NAME
pslib v3.0 - A PostScript based plotting library
DESCRIPTION
pslib was created to make the generation of PostScript page
description code easier. It is a library that contains a
series of tools that can be used to create plots. The
resulting PostScript code is ASCII text and can be edited
using any text editor. Thus, it is fairly easy to modify a
plot file even after it has been created, e.g., to change
text strings, set new gray shades or colors, experiment with
various penwidths etc. pslib is written in C but now
includes FORTRAN bindings (thanks to John Goff, WHOI) and
can therefore be called from both C and FORTRAN programs.
To use this library, you must link your plotting program
with pslib.a. pslib is the core of the GMT SYSTEM and XY
graphics programs. pslib output conforms to the Adobe
Encapsulated PostScript File Specification Version 3.0
(EPSL), and may be used as EPS files and inserted into, say,
a Word 5 document on a Mac. See Appendix F in the Technical
Reference for detailed instructions.
Before any pslib calls can be issued, the plotting system
must be initialized. This is done by calling ps_plotinit,
which defines macros, sets up the plot-coordinate system,
scales, and [optionally] opens a file where all the
PostScript code will be written. Normally, the plot code is
written to stdout. The measure unit for sizes and positions
can be set to be centimeter, inch, or m. When all plotting
is done, you must terminate the plotting system by calling
ps_plotend.
pslib uses the direct color model where red, green, and blue
are given separately, each must be in the range from 0-255.
If red < 0 then no fill operation takes place. Most plot-
items can be plotted with or without outlines. If outline
is desired (i.e., set to 1), it will be drawn using the
current linewidth and pattern. pslib uses highly optimized
macro substitutions and scales the coordinates depending on
the resolution of the hardcopy device so that the output
file is kept as compact as possible.
A wide variety of output devices that support PostScript
exist, including laserwriters (color or monochrome) and
workstations running PostScript based window systems like
SUNs OpenWindows. xnews (part of OpenWindows) or
ghostscript (public domain) can be used to create raster-
files at a user-defined resolution (DPI), making it possible
to render PostScript on a Versatec and other non-PostScript
raster devices. Regular SUN rasterfiles created under NeWS
from PostScript files can be sent to a variety of color
hardcopy units. Check the devices available on your
network.
FUNCTION CALLS
The following is a list of available functions and a short
description of what they do and what parameters they expect.
All floating point variables are expected to be double
(i.e., 8 bytes), whereas all integers are assumed to be 4
bytes long. All plotting functions are declared as func-
tions returning an int. Currently, the return value is
undefined.
ps_arc (x, y, radius, angle1, angle2, status)
double x, y, radius, angle1, angle2;
int status;
Draws a circular arc centered on (x,y) from angle
angle1 to angle2. Angles must be given in decimal
degrees. If angle1 > angle2, a negative arc is
drawn. status is a value from 0 through 3. 1
means set new anchor point, 2 means stroke the
circle, 3 means both, 0 means none of the above.
ps_axis (xpos, ypos, length, startval, stopval,
tickval, label, anotpointsize, side)
double xpos, ypos, length, startval, stopval, tickval;
int anotpointsize, side;
char *label;
Plots an axis with tickmarks, annotation, and
label. xpos, ypos, and length are in inches (or
cm or meters), anotpointsize in points (72 points
= 1 inch), else data units are used. side can be
0, 1, 2, or 3, which selects lower x-axis, right
y-axis, upper x-axis, or left y-axis, respec-
tively. labelpointsize = 1.5 * anotpointsize. A
negative tickval will reverse the sense of posi-
tive direction, e.g., to have the y-axis be posi-
tive down.
ps_circle (xcenter, ycenter, radius, red, green, blue,
outline)
double xcenter, ycenter, radius;
int red, green, blue, outline;
Plots a circle and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_clipoff ()
Resets the clip path to what it was before the
last call to clipon.
