1 The FilterGraphics Function

The FilterGraphics function prepares a buffer of raster data (which it
receives from the Universal Printer Driver) for rendering on the printer.
The FilterGraphics function is necessary if a printer does not process
graphics data in the manner supported by the Universal Printer Driver. For
example, when the Universal Printer Driver passes a byte of raster data to
a 9-pin dot-matrix printer, it orders the individual bits so that bit 7
corresponds to the top-most pin and bit 0 corresponds to the bottom-most
pin. If a given printer addresses pins in a different format, it must
provide a FilterGraphics function to correctly order the bits in each byte
of data.