diff options
| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:44:05 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:44:05 +0000 |
| commit | d318611dd6f23fcfedd50e9b9e24620b102ba96a (patch) | |
| tree | 8b9eef82ca40fdd5a8deeabf07572074c236095d /doc/groff.html.node/Drawing-Geometric-Objects.html | |
| parent | Initial commit. (diff) | |
| download | groff-d318611dd6f23fcfedd50e9b9e24620b102ba96a.tar.xz groff-d318611dd6f23fcfedd50e9b9e24620b102ba96a.zip | |
Adding upstream version 1.23.0.upstream/1.23.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/groff.html.node/Drawing-Geometric-Objects.html')
| -rw-r--r-- | doc/groff.html.node/Drawing-Geometric-Objects.html | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/doc/groff.html.node/Drawing-Geometric-Objects.html b/doc/groff.html.node/Drawing-Geometric-Objects.html new file mode 100644 index 0000000..fa0732f --- /dev/null +++ b/doc/groff.html.node/Drawing-Geometric-Objects.html @@ -0,0 +1,361 @@ +<!DOCTYPE html> +<html> +<!-- Created by GNU Texinfo 7.0.3, https://www.gnu.org/software/texinfo/ --> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +<!-- This manual documents GNU troff version 1.23.0. + +Copyright © 1994-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A +copy of the license is included in the section entitled "GNU Free +Documentation License". --> +<title>Drawing Geometric Objects (The GNU Troff Manual)</title> + +<meta name="description" content="Drawing Geometric Objects (The GNU Troff Manual)"> +<meta name="keywords" content="Drawing Geometric Objects (The GNU Troff Manual)"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta name="viewport" content="width=device-width,initial-scale=1"> + +<link href="index.html" rel="start" title="Top"> +<link href="Request-Index.html" rel="index" title="Request Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="GNU-troff-Reference.html" rel="up" title="GNU troff Reference"> +<link href="Traps.html" rel="next" title="Traps"> +<link href="Page-Motions.html" rel="prev" title="Page Motions"> +<style type="text/css"> +<!-- +a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em} +div.example {margin-left: 3.2em} +span.r {font-family: initial; font-weight: normal; font-style: normal} +span:hover a.copiable-link {visibility: visible} +strong.def-name {font-family: monospace; font-weight: bold; font-size: larger} +--> +</style> + + +</head> + +<body lang="en"> +<div class="section-level-extent" id="Drawing-Geometric-Objects"> +<div class="nav-panel"> +<p> +Next: <a href="Traps.html" accesskey="n" rel="next">Traps</a>, Previous: <a href="Page-Motions.html" accesskey="p" rel="prev">Page Motions</a>, Up: <a href="GNU-troff-Reference.html" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<h3 class="section" id="Drawing-Geometric-Objects-1">5.26 Drawing Geometric Objects</h3> +<a class="index-entry-id" id="index-drawing-requests"></a> +<a class="index-entry-id" id="index-requests-for-drawing"></a> + +<p>A few of the formatter’s escape sequences draw lines and other geometric +objects. Combined with each other and with page motion commands +(see <a class="pxref" href="Page-Motions.html">Page Motions</a>), a wide variety of figures is possible. For +complex drawings, these operations can be cumbersome; the preprocessors +<code class="code">gpic</code> or <code class="code">ggrn</code> are typically used instead. +</p> +<p>The <code class="code">\l</code> and <code class="code">\L</code> escape sequences draw horizontal and +vertical sequences of glyphs, respectively. Even the simplest of +output devices supports them. +</p> +<dl class="first-deffn"> +<dt class="deffn" id="index-_005cl_0027l_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\l<code class="code">'</code></code><span class="r"><i class="slanted">l</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cl_0027l_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-_005cl"></a> +</dd><dt class="deffnx def-cmd-deffn" id="index-_005cl_0027lc_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\l<code class="code">'</code></code><span class="r"><i class="slanted">lc</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cl_0027lc_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-horizontal-lines-_0028_005cl_0029"></a> +<a class="index-entry-id" id="index-horizontal-line_002c-drawing-_0028_005cl_0029"></a> +<a class="index-entry-id" id="index-line_002c-horizontal_002c-drawing-_0028_005cl_0029"></a> +<p>Draw a