touch handler for openlayers maps

OpenLayers.Touch.Handler.js

/*
 * touch handler for openlayers maps on mobile
 * see: http://www.openlayers.org/
 */

var map = {} // dummy object -> create & init an openlayers map

Touch = (function() { return {
    startX: 0,
    startY: 0,
    zooming: false,
    moving: false,
    Handler: function(event) {
        var touch = event.changedTouches[0];
        // bubbling
        switch (event.type) {
            case "touchstart":
                Touch.startX = touch.clientX
                Touch.startY = touch.clientY
                break;
            case "touchmove":
                event.preventDefault() // stop dragging on ipad
                Touch.zooming = (event.touches.length > 1)
                Touch.moving = (event.touches.length == 1)
                break;
            case "touchend":
                if(Touch.zooming) {
                    event.preventDefault()
                    // todo - better calc for centre of zoom pinch
                    var pos = OpenLayers.Util.pagePosition(map.div);
                    var newX = Touch.startX - pos[0]
                    var newY = Touch.startY - pos[1]
                    var newCenter = map.getLonLatFromViewPortPx( {x: newX, y: newY} );
                    map.setCenter(newCenter)
                    if(event.scale < 1) map.zoomOut()
                    else map.zoomIn()
                    Touch.zooming = false
                }
                else if(Touch.moving) {
                    event.preventDefault()
                    var center = map.getViewPortPxFromLonLat(map.getCenter());
                    var pos = OpenLayers.Util.pagePosition(map.div);
                    panX = touch.clientX - pos[0]
                    panY = touch.clientY - pos[1]
                    Touch.startX -= pos[0]
                    Touch.startY -= pos[1]
                    panX = center.x + (Touch.startX - panX)
                    panY = center.y + (Touch.startY - panY)
                    var newCenter = map.getLonLatFromViewPortPx( {x: panX, y: panY} );
                    map.setCenter(newCenter)
                    Touch.moving = false
                }
                break;
            default: 
				break;
        }
    }  // end Handler
}})()

map.div.ontouchstart = Touch.Handler;
map.div.ontouchmove = Touch.Handler;
map.div.ontouchend = Touch.Handler;