ps_clipon (xarray, yarray, npoints, red, green, blue,
flag)
double xarray[], yarray[];
int npoints, red, green, blue, flag;
Sets up a user-definable clip path. Plotting out-
side this polygon will be clipped until ps_clipoff
is called. If red >= 0 the inside of the path is
filled with the specified color. flag is used to
create complex clip paths consisting of several
disconnected regions, and takes on values 0-3.
flag = 1 means this is the first path in a multi-
segment clip path. flag = 2 means this is the
last segment. Thus, for a single path, flag = 3.
ps_colorimage (xpos, ypos, xlength, ylength, buffer,
nx, ny)
double xpos, ypos, xlength, ylength;
unsigned char buffer[];
int nx, ny;
Plots a 24-bit true color image using rgb colors.
Similar to ps_image except bits is fixed to be 8.
The rgb triplets are stored as rgbrgbrgb... This
functions sets up a call to the PostScript
colorimage operator which is not implemented in
all drivers.
ps_comment (text)
char *text;
Writes a comment (text) to the PostScript output
file, e.g. "Start of graph 2".
ps_cross (xcenter, ycenter, size)
double xcenter, ycenter, size;
Plots a cross at the specified point using current
pen-width and -pattern.
ps_diamond (xcenter, ycenter, size, red, green, blue,
outline)
double xcenter, ycenter, size;
int red, green, blue, outline;
Plots a diamond and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_ellipse (xcenter, ycenter, angle, major, minor, red,
green, blue, outline)
double xcenter, ycenter, angle, major, minor;
int red, green, blue, outline;
Plots a ellipse with its major semiaxis rotated by
angle degrees and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_hexagon (xcenter, ycenter, size, red, green, blue,
outline)
double xcenter, ycenter, size;
int red, green, blue, outline;
Plots a hexagon and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_image (xpos, ypos, xlength, ylength, buffer, nx, ny,
bits)
double xpos, ypos, xlength, ylength;
unsigned char buffer[];
int nx, ny, bits;
Plots a bit-mapped image using grayshades.
Specify position of lower left corner and size (in
inches) of image. buffer is an unsigned character
array with gray shade values (0 - 255) where 0 is
black, 255 is white. bits is number of bits pr
pixel (8, 4, or 1). nx,ny refers to the number of
elements in buffer. nx must be an integral number
of 8/bits. buffer[0] is upper left corner. E.g.
if bits = 4, then buffer[j]/16 gives shade for
pixel[2j-1] and buffer[j]%16 (mod 16) gives shade
for pixel[2j]. buffer values are stored as
columns, starting at the lower left corner and
ending at the upper right corner. See the Adobe
Systems PostScript Reference Manual for more
details.
ps_imagergb (xpos, ypos, xlength, ylength, buffer, nx,
ny)
double xpos, ypos, xlength, ylength;
unsigned char buffer[];
int nx, ny;
Plots a bit-mapped image using 24-bit color. Syn-
tax follows the colorimage operator. ps_imagec
uses three image calls to set up rgb color separa-
tions which can be understood by psto24.
ps_imagefill (x, y, n, image, imagefile, invert,
imagesize, outline, x0, y0)
double x[], y[], x0, y0;
int n, image, invert, outlinefP;
char imagefile;
Similar to ps_polygon, but fills the area with an
image pattern rather than a color or grayshade. x
and y hold the arrays of n points. 32 predefined
patterns are available (run pspatterns for exam-
ples). image gives the image number (1-32). If
set to 0, imagefile must be the name to the user's
image, which must be stored as a SUN icon file as
generated by icon_tool. If invert is TRUE (1),
the black and white pixels are interchanged before
plotting. The unit size of the image is
controlled by imagesize. If set to zero, the
image is plotted at the device resolution. If
outline is TRUE, the current penwidth is used to
draw the polygon outline. x0 and y0 set the
left/bottom boundary for the current plot.
ps_itriangle (xcenter, ycenter, size, red, green, blue,
outline)
double xcenter, ycenter, size;
int red, green, blue, outline;
Plots an inverted and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_line (xarray, yarray, npoints, type, close, split)
double xarray[], yarray[];
int npoints, type, close, split;
Draw a continuous line from the positions in the
x-y arrays. If close == 1, the first and last
point will automatically be closed by the
PostScript driver. If this is the first segment
in a multi-segment path, set type == 1. To end
the segments and have the line(s) drawn, set type
== 2. Thus, for a single segment, type must be 3.