horizontal line of length <var class="var">l</var> from the drawing position. +Rightward motion is positive. Afterward, the drawing position is at the +right end of the line. The default scaling unit is ‘<samp class="samp">m</samp>’. +</p> +<a class="index-entry-id" id="index-baseline-rule-special-character_0028_005c_005bru_005d_0029"></a> +<a class="index-entry-id" id="index-glyph_002c-underscore-_0028_005c_005bru_005d_0029"></a> +<a class="index-entry-id" id="index-line-drawing-glyph"></a> +<a class="index-entry-id" id="index-glyph_002c-for-line-drawing"></a> +<p>The optional second parameter <var class="var">c</var> is a character with which to +draw the line. The default is the baseline rule special character, +<code class="code">\[ru]</code>. +</p> +<a class="index-entry-id" id="index-dummy-character-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence"></a> +<a class="index-entry-id" id="index-character_002c-dummy-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence"></a> +<p>If <var class="var">c</var> is a valid scaling unit, put <code class="code">\&</code> after <var class="var">l</var> to +disambiguate the input. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de textbox +\[br]\\$*\[br]\l'|0\[rn]'\l'|0\[ul]' +.. +</pre></div></div> + +<p>The foregoing outputs a box rule (a vertical line), the text +argument(s), and another box rule. We employ the boundary-relative +motion operator ‘<samp class="samp">|</samp>’. Finally, the line-drawing escape sequences +draw a radical extender (a form of overline) and an underline from the +drawing position to the position coresponding to beginning of the +<em class="emph">input</em> line. The drawing position returns to just after the +right-hand box rule because the lengths of the drawn lines are negative, +as noted above. +</p></dd></dl> + +<dl class="first-deffn"> +<dt class="deffn" id="index-_005cL_0027l_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\L<code class="code">'</code></code><span class="r"><i class="slanted">l</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cL_0027l_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-_005cL"></a> +</dd><dt class="deffnx def-cmd-deffn" id="index-_005cL_0027lc_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\L<code class="code">'</code></code><span class="r"><i class="slanted">lc</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cL_0027lc_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-vertical-lines-_0028_005cL_0029"></a> +<a class="index-entry-id" id="index-vertical-line-drawing-_0028_005cL_0029"></a> +<a class="index-entry-id" id="index-line_002c-vertical_002c-drawing-_0028_005cL_0029"></a> +<a class="index-entry-id" id="index-line-drawing-glyph-1"></a> +<a class="index-entry-id" id="index-glyph-for-line-drawing"></a> +<a class="index-entry-id" id="index-box-rule-glyph-_0028_005c_005bbr_005d_0029"></a> +<a class="index-entry-id" id="index-glyph_002c-box-rule-_0028_005c_005bbr_005d_0029"></a> +<p>Draw a vertical line of length <var class="var">l</var> from the drawing position. +Downward motion is positive. The default scaling unit is ‘<samp class="samp">v</samp>’. The +default character is the box rule, <code class="code">\[br]</code>. As with vertical +motion escape sequences, text processing continues where the line ends. +<code class="code">\L</code> is otherwise similar to <code class="code">\l</code>. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">$ nroff <<EOF +This is a \L'3v'test. +EOF + ⇒ This is a + ⇒ | + ⇒ | + ⇒ |test. +</pre></div></div> + +<p>When writing text, the drawing position is at the text baseline; recall +<a class="ref" href="Page-Geometry.html">Page Geometry</a>. +</p></dd></dl> + +<p>The <code class="code">\D</code> escape sequence provides <em class="dfn">drawing commands</em> that +direct the output device to render geometrical objects rather than +glyphs. Specific devices may support only a subset, or may feature +additional ones; consult the man page for the output driver in use. +Terminal devices in particular implement almost none. See <a class="xref" href="Graphics-Commands.html">Graphics Commands</a>. +</p> +<p>Rendering starts at the drawing position; when finished, the drawing +position is left at the rightmost point of the object, even for closed +figures, except where noted. GNU <code class="code">troff</code> draws stroked (outlined) +objects with the stroke color, and shades filled ones with the fill +color. See <a