Google maps 如何在extjs中绘制地图内部的条形图

如何在ExtJS中在google地图中绘制条形图。我需要java脚本代码，用于在此地图代码中绘制条形图：

{
     xtype: 'gmappanel',
     id: 'map',
     height: 688,
     width: 1565,
     zoomLevel: 14,
     mapConfOpts: ['enableScrollWheelZoom', 'enableDoubleClickZoom', 'enableDragging'],
     mapControls: ['GSmallMapControl', 'GMapTypeControl', 'NonExistantControl'],
     center: {
               geoCodeAddr: 'St. Peters College, Kolenchery, Ernakulam, 682311, INDIA',
               marker: {title: 'St. Peters College'}
             },
     markers: [{
               lat: 42.339641,
               lng: -71.094224,
               marker: {title: 'Boston Museum of Fine Arts'},
               icon: 'resources/images/greenbtn.png',
               listeners: {
                           click: function(e) {
                           Ext.Msg.alert({title: 'Its fine', text: 'and its art.'});
                          }
                        }
                      },
                      {
                           lat: 42.339419,
                           lng: -71.09077,
                           marker: {title: 'Northeastern University'}
                       }

             ]
}