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Browse Prior Art Database

Panning by Borderline Characters

IP.com Disclosure Number: IPCOM000044579D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Mamiya, J: AUTHOR [+2]

Abstract

This article describes a method for facilitating horizontal scrolling or panning of a foreground image displayed in a viewport which is partitioned by two vertical (left and right) borderlines and two horizontal (top and bottom) borderlines. A plurality of viewports can be supported. Fig. 1 shows an example of panning from the right to the left. In this example, a display enable signal is generated for N characters, but the foreground image is actually displayed for N-1 characters so as to allow the foreground image to be panned. Therefore, as shown by a dotted line, a part of the foreground image corresponding to a single character area should be hidden. This is achieved by the present method utilizing a vertical borderline signal associated with a viewport in which the foreground image is to be panned. Fig.

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Panning by Borderline Characters

This article describes a method for facilitating horizontal scrolling or panning of a foreground image displayed in a viewport which is partitioned by two vertical (left and right) borderlines and two horizontal (top and bottom) borderlines. A plurality of viewports can be supported. Fig. 1 shows an example of panning from the right to the left. In this example, a display enable signal is generated for N characters, but the foreground image is actually displayed for N-1 characters so as to allow the foreground image to be panned. Therefore, as shown by a dotted line, a part of the foreground image corresponding to a single character area should be hidden. This is achieved by the present method utilizing a vertical borderline signal associated with a viewport in which the foreground image is to be panned. Fig. 2 shows a timing relationship between the vertical borderline (V BORDER) and display enable (DISP EN) signals with respect to the associated viewport. Both signals are generated by a CRT controller (not shown) when the viewport is to be displayed on a screen. The CRT controller activates the V BORDER for a character cycle during which a vertical borderline having, for example, two-dot width is drawn. The viewport is displayed when the DISP EN is on. In order to hide a part of the foreground image in the viewport, the V BORDER is ANDed with the DISP EN so that a force background (FORCE BG) signal is generated. The FORCE BG is...