Some printers have TrueType (TT) fonts built into the printer. Printer
drivers can increase their throughput by using the printer's internal
TrueType device fonts instead of downloading the fonts to the printer.
To get an accurate representation of printer supported TrueType fonts on
the display, there must be an associated TT font that is installed on the
system. The printer manufacturer or driver developer has the responsibility
of providing TT fonts that match the printer's TT fonts. The TT fonts must
be installed by using the Control Panel Fonts or by using the respective
Windows API AddFontResource function.
The printer driver can then use the Enginexxxx functions that are
documented in the Windows version 3.1 DDK's DDAG31WH.HLP file.
The Enginexxxx functions are:
EngineDeleteFont
EngineEnumerateFont
EngineGetCharWidth
EngineGetGlyphBmp
EngineRealizeFont
EngineSetFontContext
The Enginexxxx functions are entry points into the Windows TT rasterizer.
These functions allow a printer driver to treat TT fonts as device fonts.
By using its EnumDFonts() function, a printer driver can enumerate all the
TT fonts on the system, compare them with the printer's TT fonts and return
only the TT fonts that match. Then in the printer driver's ExtTextOut()
function, the Enginexxxx realized TT font can be mapped to the printer's TT
font and the associated printer escapes can be sent to the printer instead
of downloading a load of raster data.