<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.imageline" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>imageline</refname>
  <refpurpose>Draw a line</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>imageline</methodname>
   <methodparam><type>GdImage</type><parameter>image</parameter></methodparam>
   <methodparam><type>int</type><parameter>x1</parameter></methodparam>
   <methodparam><type>int</type><parameter>y1</parameter></methodparam>
   <methodparam><type>int</type><parameter>x2</parameter></methodparam>
   <methodparam><type>int</type><parameter>y2</parameter></methodparam>
   <methodparam><type>int</type><parameter>color</parameter></methodparam>
  </methodsynopsis>
  <para>
   Draws a line between the two given points.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &gd.image.description;
    <varlistentry>
     <term><parameter>x1</parameter></term>
     <listitem>
      <para>
       x-coordinate for first point.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>y1</parameter></term>
     <listitem>
      <para>
       y-coordinate for first point.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>x2</parameter></term>
     <listitem>
      <para>
       x-coordinate for second point.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>y2</parameter></term>
     <listitem>
      <para>
       y-coordinate for second point.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>color</parameter></term>
     <listitem>
      <para>
       The line color. &gd.identifier.color;
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &gd.changelog.image-param;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Drawing a thick line</title>
    <programlisting role="php">
<![CDATA[
<?php

function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1)
{
    /* this way it works well only for orthogonal lines
    imagesetthickness($image, $thick);
    return imageline($image, $x1, $y1, $x2, $y2, $color);
    */
    if ($thick == 1) {
        return imageline($image, $x1, $y1, $x2, $y2, $color);
    }
    $t = $thick / 2 - 0.5;
    if ($x1 == $x2 || $y1 == $y2) {
        return imagefilledrectangle($image, round(min($x1, $x2) - $t), round(min($y1, $y2) - $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color);
    }
    $k = ($y2 - $y1) / ($x2 - $x1); //y = kx + q
    $a = $t / sqrt(1 + pow($k, 2));
    $points = array(
        round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a),
        round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a),
        round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a),
        round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a),
    );
    imagefilledpolygon($image, $points, 4, $color);
    return imagepolygon($image, $points, 4, $color);
}

?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>imagecreatetruecolor</function></member>
   <member><function>imagecolorallocate</function></member>
  </simplelist>
 </refsect1>
</refentry>
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