title: How to draw multiple images on canvas and save the canvas as png image
body: <p>Hello I am trying to draw multiple images on a canvas, and after that save it as png using html2canvas and canvas2image.</p>
  
  <p>The problem is that only the last image is drawn and when I download it isn't downloading with the image.</p>
  
  <p>I am using a for loop to iterate through the images and then get the src value and their offset to draw. But I think I am missing something here, because only the last image is rendering, but not saving in the file.</p>
  
  <p>Below what I am using to render the images on the canvas:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>$(function() { 
    $("#btnSave").click(function() { 
      html2canvas($("#widget"), {
        onrendered: function(canvas) {
          var context = canvas.getContext("2d"); // returns the 2d context object
          var images = document.getElementsByClassName('simg');
          //Find actual position with parent cotainer
  
          var offsetsContainer = document.getElementsByClassName('imagesholder')[0].getBoundingClientRect();
          for (var i = 0; i &lt; images.length; i++) {
            var img = new Image() //creates a variable for a new image
            var offsets = images[i].getBoundingClientRect();
            var imgTop = offsets.top;
            var imgLeft = offsets.left;
            imageLeft = parseInt(imgLeft) - parseInt(offsetsContainer.left);
            imageTop = parseInt(imgTop) - parseInt(offsetsContainer.top);
            img.src = images[i].src; // specifies the location of the image
            img.onload = function() {
              context.drawImage(img, imageLeft, imageTop);// draws the image at the specified x and y location
            }
          }
          // Convert and download as image 
          theCanvas = canvas;
          document.body.appendChild(canvas);
  
          // Convert and download as image 
          Canvas2Image.saveAsPNG(canvas); 
          $("#img-out").append(canvas);
        }
      });
    });
  });</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>body {
      font-family: "Lucida Grande", "Lucida Sans", Arial, sans-serif;
      font-family: "HelveticaNeue-Light", "Helvetica Neue Light", "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;
  
  }
  
  .dataset {
      float: left;
      vertical-align: top;
  
  
  }
  
  .widget{
      display: inline-block;
      background-color: white;
      font-size: 14px !important;
      line-height: 20px !important;
  
      margin: 5px;
      vertical-align: top;
      color: #333;
  
      border-radius: 5px;
      margin: 10px;
      padding-bottom: 20px;
      border: 1px solid lightgray;
  
  
      border-radius:5px;
      -webkit-border-radius: 5px;
  
  
      display: inline-block;
      page-break-after: always;
  
  }
  
  .widget .header p {
     padding: 10px;
     border-bottom: 1px solid lightgrey;
     max-width: 360px;
  }
  
  .widget .header .title {
      font-weight: bold;
      vertical-align: middle;
      min-height: 36px;
      padding: 5px 10px 5px 10px;
  
  }
  
  .widget .header:hover {
      background-color: #f4f4f4;
  }
  
  .widget .header  .title.selected {
      border-color: cornflowerblue;
      background-color: #EEF;
  
  }
  
  .widget .content {
      padding: 5px;
      overflow-y: auto;
      max-height: 400px;
  }
  
  .autolayout {
      display: inline-block;
  }
  
  .element {
      width: 360px;
  }
  
  .compact .content {
      display: table;
      width: 100%;
  }
  
  .compact .row {
      display: table-row;
      width: 100%;
  }
  
  .compact .cell {
      display: table-cell;
  }
  
  .compact .row.selected {
      background-color: #eee;
  }
  
  
  
  .toolbar {
      display: block;
      vertical-align: top;
      margin: 10px;
  }
  
  .toolbar .basis {
      min-width: 100px;
  }
  
  .btn {
      /*min-width: 60px;*/
  }
  
  
  .cell.value {
      overflow: hidden;
      text-wrap: none;
      white-space: nowrap;
      text-overflow: ellipsis;
      text-align: right;
      padding-right: 10px;
  }
  
  .cell.freq {
      width: 60px;
  }
  
  .cell.glyph {
      vertical-align: middle;
      width: 100px;
  }
  
  
  .element {
  
  }
  .element table {
      table-layout: fixed;
      width: 100%;
  }
  
  .element td {
      padding: 0px;
  
  }
  
  .element .selectable:hover {
      background-color: #f4f4f4;
  }
  
  
  .element .stat {
      text-align: right;
      padding-right: 20px;
      font-weigth: bold;
      color: darkgray;
  }
  
