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# Line Division Algorithm Which Prevents Non-Rectangular Geometry on a Shared Display Screen

IP.com Disclosure Number: IPCOM000059604D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 22K

IBM

## Related People

Leonard, AG: AUTHOR [+3]

## Abstract

By using a line division algorithm, a user is protected from creating invalid (non-rectangular) geometry on a shared display screen, thus maintaining application task areas on the screen. On a display screen, application task areas must be maintained in rectangular form after a user has moved any number of lines bordering the task areas. To protect the user from creating invalid geometry on a shared display, an algorithm is presented which allows for the movement of only those lines, or line segments, which are valid. The rule that governs line division into segments is as follows: If any line is intersected, or a border line is joined by another line, it is split into line segments at the point of intersection or juncture.

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Line Division Algorithm Which Prevents Non-Rectangular Geometry on a Shared Display Screen

By using a line division algorithm, a user is protected from creating invalid (non- rectangular) geometry on a shared display screen, thus maintaining application task areas on the screen. On a display screen, application task areas must be maintained in rectangular form after a user has moved any number of lines bordering the task areas. To protect the user from creating invalid geometry on a shared display, an algorithm is presented which allows for the movement of only those lines, or line segments, which are valid. The rule that governs line division into segments is as follows: If any line is intersected, or a border line is joined by another line, it is split into line segments at the point of intersection or juncture. Otherwise, the line remains unsegmented from border to border to the next intersection, or to its termination at the point that it joins another line. For instance, in Figs. 1 and 2, which show intersection and line junction, respectively, there are four task areas. However, the line segments which are eligible for movement differ. In Fig. 1, all of the line segments, AE, BE, CE, and DE, may be moved independently. In Fig. 2, the movement of segment AE in either direction results in invalid geometry, i.e., non-rectangularity. Hence, in the Fig. 2 configuration, segments AE, AF, CF, CE and EF are not offered to the user for movement. The smallest segment...