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pslib 4.0 − A PostScript based plotting library |
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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 pen widths, 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 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 (c), inch (i), or meter (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 Sun’s 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. |
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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. |
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void ps_arc (x, y, radius, angle1, angle2,
status) |
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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. |
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void ps_axis (xpos, ypos, length, startval,
stopval, tickval, label, annotpointsize, side) |
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Plots an axis with tickmarks, annotation, and label. xpos, ypos, and length are in inches (or cm or meters), annotpointsize 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 * annotpointsize. A negative tickval will reverse the sense of positive direction, e.g., to have the y-axis be positive down. |
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void ps_circle (xcenter, ycenter, diameter,
rgb, outline) |
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Plots a circle and fills it with the specified color. If outline == 1, the outline will be drawn using current pen-width and -pattern. |
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void ps_clipoff () |
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Resets the clip path to what it was before the last call to ps_clipon. |
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void ps_clipon (xarray, yarray, npoints, rgb,
flag) |
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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. |
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void ps_colorimage (xpos, ypos, xlength,
ylength, buffer, nx, ny, depth) |
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Plots a 1-, 2-, 4-, 8-, or 24-bit deep image. This functions sets up a call to the PostScript colorimage or image operators. xpos, ypos, xlength, ylength specify the position of lower left corner and size (in inches) of image. The pixel values are stored in buffer, an unsigned character array in scanline orientation with gray shade or r/g/b values (0 - 255) where 0 is black, 255 is white. buffer[0] is upper left corner. depth is number of bits per pixel (24, 8, 4, 2, or 1). nx,ny refers to the number of pixels in image. The rowlength of buffer must be an integral number of 8/depth. E.g. if depth = 4, then buffer[j]/16 gives shade for pixel[2j-1] and buffer[j]%16 (mod 16) gives shade for pixel[2j]. When -depth is passed instead then "hardware" interpolation of the image is requested. If -nx is passed then the first three bytes of buffer holds the r/g/b color for pixels that are to be masked out using the PostScript Level 3 Color Mask method. See the Adobe Systems PostScript Reference Manual for more details. |
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void ps_colortiles (x0, y0, xlength, ylength,
buffer, nx, ny) |
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Plots a true color image based on individual color tiles. x0, y0 is the location of the lower left corner of the image in inches. xlength, ylength is the image size in inches. buffer contains rgb triplets stored as rgbrgbrgb... nx, ny is the image size in pixels. |
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void ps_command (text) |
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Writes a raw PostScript command to the PostScript output file, e.g. "1 setlinejoin". |
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void ps_comment (text) |
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Writes a comment (text) to the PostScript output file, e.g. "Start of graph 2". |
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void ps_cross (xcenter, ycenter,
diameter) |
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Plots a cross at the specified point using current pen-width and -pattern that fits inside a circle of given diameter. |
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void ps_diamond (xcenter, ycenter, diameter,
rgb, outline) |
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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. |
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void ps_ellipse (xcenter, ycenter, angle,
major, minor, rgb, outline) |
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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. |
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void ps_encode_font (font_no) |
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Will reencode this font using the current encoding vector if it is not StandardEncoding. |
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void ps_epsimage (xpos, ypos, xlength, ylength,
buffer, size, nx, ny, ox, oy) |
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Plots an Encapsulated PostScript (EPS) image. The EPS file is stored in buffer and has size bytes. This functions simply includes the image in the PostScript output stream within an appropriate wrapper. Specify position of lower left corner and size (in inches) of image. nx,ny,ox,oy refers to the width, height and origin (lower left corner) of the BoundingBox. |
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void ps_flush () |
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Flushes the output buffer. |
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void ps_hexagon (xcenter, ycenter, diameter,
rgb, outline) |
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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. |
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void ps_image (xpos, ypos, xlength, ylength,
buffer, nx, ny, bits) |
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Obsolete, simply passes arguments to ps_colorimage. |
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void ps_imagefill (x, y, n, image, imagefile,
invert, dpi, outline, f_rgb, b_rgb) |
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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. |
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void ps_bitimage (xpos, ypos, xlength, ylength,
buffer, nx, ny, invert, f_rgb, b_rgb) |
