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  16 <title>Colors (The GNU Troff Manual)</title>
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  45 <div class="section-level-extent" id="Colors">
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  50 <hr>
  51 <h3 class="section" id="Colors-1">5.21 Colors</h3>
  52 <a class="index-entry-id" id="index-colors"></a>
  53
  54 <a class="index-entry-id" id="index-stroke-color"></a>
  55 <a class="index-entry-id" id="index-color_002c-stroke"></a>
  56 <a class="index-entry-id" id="index-fill-color"></a>
  57 <a class="index-entry-id" id="index-color_002c-fill"></a>
  58 <p>GNU <code class="code">troff</code> supports color output with a variety of color spaces
  59 and up to 16 bits per channel.  Some devices, particularly terminals,
  60 may be more limited.  When color support is enabled, two colors are
  61 current at any given time: the <em class="dfn">stroke color</em>, with which glyphs,
  62 rules (lines), and geometric objects like circles and polygons are
  63 drawn, and the <em class="dfn">fill color</em>, which can be used to paint the interior
  64 of a closed geometric figure.
  65 </p>
  66 <dl class="first-deffn">
  67 <dt class="deffn" id="index-_002ecolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.color</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ecolor'> &para;</a></span></dt>
  68 <dd><a class="index-entry-id" id="index-color"></a>
  69 </dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ecolor_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.color]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ecolor_005d'> &para;</a></span></dt>
  70 <dd><a class="index-entry-id" id="index-_002ecolor-1"></a>
  71 <p>If <var class="var">n</var> is missing or non-zero, enable the output of color-related
  72 device-independent output commands (this is the default); otherwise,
  73 disable them.  This request sets a global flag; it does not produce an
  74 input token (see <a class="pxref" href="Gtroff-Internals.html"><code class="code">gtroff</code> Internals</a>).
  75 </p>
  76 <p>The read-only register <code class="code">.color</code> is&nbsp;1 if colors are enabled,
  77 0&nbsp;otherwise.
  78 </p>
  79 <p>Color can also be disabled with the <samp class="option">-c</samp> command-line option.
  80 </p></dd></dl>
  81
  82 <dl class="first-deffn">
  83 <dt class="deffn" id="index-_002edefcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.defcolor</code></strong> <var class="def-var-arguments">ident scheme color-component &hellip;</var><a class="copiable-link" href='#index-_002edefcolor'> &para;</a></span></dt>
  84 <dd><a class="index-entry-id" id="index-defcolor"></a>
  85 <p>Define a color named <var class="var">ident</var>.  <var class="var">scheme</var> selects a color space
  86 and determines the quantity of required <var class="var">color-component</var>s; it must
  87 be one of &lsquo;<samp class="samp">rgb</samp>&rsquo; (three components), &lsquo;<samp class="samp">cmy</samp>&rsquo; (three), &lsquo;<samp class="samp">cmyk</samp>&rsquo;
  88 (four), or &lsquo;<samp class="samp">gray</samp>&rsquo; (one).  &lsquo;<samp class="samp">grey</samp>&rsquo; is accepted as a synonym of
  89 &lsquo;<samp class="samp">gray</samp>&rsquo;.  The color components can be encoded as a single
  90 hexadecimal value starting with &lsquo;<samp class="samp">#</samp>&rsquo; or &lsquo;<samp class="samp">##</samp>&rsquo;.  The former
  91 indicates that each component is in the range 0&ndash;255 (0&ndash;FF), the latter
  92 the range 0&ndash;65,535 (0&ndash;FFFF).
  93 </p>
  94 <div class="example">
  95 <div class="group"><pre class="example-preformatted">.defcolor half gray #7f
  96 .defcolor pink rgb #FFC0CB
  97 .defcolor magenta rgb  ##ffff0000ffff
  98 </pre></div></div>
  99
 100 <a class="index-entry-id" id="index-f-scaling-unit"></a>
 101 <a class="index-entry-id" id="index-unit_002c-scaling_002c-f"></a>
 102 <a class="index-entry-id" id="index-scaling-unit-f"></a>
 103 <p>Alternatively, each color component can be specified as a decimal
 104 fraction in the range 0&ndash;1, interpreted using a default scaling
 105 unit of&nbsp;<code class="code">f</code>, which multiplies its value by 65,536 (but
 106 clamps it at 65,535).
 107 </p>
 108 <div class="example">
 109 <div class="group"><pre class="example-preformatted">.defcolor gray50 rgb 0.5 0.5 0.5
 110 .defcolor darkgreen rgb 0.1f 0.5f 0.2f
 111 </pre></div></div>
 112 </dd></dl>
 113
 114 <a class="index-entry-id" id="index-default-color"></a>
 115 <a class="index-entry-id" id="index-color_002c-default"></a>
 116 <p>Each output device has a color named &lsquo;<samp class="samp">default</samp>&rsquo;, which cannot be
 117 redefined.  A device&rsquo;s default stroke and fill colors are not
 118 necessarily the same.  For the <code class="code">dvi</code>, <code class="code">html</code>, <code class="code">pdf</code>,
 119 <code class="code">ps</code>, and <code class="code">xhtml</code> output devices, GNU <code class="code">troff</code>
 120 automatically loads a macro file defining many color names at startup.
