HP-UX Reference (11i v1 05/09) - 4 File Formats (vol 8)

t
terminfo(4) terminfo(4)
(ENHANCED CURSES)
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
would be ,,6,5,4,3,2,1;63, equivalent to o,o,6,5,4,3,2,1;63.
Effect of Changing Printing Resolution
If the control sequences to change the character pitch or the line pitch are used, the pin or dot spacing may
change:
HP-UX 11i Version 1: September 2005 − 31 − Hewlett-Packard Company Section 4−−357