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Plots a 1-bit image using the given foreground color f_rgb and background color b_rgb. Specify position of lower left corner and size (in inches) of image. buffer is an unsigned character array with 8 pixels per byte. nx,ny refers to the number of pixels in image. The rowlength of buffer must be an integral number of 8. buffer[0] is upper left corner. buffer values are stored as columns, starting at the lower left corner and ending at the upper right corner. If invert is 0 then the bits that are 1 are painted with the foreground color, while bits that are 0 are painted with the backgound color. If invert is 1, foreground and background are switched. To get a partly transparent image, set the first index of the foreground or background color to -1, i.e. f_rgb[0]=-1 or b_rgb[0]=1. See the Adobe Systems PostScript Reference Manual for more details. |
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void ps_itriangle (xcenter, ycenter, diameter,
rgb, outline) |
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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. |
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void ps_line (xarray, yarray, npoints, type,
close, split) |
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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. |
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unsigned char *ps_load_image (fp,
header) |
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Reads the image contents of the EPS file or Sun rasterfile pointed to by the open filepointer fp. The routine can handle Encapsulated PostScript files or 1-, 8-, 24-, or 32-bit rasterfiles in old, standard, run-length encoded, or RGB-style Sun format. |
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void ps_octagon (xcenter, ycenter, diameter,
rgb, outline) |
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Plots a octagon 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. |
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void ps_patch (xarray, yarray, npoints, rgb,
outline) |
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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. |
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void ps_pentagon (xcenter, ycenter, diameter,
rgb, outline) |
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Plots a pentagon 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. |
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void ps_pie (xcenter, ycenter, radius,
azimuth1, azimuth2, rgb, outline) |
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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. |
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void ps_plot (xabs, yabs, kpen) |
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Absolute move (kpen=3) or draw (kpen=2), using current linewidth. Use (kpen=-2) to make sure the line is stroked. |
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void ps_plotend (last_page) |
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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. |
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void ps_plotinit (plotfile, overlay, mode,
xoff, yoff, xscl, yscl, ncopies, dpi, unit, pagesize, rgb,
encoding, eps) |
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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 using the now-obsolete GMT 3.4 encoding. To use the ISOLatin1 encoding set the 5th bit to 1. 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 encoding is the name of a character encoding scheme to be used, e.g., Standard, ISOLatin1, ISO-8859-2, etc. 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. |
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void ps_plotr (xrel, yrel, kpen) |
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Move (kpen = 3) or draw (kpen = 2) relative to current point (see ps_plot). Use (kpen=-2) to make sure the line is stroked. |
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void ps_point (xcenter, ycenter,
diameter) |
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Plots a point using current pen with given diameter. Note the linecap setting must first be set to 1 for this function to work. |
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void ps_polygon (xarray, yarray, npoints, rgb,
outline) |
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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. |
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void ps_rect (x1, y1, x2, y2, rgb,
outline) |
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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. |
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void ps_rotatetrans (x, y, angle) |
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Rotates the coordinate system by angle degrees, then translates origin to (x,y). |
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void ps_segment (x0, y0, x1, y1) |
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Draws a line segment between the two points using current pen attributes. |
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void ps_setdash (pattern, offset) |
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Changes the current dashpattern. The character string pattern is set to the desired pattern. E.g., "4 2" and offset = 1 will plot like: |
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x ---- ---- ---- |
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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. |
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void ps_setfont (fontnr) |
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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, 34 = ZapfDingbats, 35 = Ryumin-Light-EUC-H, 36 = Ryumin-Light-EUC-V, 37 = GothicBBB-Medium-EUC-H, and 38 = GothicBBB-Medium-EUC-V. If fontnr is outside this range, it is set to 0. |
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void ps_setformat (n_decimals) |
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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. |
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void ps_setline (linewidth) |
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Changes the current linewidth in DPI units. 0 gives thinnest line, but the use of 0 is implementation-dependent (Works fine on most laserwriters). |
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void ps_setlinecap (cap) |
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Changes the current linecap. 0 gives butt cap [Default], 1 gives round, and 2 gives square. |
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void ps_setlinejoin (join) |
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Changes the current linejoin. 0 gives mitered [Default], 1 gives round, and 2 gives bevel joins. |
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void ps_setmiterlimit (limit) |
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Changes the current miter limit. 0 gives default miter, other values are the cutoff-, acute-"2" ce->
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