| 摘要 |
PURPOSE:To always display a map to be easily observed by detecting density for the distribution of map data in map data normalizing coordinate system and controlling the reduced scale of display corresponding to the detected data amount. CONSTITUTION:After loading a map data group in an area over a fixed range with a current spot as a center, a CPU 7 judges whether a fine control command for the reduced scale of display is outputted by the key input of an input device 21 or not, and when the fine control command is outputted, the CPU 7 detects the density for the distribution of the map data in the map data normalizing coordinate system. When the density is detected, the CPU 7 determines a zoom magnification coefficient Z corresponding to the data amount, fetches the coefficient, sets the number of graphics to a graphic counter and executes a subroutine processing for drawing one graphic. After the processing is executed, the CPU 7 decrements the graphic counter and executes the subroutine processing for drawing one graphic until a value N of the counter becomes 0. |
