Loading github project into wordpress plugin - php

Question

I am trying to use the following github project in my wordpress plugin:
PHP Object wrapper for the Google Chart API
I tried the following:
require_once(WPPLUGIN_PATH. "gchart/gChartInit.php");
$piChart = new gPieChart(); // <---- here I get the error
$piChart->addDataSet(array(112,315,66,40));
$piChart->setLabels(array("first", "second", "third","fourth"));
$piChart->setLegend(array("first", "second", "third","fourth"));
$piChart->setColors(array("ff3344", "11ff11", "22aacc", "3333aa"));
echo $piChart->getImgCode();
My problem seems to be that when I am using the above code, it jumps at line $piChart = new gPieChart(); into another wordpress-plugins autoloader and does not load the gPieChart.php properly.
The error message is:
[26-Jul-2016 20:39:59 UTC] PHP Fatal error: Class 'gPieChart' not found in /home/ubuntu/workspace/wp-content/plugins/wp-analytics-mail/sendTestMail.php on line 267
[26-Jul-2016 20:39:59 UTC] PHP Stack trace:
[26-Jul-2016 20:39:59 UTC] PHP 1. {main}() /home/ubuntu/workspace/index.php:0
[26-Jul-2016 20:39:59 UTC] PHP 2. require() /home/ubuntu/workspace/index.php:17
[26-Jul-2016 20:39:59 UTC] PHP 3. require_once() /home/ubuntu/workspace/wp-blog-header.php:19
[26-Jul-2016 20:39:59 UTC] PHP 4. include() /home/ubuntu/workspace/wp-includes/template-loader.php:75
[26-Jul-2016 20:39:59 UTC] PHP 5. include() /home/ubuntu/workspace/wp-content/themes/twentysixteen/page-analytics-analytics-mail.php:138
Any suggestions how to make the above code work?
I appreciate your reply!

Answer 1

Here's what you do.
Install Composer as per the doc or, if you're on Windows/Unix, figure out how to install the thing in your environment.
Create new file called composer.json in the root folder of your plugin (in this case wp-analytics-mail)
Again, as per the doc, paste this into the composer.json
{
"require": {
"gchartphp/gchartphp": "dev-master"
}
}
In the command line, get to the plugin folder and run composer update
Put require 'vendor/autoload.php'; somewhere close to the top of your main plugin file (sendTestMail.php)
Lower down in the same file, initialize and use the library:
$piChart = new gchart\gPieChart();