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Printing Graphics and Alphanumerics on an IBM 4224 Printer

IP.com Disclosure Number: IPCOM000039172D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 16K

Publishing Venue

IBM

Related People

Johnson, JS: AUTHOR

Abstract

This article describes a method for printing graphics and alphanumerics on an IBM 4224 printer. The method includes: o The establishment and use of a second (internally generated) graphics field on which to define areas to be blanked out, o a unique combination of Write Graphics Control (WGC) command parameters to achieve this to a satisfactory degree of accuracy; and o the internal generation of additional graphics orders to define the areas to be blanked out. INTRODUCTION Graphics Data Display Manager (GDDM) Version 2, Release 1 uses a new datastream architecture to communicate with the IBM 4224 printer. It is called the Intelligent Printer Data Stream (IPDS) architecture.

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Printing Graphics and Alphanumerics on an IBM 4224 Printer

This article describes a method for printing graphics and alphanumerics on an IBM 4224 printer. The method includes: o The establishment and use of a second (internally generated) graphics field on which to define areas to

be blanked out, o a unique combination of Write Graphics Control (WGC) command parameters to achieve this to a satisfactory

degree of accuracy; and o the internal generation of additional graphics orders to define the areas to be blanked out. INTRODUCTION Graphics Data Display Manager (GDDM) Version 2, Release 1 uses a new datastream architecture to communicate with the IBM 4224 printer. It is called the Intelligent Printer Data Stream (IPDS) architecture.

IPDS formats and protocols have been documented in a manual (GC31- 2551) describing the IBM 4224, so users are able to generate data to this level, if required. Using IPDS protocols, GDDM V2R1 can send vector graphics, image and text data to the 4224 printer.

Alphanumeric data on a GDDM page has to be converted into text data before transmission to IPDS printers. Data are sent as a sequence of structured field commands. Some of these are control or environment definition commands, and some carry the information to be printed.

THE PROBLEM On a GDDM page, alphanumerics and graphics data can both be present. Where either a part, or all, of an alpha field overlaps the graphics field, then any graphics occupying the overlapped area must not be printed if the alpha field is defined as opaque. Alpha fields are, by default, opaque. The IPDS architecture does not define the priority of one data type over another, and the result of printing 'opaque' alpha characters and graphics that occupy the same physical space is a simple 'OR' of the data. This is unacceptable, and so GDDM has to provide a means of making the graphics invisible in these cases. A GDDM SOLUTION Normally, the graphics content of a picture is sent to the printer first, to be followed by the alpha field characters, sent on a row by row basis from the top to the bottom of the page. The graphics data is rastered by the printer and printed on the paper, as receipt of the alpha data causes the baseline to move down the page. If any of the alpha fields requires underlying graphics to be blanked out, then this procedure changes.

The graphics content of the picture is still sent to the printer first. This is now followed by further graphics orders, generated internally by GDDM (of which the application is unaware) that define the position and size of all affected areas, and which cause these areas to be solid shaded in background color. The alpha field characters are then sent in the usual row by row sequence. THE METHOD When wishing to send picture data to the 4224 printer, it is first necessary to define the logical page position and size in L-units (L- units are the units used by the IPDS to describe the position and size of objects on the physical p...