| 摘要 |
PURPOSE:To always select the nearest line to the line brought to picture drawing even in the case of reduction picture drawing by providing an approximating means for approximating two points to an integer value, and an arithmetic means for calculating a picture drawing coordinate between them, based on a prescribed algorithm by using to points before approximation. CONSTITUTION:At the time of executing reduction picture drawing, a divider 18 divides a coordinate value contained in coordinate information given from a CPU 12 by a reduction rate, rounds off 5 bits or below of its decimal place, and gives a value of 4 bits below the decimal place to a picture drawing device 11. The picture drawing device 11 receives this information and generates successively a coordinate of a point brought to picture drawing by a picture drawing coordinate generator 15. Accordingly, when the coordinate information shown by a value containing a number of the decimal place or below is inputted as the case of reduction picture drawing, a picture drawing coordinate between a start point and an end point is calculated, based thereon. In such a way, comparing with the case of calculating the picture drawing coordinate by using a value being approximate to an integer as usual, an approximate error decreases, and even in the case of reduction picture drawing, a picture drawing point being near a line brought to picture drawing can always be selected. |
