How to display pie slice data and tooltip together using chart.js - pie-chart

Question

Can we display data in pie chart slice and also tolltip like the above image using chart.js?
Updated:
Here is my code in php page.
printf( '<table>' );
echo '<tr><td style="text-align: right;"><canvas id="pie-canvas-'
. $canvasId
. '" width=256px height=257px ></canvas></td><td style="text-align: left;width:360px;" id="legend" class="chart-legend"></td></tr>';
echo '<script type="text/javascript">drawPie('
. $canvasId
. ', '
. $data
.', '
. $legend
. ');</script>';
printf( '</table>' );
printf( '<script type="text/javascript" src="extlib/Chart.min.js"></script>' );
printf( '<script type="text/javascript" src="extlib/jquery-min.js"></script>' );
printf( '<script type="text/javascript">' );
?>
function drawPie( canvasId, data, legend )
{
//pie chart for machine status
var canvas = document.getElementById( "pie-canvas-" + canvasId );
var ctx = canvas.getContext( "2d" );
var midX = canvas.width/2;
var midY = canvas.height/2;
var piedata = [];
$.each(data,function(i,val){
piedata.push({value:val.hostStatusCount,color:val.color,label:val.status});
});
Chart.types.Pie.extend({
name: "PieAlt",
draw: function(){
Chart.types.Pie.prototype.draw.apply(this, arguments);
drawSegmentValues(this)
}
});
var myPieChart = new Chart(ctx).PieAlt(piedata, {
showTooltips: true,
tooltipTemplate: "<%= Math.round(circumference / 6.283 * 100) %>%"
});
var radius = myPieChart.outerRadius;
function drawSegmentValues(myPieChart)
{
//displays segements(number of machines) for each slice of pie in percentage
var length = myPieChart.segments.length;
var totalValue = 0;
for ( var i=0; i < length; i++ )
{
totalValue +=myPieChart.segments[i].value;
}
for( var i=0; i < length; i++ )
{
ctx.fillStyle="black";
var textSize = canvas.width/15;
ctx.font= textSize+"px Verdana";
// Get needed variables
var value = Math.round( ( ( myPieChart.segments[i].value ) / totalValue ) * 100 );
var startAngle = myPieChart.segments[i].startAngle;
var endAngle = myPieChart.segments[i].endAngle;
var middleAngle = startAngle + ( ( endAngle - startAngle ) / 2 );
// Compute text location
var posX = ( radius /1.5 ) * Math.cos( middleAngle ) + midX;
var posY = ( radius/1.5 ) * Math.sin( middleAngle ) + midY;
// Text offside by middle
var w_offset = ctx.measureText( value ).width / 2;
var h_offset = textSize / 4;
ctx.fillText( value+"%", posX - w_offset, posY + h_offset );
}
}
//legend for status
if( legend )
document.getElementById("legend").innerHTML = myPieChart.generateLegend();
}
<?
When mouse over the data in pie slice moved from its position.
How to solve this?

Answer 1

Extend the chart and move your drawSegmentValues to inside the draw override, like so
Chart.types.Pie.extend({
name: "PieAlt",
draw: function(){
Chart.types.Pie.prototype.draw.apply(this, arguments);
drawSegmentValues(this)
}
});
then use PieAlt
var myPieChart = new Chart(ctx).PieAlt(data, {
showTooltips: true,
tooltipTemplate: "<%= Math.round(circumference / 6.283 * 100) %>%"
});
and modify the drawSegmentValues function slightly
function drawSegmentValues(myPieChart)
{
var radius = myPieChart.outerRadius
...
Update
If you have a problem with the labels moving set the context textAlign and textBaseline properties, like so
...
ctx.font = textSize + "px Verdana";
ctx.textAlign = "start";
ctx.textBaseline = "bottom";
...