Browse Prior Art Database

Pattern Dragging

IP.com Disclosure Number: IPCOM000046007D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 64K

Publishing Venue

IBM

Related People

Halliwell, H: AUTHOR

Abstract

Dragging is a graphics term that describes the moving of a pattern, image or shape on a CRT graphics display surface from one location to another, usually using a light pen. In other words, the pattern is selected by the light pen and moved to any other location on the CRT by following the light pen.

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Pattern Dragging

Dragging is a graphics term that describes the moving of a pattern, image or shape on a CRT graphics display surface from one location to another, usually using a light pen. In other words, the pattern is selected by the light pen and moved to any other location on the CRT by following the light pen.

An essential and necessary requirement for moving a pattern, which is assumed to be stored in a data base linked list, is that the pattern contain no absolute graphic orders. An absolute graphic order means a command or operand within the linked list which is a function of the actual location of the pattern on the face of the graphics display CRT. Prior-art solutions include scanning the data base and generating a version of the pattern having no absolute orders. This approach has the disadvantage of requiring an excessive amount of time.

Another prior-art solution is to duplicate all absolute orders with relative orders in the host processer storage. This approach has the disadvantage of requiring a large memory capacity which is inefficiently used.

Another solution in the prior art is to draw all the patterns without absolute orders and patch the selected pattern for dragging, but this process is slow and causes distracting flickering of the image on the tube.

These prior-art solutions are further unattractive when the additional constraint is imposed requiring that the original pattern remain in place; i.e., the dragged image is a duplicate of the pattern which remains in its original location.

The method to be described uses the display microcode, with all patterns being drawn using absolute vectors, with some use of incremental vectors for optimization. The display processor, i.e., a processor separate from the main (host) processor...