# grn - embed Gremlin images in groff documents - man(1) - [phpMan] [_grn_(1)](https://www.chedong.com/phpMan.php/man/grn/1/markdown) General Commands Manual [_grn_(1)](https://www.chedong.com/phpMan.php/man/grn/1/markdown) ## Name grn - embed Gremlin images in _groff_ documents ## Synopsis **grn **[**-C**] [**-T _**dev_] [**-M _**dir_] [**-F _**dir_] [_file_ ...] ### grn -? ### grn --help ### grn -v ### grn --version ## Description _grn_ is a preprocessor for including _gremlin_ pictures in [_troff_(1)](https://www.chedong.com/phpMan.php/man/troff/1/markdown) input. _grn_ writes to stan‐ dard output, processing only input lines between two that start with **.GS **and **.GE**. Those lines must contain _grn_ commands (see below). These macros request a _gremlin_ file; the pic‐ ture in that file is converted and placed in the _troff_ input stream. **.GS **may be called with a **C**, **L**, or **R **argument to center, left-, or right-justify the whole _gremlin_ picture (the de‐ fault is to center). If no _file_ is mentioned, the standard input is read. At the end of the picture, the position on the page is the bottom of the _gremlin_ picture. If the _grn_ entry is ended with **.GF **instead of **.GE**, the position is left at the top of the picture. Currently only the _me_ macro package has support for **.GS**, **.GE**, and **.GF**. _grn_ produces drawing escape sequences that use _groff_'s color scheme extension (**\D'F **...**'**), and thus may not work with other _troff_s. _**grn_ commands** Each input line between **.GS **and **.GE **may have one _grn_ command. Commands consist of one or two strings separated by white space, the first string being the command and the second its operand. Commands may be upper- or lowercase and abbreviated down to one character. Commands that affect a picture's environment (those listed before “**default**”, see below) are only in effect for the current picture: the environment is reinitialized to the defaults at the start of the next picture. The commands are as follows. **1 _**N_ **2 _**N_ **3 _**N_ **4 _**N_ Set _gremlin_'s text size number 1 (2, 3, or 4) to _N_ points. The default is 12 (16, 24, and 36, respectively). **roman _**f_ **italics _**f_ **bold _**f_ **special _**f_ Set the roman (italics, bold, or special) font to _troff_'s font _f_ (either a name or number). The default is R (I, B, and S, respectively). **l _**f_ **stipple _**f_ Set the stipple font to _troff_'s stipple font _f_ (name or number). The command **stipple** may be abbreviated down as far as “**st**” (to avoid confusion with “**special**”). There is _no_ default for stipples (unless one is set by the “**default**” command), and it is in‐ valid to include a _gremlin_ picture with polygons without specifying a stipple font. **x _**N_ **scale _**N_ Magnify the picture (in addition to any default magnification) by _N_, a floating-point number larger than zero. The command **scale **may be abbreviated down to “**sc**”. **narrow _**N_ **medium _**N_ **thick _**N_ Set the thickness of _gremlin_'s narrow (medium and thick, respectively) lines to _N_ times 0.15pt (this value can be changed at compile time). The default is 1.0 (3.0 and 5.0, respectively), which corresponds to 0.15pt (0.45pt and 0.75pt, respectively). A thickness value of zero selects the smallest available line thickness. Negative val‐ ues cause the line thickness to be proportional to the current point size. **pointscale **[**off**|**on**] Scale text to match the picture. Gremlin text is usually printed in the point size specified with the commands **1**, **2**, **3**, or **4**, regardless of any scaling factors in the picture. Setting **pointscale **will cause the point sizes to scale with the picture (within _troff_'s limitations, of course). An operand of anything but **off **will turn text scaling on. ### default Reset the picture environment defaults to the settings in the current picture. This is meant to be used as a global parameter setting mechanism at the beginning of the _troff_ input file, but can be used at any time to reset the default settings. **width _**N_ Force the picture to be _N_ inches wide. This overrides any scaling factors present in the same picture. “**width 0**” is ignored. **height _**N_ Force the picture to be _N_ inches high, overriding other scaling factors. If both **width **and **height **are specified, the tighter constraint will