  
  
  .element .bar {
      height: 18px;
      display: inline-block;
      float: left;
  }
  .bar-both {
      background-color: #0a67a3 !important;
  
  }
  
  .bar-fg {
      background-color: #3e97d1 !important;
  }
  
  .bar-bg {
      background-color: #ddd !important;
  }
  
  .selected .bar-fg {
      background-color: #FC0;
  }
  
  .selected .bar-both  {
      background-color:#FA0;
  }
  
  tr.selected {
      background-color: #eee;
  }
  
  .crosstab .selectable:hover {
      background-color: #f4f4f4;
  }
  
  .crosstab tr.selected {
      background-color: #eee;
  }
  
  .crosstab .header p {
      max-width: 600px;
  }
  
  
  .crosstab td {
    padding: 0 5px 0 5px;
    text-align: right;
  }
  
  .crosstab td.value {
    min-width: 60px;
    max-width: 240px;
    text-align: left;
  }
  
  .crosstab .cell {
      vertical-align: top;
  }
  
  
  
  .crosstab th.cell {
      max-width: 120px;
      overflow: hidden;
      white-space: normal;
      text-overflow: ellipsis;
      text-align: right;
      padding-right: 10px;
      vertical-align: bottom;
  }
  
  .crosstab .n {
      color: darkgray;
  }
  .fieldlist {
  }
  
  .constraints {
      min-width:300px;
      padding: 10px;
  
      border-radius:5px;
      -webkit-border-radius: 5px;
  
  
  }
  .constraints table {
      width: 100%;
  
  }
  
  .sidenote {
    max-width:300px;
    padding: 0 10px 0px 10px;
    display: inline-block;
    vertical-align: top;
  }
  
  .headnote {
      max-width: 600px;
      padding: 10px;
      margin: 10px;
      display: inline-block;
  }
  
  .info-block {
      /*border: 1px solid lightgrey;*/
      background-color: #eee;
      vertical-align: top;
      margin: 10px;
      padding: 10px;
      display: block;
  
