Browse Prior Art Database

On-The-Fly Generation of Graphics Characters

IP.com Disclosure Number: IPCOM000037005D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 5 page(s) / 125K

Publishing Venue

IBM

Related People

Noda, H: AUTHOR [+2]

Abstract

Disclosed is a system that generates graphics characters on the fly and shows graphics images on a display that does not support a bit map function. Generally speaking, if a user wants to show graphics on a display unit, it has to be equipped with a bit map feature. However, if it is equipped with single- and double-byte user-defined characters, graphics can be composed of pieces of images, called graphics characters.

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On-The-Fly Generation of Graphics Characters

Disclosed is a system that generates graphics characters on the fly and shows graphics images on a display that does not support a bit map function. Generally speaking, if a user wants to show graphics on a display unit, it has to be equipped with a bit map feature. However, if it is equipped with single- and double-byte user-defined characters, graphics can be composed of pieces of images, called graphics characters.

This system assumes that the initial screen consists of normal characters. Whenever a piece of graphics image is written on the screen, only the corresponding normal character is replaced with a graphics character and the image is drawn with the graphics character. Conventional method using graphics characters generate a complete image by batch processing. However, data comes slowly and continuously in interactive operation. On-the-fly generation is important for an interactive interface because it allows a fast drawing operation.

A mechanism is necessary to consolidate normal and graphics characters on the screen. Normally, characters are of two types: single- byte characters for the alphabet, and double-byte characters for Kanji. A single-byte character set can represent only 256 characters, but a double-byte set can represent many more. To solve this restriction, the system provides an additional feature that replaces two adjacent single-byte characters with one double-byte character (Fig. 1).

Whenever a piece of graphics image is drawn, the code of a corresponding character in the code buffer is checked to find whether it is a graphics character. Information about the characters on the screen is stored in the code buffer, and the code points to the image in the font buffer. If the code of a corresponding character has already been replaced with that of a graphics character, the system simply overwrites the graphics image on the font buffer. If not, a new graphics character is generated as follows: (1) the code of the new graphics character is generated, (2) the font image buffer is brought for it, (3) the image of the original character is copied to the font buffer of the graphics character, (4) a "control block" is created for the graphics character, (5) the code...