class="xref" href="Colors.html">Colors</a>. Coordinates <var class="var">h</var> and <var class="var">v</var> are horizontal +and vertical motions relative to the drawing position or previous point +in the command. The default scaling unit for horizontal measurements +(and diameters of circles) is ‘<samp class="samp">m</samp>’; for vertical ones, ‘<samp class="samp">v</samp>’. +</p> +<p>Circles, ellipses, and polygons can be drawn filled or stroked. These +are independent properties; if you want a filled, stroked figure, you +must draw the same figure twice using each drawing command. A filled +figure is always smaller than an outlined one because the former is +drawn only within its defined area, whereas strokes have a line +thickness (set with ‘<samp class="samp">\D't'</samp>’). +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">\h'1i'\v'1i'\ +\# increase line thickness +\Z'\D't 5p''\ +\# draw stroked (unfilled) polygon +\Z'\D'p 3 3 -6 0''\ +\# draw filled (solid) polygon +\Z'\D'P 3 3 -6 0'' +</pre></div></div> + +<dl class="first-deffn"> +<dt class="deffn" id="index-_005cD_0027command-argument-_2026_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\D<code class="code">'</code></code><span class="r"><i class="slanted">command argument …</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cD_0027command-argument-_2026_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-_005cD"></a> +<p>Drawing command escape sequence parameters begin with an ordinary +character, <var class="var">command</var>, selecting the type of object to be drawn, +followed by <var class="var">argument</var>s whose meaning is determined by +<var class="var">command</var>. +</p> +<dl class="table"> +<dt id='index-drawing-a-spline-_0028_005cD_0027_007e-_2026_0027_0029'><span><code class="code">\D'~ <var class="var">h1</var> <var class="var">v1</var> … <var class="var">hn</var> <var class="var">vn</var>'</code><a class="copiable-link" href='#index-drawing-a-spline-_0028_005cD_0027_007e-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-spline_002c-drawing-_0028_005cD_0027_007e-_2026_0027_0029"></a> +<p>Draw a B-spline to each point in sequence, leaving the drawing position +at (<var class="var">hn</var>, <var class="var">vn</var>). +</p> +</dd> +<dt id='index-arc_002c-drawing-_0028_005cD_0027a-_2026_0027_0029'><span><code class="code">\D'a <var class="var">hc</var> <var class="var">vc</var> <var class="var">h</var> <var class="var">v</var>'</code><a class="copiable-link" href='#index-arc_002c-drawing-_0028_005cD_0027a-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-an-arc-_0028_005cD_0027a-_2026_0027_0029"></a> +<p>Draw a circular arc centered at (<var class="var">hc</var>, <var class="var">vc</var>) counterclockwise +from the drawing position to a point (<var class="var">h</var>, <var class="var">v</var>) relative to the +center. <a class="footnote" id="DOCF105" href="groff.html_fot.html#FOOT105"><sup>105</sup></a> +</p> +</dd> +<dt id='index-circle_002c-stroked_002c-drawing-_0028_005cD_0027c-_2026_0027_0029'><span><code class="code">\D'c <var class="var">d</var>'</code><a class="copiable-link" href='#index-circle_002c-stroked_002c-drawing-_0028_005cD_0027c-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-stroked-circle-_0028_005cD_0027c-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-stroked-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-circle_002c-outlined_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-an-outlined-circle-_0028_005cD_0027c-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-outlined-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a> +<p>Draw a circle of diameter <var class="var">d</var> with its leftmost point at the drawing +position. +</p> +</dd> +<dt id='index-circle_002c-filled_002c-drawing-_0028_005cD_0027C-_2026_0027_0029'><span><code class="code">\D'C <var class="var">d</var>'</code><a class="copiable-link" href='#index-circle_002c-filled_002c-drawing-_0028_005cD_0027C-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-filled-circle-_0028_005cD_0027C-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-filled-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-circle_002c-solid_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-a-solid-circle-_0028_005cD_0027C-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-solid-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a> +<p>As ‘<samp class="samp">\D'C <span class="r">…</span>'</samp>’, but the