gps
Purpose
Used as the format for storing graphics file data as
graphic primitive strings.
Description
A GPS is a graphic primitive string that is used to store
graphical data in a particular format. The plot and vtoc
commands produce GPS output files. Several commands edit
and display GPS files on various devices. A GPS is com-
posed of as many as five types of graphical data or
primitives:
comment A comment is an integer string included within
a GPS file that does not cause anything to be
displayed. All GPS files begin with a comment
of zero length.
lines A lines primitive has a variable number of
points from which zero or more connected line
segments are produced. The first point given
produces a move to that location, relocating
the graphics cursor without drawing. Succes-
sive points produce line segments from the
previous point.
arc An arc primitive has a variable number of
points to which a curve is fit. The first
point produces a move to that point. If only
two points are given, a line connecting the
points is the result. If three points are
given, a circular arc through the points is
drawn. If more than three points are given,
splines are fitted to connect the points.
text The text primitive draws characters beginning
at a given point, with the first character
centered on that point.
hardware The hardware primitive draws hardware charac-
ters or gives control commands to a hardware
device. A single point locates the beginning
location of the hardware string.
Graphic primitive strings are given as 16-bit units
called command words. The first command word determines
the primitive type and sets the length of the string.
Subsequent command words contain information in multiples
of four bits of data. The following are the types of GPS
and their parameters:
comment cw [string]
cw is the control word. The first four bits
identify the comment primitive and have the
value 0xF. The following bits give the
command word count for the primitive.
[string] is a string of characters terminated
by a null character. If the string does not
end on a command word boundary, another null
character is added to align the string with
the command word boundary.
lines cw points sw
cw is the control word. The first four bits
identify the lines primitive and have the
value 0x0. The remaining bits give the
command word count for the primitive.
points is one or more pairs of integer coordi-
nates having values within a Cartesian plane
or universe of 65,536 points on each axis
(-32,767 to +32,768).
sw is the style command word. The first eight
bits hold an integer value for color informa-
tion. The next four bits contain an integer
value for weight to indicate line thickness:
0 Narrow
1 Bold
2 Medium.
The last four bits of sw specify an integer
value giving line style information:
0 Solid
1 Dotted
2 Dot-dashed
3 Dashed
4 Long dashed.
arc cw points sw
cw is the control word. The first four bits
identify the arc primitive and have the value
0x3. The next twelve bits contain the command
word count for the primitive.
points is one or more pairs of integer coordi-
nates having values within a Cartesian plane
or universe of 65,536 points on each axis
(-32,767 to +32,768).
sw is the style command word. The first eight
bits are an integer value for color. The next
four bits contain an integer value for weight
to indicate line thickness:
0 Narrow
1 Bold
2 Medium.
The last four bits contain an integer value
setting line style:
0 Solid
1 Dotted
2 Dot-dashed
3 Dashed
4 Long dashed.
text cw point fw so [string]
cw is the control word. The first four bits
identify the text primitive and have the value
0x2. The remaining twelve bits contain the
command word count for the primitive.
point is a pair of integer coordinates that
are a value within a Cartesian plane or uni-
verse of 65,536 points per axis (-32,767 to
+32,768).
fw is a font command word. The first eight
bits contain an integer value for color infor-
mation. The next eight bits contain an
integer value for font information, with four
bits giving the weight (density) value for the
font, and four bits giving the style
(typeface) value for the font.
so is a size/orientation command word. Eight
bits specify textsize as an integer value to
indicate the size of characters drawn.
textsize represents character height in abso-
lute universe units. The actual character
height is five times the textsize value. The
next eight bits are a signed integer value for
textangle, and express the angle and direction
of rotation of the character string around the
beginning point. textangle is expressed in
degrees from the positive x axis. The
textangle value is 256/360 of its absolute
value.
hardware cw point [string]
cw is the control word. The first four bits
identify the hardware primitive and have the
value 0x4. The next twelve bits indicate the
command word count for the primitive.
point is a pair of integer coordinates that
are values within a Cartesian plane or uni-
verse of 65,536 points on each axis (-32,767
to +32,768). This point is the starting point
for the string, which is a string of hardware
characters or control commands to a hardware
device.
Related Information
In this book: "stat.h."
The stat and toc commands in AIX Operating System Com-
mands Reference.