Referencing locales

Important

The modern print platform is Windows' preferred means of communicating with printers. We recommend that you use Microsoft's IPP inbox class driver, along with Print Support Apps (PSA), to customize the print experience in Windows 10 and 11 for printer device development.

For more information, see Modern print platform and the Print support app design guide.

Using GPD files

GPD files can reference a system's locale. Typically, locale identifiers are used within *Switch statements, where parameters such as default paper sizes and resource DLLs can be specified in a locale specific manner.

To reference locale information, the GPD file must contain an *Include statement that includes the file locale.gpd, which is included in the with the Windows Driver Kit (WDK), as follows:

*Include: locale.gpd

This GPD file defines a feature named "Locale", and defines options for many locales. (Refer to the file to see which locales are defined.) Following is an example usage of these locale options. The example bases the default paper size on the locale.

*Feature: PaperSize
{
...
    Option: A4
    {
    }
    ...
*switch: Locale
{
    *case: English_United_States
    {
        *DefaultOption: Letter
    }
    *case: English_United_Kingdom
    {
        *DefaultOption: A4
    }
    *default:
    {
        *DefaultOption: Letter
    }
} *% End of switch
} *% End of Feature: PaperSize

At run time, Unidrv determines the system's default locale by calling GetSystemDefaultLCID. When a printer is installed, the GPD parser reads the printer's GPD file and uses information within the *Case statement associated with the default locale. Note that if the system's locale is changed after the printer is installed, locale-based options are not changed.

Here is another example, which selects a resource DLL based on the locale. The resource DLL can contain locale-specific resources, such as display strings.

*switch: Locale
{
    *case: English_United_States
    {
        *ResourceDLL: english.dll
    }
    *case: German_Standard
    {
        *ResourceDLL: german.dll
    }
    *default:
    {
        *ResourceDLL: english.dll
    }
}

Setting default paper size by locale

You might want to have your driver assign the default paper size, either metric or non-metric, based upon the user's geographic location.

The following algorithm retrieves the default system locale and then uses country/region codes to determine whether the system locale represents a country that typically uses metric or non-metric paper sizes. With this information, your driver can set the default paper size appropriately, such as A4 for countries that use the metric system and Letter size for countries that don't.

1. Use the GetLocaleInfo function to retrieve the default system locale. Use LOCALE_SYSTEM_DEFAULT for the first parameter, Locale, and LOCALE_ICOUNTRY for the second parameter, LCType.

2. Use the default system locale obtained from GetLocaleInfo to determine metric or non-metric paper size.

   • Non-metric if default system locale is:

     • CTRY_UNITED_STATES, or

     • CTRY_CANADA, or

     • Greater than or equal to 50, but less than 60 and not CTRY_BRAZIL, or

     • Greater than or equal to 500, but less than 600

   • Metric otherwise.