determine the scale of the picture. **height **and **width **commands are not saved with a “**default**” command. They will, however, affect point size scaling if that option is set. **file _**name_ Get picture from _gremlin_ file _name_ located the current directory (or in the library directory; see the **-M **option above). If multiple **file **commands are given, the last one controls. If _name_ doesn't exist, an error message is reported and processing con‐ tinues from the **.GE **line. ### Usage with groff Since _grn_ is a preprocessor, it has no access to elements of formatter state, such as inden‐ tation, line length, type size, or register values. Consequently, no _troff_ input can be placed between the **.GS **and **.GE **macros. However, _gremlin_ text elements are subsequently processed by _troff_, so anything valid in a single line of _troff_ input is valid in a line of _gremlin_ text (barring the dot control character “.” at the beginning of a line). Thus, it is possible to have equations within a _gremlin_ figure by including in the _gremlin_ file _eqn_ ex‐ pressions enclosed by previously defined delimiters (e.g., “$$”). When using _grn_ along with other preprocessors, it is best to run [_tbl_(1)](https://www.chedong.com/phpMan.php/man/tbl/1/markdown) before _grn_, [_pic_(1)](https://www.chedong.com/phpMan.php/man/pic/1/markdown), and/or _ideal_ to avoid overworking _tbl_. [_eqn_(1)](https://www.chedong.com/phpMan.php/man/eqn/1/markdown) should always be run last. [_groff_(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown) will au‐ tomatically run preprocessors in the correct order. A picture is considered an entity, but that doesn't stop _troff_ from trying to break it up if it falls off the end of a page. Placing the picture between “keeps” in the _me_ macros will ensure proper placement. _grn_ uses _troff_'s registers **g1 **through **g9 **and sets registers **g1 **and **g2 **to the width and height of the _gremlin_ figure (in device units) before entering the **.GS **macro (this is for those who want to rewrite these macros). ### Gremlin file format There exist two distinct _gremlin_ file formats: the original format for AED graphic terminals, and the Sun or X11 version. An extension used by the Sun/X11 version allowing reference points with negative coordinates is _not_ compatible with the AED version. As long as a _grem‐_ _lin_ file does not contain negative coordinates, either format will be read correctly by ei‐ ther version of _gremlin_ or _grn_. The other difference in Sun/X11 format is the use of names for picture objects (e.g., **POLYGON**, **CURVE**) instead of numbers. Files representing the same picture are shown below. sungremlinfile gremlinfile 0 240.00 128.00 0 240.00 128.00 CENTCENT 2 240.00 128.00 240.00 128.00 185.00 120.00 185.00 120.00 240.00 120.00 240.00 120.00 296.00 120.00 296.00 120.00 * -1.00 -1.00 2 3 2 3 10 A Triangle 10 A Triangle POLYGON 6 224.00 416.00 224.00 416.00 96.00 160.00 96.00 160.00 384.00 160.00 384.00 160.00 * -1.00 -1.00 5 1 5 1 0 0 -1 -1 • The first line of each _gremlin_ file contains either the string “**gremlinfile**” (AED) or “**sun‐** **gremlinfile**” (Sun/X11). • The second line of the file contains an orientation and _x_ and _y_ values for a positioning point, separated by spaces. The orientation, either **0 **or **1**, is ignored by the Sun/X11 ver‐ sion. **0 **means that _gremlin_ will display things in horizontal format (a drawing area wider than it is tall, with a menu across the top). **1 **means that _gremlin_ will display things in vertical format (a drawing area taller than it is wide, with a menu on the left side). _x_ and _y_ are floating-point values giving a positioning point to be used when this file is read into another file. The stuff on this line really isn't all that important; a value of “**1 0.00 0.00**” is suggested. • The rest of the file consists of zero or more element specifications. After the last ele‐ ment specification is a line containing the string “**-1**”. • Lines longer than 127 characters are truncated to that length. ### Element specifications • The first line of each element contains a single decimal number giving the type of the ele‐ ment (AED) or its name (Sun/X11). _gremlin_ File Format: Object Type Specification ───────────────────────────────────────────────────────── AED Number Sun/X11 Name Description **0 BOTLEFT **bottom-left-justified text **1 BOTRIGHT **bottom-right-justified text **2 CENTCENT **center-justified text **3 VECTOR **vector **4 ARC **arc **5 CURVE **curve **6 POLYGON **polygon **7 BSPLINE **b-spline **8 BEZIER **Bézier **10 TOPLEFT **top-left-justified text **11 TOPCENT **top-center-justified text **12 TOPRIGHT **top-right-justified text **13 CENTLEFT **left-center-justified text **14 CENTRIGHT **right-center-justified text **15 BOTCENT **bottom-center-justified text • After the object type comes a variable number of lines, each specifying a point used to display the element. Each line contains an x-coordinate and a y-coordinate in floating- point format, separated by spaces. The list of points is terminated by a line containing the string “**-1.0 -1.0**” (AED) or a single asterisk, “*****” (Sun/X11). • After the points comes a line containing two decimal values, giving the brush and size for the element. The brush determines the style in which things are drawn. For vectors, arcs, and curves there are six valid brush values. **1 **thin dotted lines **2 **thin dot-dashed lines **3 **thick solid lines **4 **thin dashed lines **5 **thin solid lines **6 **medium solid lines For polygons, one more value, 0, is valid. It specifies a polygon with an invisible bor‐ der. For text, the brush selects a font as follows. **1 **roman (R font in _troff_) **2 **italics (I font in _troff_) **3 **bold (B font in _troff_) **4 **special (S font in _troff_) If you're using _grn_ to run your pictures through _groff_, the font is really just a starting font. The text string can contain formatting sequences like “\fI” or “\d” which may change the font (as well as do many other things). For text, the size field is a decimal value between 1 and 4. It selects the size of the font in which the text will be drawn. For polygons, this size field is interpreted as a stipple number to fill the polygon with. The number is used to index into a stipple font at print time. • The last line of each element contains a decimal number and a string of characters, sepa‐ rated by a single space. The number is a count of the number of characters in the string. This information is used only for text elements, and contains the text string. There can be spaces inside the text. For arcs, curves, and vectors, the character count is zero (**0**), followed by exactly one space before the newline. ### Coordinates _gremlin_ was designed for AED terminals, and its coordinates reflect the AED coordinate space. For vertical pictures, _x_ values range 116 to 511, and _y_ values from 0 to 483. For horizontal pictures, _x_ values range from 0 to 511, and _y_ values from 0 to 367. Although you needn't ab‐ solutely stick to this range, you'll get better results if you at least stay in this vicin‐ ity. Also, point lists are terminated by a point of (-1, -1), so you shouldn't ever use neg‐ ative coordinates. _gremlin_ writes out coordinates using the [_printf_(3)](https://www.chedong.com/phpMan.php/man/printf/3/markdown) format “%f1.2”; it's probably a good idea to use the same format if you want to modify the _grn_ code. ### Sun/X11 coordinates There is no restriction on the range of coordinates used to create objects in the Sun/X11 version of _gremlin_. However, files with negative coordinates _will_ cause problems if dis‐ played on the AED. ## Options **-? **and **--help **display a usage message, while **-v **and **--version **show version information; all exit afterward. ### -C newline. ### -F _ _DESC_ file before the default font directories _/usr/share/groff/site-font_, _/usr/share/_ _groff/1.23.0/font_, and _/usr/lib/font_. ### -M _ rent directory, the home directory, _/usr/share/groff/site-tmac_, and _/usr/share/groff/_ _1.23.0/tmac_, in that order. ### -T _ list of valid devices. ## Files _/usr/share/groff/1.23.0/font/dev_name_/DESC_ describes the output device _name_. ## Authors David Slattengren and Barry Roitblat wrote the original Berkeley _grn_. Daniel Senderowicz and Werner Lemberg modified it for _groff_. **See also** [_gremlin_(1)](https://www.chedong.com/phpMan.php/man/gremlin/1/markdown), [_groff_(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown), [_pic_(1)](https://www.chedong.com/phpMan.php/man/pic/1/markdown), [_ideal_(1)](https://www.chedong.com/phpMan.php/man/ideal/1/markdown) groff 1.23.0 31 March 2024 [_grn_(1)](https://www.chedong.com/phpMan.php/man/grn/1/markdown)