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<h2>6. Decorating Objects
<a name="6. Decorating Objects"></a>
</h2>
<h3>6.1. Text Special Effects
<a name="6.1. Text Special Effects"></a>
</h3>
<p style="margin-top: 1em">All <b>pic</b> implementations
support the following font-styling escapes within text
objects:</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="16%">
<p style="margin-top: 1em">\fR, \f1</p></td>
<td width="84%">
</td></tr>
</table>
<p style="margin-left:10%;">Set Roman style (the
default)</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="16%">
<p style="margin-top: 1em">\fI, \f2</p></td>
<td width="84%">
</td></tr>
</table>
<p style="margin-left:10%;">Set Italic style</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="16%">
<p style="margin-top: 1em">\fB, \f3</p></td>
<td width="84%">
</td></tr>
</table>
<p style="margin-left:10%;">Set Bold style</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="18%">
<p style="margin-top: 1em">\fP </p> </td>
<td width="82%">
</td></tr>
</table>
<p style="margin-left:10%;">Revert to previous style; only
works one level deep, does not stack.</p>
<p style="margin-top: 1em">In the <b>pic</b>
implementations that are preprocessors for a toolchain that
include <b>[gtn]roff</b>, text objects may also contain
<b>[gtn]roff</b> vertical- and horizontal-motion escapes
such as \h or \v. Troff special glyphs are also available.
All \-escapes will be passed through to the postprocessing
stage and have their normal effects. The base font family is
set by the <b>[gtn]roff</b> environment at the time the
picture is rendered.</p>
<p style="margin-top: 1em"><b>pic2plot</b> replaces
<b>[gtn]roff</b> horizontal- and vertical-motion escapes
with \-escapes of its own. Troff special glyphs are not
available, but in most back ends Latin-1 special characters
and a square-root radical will be. See the <b>pic2plot</b>
documentation for full details.</p>
<h3>6.2. Dashed Objects
<a name="6.2. Dashed Objects"></a>
</h3>
<p style="margin-top: 1em">We’ve already seen that
the modifier <b>dashed</b> can change the line style of an
object from solid to dashed. GNU <b>gpic</b> permits you to
dot or dash ellipses, circles, and arcs (and splines in TeX
mode only); some versions of DWB may only permit dashing of
lines and boxes. It’s possible to change the dash
interval by specifying a number after the modifier.</p>
<p align="center" style="margin-top: 1em"><img src="img/pic18.png" alt="Image img/pic18.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-1:
Dashed objects</p>
<h3>6.3. Dotted Objects
<a name="6.3. Dotted Objects"></a>
</h3>
<p style="margin-top: 1em">Another available qualifier is
<b>dotted</b>. GNU <b>gpic</b> permits you to dot or dash
ellipses, circles, and arcs (and splines in TeX mode only);
some versions of DWB may only permit dashing of lines and
boxes. It too can be suffixed with a number to specify the
interval between dots:</p>
<p align="center" style="margin-top: 1em"><img src="img/pic19.png" alt="Image img/pic19.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-2:
Dotted objects</p>
<h3>6.4. Rounding Box Corners
<a name="6.4. Rounding Box Corners"></a>
</h3>
<p style="margin-top: 1em">It is also possible, in GNU
<b>gpic</b> only, to modify a box so it has rounded
corners:</p>
<p align="center" style="margin-top: 1em"><img src="img/pic20.png" alt="Image img/pic20.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-3:
<b>box rad</b> with increasing radius values</p>
<p style="margin-top: 1em">Radius values higher than half
the minimum box dimension are silently truncated to that
value.</p>
<h3>6.5. Slanted Boxes
<a name="6.5. Slanted Boxes"></a>
</h3>
<p style="margin-top: 1em">GNU <b>gpic</b> supports slanted
boxes:</p>
<p align="center" style="margin-top: 1em"><img src="img/pic21.png" alt="Image img/pic21.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-4:
Various slanted boxes.</p>
<p style="margin-top: 1em">The <b>xslanted</b> and
<b>yslanted</b> attributes specify the x and y offset,
respectively, of the box’s upper right corner from its
default position.</p>
<h3>6.6. Arrowheads
<a name="6.6. Arrowheads"></a>
</h3>
<p style="margin-top: 1em">Lines and arcs can be decorated
as well. Any line or arc (and any spline as well) can be
decorated with arrowheads by adding one or more as
modifiers:</p>
<p align="center" style="margin-top: 1em"><img src="img/pic22.png" alt="Image img/pic22.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-5:
Double-headed line made with <b>line <- -></b></p>
<p style="margin-top: 1em">In fact, the <b>arrow</b>
command is just shorthand for <b>line -></b>. And there
is a double-head modifier <->, so the figure above
could have been made with <b>line <-></b>.</p>
<p style="margin-top: 1em">Arrowheads have a <b>width</b>
attribute, the distance across the rear; and a <b>height</b>
attribute, the length of the arrowhead along the shaft.</p>
<p style="margin-top: 1em">Arrowhead style is controlled by
