Controller.php

<?php
use Piwik\Core\Piwik;
use Piwik\Core\Piwik_Common;

/**
 * Piwik - Open source web analytics
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 *
 * @category Piwik_Plugins
 * @package Piwik_ImageGraph
 */

class Piwik_ImageGraph_Controller extends Piwik_Controller
{
    // Call metadata reports, and draw the default graph for each report.
    public function index()
    {
        Piwik::checkUserHasSomeAdminAccess();
        $idSite = Piwik_Common::getRequestVar('idSite', 1, 'int');
        $period = Piwik_Common::getRequestVar('period', 'day', 'string');
        $date = Piwik_Common::getRequestVar('date', 'today', 'string');
        $_GET['token_auth'] = Piwik::getCurrentUserTokenAuth();
        $reports = Piwik_API_API::getInstance()->getReportMetadata($idSite, $period, $date);
        $plot = array();
        foreach ($reports as $report) {
            if (!empty($report['imageGraphUrl'])) {
                $plot[] = array(
                    // Title
                    $report['category'] . ' › ' . $report['name'],
                    //URL
                    Piwik::getPiwikUrl() . $report['imageGraphUrl']
                );
            }
        }
        $view = new Piwik_View('@ImageGraph/index');
        $view->titleAndUrls = $plot;
        echo $view->render();
    }

    // Draw graphs for all sizes (DEBUG)
    public function testAllSizes()
    {
        Piwik::checkUserIsSuperUser();

        $view = new Piwik_View('@ImageGraph/testAllSizes');
        $this->setGeneralVariablesView($view);

        $period = Piwik_Common::getRequestVar('period', 'day', 'string');
        $date = Piwik_Common::getRequestVar('date', 'today', 'string');

        $_GET['token_auth'] = Piwik::getCurrentUserTokenAuth();
        $availableReports = Piwik_API_API::getInstance()->getReportMetadata($this->idSite, $period, $date);
        $view->availableReports = $availableReports;
        $view->graphTypes = array(
            '', // default graph type
//			'evolution',
//			'verticalBar',
//			'horizontalBar',
//			'pie',
//			'3dPie',
        );
        $view->graphSizes = array(
            array(null, null), // default graph size
            array(460, 150), // standard phone
            array(300, 150), // standard phone 2
            array(240, 150), // smallest mobile display
            array(800, 150), // landscape mode
            array(600, 300, $fontSize = 18, 300, 150), // iphone requires bigger font, then it will be scaled down by ios
        );
        echo $view->render();
    }

}