Introduced Support for marker snapshot in leaflet

There is still a problem when the map is panned.
When possible, you have to parse the transform inline style of the mapdiv to properly shift the clonded marker div to snap (or properly set the canvas).

web/client/components/map/leaflet/snapshot/GrabMap.jsx

@@ -197,8 +197,30 @@ let GrabLMap = React.createClass({
 
                 });
                 let finialize = () => {
-                    this.props.onStatusChange("READY", this.isTainted(finalCanvas));
-                    this.props.onSnapshotReady(canvas, null, null, null, this.isTainted(finalCanvas));
+                    // TODO parse map-div transform to shift all markers toghether properly
+                    let markers = this.mapDiv.getElementsByClassName("leaflet-marker-pane");
+                    if ( markers && markers.length > 0) {
+                        let newCanvas = this.refs.canvas.cloneNode();
+                        newCanvas.width = newCanvas.width + left;
+                        html2canvas(markers, {
+                                // you have to provide a canvas to avoid html2canvas to crop the image
+                                canvas: newCanvas,
+                                logging: false,
+                                proxy: this.proxy,
+                                allowTaint: props && props.allowTaint,
+                                // TODO: improve to useCORS if every source has CORS enabled
+                                useCORS: props && props.allowTaint
+                        }).then( (c) => {
+                            let cx = finalCanvas.getContext("2d");
+                            cx.globalAlpha = 1;
+                            cx.drawImage(c, -1 * left, 0);
+                            this.props.onStatusChange("READY", this.isTainted(finalCanvas));
+                            this.props.onSnapshotReady(canvas, null, null, null, this.isTainted(finalCanvas));
+                        });
+                    } else {
+                        this.props.onStatusChange("READY", this.isTainted(finalCanvas));
+                        this.props.onSnapshotReady(canvas, null, null, null, this.isTainted(finalCanvas));
+                    }
                 };
 
                 if (svg) {