php-doc-en/reference/image/functions/imagegif.xml

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<refentry xml:id="function.imagegif" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>imagegif</refname>
  <refpurpose>&gd.image.output;</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>imagegif</methodname>
   <methodparam><type>GdImage</type><parameter>image</parameter></methodparam>
   <methodparam choice="opt"><type class="union"><type>resource</type><type>string</type><type>null</type></type><parameter>file</parameter><initializer>&null;</initializer></methodparam>
  </methodsynopsis>
  <para>
   <function>imagegif</function> creates the <acronym>GIF</acronym>
   file in <parameter>file</parameter> from the image <parameter>image</parameter>. The
   <parameter>image</parameter> argument is the return from the
   <function>imagecreate</function> or <literal>imagecreatefrom*</literal>
   function.
  </para>
  <para>
   The image format will be <acronym>GIF87a</acronym> unless the
   image has been made transparent with
   <function>imagecolortransparent</function>, in which case the
   image format will be <acronym>GIF89a</acronym>.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &gd.image.description;
    <varlistentry>
     <term><parameter>file</parameter></term>
     <listitem>
      <para>&gd.image.path;</para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
  &gd.return.trueonerror;
 </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>Outputting an image using <function>imagegif</function></title>
    <programlisting role="php">
<![CDATA[
<?php
// Create a new image instance
$im = imagecreatetruecolor(100, 100);

// Make the background white
imagefilledrectangle($im, 0, 0, 99, 99, 0xFFFFFF);

// Draw a text string on the image
imagestring($im, 3, 40, 20, 'GD Library', 0xFFBA00);

// Output the image to browser
header('Content-Type: image/gif');

imagegif($im);
imagedestroy($im);
?>
]]>
    </programlisting>
   </example>
   <example>
    <title>Converting a PNG image to GIF using <function>imagegif</function></title>
    <programlisting role="php">
<![CDATA[
<?php

// Load the PNG
$png = imagecreatefrompng('./php.png');

// Save the image as a GIF
imagegif($png, './php.gif');

// Free from memory
imagedestroy($png);

// We're done
echo 'Converted PNG image to GIF with success!';
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    The following code snippet allows you to write more
    portable PHP applications by auto-detecting the
    type of GD support which is available. Replace
    the sequence <literal>header ("Content-Type: image/gif");
    imagegif ($im);</literal> by the more flexible sequence:
    <informalexample>
     <programlisting role="php">
<![CDATA[
<?php
// Create a new image instance
$im = imagecreatetruecolor(100, 100);

// Do some image operations here

// Handle output
if(function_exists('imagegif'))
{
    // For GIF
    header('Content-Type: image/gif');

    imagegif($im);
}
elseif(function_exists('imagejpeg'))
{
    // For JPEG
    header('Content-Type: image/jpeg');

    imagejpeg($im, NULL, 100);
}
elseif(function_exists('imagepng'))
{
    // For PNG
    header('Content-Type: image/png');

    imagepng($im);
}
elseif(function_exists('imagewbmp'))
{
    // For WBMP
    header('Content-Type: image/vnd.wap.wbmp');

    imagewbmp($im);
}
else
{
    imagedestroy($im);

    die('No image support in this PHP server');
}

// If image support was found for one of these
// formats, then free it from memory
if($im)
{
    imagedestroy($im);
}
?>
]]>
     </programlisting>
    </informalexample>
   </para>
  </note>
  <note>
   <para>
    You can use the function
    <function>imagetypes</function> for checking
    the presence of the various supported image formats:
    <informalexample>
     <programlisting role="php">
<![CDATA[
<?php
if(imagetypes() & IMG_GIF)
{
    header('Content-Type: image/gif');
    imagegif($im);
}
elseif(imagetypes() & IMG_JPG)
{
    /* ... etc. */
}
?>
]]>
     </programlisting>
    </informalexample>
   </para>
  </note>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>imagepng</function></member>
   <member><function>imagewbmp</function></member>
   <member><function>imagejpeg</function></member>
   <member><function>imagetypes</function></member>
  </simplelist>
 </refsect1>
</refentry>
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