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		Report on Genoa PCL6 FTS and LaserJet 6MP

This document presents the results of Artifex's investigation of
discrepancies between the Genoa PCL6 Functional Test Suite, the published
PCL XL Feature Reference Protocol Class 1.1 specification, and the behavior
of the H-P LaserJet 6MP printer.

		Report on Genoa PCL6 FTS and LaserJet 6MP

Introduction
============

In the course of validating our PCL XL interpreter using the Genoa PCL6
Functional Test Suite (FTS), we observed a number of discrepancies that,
after careful investigation, we concluded were due to problems in the FTS
and/or the printer firmware.  In this document, we present these in detail.

This document should be read in conjunction with our separate report on
discrepancies between the specification and the firmware independent of the
Genoa FTS.

Changes in a given revision of this document are marked with the revision
number in [brackets].  Revision history:
		first issued December 6, 1996
		rev. [1] December 22, 1996
		rev. [2] February 6, 1997

General
=======

We noticed that in many places, the input data contain an extra PopGS that
doesn't have a matching PushGS.  The published specification says that this
is invalid (i.e., the existence of a PushGS is part of the precondition for
PopGS).  Apparently the printer ignores the extra PopGS.

Individual tests
================

[2] t101 - BeginSession
-----------------------

On pages 2 and 3, in the LJ5 printouts, the characters are not distorted
(stretched vertically on page 2, compressed vertically on page 3) to match
the non-uniform UnitsPerMeasure.  This is a bug in the LJ5 firmware that has
been corrected in the LJ 6MP.

t203 - SetFont
--------------

On panel 3 the exclamation points spacing is not correct.  The artifex
interpreter does not mix different downloaded fonts and maintain the
same spacing as HP.  The proper behavior is undocumented and never
used in real world examples.

t305 - SetColorSpace
--------------------

The two lower rectangles in image 03 are stroked with gray, and are not
painted.  The comment on this image says "The 2nd and 3rd rectangles should
be stroked and painted with black color."  [1] See the entry for
SetColorSpace in the discrepancies report.

t310 - SetCharShear

On page 1 panel 1 the character shear setting results in font scaling
factors thar are zero.  The Artifex interpreter produces no result,
the HP 4600 produces a thin one pixel line for the character.  We do
not attempt to emulate this.


t314 - SetFillMode
------------------

The lower figure in all 3 images, ostensibly drawn with the non-zero winding
number rule, is clearly not drawn with this rule.  [1] See the discussion of
clipping and of SetClipIntersect in the discrepancies report.


t321 - SetClipIntersect
-----------------------

In the lower figure of image 01, the dark lines stop at the edges of an
invisible rectangle rather than extending all the way to the ellipse.  This
is consistent with the interpretation of SetClipIntersect documented in the
discrepancies report, but not with the published specification.

t322 - SetClipRectangle
-----------------------

In image 03, the rectangle border is a medium gray.  However, the input data
are as follows:

	NewPath
	200 @GrayLevel SetBrushSource
	120 @GrayLevel SetPenSource
	40 @PenWidth SetPenWidth
	0 @ClipRegion [1200 400 2000 2200] @BoundingBox SetClipRectangle
	[1200 400 2000 2200] @BoundingBox Rectangle
	20 @GrayLevel SetPenSource
	0 2925 @Point SetCursor
	2400 0 @EndPoint LinePath
	PaintPath

The Rectangle operator is supposed to leave the path set to a rectangle, so
the final PaintPath should paint both the rectangle and the line a very dark
gray; however, as noted in the discrepancies report, Rectangle actually
clears the path.

t325 - SetClipMode
------------------

The middle figure of image 03 is a solid disk.  However, the input data are
as follows:

	0 @GrayLevel SetBrushSource
	[300 300 4500 2625] @BoundingBox Rectangle
	PushGS
	0 @ClipMode SetClipMode
	[1800 2325 3000 3525] @BoundingBox EllipsePath
	[2100 2625 2700 3225] @BoundingBox EllipsePath
	0 @ClipRegion SetClipReplace
	0 @GrayLevel SetBrushSource
	[300 2250 4500 3600] @BoundingBox Rectangle

Again, if Rectangle left the path set as documented, this would draw (part
of) the rectangle as well as the disk.


[2] t329 - SetHalftoneMethod
----------------------------

The DitherOrigin of the halftone is incorrectly set relative to the origin
of the default (rotated) user coordinate system rather than to the current
user coordinate system.  This causes the patterns to be shifted slightly
relative to the Genoa printout.  For a test example, see our separate report
on firmware discrepancies.

t409 - Ellipse
--------------

Image 04 is light gray.  However, it should actually be painted with an
outer stripe of light gray and an inner strip of dark gray:

	1 @ColorSpace SetColorSpace
	255 @GrayLevel SetBrushSource
	180 @GrayLevel SetPenSource
	160 @PenWidth SetPenWidth
	[300 300 2100 800] @BoundingBox RectanglePath	% no-op
	[300 1100 2100 1600] @BoundingBox Ellipse
	60 @GrayLevel SetPenSource
	60 @PenWidth SetPenWidth
	PaintPath

The Ellipse command should leave the path set, and the final PaintPath
should erase the interior of the ellipse (including the inner half of the
lighter stripe) and then repaint the annulus with the darker color with the
narrower pen.  This is the same problem as in t322 and t325.

t413 - Pie
----------

Image 05 shows the same problem as noted under t409.

t415 - Rectangle
----------------

Image 02 shows the same problem as noted under t322 and t325.

t202.bin (Protocol 2.0 fts)
---------------------------

Panel 01 and others show incorrect spacing when rendering downloaded
TrueType fonts.  This only happens with the AGFA scaler and resolutions
lower than printer resolutions.

t422.bin (Protocol 2.0 fts)
---------------------------

A raster pattern of height 1 results in a 0 area pattern which
produces an error.  The error only happens if the device resolution is
less than 300 dpi.