      /*box-shadow: 0 0 0 0px #9bc0cf, 0 0 0 3px #e0ebf0;*/
  }
  
  .menu-item {
  }
  
  .menu-item-value {
      text-align: right;
      float: right;
  }
  
  .gradient-blue {
      background: #b8e1fc;
      background: -moz-linear-gradient(top, #b8e1fc 0%, #a9d2f3 10%, #90bae4 25%, #90bcea 37%, #90bff0 50%, #6ba8e5 51%, #a2daf5 83%, #bdf3fd 100%); /* FF3.6+ */
      background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #b8e1fc), color-stop(10%, #a9d2f3), color-stop(25%, #90bae4), color-stop(37%, #90bcea), color-stop(50%, #90bff0), color-stop(51%, #6ba8e5), color-stop(83%, #a2daf5), color-stop(100%, #bdf3fd)); /* Chrome,Safari4+ */
      background: -webkit-linear-gradient(top, #b8e1fc 0%, #a9d2f3 10%, #90bae4 25%, #90bcea 37%, #90bff0 50%, #6ba8e5 51%, #a2daf5 83%, #bdf3fd 100%); /* Chrome10+,Safari5.1+ */
      background: -o-linear-gradient(top, #b8e1fc 0%, #a9d2f3 10%, #90bae4 25%, #90bcea 37%, #90bff0 50%, #6ba8e5 51%, #a2daf5 83%, #bdf3fd 100%); /* Opera 11.10+ */
      background: -ms-linear-gradient(top, #b8e1fc 0%, #a9d2f3 10%, #90bae4 25%, #90bcea 37%, #90bff0 50%, #6ba8e5 51%, #a2daf5 83%, #bdf3fd 100%); /* IE10+ */
      background: linear-gradient(to bottom, #b8e1fc 0%, #a9d2f3 10%, #90bae4 25%, #90bcea 37%, #90bff0 50%, #6ba8e5 51%, #a2daf5 83%, #bdf3fd 100%); /* W3C */
      filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#b8e1fc', endColorstr='#bdf3fd', GradientType=0); /* IE6-8 */
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="https://cdn.jsdelivr.net/npm/canvas2image@1.0.5/canvas2image.min.js"&gt;&lt;/script&gt;
  &lt;script src="https://github.com/niklasvh/html2canvas/releases/download/0.4.1/html2canvas.js"&gt;&lt;/script&gt;
  &lt;div id="widget" class="widget" field="AGE" roundby="20" description="Patient age, in years"&gt;
    &lt;div class="header"&gt;
      &lt;h3&gt;
        Testing header
      &lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="imagesholder"&gt;
      &lt;img src="https://lorempixel.com/output/technics-q-c-100-50-2.jpg" class="simg"/&gt;
      &lt;img src="https://lorempixel.com/output/technics-q-c-100-50-8.jpg" class="simg"/&gt;
      &lt;img src="https://lorempixel.com/output/technics-q-c-100-50-3.jpg" class="simg"/&gt;
    &lt;/div&gt;
    &lt;div class="element ng-scope"&gt;
      &lt;div class="content"&gt;
        &lt;table&gt;
          &lt;colgroup&gt;
            &lt;col/&gt;
            &lt;col width="60x"/&gt;
            &lt;col width="100px"/&gt;
          &lt;/colgroup&gt;
          &lt;thead&gt;
            &lt;tr&gt;
              &lt;th class="cell value"&gt;Value&lt;/th&gt;
              &lt;th class="cell freq"&gt;Freq&lt;/th&gt;
              &lt;th class="cell value"&gt;&lt;/th&gt;
            &lt;/tr&gt;
          &lt;/thead&gt;
          &lt;tbody&gt;
            &lt;tr class="selectable"&gt;
              &lt;td class="cell value"&gt;&lt;span tooltip="0 to 19"&gt;0 to 19&lt;/span&gt;&lt;/td&gt;
              &lt;td class="cell freq"&gt;17.2%&lt;/td&gt;
              &lt;td class="cell glyph"&gt;
                &lt;span class="bar bar-both" style="width: 17.234468937875754%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-fg" style="width: 0%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-bg" style="width: 0%;"&gt;&lt;/span&gt;
              &lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr class="selectable"&gt;
              &lt;td class="cell value"&gt;&lt;span tooltip="20 to 39"&gt;20 to 39&lt;/span&gt;&lt;/td&gt;
              &lt;td class="cell freq"&gt;18.0%&lt;/td&gt;
              &lt;td class="cell glyph"&gt;
                &lt;span class="bar bar-both" style="width: 18.03607214428858%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-fg" style="width: 0%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-bg" style="width: 0%;"&gt;&lt;/span&gt;
              &lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr data-key="40" class="selectable"&gt;
              &lt;td class="cell value"&gt;&lt;span tooltip="40 to 59"&gt;40 to 59&lt;/span&gt;&lt;/td&gt;
              &lt;td class="cell freq ng-binding"&gt;34.3%&lt;/td&gt;
              &lt;td class="cell glyph"&gt;
                &lt;span class="bar bar-both" style="width: 34.2685370741483%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-fg" style="width: 0%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-bg" style="width: 0%;"&gt;&lt;/span&gt;
              &lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr class="selectable"&gt;
              &lt;td class="cell value"&gt;&lt;span tooltip="60 to 79"&gt;60 to 79&lt;/span&gt;&lt;/td&gt;
              &lt;td class="cell freq ng-binding"&gt;24.0%&lt;/td&gt;
              &lt;td class="cell glyph"&gt;
                &lt;span class="bar bar-both" style="width: 24.04809619238477%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-fg" style="width: 0%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-bg" style="width: 0%;"&gt;&lt;/span&gt;
              &lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr data-key="80" class="selectable"&gt;
              &lt;td class="cell value"&gt;&lt;span tooltip="80 to 99"&gt;80 to 99&lt;/span&gt;&lt;/td&gt;
              &lt;td class="cell freq"&gt;6.4%&lt;/td&gt;
              &lt;td class="cell glyph"&gt;
                &lt;span class="bar bar-both" style="width: 6.4128256513026045%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-fg" style="width: 0%;"&gt;&lt;/span&gt;
                &lt;span class="bar bar-bg" style="width: 0%;"&gt;&lt;/span&gt;
              &lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr&gt;
              &lt;td class="stat"&gt;Mean&lt;/td&gt;
              &lt;td &gt;46.1&lt;/td&gt;
            &lt;/tr&gt;
          &lt;/tbody&gt;
        &lt;/table&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  &lt;br/&gt;
  &lt;input type="button" id="btnSave" value="Save PNG"/&gt;
  
  &lt;div id="img-out"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>