The line is drawn using the current penwidth.
Only if split is TRUE may ps_line use multiple
strokes to draw lines longer that MAX_PATH.
ps_polygon will call ps_line with split = FALSE
since the path must be continuous. If split is
FALSE and the pathlength exceeds MAX_PATH a warn-
ing will be issued.
ps_patch (xarray, yarray, npoints, red, green, blue,
outline)
double xarray[], yarray[];
int npoints, red, green, blue, outline;
Identical to ps_polygon except polygon must be <
20 points long and there will be no attempt to
shorten the path by discarding unnecessary inter-
mediate points along straight segments. Primarily
used when painting large number of small polygons
and not waste output space.
ps_pie (xcenter, ycenter, radius, azimuth1, azimuth2,
red, green, blue, outline)
double xcenter, ycenter, radius, azimuth1, azimuth2;
int red, green, blue, outline;
Plots a sector of a circle and paints it with the
specified RGB combination. If outline == 1, the
outline will be drawn using current pen-width and
-pattern.
ps_plot (xabs, yabs, kpen)
double xabs, yabs;
int kpen;
Absolute move (kpen=3) or draw (kpen=2), using
current linewidth.
ps_plotend (last_page)
int last_page;
Terminates the plotting sequence and closes plot
file (if other than stdout). If last_page == 1,
then a PostScript showpage command is issued,
which initiates the printing process on hardcopy
devices.
ps_plotinit (plotfile, overlay, mode, xoff, yoff, xscl,
yscl, ncopies, dpi, unit, pagewidth, rgb, eps)
char *plotfile;
int overlay, mode, ncopies, dpi, unit;
double xoff, yoff, xscl, yscl, pagewidth;
int rgb[3]; struct EPS * eps;
Initializes the plotting. If plotfile == NULL (or
""), then output is sent to stdout, else output is
sent to plotfile. overlay should be 1 only if you
plan to append it to some existing PostScript
file. mode contains three flags in the three
lowest bits. The lowest bit controls the plot
orientation and can be 0 (Landscape) or 1 (Por-
trait). The next bit, if set to 1, will re-encode
the fonts to include European accented characters.
The third bit controls the format used to write
PostScript images: 0 means binary, 1 means hexade-
cimal. Most printers needs the latter while some
can handle binary which are 50% smaller and there-
fore execute faster. xoff,yoff are used to move
the origin from the default position in the lower
left corner. xscl,yscl are used to scale the
entire plot (Usually set to 1.0, 1.0). Set
ncopies to get more than 1 copy. dpi sets the
hardcopy resolution in dots pr units. For optimum
plot quality and processing speed, choose dpi to
match the intended plotter resolution. Examples
are 300 for most laserwriters, 2540 for Linotype-
300, and ~85 for SUN screens. When in doubt, use
300. unit can be any of 0 (CM), 1 (INCH), or 2
(M), telling the plot system what units are used
for distance and sizes. Note that, regardless of
choice of unit, dpi is still in dots-pr-inch.
pagewidth means the physical width of the plotting
media, typically 8.5 inches for laserwriter
plotters. The rgb array holds the color of the
page (usually white = 255,255,255). The EPS
structure is defined in the pslib.h include file
and contains information that will make up the
comments header of a EPS file. Programmers who
plan to call pslib routines should read the com-
ments in pslib.h first. Note that the FORTRAN
binding does not expect this last argument.
ps_plotr (xrel, yrel, kpen)
double xrel, yrel;
int kpen;
Move (kpen = 3) or draw (kpen = 2) relative to
current point (see ps_plot).
ps_polygon (xarray, yarray, npoints, red, green, blue,
outline)
double xarray[], yarray[];
int npoints, red, green, blue, outline;
Creates a colored polygon from the positions in
the x-y arrays. Polygon will automatically be
closed by the PostScript driver. If outline == 0,
no outline is drawn. If outline == 1, the outline
is drawn using current penwidth.
