Why is chart.js canvas not respecting the padding of the container element?

Question

I am using Chart.js with a simple line chart but the width and height properties calculated by Chart.js seem to be based on the total width and height of the parent element ignoring padding.

var options = {      maintainAspectRatio: false,      responsive: true  };    var data = {      labels: ["", "", "", "", "", "", ""],      datasets: [          {              label: "My First dataset",              fillColor: "rgba(220,220,220,0.2)",              strokeColor: "rgba(220,220,220,1)",              pointColor: "rgba(220,220,220,1)",              pointStrokeColor: "#fff",              pointHighlightFill: "#fff",              pointHighlightStroke: "rgba(220,220,220,1)",              data: [65, 59, 80, 81, 56, 55, 40]          },          {              label: "My Second dataset",              fillColor: "rgba(151,187,205,0.2)",              strokeColor: "rgba(151,187,205,1)",              pointColor: "rgba(151,187,205,1)",              pointStrokeColor: "#fff",              pointHighlightFill: "#fff",              pointHighlightStroke: "rgba(151,187,205,1)",              data: [28, 48, 40, 19, 86, 27, 90]          }      ]  };    var ctx1 = document.getElementById("mychart1").getContext("2d");  var myNewChart = new Chart(ctx1).Line(data, options);

.container {      padding: 15px 15px 15px 15px;      width: 300px;      height: 200px;      border: 1px solid black;  }    .child {      display: inline-block;      border: 1px solid red;      width:100%;      height:100%;  }

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/1.1.1/Chart.js"></script>      <div class='container'>      <canvas id='mychart1' class='child'></canvas>  </div>  <br>  <div class='container'>      <div class='child'>test</div>  </div>

JSFiddle

The second container and child shows the behaviour I am expecting. Is this a bug with how Chart.js calculates the width and height of the canvas or am I making a styling mistake?

Answer 1

I also needed a responsive canvas and had this issue. This was my fix:

<div>     <canvas id="chart"></canvas> </div> 

Since Chart.js scales the canvas to the width of the container, ignoring the padding, I just wrapped the canvas in a div. The div scales to the container with padding, respecting the padding, and then the responsive Chart.js canvas scales to the div.