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Line thickness drawing issue with discontinuities

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  • #6244

    I have noticed that the line chart doesn’t draw the lines with consistent thickness when there are discontinuities in the graph. It looks like some part are re-drawn, or drawn thicker than requested.

    A simple way of reproducing the issue, with the realtime example:


    Change the y value assigned so that there are discontinuities once in a while:

    y: ((xVal%100)<5) ? “” :yVal

    And set a very narrow line thickness, so that the issue is more noticeable. I actually noticed it with lineThickness = 1, but for the sake of reproducing the error, let’s assign something really small, like 0.01.

    lineThickness: 0.01,

    The graph should be barely visible, but it is more visible (thicker line) in some parts than in others.

    The full html (copy-pasted from the modified example) would be:

    	<script type="text/javascript">
    	window.onload = function () {
    		var dps = []; // dataPoints
    		var chart = new CanvasJS.Chart("chartContainer",{
    			title :{
    				text: "Live Random Data"
    			data: [{
    				type: "line",
                    lineThickness: 0.01,
    				dataPoints: dps 
    		var xVal = 0;
    		var yVal = 100;	
    		var updateInterval = 20;
    		var dataLength = 500; // number of dataPoints visible at any point
    		var updateChart = function (count) {
    			count = count || 1;
    			// count is number of times loop runs to generate random dataPoints.
    			for (var j = 0; j < count; j++) {	
    				yVal = yVal +  Math.round(5 + Math.random() *(-5-5));
    					x: xVal,
    					y: ((xVal%100)<5) ? "" :yVal
    			if (dps.length > dataLength)
    		// generates first set of dataPoints
    		// update chart after specified time. 
    		setInterval(function(){updateChart()}, updateInterval); 
    	<script type="text/javascript" src="https://cdn.canvasjs.com/canvasjs.min.js"></script>
    	<div id="chartContainer" style="height: 300px; width:100%;">

    PS. Congratulations on the library. It is very simple, lightweight, and powerful at the same time.

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