Adding 'enableShiftDrag' if we want to keep the original Leaflet func…

…tionality on top of having the button.

README.md

@@ -21,6 +21,7 @@ Then add the Control to your map:
 
 # Options
 
+* **enableShiftDrag** Enable the original functionality of Leaflet's shift-drag box zoom, in addition to the button.
 * **iconClasses** Any valid classes for an icon element. Used for easily adding a custom icon to the button.
 * **iconColor** Use to set the color of the custom icon. Accepts anything valid for a standard CSS color value, e.g. "black", "#000000", etc. Defaults to "black".
 * **keepOn** Boolean. Controls whether the zoombox state ends when drawing a zoom, or whether it's kept on. Defaults to false.

dist/leaflet-control-boxzoom-src.js

@@ -57,7 +57,9 @@ L.Control.BoxZoom = L.Control.extend({
         L.DomUtil.addClass(this.controlDiv,'leaflet-control-boxzoom-active');
         this.active = true;
         this.map.dragging.disable();
-        this.map.boxZoom.addHooks();
+        if (!this.options.enableShiftDrag) {
+            this.map.boxZoom.addHooks();
+        }
 
         this.map.on('mousedown', this.handleMouseDown, this);
         this.map.on('boxzoomend', this.setStateOff, this);
@@ -72,7 +74,9 @@ L.Control.BoxZoom = L.Control.extend({
         this.active = false;
         this.map.off('mousedown', this.handleMouseDown, this);
         this.map.dragging.enable();
-        this.map.boxZoom.removeHooks();
+        if (!this.options.enableShiftDrag) {
+            this.map.boxZoom.removeHooks();
+        }
 
         L.DomUtil.removeClass(this.map._container,'leaflet-control-boxzoom-active');
     },