the style variable <b>arrowhead</b>. The DWB and GNU
versions interpret it differently. DWB defaults to open
arrowheads and an <b>arrowhead</b> value of 2; the
Kernighan paper says a value of 7 makes solid
arrowheads. GNU <b>gpic</b> defaults to solid arrowheads and
an <b>arrowhead</b> value of 1; a value of 0
produces open arrowheads. Note that solid arrowheads are
always filled with the current outline color.</p>
<h3>6.7. Line Thickness
<a name="6.7. Line Thickness"></a>
</h3>
<p style="margin-top: 1em">It’s also possible to
change the line thickness of an object (this is a GNU
extension, DWB <b>pic</b> doesn’t support it). The
default thickness of the lines used to draw objects is
controlled by the <b>linethick</b> variable. This gives the
thickness of lines in points. A negative value means use the
default thickness: in TeX output mode, this means use a
thickness of 8 milliinches; in TeX output mode with the
<b>-c</b> option, this means use the line thickness
specified by <b>.ps</b> lines; in troff output mode, this
means use a thickness proportional to the pointsize. A zero
value means draw the thinnest possible line supported by the
output device. Initially it has a value of -1. There is also
a <b>thickness</b> attribute (which can be abbreviated to
<b>thick</b>). For example, <b>circle thickness 1.5</b>
would draw a circle using a line with a thickness of 1.5
points. The thickness of lines is not affected by the value
of the <b>scale</b> variable, nor by any width or height
given in the <b>.PS</b> line.</p>
<h3>6.8. Invisible Objects
<a name="6.8. Invisible Objects"></a>
</h3>
<p style="margin-top: 1em">The modifier <b>invis[ible]</b>
makes an object entirely invisible. This used to be useful
for positioning text in an invisible object that is properly
joined to neighboring ones. Newer DWB versions and GNU
<b>pic</b> treat stand-alone text in exactly this way.</p>
<h3>6.9. Filled Objects
<a name="6.9. Filled Objects"></a>
</h3>
<p style="margin-top: 1em">It is possible to fill boxes,
circles, and ellipses. The modifier <b>fill[ed]</b>
accomplishes this. You can suffix it with a fill value; the
default is given by the style variable <b>fillval</b>.</p>
<p style="margin-top: 1em">DWB <b>pic</b> and <b>gpic</b>
have opposite conventions for fill values and different
defaults. DWB <b>fillval</b> defaults to 0.3 and smaller
values are darker; GNU <b>fillval</b> uses 0 for white and 1
for black.</p>
<p align="center" style="margin-top: 1em"><img src="img/pic23.png" alt="Image img/pic23.png"></p>
<p align="center" style="margin-top: 1em">Figure 6-6:
<b>circle fill; move; circle fill 0.4; move; circle fill
0.9;</b></p>
<p style="margin-top: 1em">GNU <b>gpic</b> makes some
additional guarantees. A fill value greater than 1 can also
be used: this means fill with the shade of gray that is
currently being used for text and lines. Normally this is
black, but output devices may provide a mechanism for
changing this. The invisible attribute does not affect the
filling of objects. Any text associated with a filled object
is added after the object has been filled, so that the text
is not obscured by the filling.</p>
<p style="margin-top: 1em">The closed-object modifier
<b>solid</b> is equivalent to <b>fill</b> with the darkest
fill value (DWB <b>pic</b> had this capability but mentioned
it only in a reference section).</p>
<h3>6.10. Colored Objects
<a name="6.10. Colored Objects"></a>
</h3>
<p style="margin-top: 1em">As a GNU extension, three
additional modifiers are available to specify colored
objects. <b>outline</b> sets the color of the outline,
<b>shaded</b> the fill color, and <b>color</b> sets both.
All three keywords expect a suffix specifying the color.
Example:</p>
<p align="center" style="margin-top: 1em"><font color="#000000"><img src="img/pic24.png" alt="Image img/pic24.png"></font></p>
<p align="center" style="margin-top: 1em"><font color="#000000">Figure
6-7: <b>box color "yellow"; arrow color
"cyan"; circle shaded "green" outline
"black";</b></font></p>
<p style="margin-top: 1em"><font color="#000000">Alternative
spellings are <b>colour</b>, <b>colored</b>,
<b>coloured</b>, and <b>outlined</b>.</font></p>
<p style="margin-top: 1em"><font color="#000000">Predefined
color names for <i>[gtn]roff</i>-based <b>pic</b>
implementations are defined in the device macro files, for
example <tt>ps.tmac</tt>; additional colors can be defined
with the <b>.defcolor</b> request (see the manual page of
GNU <i>troff</i>(1) for more details). Currently, color
support is not available at all in TeX mode.</font></p>
<p style="margin-top: 1em"><font color="#000000">The
<i>pic2plot</i>(1) carries with its own set of color names,
essentially those recognized by the X window system
with “grey” accepted as a variant of
“gray”.</font></p>
<p style="margin-top: 1em"><font color="#000000"><b>pic</b>
assumes that at the beginning of a picture both glyph and
fill color are set to the default value.</font></p>
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