Font Installation and Deletion

A font must already be resident on a given device or installed in the Windows font table in order for an application to draw text using glyphs from that font. The Windows font table is an internal array that identifies all nondevice fonts that are available to a Windows-based application. An application can retrieve the names of fonts currently installed on a device and stored in the internal font table by calling the EnumFontFamilies or ChooseFont function.

An application can install a font by calling the font-installation function AddFontResource. The AddFontResource function loads a font that is stored in a font-resource file.

In the case of TrueType fonts, an additional step is sometimes necessary before the font can be installed in the font table. Some font manufacturers ship only the TrueType font-data files (identified by the .TTF extension). Before Windows can load these fonts, it requires a corresponding header file (identified by the .FOT extension). To create this header file, an application must call the CreateScalableFontResource function and pass the name of the font-data file as the third parameter. When this header file is created, an application can install the font by calling the AddFontResource function and passing the name of the new header file.

When an application finishes using an installed font, it must remove that font by calling the RemoveFontResource function.

Whenever an application calls the functions that add and delete font resources, it should also call the SendMessage function and send a WM_FONTCHANGE message to all top-level windows in the system. This message notifies other applications that the internal font table has been altered by an application that added or removed a font.