imagealphablending.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.imagealphablending" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>imagealphablending</refname>
  <refpurpose>Set the blending mode for an image</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>imagealphablending</methodname>
   <methodparam><type>GdImage</type><parameter>image</parameter></methodparam>
   <methodparam><type>bool</type><parameter>enable</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>imagealphablending</function> allows for two different
   modes of drawing on truecolor images. In blending mode, the
   alpha channel component of the color supplied to all drawing function,
   such as <function>imagesetpixel</function> determines how much of the
   underlying color should be allowed to shine through.  As a result, gd
   automatically blends the existing color at that point with the drawing color,
   and stores the result in the image.  The resulting pixel is opaque.  In
   non-blending mode, the drawing color is copied literally with its alpha channel
   information, replacing the destination pixel.  Blending mode is not available
   when drawing on palette images.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &gd.image.description;
    <varlistentry>
     <term><parameter>enable</parameter></term>
     <listitem>
      <para>
       Whether to enable the blending mode or not. On true color images 
       the default value is &true; otherwise the default value is &false;
      </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;
  <example>
   <title><function>imagealphablending</function> usage example</title>
   <programlisting role="php">
<![CDATA[
<?php
// Create image
$im = imagecreatetruecolor(100, 100);

// Set alphablending to on
imagealphablending($im, true);

// Draw a square
imagefilledrectangle($im, 30, 30, 70, 70, imagecolorallocate($im, 255, 0, 0));

// Output
header('Content-Type: image/png');

imagepng($im);
?>
]]>
   </programlisting>
  </example>
 </refsect1>
</refentry>
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