Google Map screen capture is not working for marker and marker cluster using html2canvas

Question

I am doing python project using flask where I used google map api to show the map in the project. I implement html2canvas script to capture the map successfully. But I hav

Answer 1

1) Use useCORS:true or use proxy, never use both at the same time.

2) Your routes are different, see:

• virtual_path = '/gpsDataMap/images/'

• @surveyApp_module.route('/gpsDataMap/html2canvas/images/<image>')

3) Your proxy route, seems to be wrong (in your Javascript):

• "proxy":"/surveyApp/gpsDataMap/html2canvas-proxy",

• @surveyApp_module.route('/gpsDataMap/html2canvas-proxy')

---

You do not realize all errors, why the userCORS with the "PROXY" get confused.

Fix all routes (routes are their virtual paths) and fix your javascript (don't use userCORS:), see:

$(window).load(function(){
    $('#saveMap').click(function(){
        html2canvas(document.getElementById('map'), {
                "logging": true, //Enable log (use Web Console for get Errors and Warnings)
                //useCORS:true, "COMMENTED", remove useCORS
                "proxy": YOUR_FIXED_ROUTE,
                "onrendered": function(canvas) {
                    var img = new Image();
                    img.onload = function() {
                        img.onload = null;
                        document.body.appendChild(img);
                    };

                    img.onerror = function() {
                        img.onerror = null;
                        if(window.console.log) {
                            window.console.log("Not loaded image from canvas.toDataURL");
                        } else {
                            alert("Not loaded image from canvas.toDataURL");
                        }
                    };
                    img.src = canvas.toDataURL("image/png");
                }
        });
    });
});

---

See, this is absolute path mixed with "routes":

GET http://127.0.0.1:5555/home/bhim/app/surveyApp_bhim/images/a0af53c02bd2f2aed37f1d895edcf3485117c512.png 404 (NOT FOUND) html2canvas.js:2249

The route of proxy response for any reason is wrong, use this:

1) Edit your code, like this:

@surveyApp_module.route('/gpsDataMap/html2canvas-proxy')
def html2canvas_proxy():
    print ("is this proxy really calling ");
    h2c = html2canvasproxy(request.args.get('callback'), request.args.get('url'))
    h2c.userAgent(request.headers['user_agent'])

    if request.referrer is not None:
        h2c.referer(request.referrer)

    if request.args.get('debug_vars'): #Added
        return Response((',\n'.join(h2c.debug_vars())), mimetype='text/plain') #Added

    h2c.route(real_path, virtual_path)

    r = h2c.result()
    return Response(r['data'], mimetype=r['mime'])

2) Run in browser:

http://127.0.0.1:5000/gpsDataMap/html2canvas-proxy?callback=console.log&url=http://www.google.com&debug_vars=1

3) Get results and post in your queston.

Answer 2

please try this first it may work for you.

<script src="http://maps.googleapis.com/maps/api/js?key=AIzaSyDY0kkJiTPVd2U7aTOAwhc9ySH6oHxOIYM&sensor=false">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.js"></script> 
<script type="text/javascript" src ="http://code.jquery.com/jquery-1.9.0.min.js"></script>
<script type="text/javascript" src="html2canvas.js?rev032"></script> 



<script type="text/javascript">

function initialize()
    {
    var mapProp = {
          center:new google.maps.LatLng(51.508742,-0.120850),
          zoom:5,
          mapTypeId:google.maps.MapTypeId.ROADMAP
      };
    var map=new google.maps.Map(document.getElementById("googleMap"), mapProp);
}

google.maps.event.addDomListener(window, 'load', initialize);

 $(window).load(function(){

    $('#load').click(function(){

            html2canvas($('#googleMap'), {
            useCORS: true,
                onrendered: function (canvas) {
                var dataUrl= canvas.toDataURL("image/png").replace("image/png", "image/octet-stream");

                window.location.href = dataUrl;
                                    }
            });

    });
});
</script>
</head>

<body>
<div id="googleMap" style="width:500px;height:380px;"></div>
<input type="button" value="Save" id="load"/>
</body>

Answer 3

To save markers (workaround for html2canvas):

(Source#1) : http://humaan.com/custom-html-markers-google-maps/
(Source#2) : http://jsfiddle.net/BCr2B/99/

Its quick and quite simple to implement your own markers, which then circumvents the tainted problems.

function HTMLMarker(lat, lng, col) {
    this.lat = lat;
    this.lng = lng;
    this.col = col;
    this.pos = new google.maps.LatLng(lat, lng);
}

HTMLMarker.prototype = new google.maps.OverlayView();
HTMLMarker.prototype.onRemove = function() {}
HTMLMarker.prototype.onAdd = function() {}
HTMLMarker.prototype.draw = function() {
    var self = this;
    var div = this.div;

    if(!div) {
        div = this.div = document.createElement('div');
        div.className = 'marker';
        div.style.position = 'absolute';
        div.style.width = '32px';
        div.style.height = '32px';

        switch(this.col) {
            case "green":
                div.innerHTML = '<img src="/images/green-dot.png">';
                break;
            case "yellow":
                div.innerHTML = '<img src="/images/yellow-dot.png">';
                break;
            case "red":
                div.innerHTML = '<img src="/images/red-dot.png">';
                break;
        }

        var panes = this.getPanes();
        panes.overlayImage.appendChild(div);
    }


    var position = this.getProjection().fromLatLngToDivPixel(this.pos);
    div.style.left = position.x - 16 + "px";
    div.style.top = position.y - 32 + "px";
}

Then just add:

var htmlMarker = new HTMLMarker(data[gps].Latitude, data[gps].Longitude, "green");
markersArray.push(htmlMarker.setMap(map));

When you export in this way, the map markers are added successfully as they come from a local source.