SAMPLE: KEYBFONT.EXE: Input Language and Font Matching

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The information in this article applies to:

• Microsoft Win32 Software Development Kit (SDK), versions 3.5, 3.51, 4.0

SUMMARY

In Windows 95 and Windows NT 4.0 non-Unicode applications, when the input language changes and, as a result, the default character set supported by this language also changes, the script of the current font should also be changed, such as changing the input language from English to Russian. By the same token, when the character set (script) of the font changes, the input language should be changed to match the new script, such as changing from Times New Roman Western script to Times New Roman Cyrillic script. Note that in Windows NT 4.0 Unicode applications, changing the font is not necessary because of support for multicharset fonts. For these applications, the methods described here can be used to detect if a given language is supported by a given font.

The KEYBFONT sample demonstrates the use of WM_INPUTLANGCHANGEREQUEST and WM_INPUTLANGCHANGE messages to match the current font to the input language. If the current font is changed, the list of loaded keyboard drivers is scanned for a match and, if one is found, the font is allowed to change. Otherwise, an error message is displayed and the font does not change. If the input language changes, the scripts of the current font are scanned for a match and, if none is found, an error message is displayed and the input language does not change.

Download KEYBFONT.EXE, a self-extracting file, from the following services:

• Microsoft's World Wide Web site on the Internet

        On the www.microsoft.com home page, click the Support icon
        Click Knowledge Base, and select the product
        Enter kbfile KEYBFONT.EXE (size: 37016 bytes) 
                                 , and click GO!
        Open the article, and click the button to download the file
  
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the Softlib/Mslfiles folder
        Get KEYBFONT.EXE (size: 37016 bytes) 
  

• The Microsoft Network

        On the Edit menu, click Go To, and then click Other Location
        Type "mssupport" (without the quotation marks)
        Double-click the MS Software Library icon
        Find the appropriate product area
        Locate and download KEYBFONT.EXE
  

• Microsoft Partner Network (MSPN)

        On MSPN Desktop, double-click the Software Library icon
        Search for KEYBFONT.EXE
        Display results and download
  

• Microsoft Download Service (MSDL)

        Dial (206) 936-6735 to connect to MSDL
        Download KEYBFONT.EXE (size: 37016 bytes) 
  

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   TITLE     : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

The WM_INPUTLANGCHANGEREQUEST message is sent when the user chooses an input language, either with an input language change hotkey (see Control Panel.Keyboard.Language.Switch Languages) or from the language indicator on the system taskbar. This indicator will only be present if more than one keyboard layout has been installed and the indicator is enabled. An application can accept the change by passing the message to the DefWindowProc function, or reject the change, preventing it from taking place, by returning immediately.

In this sample, during WM_INPUTLANGCHANGEREQUEST, the character set of the requested language is compared to the default character set of each font script in the current font family via EnumFontFamilies(). If the font is not supported, the function returns immediately, disallowing any language change request.

The WM_INPUTLANGCHANGE message is sent to the top-most affected window after a task's locale has been changed. It should be used to make any application-specific settings, such as changing the current font script, and passed on to the DefWindowProc function to be passed on to any children.

In this sample, during WM_INPUTLANGCHANGE, the script of the current font is changed to match the character set of the language the user has switched to.

REFERENCES

For more information on font scripts and multilanguage keyboard support, please see the Chapter "Accommodating Multilingual I/O on Microsoft Windows" in "Developing International Software", by Nadine Kano (MS Press ISBN: 1-55615-840-8).