PCL/HP LaserJet Printer Driver - Printers and Fonts Kit(3.1)

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◄Up► ◄Next► ◄Previous► ──────────────────────────────────────────────────────────────────────────── The Microsoft Windows PCL printer driver supports a wide variety of printers including the Hewlett-Packard printers that use Printer Control Language (PCL) and fonts. This topic provides a brief overview of the features for the driver and in particular those features new for Windows 3.1. Features for Windows 3.1 The printer driver for HP LaserJet printers that use PCL includes the following new features for Windows 3.1: ♦ Memory Tracking. This allows users to manage the memory usage on the printer. This especially useful when using multiple downloadable fonts. ♦ TrueType as Graphics. This allows for drawing glyphs using outlines rather then downloaded glyphs. ♦ User-Specified Position and Thickness for TrueType Fonts. This allows for user control of the appearance of glyphs from TrueType fonts. ♦ ResetDC Function. This allows users to change the page orientation or paper tray in the middle of a print job. ♦ Standard Dialog Boxes. This provides a consistent user interface between printer drivers and applications. Soft Fonts and Cartridges Because of the large number of downloadable and cartridge fonts available for HP LaserJet printers, the driver can only have a few of these fonts built into it. The driver supports the installation of additional fonts by supplying a utility called the Printer Font Installer. The Printer Font Installer adds support for soft fonts and font cartridges by installing PFM and PCM files and associated screen and soft font files. The font cartridge manufacturer can use the PFM Editor to create PFM and PCM files to accompany the font cartridge, or create these files on their own. PFM Files for HP Printers that Use PCL The Printer Font Metrics (PFM) files for PCL printers have the following form: PFMHEADER Header; /* font header */ WORD WidthTable[]; /* variable-width fonts only */ PFMEXTENSION Extensions; /* extensions */ char DeviceName[]; /* printer device name */ char FaceName[]; /* font name */ EXTTEXTMETRIC ExtTextMetrics; /* extended-text metrics (optional)*/ WORD ExtentTable[]; /* unscaled character widths */ DRIVERINFO DriverInfo; /* driver-specific info (optional)*/ PAIRKERN KerningPairs[]; /* pair-kerning table (optional) */ KERNTRACK KerningTracks[]; /* track-kerning table (optional) */ The width table is present if the dfPixWidth member is zero, which indicates a variable-width font. (Otherwise, for fixed-width fonts the width of all the characters in the font equals the value in the dfPixWidth member and no width table is given.) The width table is an array of words containing the widths in device units of characters in the range from dfFirstChar to dfLastChar. The width of a character c can be located using the formula: width = WidthTable [c - dfFirstChar] The size of the table is dfLastChar - dfFirstChar + 2 words. The last word is not used and is set to zero; it should be present for compatibility with the Windows screen-font file format. If your font contains kern pairs, you must fill in the EXTTEXTMETRIC structure to indicate the number of kern pairs. Do not leave the other members blank; fill them in with reasonable values in the event an application uses them. Eventually, there will be PFM files that describe scalable PCL fonts. To guarantee that your raster fonts are never interpreted as scalable fonts, make sure that the members for scaling information in the EXTTEXTMETRIC structure indicate a nonscaling font: etmMasterHeight = etmMasterUnits = etmMinScale = etmMaxScale = dfPixHeight The PCL driver for Windows supports five possible character translations. It determines which internal translation table to use based upon the value of the symbolSet member of the xtbl member. Following are the symbol sets and their corresponding translation tables. Symbol set Translation table ──────────────────────────────────────────────────────────────────────────── epsymECMA94 ECMA94_Trans epsymGENERIC7 GENERIC7_Trans epsymGENERIC8 GENERIC8_Trans epsymRoman8 Roman8_Trans epsymUSASCII USASCII_Trans The translation tables are stored in the TRANS.H file. For epsymRoman8, epsymUSASCII, and epsymECMA94, the driver attempts to derive Windows ANSI from the symbol set. For epsymGENERIC8 and epsymGENERIC7, the driver simply lets an 8- or 7-bit symbol set pass through to the printer unchanged. The driver assumes the width table in the PFM file contains the widths of the characters after translation. If you set epsymRoman8, epsymUSASCII, or epsymECMA94 for the symbolSet member of xtbl member, you must use the appropriate translation table in TRANS.H to do an inverse translation when building the width table. Following is a sample of the translation table for epsymRoman8: #define HP_DF_CH ((BYTE) 0x7F) unsigned char <+> Roman8_Trans[] = { HP_DF_CH, NULL, /* 80 */ HP_DF_CH, NULL, /* 81 */ ... 'Y' , 0xa8, /* dd */ 0xf0, NULL, /* de */ 0xde, NULL, /* df */ 0xc8, NULL, /* e0 */ ... 