====== PHP and gdlib ======

Some plugins might use functions like **ImageCreate** or **ImagePng** or others to create PNG or JPEG images dynamically. In this case PHP must have been installed on your machine/webserver with gdlib support. Otherwise nothing will happen except no images are created. This means even so the required lib is not installed you might not see any warning or error messages.

===== Checking for gdlib support =====

If you install a file including the code

<code php>
<?php phpinfo(); ?>
</code>

on your webserver and open the URL to the file in a browser, then information about the installed PHP version will appear. There should be a section with the heading **GD**. Otherwise gdlib is not installed.

You can also use the following code to have a simple and clear indication:

<code php>
<?php
if (extension_loaded('gd') && function_exists('gd_info')) {
    echo "PHP GD library is installed on your web server";
}
else {
    echo "PHP GD library is NOT installed on your web server";
}
?>
</code>

If there is no gdlib installed, then you need to install it to make plugins work which require it.

===== Installing gdlib support for PHP =====

Please find installation instructions here. Please remember that a **restart of the webserver** might be required after installing gdlib support to make the change take affect.

==== Ubuntu ====

On Ubuntu just run

<code>
sudo apt-get install php5-gd
</code>

On CentOS just run

<code>
sudo yum install php-gd
</code>

FIXME Provide installation instructions for other OS

===== Plugins requiring gdlib =====

The following plugins are known to require gdlib:

  * [[plugin:fontcolor|fontcolor]]
  * [[plugin:rrdgraph|RRD Graph Plugin]]
  * [[plugin:livemark|LiveMark Plugin]]