| 摘要 |
PURPOSE:To prevent a diagram erased at the overlapped part of the diagram from being retrieved again, by checking a diagram data table formed newly earlier, in obtaining the diagram coincident with a prescribed point or located near. CONSTITUTION:The constitution of a diagram data storage area is shown in Figure. In displaying a new diagram on a display screen in addition to diagram data tables 7-1, 7-4, the new data 7-5 is formed (not shown) and located after the data 7-4. In retrieving a line designated at a point P, a square frame is provided around the point P, the data storage area is checked and lines crossing the frames of the square are obtained. In retrieving a point designated at the point P, points other than the point P in existence in the square frames are obtained. This retrieval is performed in the direction from the lower to the upper side of the diagram data storage area (reverse direction as display direction). |
