Text inside Doughnut Chart.js

gistfile1.txt

Chart.pluginService.register({
		beforeDraw: function (chart) {
			if (chart.config.options.elements.center) {
        //Get ctx from string
        var ctx = chart.chart.ctx;

				//Get options from the center object in options
        var centerConfig = chart.config.options.elements.center;
      	var fontStyle = centerConfig.fontStyle || 'Arial';
				var txt = centerConfig.text;
        var color = centerConfig.color || '#000';
        var sidePadding = centerConfig.sidePadding || 20;
        var sidePaddingCalculated = (sidePadding/100) * (chart.innerRadius * 2)
        //Start with a base font of 30px
        ctx.font = "30px " + fontStyle;

				//Get the width of the string and also the width of the element minus 10 to give it 5px side padding
        var stringWidth = ctx.measureText(txt).width;
        var elementWidth = (chart.innerRadius * 2) - sidePaddingCalculated;

        // Find out how much the font can grow in width.
        var widthRatio = elementWidth / stringWidth;
        var newFontSize = Math.floor(30 * widthRatio);
        var elementHeight = (chart.innerRadius * 2);

        // Pick a new font size so it will not be larger than the height of label.
        var fontSizeToUse = Math.min(newFontSize, elementHeight);

				//Set font settings to draw it correctly.
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        var centerX = ((chart.chartArea.left + chart.chartArea.right) / 2);
        var centerY = ((chart.chartArea.top + chart.chartArea.bottom) / 2);
        ctx.font = fontSizeToUse+"px " + fontStyle;
        ctx.fillStyle = color;

        //Draw text in center
        ctx.fillText(txt, centerX, centerY);
			}
		}
	});



// Option: 
options: {
  elements: {
     center: {
       text: '90%',
       sidePadding: 60
     }
   }
}