html2canvas - no screenshot for iframe

问题

I have a task where i need to load a URL (e.g www.yahoo.com) , on my webpage, and take screenshot. I am using html2canvas for screenshot and appending it to the body of the page.

The page specified by the URL is successfully loaded in an iframe inside a div element. But when i try to take screenshot of that, the iframe area comes blank.

Below is the code for previewURL and screenshot.

//to preview the URL content
function previewUrl(url,target){
    //use timeout coz mousehover fires several times
    clearTimeout(window.ht);
    window.ht = setTimeout(function(){
    var div = document.getElementById(target);
    div.innerHTML = '<iframe style="width:100%;height:100%;" frameborder="0" src="' + url + '" />';
    },20);      
}

function pic() {
      html2canvas(document.body, {
      onrendered: function(canvas) {
          document.body.appendChild(canvas);
         }
     });
 };

And the HTML part goes here :

<body>
    <input type="button" class="clear-button" onclick="pic();" value="Take Screenshot" >
    <a href="http://www.yahoo.com" onmouseover="previewUrl(this.href,'div1')">Hover to load</a>
    <div id="div1"></div>

</body>

The screenshot looks something like this :

I am stuck and don't understand why is this happening. I want something similar to this which can load URL and then onclick can give me screenshot.

回答1:

The problem here is that you are not pointing correctly to the part of the iframe that you want to take the screenshot, instead your are pointing directly to the document body.

you can try this:

var body = $(iframe).contents().find('body')[0];
        html2canvas(body, {
            onrendered: function( canvas ) {
                $("#content").empty().append(canvas);
            },

Hope this helps!