GRAPHIC PROCESSING UNIT

A painting processing unit obtains minimum and maximum values of data of a graphic in the Y direction, and effective scan lines are initialized. Then, it obtains coordinates of intersection points of the graphic contour and the scan lines, and X coordinates are sequentially registered in an edge list. A judgment is made as to whether the edge list has overflowed. If it has not overflowed, the edge list is rearranged after registering X coordinates of all intersection points, and painting is performed. If it has overflowed, the graphic is divided in two, and the effective scan lines are reset within a range of one-half of the initialized range. Then, all intersection points of contour and scan lines are obtained again, and only the X coordinates of intersection points within the reset effective scan lines are registered in the edge list. If there is no overflow, the divided graphic only within the range of the reset effective scan lines is painted. By the above processes, graphic painting according to an ordered edge list algorithm can be performed with lower memory capacity.