On a Windows NT computer, Windows 3.x-based (16 bit) applications are supported by a Graphical Device Interface 32 (GDI32) engine. The GDI32 engine translates print and display application programming interface (API) calls to 32-bit WIN32 services.
The GDI32 graphics engine (Gdi32.dll) is the printing component that provides What You See Is What You Get (WYSIWYG) support across devices. The graphics engine communicates with Windows-based applications through the Windows Graphics Device Interface (GDI) and with printer drivers through the Device Driver Interface (DDI).
When a Windows-based application creates a print job, it describes the output it wants in a series of GDI commands. The GDI32 graphics engine is the component that translates these GDI commands into the DDI commands understood by components such as printer drivers and print processors.
The GDI32 graphics engine queries the printer driver to identify the capabilities of the print device, including supported fonts. Using this information, the GDI32 graphics engine uses other DDI commands to specify the positioning of each character in the document by the print device. The GDI32 graphics engine also uses DDI commands to define how the print device should draw and fill graphics and how to manipulate and print bitmaps.
The GDI32 graphics engine provides services to the printer driver, including compatibility with the environment subsystem (for example, MS-DOS or OS/2) and performance optimization, caching, client-server communications, and ANSI-to-Unicode conversion.
The GDI32 graphics engine calls the printer driver and provides information about the type of print device needed and the data type used. In response, the printer driver provides the graphics engine with the fully qualified path name for the print device and printer-setting information. This information is passed to the spooler.