| 摘要 |
PURPOSE:To satisfactorily invert a picture by comparing an old area with a new area when the position of a designated area displayed on a display is changed and erasing the image in an old designated area excluding an overlapped part between the old and new areas while keeping this overlapped area in its original state so that a new designated area is set under the same display state as said overlapped part. CONSTITUTION:The form of a raster scan display picture is specified by a rectangular area 1 enclosed by apexes A-D. Then the area 1 is moved down and a cursor 2 is set within the area 1 to designate shift processing. The cursor 2 is moved down obliquely toward the right and a program is decided so that the area 1 is moved in response to the shift value and the shift direction of the cursor 2. Then a new rectangular area 1' enclosed by apexes A-D is designated by the shift of the cursor 2. in this case, an overlapped area enclosed by apexes A', P, C and Q is not inverted for display. An area enclosed by apexes A, B, P, A', Q and D is inverted and an area enclosed by apexes P, B', C', D', Q and C is defined as a negative picture.
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