NAME
pslib v3.2 - 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 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
rasterfiles 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 functions returning an int. Currently, the return value
is undefined.
void 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.
void 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,
respectively. labelpointsize = 1.5 * anotpointsize. A
negative tickval will reverse the sense of positive
direction, e.g., to have the y-axis be positive down.
void ps_circle (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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.
void ps_clipoff ()
Resets the clip path to what it was before the last call to
clipon.
void ps_clipon (xarray, yarray, npoints, rgb, flag)
double xarray[], yarray[];
int npoints, rgb[3], flag;
Sets up a user-definable clip path. Plotting outside 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.
void 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.
void ps_comment (text)
char *text;
Writes a comment (text) to the PostScript output file, e.g.
"Start of graph 2".
void ps_cross (xcenter, ycenter, diameter)
double xcenter, ycenter, diameter;
Plots a cross at the specified point using current pen-width
and -pattern that fits inside a circle of given diameter.
void ps_diamond (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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. The symbol will fit inside a circle of
given diameter.
void ps_ellipse (xcenter, ycenter, angle, major, minor, rgb,
outline)
double xcenter, ycenter, angle, major, minor;
int rgb[3], 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.
void ps_hexagon (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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. The symbol will fit inside a circle of
given diameter.
void 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 pixels
in image. The rowlength of buffer 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.
void ps_imagefill (x, y, n, image, imagefile, invert, imagedpi,
outline, template, r_rgb, b_rgb)
double x[], y[], x0, y0;
int n, image, invert, imagedpi, outline, template, f_rgb[3],
b_rgb[3];
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. 90 predefined patterns are available
(See GMT Appendix E). image gives the image number (1-90).
If set to 0, imagefile must be the name to the user's image,
which must be stored as a SUN 1-, 8-, or 24-bit rasterfile.
1-bit images only: (i) If invert is TRUE (1), the black and
white pixels are interchanged before plotting. (ii) If
template is TRUE (1), the set pixels are colored using the
RGB combination in f_rgb, while the unset are painted with
b_rgb. The unit size of the image is controlled by
imagedpi. 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.
void ps_itriangle (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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. The symbol will fit inside a circle of
given diameter.
void 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 warning will be issued.
unsigned char *ps_loadraster (fp, header, invert, monochrome,
template, f_rgb, b_rgb)
FILE *fp;
struct rasterfile *header;
BOOLEAN invert, monochrome, template;
int f_rgb[], b_rgb[];
Reads the image contents of the Sun rasterfile pointed to by
the open filepointer fp. The header must first be obtained
with ps_read_rasheader. If invert is TRUE then 1-bit images
will be bit-reversed. If monochrome is TRUE then color
images are converted to grayimages using the TV YIQ
translation. If template is TRUE then 1-bit images will be
colorized using the for- and background colors provided in
f_rgb and b_rgb. The routine can handle 1-, 8-, 24-, or
32-bit files in old, standard, run-length encoded, or RGB-
style Sun format.
void ps_patch (xarray, yarray, npoints, rgb, outline)
double xarray[], yarray[];
int npoints, rgb[3], 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 intermediate points along straight
segments. Primarily used when painting large number of
small polygons and not waste output space.
void ps_pie (xcenter, ycenter, radius, azimuth1, azimuth2, rgb,
outline)
double xcenter, ycenter, radius, azimuth1, azimuth2;
int rgb[3], 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.
void ps_plot (xabs, yabs, kpen)
double xabs, yabs;
int kpen;
Absolute move (kpen=3) or draw (kpen=2), using current
linewidth.
void 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.
void ps_plotinit (plotfile, overlay, mode, xoff, yoff, xscl,
yscl, ncopies, dpi, unit, pagesize, rgb, eps)
char *plotfile;
int overlay, mode, ncopies, dpi, unit;
double xoff, yoff, xscl, yscl;
int pagesize[2], 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 (Portrait). 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 hexadecimal. Most printers needs the latter while
some can handle binary which are 50% smaller and therefore
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. pagesize means the physical width
and height of the plotting media in points, (typically 612
by 792 for Letter or 595 by 842 for A4 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 comments in pslib.h first.
Note that the FORTRAN binding does not expect this last
argument.
void ps_plotr (xrel, yrel, kpen)
double xrel, yrel;
int kpen;
Move (kpen = 3) or draw (kpen = 2) relative to current point
(see ps_plot).
void ps_polygon (xarray, yarray, npoints, rgb, outline)
double xarray[], yarray[];
int npoints, rgb[3], 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.
int ps_read_rasheader (fp, header)
FILE *fp;
struct rasterfile *header;
Using the pointer fp to the open file, return the header
structure of the Sun rasterfile. This call is portable as
it operates on the byte level. Once the header is returned
you may obtain the raster image with ps_loadraster.
void ps_rect (x1, y1, x2, y2, rgb, 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.
void ps_rotatetrans (x, y, angle)
double x, y, angle;
Rotates the coordinate system by angle degrees, then
translates origin to (x,y).
void 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 plotted). 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.
void 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.
void 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.
void 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).
void ps_setpaint (rgb)
int rgb[3];
Changes the current RGB setting for pens and text.
void ps_square (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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. The symbol will fit inside a circle of
given diameter.
void ps_star (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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. The symbol will fit inside a circle of
given diameter.
void 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 negative, 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 Mathematical 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). Normally, the text is typed
using solid characters. To draw outline characters, set
form == 1.
void ps_textbox (x, y, pointsize, text, angle, justify, outline,
dx, dy, rgb)
double x, y, angle, dx, dy;
char *text;
int pointsize, justify, outline, rgb[3];
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 rectangle, and whether its outline should
be drawn. More room between text and rectangle can be
obtained by setting dx and dy accordingly.
void ps_transrotate (x, y, angle)
double x, y, angle;
Translates the origin to (x,y), then rotates the coordinate
system by angle degrees.
void ps_triangle (xcenter, ycenter, diameter, rgb, outline)
double xcenter, ycenter, diameter;
int rgb[3], 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 -pattern. The symbol will fit
inside a circle of given diameter.
void ps_vector (xtail, ytail, xtip, ytip, tailwidth, headlength,
headwidth, headshape, rgb, outline)
double xtail, ytail, xtip, ytip, tailwidth, headlength,
headwidth, headshape;
int rgb[3], 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 intersection point between the
base of a straight vector 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 Technology, 1680
East-West Road, Honolulu, Hawaii 96822, (808) 956-4778, Internet
address: wessel@soest.hawaii.edu.
BUGS
Caveat Emptor: The author is not responsible for any disasters,
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 Laserwriters,
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
specifications 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.
REFERENCES
Adobe Systems Inc., 1990, PostScript language reference manual, 2nd
edition, Addison-Wesley, (ISBN 0-201-18127-4).
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