HP-UX Reference (11i v3 07/02) - 4 File Formats (vol 8)

t
terminfo(4) terminfo(4)
(ENHANCED CURSES)
When used with a character set number in a call to tparm(), the csnm string will produce the equivalent
name. These names should be used as a reference only. No naming convention is implied, although anyone
who creates a terminfo entry for a printer should use names consistent with the names found in user
documents for the printer. Application developers should allow a user to specify a character set by number
(leaving it up to the user to examine the csnm string to determine the correct number), or by name, where
the application examines the csnm string to determine the corresponding character set number.
These capabilities are likely to be used only with dot-matrix printers. If they are not available, the strings
should not be defined. For printers that have manually changed print-wheels or font cartridges, the
boolean daisy is set.
Dot-Matrix Graphics
Dot-matrix printers typically have the capability of reproducing raster graphics images. Three numeric
capabilities and three string capabilities help a program draw raster-graphics images independent of the
type of dot-matrix printer or the number of pins or dots the printer can handle at one time.
Dot-Matrix Graphics
npins Number of pins, N,inprint-head
spinv Spacing of pins vertically in pins per inch
spinh Spacing of dots horizontally in dots per inch
porder Matches software bits to print-head pins
sbim Start printing bit image graphics, B bits wide
rbim End printing bit image graphics
The sbim string is used with a single argument, B, the width of the image in dots.
The model of dot-matrix or raster-graphics that terminfo presents is similar to the technique used for
most dot-matrix printers: each pass of the printer’s print-head is assumed to produce a dot-matrix that is
N dots high and B dots wide. This is typically a wide, squat, rectangle of dots. The height of this rectangle
in dots will vary from one printer to the next; this is given in the npins numeric capability. The size of
the rectangle in fractions of an inch will also vary; it can be deduced from the spinv and spinh numeric
capabilities. With these three values an application can divide a complete raster-graphics image into
several horizontal strips, perhaps interpolating to account for different dot spacing vertically and horizon-
tally.
The sbim and rbim strings start and end a dot-matrix image, respectively. The sbim string is used with
a single argument that gives the width of the dot-matrix in dots. A sequence of "image-data bytes" are sent
to the printer after the sbim string and before the rbim string. The number of bytes is a integral multi-
ple of the width of the dot-matrix; the multiple and the form of each byte is determined by the porder
string as described below.
The porder string is a comma separated list of pin numbers optionally followed by an numerical offset.
The offset, if given, is separated from the list with a semicolon. The position of each pin number in the list
corresponds to a bit in an 8-bit data byte. The pins are numbered consecutively from 1 to npins, with 1
being the top pin. Note that the term "pin" is used loosely here; "ink-jet" dot-matrix printers don’t have
pins, but can be considered to have an equivalent method of applying a single dot of ink to paper. The bit
positions in porder are in groups of 8, with the first position in each group the most significant bit and the
last position the least significant bit. An application produces 8-bit bytes in the order of the groups in
porder.
An application computes the "image-data bytes" from the internal image, mapping vertical dot positions in
each print-head pass into 8-bit bytes, using a 1 bit where ink should be applied and 0 where no ink should
be applied. This can be reversed (0 bit for ink, 1 bit for no ink) by giving a negative pin number. If a posi-
tion is skipped in porder, a 0 bit is used. If a position has a lower case "x" instead of a pin number, a 1 bit
is used in the skipped position. For consistency, a lower case "o" can be used to represent a 0 filled, skipped
bit. There must be a multiple of 8 bit positions used or skipped in porder; if not, low-order bits of the last
byte are set to 0. The offset, if given, is added to each data byte; the offset can be negative.
Some examples may help clarify the use of the porder string. The AT&T 470, AT&T 475 and C.Itoh 8510
printers provide eight pins for graphics. The pins are identified top to bottom by the 8 bits in a byte, from
least significant to most. The porder strings for these printers would be 8,7,6,5,4,3,2,1. The AT&T
478 and AT&T 479 printers also provide eight pins for graphics. However, the pins are identified in the
reverse order. The porder strings for these printers would be 1,2,3,4,5,6,7,8. The AT&T 5310,
AT&T 5320, Digital LA100, and Digital LN03 printers provide six pins for graphics. The pins are identified
top to bottom by the decimal values 1, 2, 4, 8, 16 and 32. These correspond to the low six bits in an 8-bit
byte, although the decimal values are further offset by the value 63. The porder string for these printers
HP-UX 11i Version 3: February 2007 − 33 − Hewlett-Packard Company 517