MAP SCROLLING DEVICE

摘要

A prefetch drawing size calculation unit (6) determines the prefetch drawing size on the basis of the scroll speed and the scroll direction. A prefetch drawing area calculation unit (7) determines the prefetch drawing area from the scroll speed, the scroll direction and the prefetch drawing size. A background drawing memory (11) stores the map data in the prefetch drawing area and switches over to the foreground drawing memory (12). A rectangle cutout unit (14) cuts out a display rectangle portion from the switched over foreground memory (12), and the display rectangle is displayed on the display unit (15).