0xef, NULL }; /* ff */ The table translates characters in the range from 128 to 255. The driver uses the character it receives from the application to index into the translation table. It replaces the character with the first entry in the table. If the second entry is not a NULL entry, it overstrikes the first character with the second character. For example, when the driver detects character 0xDD (that is, the Y-acute (Y) in the text stream), the driver will output a capital "Y" overstruck by the acute accent. When the overstrike character is present, the driver guarantees that the width of the character pair equals the width of the first character. If the driver-specific data structure is not present, or the symbolSet member of xtbl member equals a symbol set other than epsymRoman8, epsymUSASCII, epsymECMA94, epsymGENERIC8, or epsymGENERIC7, the driver will use the epsymGENERIC8 translation as a default if the dfLastChar member of the PFMHEADER structure is greater than 127 (an 8-bit font). Otherwise, it will use the epsymGENERIC7 translation. PFM Files for Scalable PCL Fonts Currently, the PCL driver for Windows supports only nonscaling PCL fonts. The driver will detect scalable fonts by examining the etmMinScale and etmMaxScale members in the EXTTEXTMETRIC structure. If they are equal, it will assume a nonscaling font. A PFM file for scalable PCL font must have the following form: PFMHEADER Header; /* font header */ WORD WidthTable[]; /* variable-width fonts only */ PFMEXTENSION Extensions; /* extensions */ char DeviceName[]; /* printer device name */ char FaceName[]; /* font face name */ EXTTEXTMETRIC ExtTextMetrics; /* extended text metrics (optional)*/ WORD ExtentTable[]; /* unscaled character widths */ DRIVERINFO DriverInfo; /* driver-specific info (optional)*/ PAIRKERN KerningPairs[]; /* pair-kerning table (optional) */ KERNTRACK KerningTracks[]; /* track-kerning table (optional) */ In the PFMHEADER structure, the dfPixHeight member must contain the height of a default font size (same as 12 points). For variable-width fonts, the width-table array contains widths for the default point size. In the DRIVERINFO structure, the epEscape member must be nonzero (that is, a printer escape must be provided). Optionally, pair-kern and track-kern tables may be provided. The default font size and width table should be provided for consistency with the existing driver. If they differ and the dfExtMetricsOffset member is not NULL, the driver will assume a scalable font. An extent table must be supplied for scalable fonts. The extent table is an array of words containing the unscaled widths of the characters. The range of the table should be from dfFirstChar to dfLastChar. The size of the table should be dfLastChar - dfFirstChar + 1 word. The driver will scale the characters using the formulas based on the etmMasterHeight and etmMasterUnits members. The driver will not support the ENABLERELATIVEWIDTHS escape, as this would be difficult to support with scaling and nonscaling fonts intermixed (scaling fonts use font units; nonscaling fonts use device units). The driver will assume the dfVertRes member equals 300 dpi. Remember that etmMasterHeight, etmMinScale, and etmMaxScale must be expressed in device units. If the intended printer does not force its widths to 300 dpi units (that is, etmMasterUnits does not equal etmMasterHeight), the driver will attempt to correct for roundoff error between the printer's units and the driver's imposed 300 dpi units. The driver will correct for the error by maintaining a running roundoff value during output of a single line of text. You must provide the driver-specific data structure. As described earlier, the symbolSet member of xtbl member must be equal to epsymRoman8, epsymUSASCII, epsymECMA94, epsymGENERIC8, or epsymGENERIC7. Use an inverse translation of the tables provided in the TRANS.H file to build the extent table if you select epsymRoman8, epsymUSASCII, or epsymECMA94. You must also provide an escape string pointed to by the epEscape member in the driver-specific data structure. The driver will send this escape to the printer to select the font. If pair or track kerns exist, they should use the same units as the character widths in the extent table. Permanent Soft Fonts Permanent soft fonts are downloaded to the printer when the printer is turned on, and remain there until the printer is turned off. Permanent fonts are downloaded to the printer sometime after power up. The driver does not have to be active, nor does Windows need to be running for permanent fonts to be downloaded to the printer. In fact, permanent fonts are typically downloaded to the printer when the user first turns on the computer. Initialization Settings for PCL Printers The printer driver for HP printers that use PCL uses a number of sections and settings in the WIN.INI file. Users set these settings by using the driver's Printer Setup dialog box or the Printer Font Installer. Normally, the user should have no need to modify these settings directly. The most important settings for the driver are the softfonts and softfontn settings. These set the number of and define the PFM or PCM files for the soft fonts and cartridges for the printer. The Printer Font Installer sets these settings when the user installs fonts. However, notice that the driver has no control over the order of the settings in the WIN.INI file, and the driver does not currently "delete" settings from the WIN.INI file. The order of settings in the WIN.INI file is insignificant and has no effect on the operation of the driver. If the driver does not delete an entire entry line from WIN.INI, it removes everything to the right of the equal sign (=). The title text to the left of the equal sign remains there until the user manually removes it. The Windows Printer Font Installer, used in conjunction with the HP LaserJet driver that uses PCL, also requires these settings that associated permanently downloaded fonts with their corresponding PFM files. The following shows the general form for these settings: C:\PCLFONTS\HVPB0140.PFM=C:\PCLFONTS\HV140BPN.USP C:\PCLFONTS\TRPR0120.PFM=C:\PCLFONTS\TR120BPN.USP The Printer Font Installer in the driver for HP printers that use PCL uses these settings to preserve the filenames of the permanently downloaded fonts. If the fonts are changed to temporary fonts, these settings are removed and the soft font filenames are added with the appropriate softfontn setting. ♦