Xerox 721P87491 manual Printer Controller operations, Scan conversion details, Stroke

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POSTSCRIPT

Printer Controller operations

The DocuPrint NPS Printer Controller operates as follows:

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PostScript stdout messages are printed on the “JOB MESSAGES AND ERRORS” page. DocuPrint PostScript prints error messages directed to %stderr on the “JOB MESSAGES AND ERRORS” page as well.

PostScript font substitution error messages appear on the “JOB MESSAGES AND ERRORS” page only when the requested font is not present and is not one of the DocuPrint base 51 font set.

•DocuPrint does not emulate the serial communications handling aspects of the LaserWriter. Notably, DocuPrint syntactically treats control-D and control-Z as literal characters in ASCII strings and binary data, not as end-of-file delimiters. Also, DocuPrint does not strip high bits from character string data. Instead DocuPrint treats all input bytes as valid PostScript.

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DocuPrint handles ASCII or binary input transparently and does not require two input modes.

DocuPrint wraps each PostScript document with a save and restore to ensure that documents are independent. DocuPrint NPS implements the exitserver operator to permit modifying PostScript virtual memory within a document, but not across documents.

DocuPrint performs standard PostScript error handling when it encounters LaserWriter-specific operators that DocuPrint NPS does not implement. The error handling process produces a standard PostScript “undefined command” message and flushes the master to end-of-file.

Scan conversion details

DocuPrint NPS uses the scan conversion rules to control the

PostScript painting operators stroke, fill, clip, and image.

The scan conversion process and rules are not defined as part of the PostScript language. They are subject to variations depending on algorithms used in different PostScript printing devices to achieve the most accurate rendition possible. The sections below describe the stroke and fill operators.

Stroke

Stroke refers to painting a line that follows the current path, is centered on the path, and has sides parallel to the path segment. “Path” includes a thickness set by the operator setlinewidth.

DocuPrint NPS turns on any device pixels whose centers lie within the width of the path to be stroked. The pixels whose centers lie outside of the width of the path are turned off.

2-18	XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES

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Contents Version 7.1 August 2000 721P87491 Page Ozone information Laser safetyOperation safety Conductor may result in risk of electrical shock. grounding Table of contents PostScript Vipp IndexViii Conventions ContentsAbout this guide Introduction PostScript publications Related publicationsRelated information HP PCL 5 publications Vipp publicationPCL Maintaining image qualityOFF PCL 5 media support PCL 5 font supportPCL 5 fonts installed with NPS software PCL Copy command PCL command supportPJL commands PCL Copy command example Duplex PCL Copy command examplePCL Duplex commands PCL Duplex commands DocuPrint NPS Collated HP LaserJet 4siPCL Job Separation command PCL Paper Source command tray assignment PCL media selectionPrecedence in selecting media PCL Output Bin command PCL Offset Registration commandsPCL 5c support PCL 5 coding recommendationsPCL 5c coding recommendations PCL 5c functions not applicable to DocuPrint NPSDriver recommendations for PCL 5c Limitations for custom PCL 5c driversFloating-point arithmetic and math operators Coordinate system default matrixImplementation-dependent operations Font Typeface FontsAdobe Type1 PostScript fonts Loading fonts User-defined fontsUsing Adobe Type 1 fonts Type 1 fontsUsing a Type 1 font in a document Producing Type 1 fonts for use with DocuPrintSystem Dict PostScript with embedded PJL commandsPostScript language extensions User Dict Server DictDfltkIdleArry needflush Status DictIdleTime Dictionary Nonstandard definitions Printer resolution and resolution enhancement Appearance consistencyExamples of nonstandard definitions Statusdict UserdictDpi image Printed on a 300 dpi printer Printer imaging characteristics Font consistency Proprietary PostScript extensionsControl-Z and superfluous errors Control-D as binary data and end-of-job Solution to control-Z and control-D problems Multiple jobs in one input file DocuPrint NPS implementation of PostScript Level Simulated mixed plexStroke Printer Controller operationsScan conversion details Fill ShapesImages Zero-width lines strokesCurved shapes Image quality Rendering of color and gray values transfer function PostScript printer description PPD files Implementation limitsQuantity Limit Description File operators and standard devicesImplementation limits Path limits PostScript VM limitsSetCacheDevice Device orientation and setscreen operatorArc to Bezier conversion-pathforall PostScript storage object size limitsObsolete operators-banddevice, framedevice, renderbands Scan order and rotation Creating the necessary PostScript Ccitt Group 3Print performance related to image printing Purpose Image orientation mismatch aImage orientation mismatch B 10.Image pixel sequence example Considerations SummaryScan resolution and scaling 11.Scaling and resolution example12.PostScript with embedded image normal scan order MaxX exch def /minY exch def /minX exch def 14.Actual PostScript print Page Vipp Functionality Operating environmentVipp line mode extension XGFNub Page Symbols CcittIndex PCL PPD Index