在新的HTML窗口中保存画布和弹出窗口

Question

My html 5 canvas is being saved to a server via php. It also pops up in a new window that is not html. The new window only contains the png image. I would like this new popup window to be able to share to social media. I know about auth2.0 and setting that up. What I don't know is how to get my png created from the saved canvas to popup on a new html page so I can add my social media tools. I am pretty sure it would be an edit to this line, window.open(testCanvas.toDataURL("images/png"));.

function saveImage() {
cursor.visible = false; stage.update();
var canvasData = testCanvas.toDataURL("image/png");
window.open(testCanvas.toDataURL("images/png"));
var xmlHttpReq = false;       
if (window.XMLHttpRequest) {
ajax = new XMLHttpRequest();
cursor.visible = true; stage.update();
}

else if (window.ActiveXObject) {
ajax = new ActiveXObject("Microsoft.XMLHTTP");
}
ajax.open('POST', 'testSave.php', false);
ajax.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
ajax.onreadystatechange = function() {
console.log(ajax.responseText);
}
ajax.send("imgData="+canvasData);
}

Answer 1

New example without server side (using localStorage)

On the first page:

<input type="file" id="upfile" />
<script>
    $ = function(id) { return document.getElementById(id); };

    $('upfile').onchange = function(e) {
        var files = e.target.files;
        for (var i = 0; i < files.length; i++)
        {
            var f = files[i];
            if (! f.type.match('image.*'))
                continue;
            var reader = new FileReader();
            reader.onload = (function(filecontent) {
                return function(ev) {
                    var b64data = ev.target.result;
                    localStorage.setItem('img', b64data);
                    window.open('popup.html', 'popup', 'width=600,height=400');
                };
            })(f);
            reader.readAsDataURL(f);
        }
    };
</script>

In the popup page:

<img src="" id="thepicture" />

<script>
window.onload = function() {
    document.getElementById('thepicture').src = localStorage.getItem('img');
};
</script>

Check the working demo here