 121 By the same mechanism, the devices supported by <code class="code">grotty</code> recognize
 122 the eight standard ISO&nbsp;6429/EMCA-48 color names.<a class="footnote" id="DOCF86" href="groff.html_fot.html#FOOT86"><sup>86</sup></a>
 123 </p>
 124 <dl class="first-deffn">
 125 <dt class="deffn" id="index-_002egcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.gcolor</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">color</i></span>]</var><a class="copiable-link" href='#index-_002egcolor'> &para;</a></span></dt>
 126 <dd><a class="index-entry-id" id="index-gcolor"></a>
 127 </dd><dt class="deffnx def-cmd-deffn" id="index-_005cmc"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m</code><span class="r"><i class="slanted">c</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cmc'> &para;</a></span></dt>
 128 <dd><a class="index-entry-id" id="index-_005cm"></a>
 129 </dd><dt class="deffnx def-cmd-deffn" id="index-_005cm_0028co"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m(</code><span class="r"><i class="slanted">co</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cm_0028co'> &para;</a></span></dt>
 130 <dt class="deffnx def-cmd-deffn" id="index-_005cm_005bcolor_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m[</code><span class="r"><i class="slanted">color</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cm_005bcolor_005d'> &para;</a></span></dt>
 131 <dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002em_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.m]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002em_005d'> &para;</a></span></dt>
 132 <dd><a class="index-entry-id" id="index-_002em"></a>
 133 <p>Set the stroke color to <var class="var">color</var>.
 134 </p>
 135 <div class="example">
 136 <div class="group"><pre class="example-preformatted">.gcolor red
 137 The next words
 138 .gcolor
 139 \m[red]are in red\m[]
 140 and these words are in the previous color.
 141 </pre></div></div>
 142
 143 <p>The escape sequence <code class="code">\m[]</code> restores the previous stroke color, as
 144 does a <code class="code">gcolor</code> request without an argument.
 145 </p>
 146 <a class="index-entry-id" id="index-stroke-color-name-register-_0028_002em_0029"></a>
 147 <a class="index-entry-id" id="index-name_002c-stroke-color_002c-register-_0028_002em_0029"></a>
 148 <a class="index-entry-id" id="index-color-name_002c-stroke_002c-register-_0028_002em_0029"></a>
 149 <p>The name of the current stroke color is available in the read-only
 150 string-valued register &lsquo;<samp class="samp">.m</samp>&rsquo;; it is associated with the environment
 151 (see <a class="pxref" href="Environments.html">Environments</a>).  It interpolates nothing when the stroke color
 152 is the default.
 153 </p>
 154 <p><code class="code">\m</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>
 155 (see <a class="pxref" href="Gtroff-Internals.html"><code class="code">gtroff</code> Internals</a>).  It therefore can be used in requests like
 156 <code class="code">mc</code> (which expects a single character as an argument) to change
 157 the color on the fly:
 158 </p>
 159 <div class="example">
 160 <div class="group"><pre class="example-preformatted">.mc \m[red]x\m[]
 161 </pre></div></div>
 162 </dd></dl>
 163
 164 <dl class="first-deffn">
 165 <dt class="deffn" id="index-_002efcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fcolor</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">color</i></span>]</var><a class="copiable-link" href='#index-_002efcolor'> &para;</a></span></dt>
 166 <dd><a class="index-entry-id" id="index-fcolor"></a>
 167 </dd><dt class="deffnx def-cmd-deffn" id="index-_005cMc"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M</code><span class="r"><i class="slanted">c</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cMc'> &para;</a></span></dt>
 168 <dd><a class="index-entry-id" id="index-_005cM"></a>
 169 </dd><dt class="deffnx def-cmd-deffn" id="index-_005cM_0028co"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M(</code><span class="r"><i class="slanted">co</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cM_0028co'> &para;</a></span></dt>
 170 <dt class="deffnx def-cmd-deffn" id="index-_005cM_005bcolor_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M[</code><span class="r"><i class="slanted">color</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cM_005bcolor_005d'> &para;</a></span></dt>
 171 <dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eM_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.M]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eM_005d'> &para;</a></span></dt>
 172 <dd><a class="index-entry-id" id="index-_002eM"></a>
 173 <p>Set the fill color for objects drawn with <code class="code">\D'&hellip;'</code> escape
 174 sequences.  The escape sequence <code class="code">\M[]</code> restores the previous fill
 175 color, as does an <code class="code">fcolor</code> request without an argument.
 176 </p>
 177 <a class="index-entry-id" id="index-background-color-name-register-_0028_002eM_0029"></a>
 178 <a class="index-entry-id" id="index-name_002c-background-color_002c-register-_0028_002eM_0029"></a>
 179 <a class="index-entry-id" id="index-color-name_002c-background_002c-register-_0028_002eM_0029"></a>
 180 <a class="index-entry-id" id="index-fill-color-name-register-_0028_002eM_0029"></a>
 181 <a class="index-entry-id" id="index-name_002c-fill-color_002c-register-_0028_002eM_0029"></a>
 182 <a class="index-entry-id" id="index-color-name_002c-fill_002c-register-_0028_002eM_0029"></a>
 183 <p>The name of the current fill color is available in the read-only
 184 string-valued register &lsquo;<samp class="samp">.M</samp>&rsquo;; it is associated with the environment
 185 (see <a class="pxref" href="Environments.html">Environments</a>).  It interpolates nothing when the fill color
 186 is the default.  <code class="code">\M</code> doesn&rsquo;t produce an input token in GNU
 187 <code class="code">troff</code>.
 188 </p>
 189 <p>Create an ellipse with a red interior as follows.
 190 </p>
 191 <div class="example">
 192 <div class="group"><pre class="example-preformatted">\M[red]\h'0.5i'\D'E 2i 1i'\M[]
 193 </pre></div></div>
 194 </dd></dl>
 195
 196
 197
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