使用getLonLatFromViewPortPx屏幕坐标转成经

获取屏幕坐标点

getScreenCoordinate(){
    var mercator = {};
    var clientObj = {
        x:event.changedTouches ? event.changedTouches[0].clientX:event.clientX,
        y:event.changedTouches ? event.changedTouches[0].clientY:event.clientY
    };
    mercator = map.getLonLatFromViewPortPx(clientObj);
    //得到的坐标mercator为900913坐标系，类似下面的坐标
    /*
    {
        lat:2647641.5511348,
        lon:12619918.294793
    }
    */
}