International Business Machines Corporation

Shigeru Matsubara

David Carl Frank

Stephen P Thompson

Hiroshi Satoh

Toshiroh Tabata

Tohru Mori

Method and apparatus for displaying a horizontal screen separator line between two screen areas. A first step operates a display screen controller (12) in a split screen mode of operation so as to display a first screen area (3) at an upper portion of a display screen (18) and a second screen area (4) at a lower portion of the display screen. The step of operating further includes a step of reading data from a screen memory (42) and displaying rows of corresponding alphanumeric characters. Each character is displayed as a plurality of image pixels arranged along a first number of horizontal scan lines. A further step displays a horizontal visual separator (2) between a last row of the first screen area and a first row of the second screen area. The step of displaying the horizontal visual separator includes the steps of (a) reading data from the screen memory and beginning a display of a row of corresponding visual separator characters; and (b) terminating the display of the row of corresponding visual separator characters after displaying a second number of horizontal scan lines that is less than the first number of horizontal scan lines.

Method and apparatus for displaying a screen separator line

An area fill technique for graphic images is disclosed wherein the contour lines constituting an image are given in a series of line segments or a series of vectors, and horizontal line segments are ignored. Each line segment other than the horizontal ones is specified by the coordinate addresses for the start and end points in one direction, that is, from top to bottom or from bottom to top. Each is then converted into approximate pixels in the X-Y coordinate system, and stored in a random access work memory. The pixels of each line segment are stored in the work memory according to a rule whereby each line segment is represented by one pixel per horizontal line, and is written by taking exclusive OR of its pixels, excluding the start point, with read pixel data at corresponding coordinate addresses in the work memory. Thus, an even number of contour line pixels exist in each horizontal line in the work memory, and, area fill can be realized by scanning each horizontal line in the work memory and turning on pixel memory cells from an odd numbered contour line pixel to an even numbered contour line pixel. This technique makes it possible to easily perform area fill even for complicated images.

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Yamato, Japan

Shigeru Matsubara