## DESCRIPTION

d.graph draws graphics that are described either from standard input (default), or within a file (if an input file name is identified on the command line). If graphics commands are entered from standard input, a CTRL-d is used to signal the end of input to d.graph. Coordinates are given either as a percentage of frame height and width (default) or in geographic coordinates (with the -m flag).

The program can be run interactively or non-interactively. The user can run the program completely non-interactively by specifying the name of a graphics file containing the d.graph graphics commands. If run non-interactively the d.graph command is saved to the display's dedraw history. The user can also elect to run the program partially interactively, by specifying any/all of the parameters except the graphics file input=name parameter on the command line. In this case, d.graph will expect the user to input d.graph graphics commands from standard input (i.e., the keyboard) and will (silently) prompt the user for these graphics commands.

Alternately, the user can simply type d.graph on the command line, and be prompted for the values of all parameters. In this case, the user is presented with the standard GRASS GUI interface.

The default coordinate system used is 0-100 percent of the active frame in x and similarly 0-100 in y, regardless of the graphics monitor display frame size and aspect. The (0,0) location is the lower left corner of the active graphics monitor display frame. All values may be floating point. If the -m flag is given, geographic coordinates will be used instead.

## COMMANDS

The graphics language is simple, and uses the following commands:

  [ # | move | draw | polygon | polyline | color | text | size | symbol | rotation | icon | width ]

# comment
  A line of comment which is ignored in the processing.
move xpos ypos
  The current location is updated to xpos ypos. Unless the -m flag is used, values are stated as a percent of the active display frame's horizontal (xpos) and vertical (ypos) size, and may be floating point values. Values are between 0-100. Note. A space must separate xpos and ypos.
draw xpos ypos
  A line is drawn in the current color from the current location to the new location xpos ypos, which then becomes the current location. Unless the -m flag is used, values are stated as a percent of the active display frame's horizontal (xpos) and vertical (ypos) size, and may be floating point values. Values are between 0-100. Note. A space must separate xpos and ypos.
polygon
xpos ypos
xpos ypos
...
  The coordinates appearing beneath the word polygon, one pair per line, circumscribe a polygon that is to be filled with the current color.
polyline
xpos ypos
xpos ypos
...
  The coordinates appearing beneath the word polyline, one pair per line, circumscribe a polygon that is not to be filled with color.
color color
  Sets the current color to that stated; subsequent graphics will be drawn in the stated color, until the current color is set to a different color. Options are red, orange, yellow, green, blue, indigo, violet, brown, magenta, gray, white, black, an R:G:B triplet (separated by colons), or the word "none" (draws in the default background color).
text line-of-text
  The stated text is drawn at the current location using the current color, and the new current location is then positioned at the end of the text string.
size xper yper
  Subsequent text will be drawn such that the text is xper percent of the graphics monitor display frame wide and yper percent of the frame high. By default, the text size is set to 5 percent of the active frame's width and 5 percent of the frame's height. If only one value is given, then that value will be used for both x and y scaling.
  Note. A space must separate xper and yper.
symbol type size xper yper [line_color [fill_color]]
  A symbol is drawn at the given size on the display monitor. The xper and yper options define the center of the icon and are given as a percentage of the display frame (`0,0` is lower left). The symbol can be any of those stored in `$GISBASE/etc/symbol/` (e.g. basic/circle) or stored in the user's mapset directory in the form `$MAPSET/symbol/`type/name. The colors may be either a standard color name, an R:G:B triplet, or "none". If using an R:G:B triplet, each color value can range from 0-255. If not specified the default line_color is black and the default fill_color is grey.
rotation angle
  Subsequent text and symbols will be drawn such that they are rotated angle degrees counter-clockwise from east.
icon type size x y
  Draws an icon of types o, x, or + with specified size (in %) at location x,y. Note: type o designates a square.
width value
  Subsequent lines (including non-FreeType text) will be drawn with the given pixel thickness.
  The default value is 0.

## EXAMPLES

For an example use of d.graph, examine the contents of the command file grass_logo.txt located in the d.graph source code directory. It will draw the CERL GRASS logo using the d.graph graphing commands stored in the file. Note that the coordinates in the grass_logo.txt file were taken directly off an image drawn by hand on graph paper.

A dynamic example can be found in the d.polar shell script.

### Draw a "star" symbol at a given map coordinate

    echo "symbol basic/star 20 2264417 5413182 black red" | d.graph -m

### Split the screen into quadrants:

    d.frame -s full_screen

    d.graph << EOF
      color 80:80:120
      polygon
       0 49.75
       0 50.25
       100 50.25
       100 49.75
      polygon
       49.85 0
       50.15 0
       50.15 100
       49.85 100
    EOF

## NOTES

d.graph remembers the last screen location (xpos ypos) to which the user moved, even after the user erases the display frame. If the user runs d.graph repeatedly, and wishes to start anew with the default (xpos ypos) screen location, the user should clear the display frame between runs of d.graph.

## LIMITATIONS

There are no automated ways of generating graphic images. It is anticipated that GRASS user sites will write programs to convert output from a resident graphics editor into GRASS d.graph format. (e.g. EPS -> d.graph, perhaps with the help of a pstoedit plugin)

## SEE ALSO

d.font, d.labels, d.polar, d.text, d.where

## AUTHOR

James Westervelt, U.S. Army Construction Engineering Research Laboratory