HTML2Canvas converting overflowed content to image

Question

I have a div which is pretty overflowed. It basically includes a big organization chart. What I want to do is exporting whole content of div rather than visible part with html2canvas library but I couldn't achieve it so far. Following piece of code doesn't render full content. Is there a way to achieve it?

function export(){  
    html2canvas( [ document.getElementById('diagram') ], {
        onrendered: function(canvas) {

            var dataUrl = canvas.toDataURL();
            window.open(dataUrl, "toDataURL() image", "width=800, height=800");
            //Canvas2Image.saveAsPNG(canvas);
        }
     });
}

I am using BasicPrimitives library to generate organization charts. It takes a div and insert all elements to it. Since my chart is moderately big, it overflows from its container. Xhtml code is as follows:

<rich:panel style="float: left; width: 100%;">
     <div style="float: left; height:600px; margin-left: 1%;  width: 19%; border-style: dotted; border-width:1px;">
          Some irrelevant content
     </div>
     <div id="diagram" class='diagram' style="float: right; height:600px;  width: 59%; border-style: dotted; border-width:1px;">
          This is the div all charts are dynamically inserted
     </div>
     <div style="float: left; height:600px; margin-left: 1%;  width: 19%; border-style: dotted; border-width:1px;">
          Some more irrelevant content 
     </div>
</rich:panel>

Answer 1

I don't know if there's a straightforward option in html2canvas to do this (i.e. an option to set all overflow to visible) but a roundabout way might be to set the parent of the diagram element's overflow property to visible when your export function is called, then set it back to hidden again on html2canvas' onrendered callback so that the user has minimal time to perceive it:

function export(){ 
document.getElementById('diagram').parentNode.style.overflow = 'visible'; //might need to do this to grandparent nodes as well, possibly.
    html2canvas( [ document.getElementById('diagram') ], {
        onrendered: function(canvas) {
            document.getElementById('diagram').parentNode.style.overflow = 'hidden';
            var dataUrl = canvas.toDataURL();
            window.open(dataUrl, "toDataURL() image", "width=800, height=800");
            //Canvas2Image.saveAsPNG(canvas);
        }
     });
}

Answer 2

Give a try to dom-to-image, it works better for me since I have to set specific size, and show and element that hides for some screen size:

function convertCanvasAndSend(idElement, nameImage) {
var element = document.getElementById(idElement);
var styleOrig = element.getAttribute("style");
element.setAttribute("style", "width: 1400px; height: 480px;");
element.querySelector("ANY_HIDDEN_YOU NEED").setAttribute("style", "display: block;");
domtoimage.toBlob(element)
.then(function (blob) {
    window.saveAs(blob, nameImage + '.png');
    element.setAttribute("style", styleOrig);
    element.querySelector("ANY_HIDDEN_YOU NEED").setAttribute("style", styleOrigInnDiv);
});

}