encounter a problem if you follow the advice in step 3. For additional information, please see the following article in the Microsoft Knowledge Base:
187684 BUG: Assert When Calling AfxFreeLibrary from ExitInstance
Once you establish that the application works as expected, you can use App Studio to translate the resources in the DLL project and make additional copies of the project to localize for other languages.

For more information on this procedure, see the Microsoft Foundation Class Library Technical Notes. The Visual C++ 1.0 for Windows setup program creates an MFC Tech Notes icon in the Visual C++ 1.0 group.

Properties

Article ID: 147149 - Last Review: October 26, 2013 - Revision: 4.0
Applies to
  • Microsoft Foundation Class Library 4.2, when used with:
    • Microsoft Visual C++ 1.0 Professional Edition
    • Microsoft Visual C++ 1.52 Professional Edition
    • Microsoft Visual C++ 2.1
    • Microsoft Visual C++ 2.2
Keywords: 
kbnosurvey kbarchive kbcode kbhowto kblocalization KB147149

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