Some printers have many fonts, others have none. The minidriver font data resources define which fonts are available depending on the current configuration of the printer. For example, dot matrix printers have no fonts when printing in landscape mode. Fonts can also be cached in the printer. The Laserjet printer enables fonts to be downloaded from disk, including TrueType fonts. In this case, the bitmap information is taken from the TrueType fonts and is downloaded to the printer to create a device font that can be processed quickly, thereby reducing the size of the data stream.
To render text with device fonts and retrieve font data in response to application queries, RasDD requires PFM and font selection commands. The character data for device fonts is stored in the printer or in a font cartridge. Printers render text faster with device fonts because the bitmap or vector data is device resident and does not require downloading from the disk to the printer.
A CTT for 16-bit drivers and RLE format for 32-bit drivers are used by RasDD to map characters from a printer's native character and symbol set to the Windows ANSI character set to identify the printable characters. The current version of the Windows ANSI character set contains 244 entries. RasDD provides support for some of the common code pages and symbol sets to eliminate redundancy in a large number of individual printer drivers and permit individual drivers to support the less common ones. The font data resources and the CTT-data resources differ from the resources used in the Windows NT minidriver.