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

问题

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?

回答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";
...

来源：https://stackoverflow.com/questions/35788960/how-to-display-pie-slice-data-and-tooltip-together-using-chart-js

标签

pie-chart

chart.js