circle is filled. +</p> +</dd> +<dt id='index-ellipse_002c-stroked_002c-drawing-_0028_005cD_0027e-_2026_0027_0029'><span><code class="code">\D'e <var class="var">h</var> <var class="var">v</var>'</code><a class="copiable-link" href='#index-ellipse_002c-stroked_002c-drawing-_0028_005cD_0027e-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-stroked-ellipse-_0028_005cD_0027e-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-stroked-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-ellipse_002c-outlined_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-an-outlined-ellipse-_0028_005cD_0027e-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-outlined-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a> +<p>Draw an ellipse of width <var class="var">h</var> and height <var class="var">v</var> with its leftmost +point at the drawing position. +</p> +</dd> +<dt id='index-ellipse_002c-filled_002c-drawing-_0028_005cD_0027E-_2026_0027_0029'><span><code class="code">\D'E <var class="var">x</var> <var class="var">y</var>'</code><a class="copiable-link" href='#index-ellipse_002c-filled_002c-drawing-_0028_005cD_0027E-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-filled-ellipse-_0028_005cD_0027E-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-filled-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-ellipse_002c-solid_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-a-solid-ellipse-_0028_005cD_0027E-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-solid-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a> +<p>As ‘<samp class="samp">\D'e <span class="r">…</span>'</samp>’, but the ellipse is filled. +</p> +</dd> +<dt id='index-line_002c-drawing-_0028_005cD_0027l-_2026_0027_0029'><span><code class="code">\D'l <var class="var">dx</var> <var class="var">dy</var>'</code><a class="copiable-link" href='#index-line_002c-drawing-_0028_005cD_0027l-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-line-_0028_005cD_0027l-_2026_0027_0029"></a> +<p>Draw line from the drawing position to (<var class="var">h</var>, <var class="var">v</var>). +</p> +<p>The following is a macro for drawing a box around a text argument; for +simplicity, the box margin is a fixed at 0.2<span class="dmn">m</span>. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de TEXTBOX +. nr @wd \w'\\$1' +\h'.2m'\ +\h'-.2m'\v'(.2m - \\n[rsb]u)'\ +\D'l 0 -(\\n[rst]u - \\n[rsb]u + .4m)'\ +\D'l (\\n[@wd]u + .4m) 0'\ +\D'l 0 (\\n[rst]u - \\n[rsb]u + .4m)'\ +\D'l -(\\n[@wd]u + .4m) 0'\ +\h'.2m'\v'-(.2m - \\n[rsb]u)'\ +\\$1\ +\h'.2m' +.. +</pre></div></div> + +<p>The argument is measured with the <code class="code">\w</code> escape sequence. Its width +is stored in register <code class="code">@wd</code>. <code class="code">\w</code> also sets the registers +<code class="code">rst</code> and <code class="code">rsb</code>; these contain its maximum vertical extents of +the argument. Then, four lines are drawn to form a box, offset by the +box margin. +</p> +</dd> +<dt id='index-polygon_002c-stroked_002c-drawing-_0028_005cD_0027p-_2026_0027_0029'><span><code class="code">\D'p <var class="var">h1</var> <var class="var">v1</var> … <var class="var">hn</var> <var class="var">vn</var>'</code><a class="copiable-link" href='#index-polygon_002c-stroked_002c-drawing-_0028_005cD_0027p-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-stroked-polygon-_0028_005cD_0027p-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-stroked-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-polygon_002c-outlined_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-an-outlined-polygon-_0028_005cD_0027p-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-outlined-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a> +<p>Draw polygon with vertices at drawing position and each point in +sequence. GNU <code class="code">troff</code> closes the polygon by drawing a line from +(<var class="var">hn</var>, <var class="var">vn</var>) back to the initial drawing position. +Afterward, the drawing position is left at (<var class="var">hn</var>, <var class="var">vn</var>). +</p> +</dd> +<dt id='index-polygon_002c-filled_002c-drawing-_0028_005cD_0027P-_2026_0027_0029'><span><code class="code">\D'P <var class="var">dx1</var> <var class="var">dy1</var> <var class="var">dx2</var> <var class="var">dy2</var> …'</code><a