1.1.2 Interaction Between an Application and the Driver

After a Windows application creates a printer-device context, it can render
output on the printer by calling GDI functions. When an application calls a
GDI function, the following occurs:

1.  GDI calls the appropriate functions in the driver.

2.  If the function is a query or information function, the driver returns
    the requested data.

3.  If the function is an output function, the driver creates a
    device-command string.