ps_rect (x1, y1, x2, y2, red, green, blue, outline)
double x1, y1, x2, y2;
int red, green, blue, outline;
Plots a colored rectangle. (x1,y1) and (x2,y2) are
any two corners on a diagonal. If outline == 1,
the outline will be drawn using current pen-width
and -pattern.
ps_rotatetrans (x, y, angle)
double x, y, angle;
Rotates the coordinate system by angle degrees,
then translates origin to (x,y).
ps_setdash (pattern, offset)
char *pattern;
int offset;
Changes the current dashpattern. The character
string pattern is set to the desired pattern.
E.g., "4 2" and offset = 1 will plot like:
x ---- ---- ----
etc, where x is starting point (The x is not plot-
ted). That is, the line is made up of a repeating
pattern of a 4 units long line and a 2 unit long
gap, starting 1 unit after the x. To reset to
solid line, specify pattern = NULL ("") and offset
= 0. Units are in dpi units.
ps_setfont (fontnr)
int fontnr;
Changes the current font number to fontnr. The
fonts available are: 0 = Helvetica, 1 = H. Bold,
2 = H. Oblique, 3 = H. Bold-Oblique, 4 = Times, 5
= T. Bold, 6 = T. Italic, 7 = T. Bold Italic, 8 =
Courier, 9 = C. Bold, 10 = C Oblique, 11 = C Bold
Oblique, 12 = Symbol, 13 = AvantGarde-Book, 14 =
A.-BookOblique, 15 = A.-Demi, 16 = A.-DemiOblique,
17 = Bookman-Demi, 18 = B.-DemiItalic, 19 = B.-
Light, 20 = B.-LightItalic, 21 = Helvetica-Narrow,
22 = H-N-Bold, 23 = H-N-Oblique, 24 = H-N-
BoldOblique, 25 = NewCenturySchlbk-Roman, 26 =
N.-Italic, 27 = N.-Bold, 28 = N.-BoldItalic, 29 =
Palatino-Roman, 30 = P.-Italic, 31 = P.-Bold, 32 =
P.-BoldItalic, 33 = ZapfChancery-MediumItalic. If
fontnr is outside this range, it is set to 0.
ps_setformat (n_decimals)
int n_decimals;
Sets number of decimals to be used when writing
color or gray values. The default setting of 3
gives 1000 choices per red, green, and blue value,
which is more than the 255 choices offered by most
24-bit platforms. Choosing a lower value will
make the output file smaller at the expense of
less color resolution. Still, a value of 2 gives
100 x 100 x 100 = 1 million colors, more than most
eyes can distinguish. For a setting of 1, you
will have 10 nuances per primary color and a total
of 1000 unique combinations.
ps_setline (linewidth)
int linewidth;
Changes the current linewidth in DPI units. 0
gives thinnest line, but the use of 0 is
implementation-dependent (Works fine on most
laserwriters).
ps_setpaint (red, green, blue)
int red, green, blue;
Changes the current RGB setting for pens and text.
ps_square (xcenter, ycenter, sidelength, red, green,
blue, outline)
double xcenter, ycenter, sidelength;
int red, green, blue, outline;
Plots a square and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_star (xcenter, ycenter, radius, red, green, blue,
outline)
double xcenter, ycenter, radius;
int red, green, blue, outline;
Plots a star and fills it with the specified
color. If outline == 1, the outline will be drawn
using current pen-width and -pattern.
ps_text (x, y, pointsize, text, angle, justify, form)
double x, y, angle;
char *text;
int pointsize, justify, form;
The text is plotted starting at (x,y), and will
make an angle with the horizontal. The point
(x,y) maps onto different points of the textstring
by giving various values for justify. It is used
as follows:
9------------10----------- 11
| |
5 6 7
| |
1------------ 2------------ 3
The box represents the textstring. E.g., to plot
a textstring with its center of gravity at (x,y),
you must use justify == 6. If justify is nega-
tive, then all leading and trailing blanks are
stripped before plotting. Certain character
sequences (flags) have special meaning to ps_text.