class="copiable-link" href='#index-polygon_002c-filled_002c-drawing-_0028_005cD_0027P-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-drawing-a-filled-polygon-_0028_005cD_0027P-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-filled-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-polygon_002c-solid_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-drawing-a-solid-polygon-_0028_005cD_0027P-_2026_0027_0029"></a> +<a class="index-entry-id" id="index-solid-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a> +<p>As ‘<samp class="samp">\D'P <span class="r">…</span>'</samp>’, but the polygon is filled. +</p> +<p>The following macro is like the ‘<samp class="samp">\D'l'</samp>’ example, but shades the +box. We draw the box before writing the text because colors in GNU +<code class="code">troff</code> have no transparency; in othe opposite order, the filled +polygon would occlude the text. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de TEXTBOX +. nr @wd \w'\\$1' +\h'.2m'\ +\h'-.2m'\v'(.2m - \\n[rsb]u)'\ +\M[lightcyan]\ +\D'P 0 -(\\n[rst]u - \\n[rsb]u + .4m) \ + (\\n[@wd]u + .4m) 0 \ + 0 (\\n[rst]u - \\n[rsb]u + .4m) \ + -(\\n[@wd]u + .4m) 0'\ +\h'.2m'\v'-(.2m - \\n[rsb]u)'\ +\M[]\ +\\$1\ +\h'.2m' +.. +</pre></div></div> + +</dd> +<dt id='index-line-thickness-_0028_005cD_0027t-_2026_0027_0029'><span><code class="code">\D't <var class="var">n</var>'</code><a class="copiable-link" href='#index-line-thickness-_0028_005cD_0027t-_2026_0027_0029'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-thickness-of-lines-_0028_005cD_0027t-_2026_0027_0029"></a> +<p>Set the stroke thickness of geometric objects to <var class="var">n</var> basic units. A +zero <var class="var">n</var> selects the minimal supported thickness. A negative +<var class="var">n</var> selects a thickness proportional to the type size; this is the +default. +</p></dd> +</dl> +</dd></dl> + +<p>In a hazy penumbra between text rendering and drawing commands we locate +the bracket-building escape sequence, <code class="code">\b</code>. It can assemble +apparently large glyphs by vertically stacking ordinary ones. +</p> +<dl class="first-deffn"> +<dt class="deffn" id="index-_005cb_0027contents_0027"><span class="category-def">Escape sequence: </span><span><strong class="def-name"><code class="t">\b<code class="code">'</code></code><span class="r"><i class="slanted">contents</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cb_0027contents_0027'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-_005cb"></a> +<a class="index-entry-id" id="index-pile_002c-glyph-_0028_005cb_0029"></a> +<a class="index-entry-id" id="index-glyph-pile-_0028_005cb_0029"></a> +<a class="index-entry-id" id="index-stacking-glyphs-_0028_005cb_0029"></a> +<p>Pile and center a sequence of glyphs vertically on the output line. +<em class="dfn">Piling</em> stacks glyphs corresponding to each character in +<var class="var">contents</var>, read from left to right, and placed from top to bottom. +GNU <code class="code">troff</code> separates the glyphs vertically by 1<span class="dmn">m</span>, and the +pile itself is centered 0.5<span class="dmn">m</span> above the text baseline. The +horizontal drawing position is then advanced by the width of the widest +glyph in the pile. +</p> +<a class="index-entry-id" id="index-_005cb_002c-limitations-of"></a> +<a class="index-entry-id" id="index-limitations-of-_005cb-escape-sequence"></a> +<p>This rather inflexible positioning algorithm doesn’t work with the +<code class="code">dvi</code> output device since its bracket pieces vary in height. +Instead, use the <code class="code">geqn</code> preprocessor. +</p> +<p><a class="ref" href="Manipulating-Spacing.html">Manipulating Spacing</a> describes how to adjust the vertical spacing +of the output line with the <code class="code">\x</code> escape sequence. +</p> +<p>The application of <code class="code">\b</code> that lends its name is construction of +brackets, braces, and parentheses when typesetting mathematics. We +might construct a large opening (left) brace as follows. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">\b'\[lt]\[bv]\[lk]\[bv]\[lb]' +</pre></div></div> + +<p>See <cite class="cite">groff_char<span class="r">(7)</span></cite> for a list of special character +identifiers. +</p></dd></dl> + + + +</div> +<hr> +<div class="nav-panel"> +<p> +Next: <a href="Traps.html">Traps</a>, Previous: <a href="Page-Motions.html">Page Motions</a>, Up: <a href="GNU-troff-Reference.html">GNU <code class="code">troff</code> Reference</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |