Calling a function from highcharts upon clicking the piechart - php

Question

I would like to call a function when someone clicks on the pie-chart which I built using Highchart.
My pie chart code is:
function open_risk_level_pie()
{
$chart = new Highchart();
$chart->chart->renderTo = "open_risk_level_pie";
$chart->chart->plotBackgroundColor = lightblue;
$chart->chart->plotBorderWidth = null;
$chart->chart->plotShadow = false;
$chart->title->text = "Risk Level";
$chart->tooltip->formatter = new HighchartJsExpr("function() {
return '<b>'+ this.point.name +'</b>: '+ this.point.y; }");
$chart->plotOptions->pie->allowPointSelect = 1;
$chart->plotOptions->pie->cursor = "pointer";
$chart->plotOptions->pie->dataLabels->enabled = false;
$chart->plotOptions->pie->showInLegend = 1;
$chart->plotOptions->pie->colors = array('red', 'orange', 'yellow', 'black');
$chart->credits->enabled = false;
$array = //some db access code
$high = $array[0][0];
$medium = $array[1][0];
$low = $array[2][0];
// If the array is empty
if (empty($array))
{
$data[] = array("No Data Available", 0);
}
// Otherwise
else
{
// Create the data array
foreach ($array as $row)
{
$data[] = array($row['level'], (int)$row['num']);
}
$chart->series[] = array('type' => "pie",
'name' => "Level",
'data' => $data);
}
echo "<div id=\"open_risk_level_pie\"></div>\n";
echo "<script type=\"text/javascript\">";
echo $chart->render("open_risk_level_pie");
echo "</script>\n";
}
Now I want to call a function whenever someone clicks on the pie chart. I have searched a lot, but unable to find. Some sites mentioned to use "formatter", but I failed to use it. If formatter is the solution for my question please give me steps for the above code.

Answer 1

Use an on click event for a slice.
Docs.