To get to a specific string, you need three things: the package list handle (EFI_HII_HANDLE), the string identifier (EFI_STRING_ID) and the language. Since you are normally using the platform's current language, you generally don't have to worry about that and use the default setting.
There are two sets of string-related protocols: (a) those which add, modify and remove strings from the HII Database and (b) those which create a bitmap using the strings text.
With EFI_HII_STRING_PROTOCOL, you can create new strings, retrieve the string's text, change the string's text and find out which languages are supported.
- NewString() lets you create a new string within a specific package list and returns back a new string identifier. You can specify (if you want), the language and the font information. If you don't specify the language, the platform's current language is used. If you don't specify a font, then the platform's standard font is used.
- GetString() retrieves information about a specific string, including the string's text and the associated font. If you don't specify the language, the platform's current language is used.
- SetString() changes information about a specific string, including the string's text and (optionally), the string's font information. If you don't specify the language, the platform's current language is used.
- GetLanguages() reports the languages that are supported by a specific package list.
- GetSecondaryLanguages() reports the regional versions of a specific language supported by a specific package list. For example, if you passed in "en", it might return "en-US", "en-UK" "en-PH" if there were specific translations for those regional variations in English.
- StringToImage() draws a string's text onto a bitmap or the screen at a specific location. If the font is not specified, then the platform's standard font is used instead. If the language is not specified, then the platform's current language is used. This function also allows you to clip the text to a rectangle in a variety of ways, wrap the text, draw transparently and handle multi-line text. Even more useful to sophisticated users, it also reports the positioning of each character in the string in the bitmap so that user-interface code can use it for cursor movement and mouse selection.
- StringIdToImage() does the same thing, except that you pass in a string identifier and a package list handle.