Creating a Joomla system plugin

This documentation is for Smart Slider 3.3+

System plugins are loading in every pages, so it's good to make them, because you can add extra codes to ours without having to put it into our folders, which will be overwritten with the next update.

What you need is to create a folder in here:
plugins/system/

Let's call it example:
plugins/system/example

Then put three files inside it. The first one should be the index.html, which should only have this code:

<html><body></body></html>

The second file should be a php file, which should have the same name what your folder had, in my case example.php
This will be the file, which is called in everywhere, so it should have the php code, what you would like to run.

The third file is an xml file, which contains the informations of your plugin. This should have the same name too: example.xml
and the code should be something like this:

<?xml version="1.0" encoding="utf-8"?>
<extension version="3.4" type="plugin" group="editors-xtd" method="upgrade">
    <name>Example plugin</name>
    <author>John Doe</author>
    <creationDate>April 2015</creationDate>
    <copyright>Copyright (C) 2005 - 2015 Open Source Matters. All rights reserved.</copyright>
    <license>GNU General Public License version 2 or later; see LICENSE.txt</license>
    <description>Example plugin</description>
    <files>
        <filename plugin="example">example.php</filename>
        <filename>index.html</filename>
    </files>
</extension>

So the important parts are to have the files listed. After this you can install your plugin at your admin area -> Extensions -> Manage -> Discover. Then publish it at the Extensions -> Plugins. In the next example you can see the process with images.

Example - Creating a generator

Create these folders:
plugins\system\smartslidergenerator\
plugins\system\smartslidergenerator\sources\

These files with the given code:
index.html

<html><body></body></html>

smartslidergenerator.php

<?php
require_once(dirname(__FILE__) . '/../../../libraries/nextend2/nextend/joomla/library.php');
require_once(dirname(__FILE__) . '/../../../libraries/nextend2/smartslider/smartslider/libraries/slider/generator/generatorFactory.php');
require_once(dirname(__FILE__) . '/../../../libraries/nextend2/smartslider/smartslider/libraries/plugins/N2SliderGeneratorPluginAbstract.php');

class N2SSPluginGeneratorCustom extends N2SliderGeneratorPluginAbstract {
	protected $name = 'custom';
	protected $url = '#';

	public function getLabel() {
		return 'Custom';
	}

	public function isInstalled() {
		return true;
	}

	protected function loadSources() {
		new N2GeneratorCustom($this, 'source', n2_('Source'));
	}

	public function getPath() {
		return dirname(__FILE__) . DIRECTORY_SEPARATOR;
	}
}

N2SSGeneratorFactory::addGenerator(new N2SSPluginGeneratorCustom);

smartslidergenerator.xml

<?xml version="1.0" encoding="utf-8"?>
<extension version="3.4" type="plugin" group="editors-xtd" method="upgrade">
    <name>Smart Slider Custom Generator</name>
    <author>Gabor Racz</author>
    <creationDate>April 2015</creationDate>
    <copyright>Copyright (C) 2005 - 2015 Open Source Matters. All rights reserved.</copyright>
    <license>GNU General Public License version 2 or later; see LICENSE.txt</license>
    <description>Smart Slider custom generator</description>
    <files>
        <filename plugin="smartslidergenerator">smartslidergenerator.php</filename>
        <filename>index.html</filename>
    </files>
</extension>

dynamic.png
This should be the image you want in our backend.

Go into the sources folder you created, and put this file in it:
smartslidergeneratorsource.php

<?php
N2Loader::import('libraries.slider.generator.abstract', 'smartslider');
class N2GeneratorCustom extends N2GeneratorAbstract {
    protected $layout = 'image_extended';
    public function renderFields($form) {
        parent::renderFields($form);

        $filter = new N2Tab($form, 'filter', n2_('Filter'));		
		new N2ElementText($filter, 'mytext', 'My text', '');
    }

    protected function _getData($count, $startIndex) {        
	$data = array();        
	$data[0]['my_variable'] = 'one';
	$data[1]['my_variable'] = 'two';
	$data[2]['my_variable'] = 'three';
        return $data;
    }
}

This file is the most important, so you are putting the possible options here and return the result inside the _getData function. To better understand this part, check out the generator developer documentation.

Now go to the Extensions -> Manage