| 摘要 |
When a portable device cannot connect to a network, offline navigation directions are generated and displayed by obtaining navigation instructions stored on the portable device which direct a user from a first location to a second location. When a network connection later becomes available, the portable device obtains online navigation directions from the first location to the second location from a navigation server. The portable device updates the offline navigation directions in a least disruptive manner, with information from the online navigation directions by determining the difference between the online and the offline navigation directions. If the online and offline navigation directions are similar, the portable device updates the display with estimated time data, traffic data, etc., from the online navigation directions. On the other hand, if there is a significant difference between the online and offline navigation directions, the portable device displays the online navigation directions as an alternative route. |