@~ toggles between current font and the Mathemati-
cal Symbols font. @%no% sets font to no; @%%
resets to starting font. @- turns subscript
on/off, @+ turns superscript on/off, @# turns
small caps on/off, and @\ will make a composite
character of the following two character. Give
fontsize in points (72 points = 1 inch). Nor-
mally, the text is typed using solid characters.
To draw outline characters, set form == 1.
ps_textbox (x, y, pointsize, text, angle, justify, out-
line, dx, dy, red, green, blue)
double x, y, angle, dx, dy;
char *text;
int pointsize, justify, outline, red, green, blue;
This function is used in conjugation with ps_text
when a box surrounding the text string is desired.
Taking most of the arguments of ps_text, the user
must also specify the color of the resulting rec-
tangle, and whether its outline should be drawn.
More room between text and rectangle can be
obtained by setting dx and dy accordingly.
ps_transrotate (x, y, angle)
double x, y, angle;
Translates the origin to (x,y), then rotates the
coordinate system by angle degrees.
ps_triangle (xcenter, ycenter, size, red, green, blue,
outline)
double xcenter, ycenter, size;
int red, green, blue, outline;
Plots a triangle and paints it with the specified
RGB combination. If outline == 1, the outline
will be drawn using current pen-width and -pat-
tern.
ps_vector (xtail, ytail, xtip, ytip, tailwidth,
headlength, headwidth, headshape, red, green, blue,
outline)
double xtail, ytail, xtip, ytip, tailwidth, headlength,
headwidth, headshape;
int red, green, blue, outline;
Draws a vector of size and appearance as specified
by the various parameters. headshape can take on
values from 0-1 and specifies how far the inter-
section point between the base of a straight vec-
tor head and the vector line is moved toward the
tip. 0 gives a triangular head, 1.0 gives an
arrow shaped head. If outline == 1, the outline
will be drawn using current penwidth.
AUTHOR
Paul Wessel, School of Ocean and Earth Science and Technol-
ogy, 2525 Correa Road, Honolulu, Hawaii 96822, (808) 956-
4778, Internet address: wessel@soest.hawaii.edu.
BUGS
Caveat Emptor: The author is not responsible for any disas-
ters, suicide attempts, or ulcers caused by correct or
incorrect use of pslib. If you find bugs, please report
them to the author by electronic mail. Be sure to provide
enough detail so that I can recreate the problem.
RESTRICTIONS
Due to the finite memory of some output devices like Laser-
writers, certain restrictions due to limitations of the
PostScript interpreter apply: For now, the arrays passed to
ps_clipon and ps_polygon must contain less than about 1350
points. Also, the buffer array passed to ps_image must be
able to fit in the available memory. Check the specifica-
tions of the hardcopy device you are using. Note that some
Raster Image Processors (RIPs) do not support direct color
so that the colors you get may not be exactly the ones you
wanted. This is a limitation of the RIP, not the underlying
PostScript code generated by pslib.
SEE ALSO
ps2ras, psto24
REFERENCES
Wessel, P., and W. H. F. Smith, 1995, The Generic Mapping
Tools (GMT) version 3.0 Technical Reference & Cookbook,
SOEST/NOAA.
Wessel, P., and W. H. F. Smith, 1995, New Version of the
Generic Mapping Tools Released, EOS Trans. AGU, 76, p. 329.
Wessel, P., and W. H. F. Smith, 1995, New Version of the
Generic Mapping Tools Released,
http://www.agu.org/eos_elec/95154e.html, Copyright 1995 by
the American Geophysical Union.
Wessel, P., and W. H. F. Smith, 1991, Free Software Helps
Map and Display Data, EOS Trans. AGU, 72, p. 441.
Adobe Systems Inc., 1990, PostScript language reference
manual, 2nd edition, Addison-Wesley, (ISBN 0-201-18127-4).