| 摘要 |
Below a transparent board-like digitizer, a screen of the same size as that of the digitizer is placed. Scenes of a display device is displayed on the screen. A co-ordinates standard of the digitizer is set to be identical with that of the screen. Thereby, the point indicated on the digitizer of a first cursor device is shown at a position corresponding to that of the point indicated by means of the cursor. The screen displays a right-angle scale lines controlled by a second cursor device on the digitizer. The right-angle scale lines can carry out parallel movements and rotations on the screen. In a drafting mode of the digitizer, the operator hits each points shown on the digitizer through the first cursor device on the basis of, or with reference to the right-angle scale lines in order to draw patterns on the screen. The center of the right-angle scale lines is moved to, or into, an area of the original pattern on the screen. The area intended to enlarged, by using the second cursor device in order to make the control apparatus to of an enlargedly displaying or indication mode. Thus, an enlarge indication area is formed on the screen using the center of the right-angle scale lines as a standard. In the area, an enlarged pattern or picture is displayed overlapping on the original one with the original width of the lines and the enlarged length of the lines of the original pattern. Accordingly, the operator can use the first cursor device to draw patterns in the enlarged indication area.
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