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Method for Device-Independent Text Layout

IP.com Disclosure Number: IPCOM000074373D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 54K

Publishing Venue

IBM

Related People

Norton, HT: AUTHOR [+3]

Abstract

Programs are often required to produce output for devices which have different functional characteristics (e.g., for text output, one device advances in picas and points and another in tenths of inches). In the past, this was accomplished by having switches and values contained in the program. By testing these indicators during program execution, different device-specific logic paths were executed and device-specific output was produced. This technique made it difficult to support an additional device and supporting another device resulted in an increase in the size of the program because of the addition of new switches and values and new device-specific logic paths.

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Method for Device-Independent Text Layout

Programs are often required to produce output for devices which have different functional characteristics (e.g., for text output, one device advances in picas and points and another in tenths of inches). In the past, this was accomplished by having switches and values contained in the program. By testing these indicators during program execution, different device-specific logic paths were executed and device-specific output was produced. This technique made it difficult to support an additional device and supporting another device resulted in an increase in the size of the program because of the addition of new switches and values and new device-specific logic paths.

The device-independent method, described here for text processing, solves these problems by means of: 1) A Device Description Table (DDT)

2) Generalized Text Processor (GTP)

3) A Generalized Format Language (GFL)

4) The Output Adaptation Routines (OAR).

The DDT is a table that describes the characteristics of the device (e.g., device horizontal increment or device minimum vertical increment, etc.) The units of the DDT are small compared with those of all devices. One DDT is constructed for each device supported, and the collection of DDT's (in a common format) is placed on a file, accessible by the GTP.

The GTP places text on formatted pages in accordance with the parameters specified in the DDT for the device to be used. The internal units of the GTP are the same as those of the DDT.

The GFL is a combination of text and universal format controls. The universal formatting controls describe the format of a line or page (e.g., 'CS=nnnnn' may be defined to express the character spacing, where the unit of measu...