[gs-devel] Ghostscript and GhostPDL 9.04 release

Chris Liddell chris.liddell at artifex.com
Mon Aug 8 17:35:35 UTC 2011


Artifex Software, Inc. is happy to announce the release of
GPL Ghostscript 9.04 and GhostPDL 9.04.


The source packages is available here:

http://www.ghostscript.com/download

And from the following mirrors:

http://code.google.com/p/ghostscript/downloads/list
https://sourceforge.net/projects/ghostscript/file/GPL%20Ghostscript/9.04


This is the fourth full release in the stable 9.x series.

This release includes fixes and solutions for a number of serious 
problems from the earlier 9.x releases and so we strongly encourage 
those using earlier 9.x releases to upgrade to this new version, to reap 
the benefits of those fixes.

In addition, those still using Ghostscript 8.71 and earlier should begin 
migration to 9.x soon since many improvements, features and fixes from 
the 9.x versions are impractical to back-port to these legacy versions.

Highlights in this release include:

     * Transition source base to git source control - not a big deal for 
most users, but an important change for those develop Ghostscript and 
GhostPDL.

     * This release introduces flexibility for controlling color based 
upon the graphic object type. In particular, it is now possible to 
specify unique output ICC profiles and rendering intents for vector 
graphic, image and tex portions of a document. It is also possible to 
override source color specifications and use specified ICC profiles and 
rendering intents for RGB and CMYK vector graphics, images and text 
portions of a document. Finally, DeviceGray source colors can now easily 
be specified to map either to K only or composite CMYK when the output 
device supports CMYK colorants.

     * New tiffscaled8 and tiffscaled24 devices. Add new tiffscaled8 and 
tiffscaled24 devices, copied and modified from tiffscaled. These output 
greyscale and 24bit rgb instead of tiffscaleds mono output. 
MinFeatureSize is ignored for these devices as it's meaningless for 
contone output. Downscaling is also now supported for png16m and 
pnggray, and a new pngmonod device has been implemented which uses 
grayscale rendering internally and then 
downscales/min_feature_sizes/error diffuses to monochrome.

     * The PDF interpreter will now try continue interpreting a PDF 
after encountering an error in a stream. The previous bevahior can be 
reinstated by passing -dPDFSTOPONERROR to Ghostscript.

     * Re-enable x11alpha as the default device on Unix systems, now 
that compatibility problems between anti-aliased output and transparency 
are resolved.

     * Update libjpeg to version 8c.

     * Experimental Text output/extraction device

       The txtwrite device has undergone some development, and now has 
genuine functionality. It accepts any input format which GhostPDL 
supports, and uses a combination of methods to try and determine the 
Unicode values for any text contained in the document.

       The code descends a hierarchy of methods in this process, 
starting with the most reliable and only falling back to less reliable 
methods when better methods fail. The current hierarchy is as follows:
          1. ToUnicode CMaps (PostScript or PDF) or GlyphNamesToUnicode 
tables (PostScript).
          2. Glyph names of the form 'unixxxx'.
          3. Glyph names defined in the Adobe Glyph List document.
          4. Input character code.

       Method 1 is highly reliable, method 4 is a best guess and not 
terribly reliable, though it will work for many files. It is probably 
most reliable for PostScript and PCL files.

       The device currently has one parameter 'TextFormat' which 
controls whether the output is Unicode text reflecting the layout of the 
original document (-dTextFormat=0) or a format intended for use by 
developers which includes the Unicode text and some formatting 
information, such as the size and position of the text, and the font in 
use (-dTextFormat=1).

       Note that his device does not do OCR (Optical Character 
Recognition) it is not capable of finding 'text' which is part of an 
image. However it will recover the 'invisible' text from PDF documents 
which have been scanned and OCR'ed by Acrobat for searching. Such text 
has a render mode of 3.

       This is the first release of this code and is very much an alpha 
release, we expect problems.

       In particular the TextFormat=0 output is likely to be incorrect, 
and will only work with top-to-bottom left-to-right text. It will 
probably also be confused by landscape documents printed on portrait media.

       TextFormat=1 should be more reliable, but there may be cases 
where text is dropped from the output. Text in PostScript documents 
using charpath is not yet supported for example.

       We do encourage feedback on the state of this device, and would 
be interested in hearing what kind of output would be useful for 
developers using TextFormat=1. For now, however, please do not raise 
bugs through Bugzilla, instead please send feedback to the gs-devel 
mailing list.


     * Experimental Unicode/UTF8 Support on Windows

       This release introduces some experimental build-time optional 
support for UNICODE pathnames on Windows. Essentially this works by 
following the model that Linux (and MacOS) have followed for years.

       If this code is enabled, then the way ghostscript handles command 
lines, registry settings, file accesses and other api calls with top bit 
set characters in (i.e. codes >= 128) will change. The net benefit of 
this change is that ghostscript will now be able to cope with accessing 
files with unicode characters (i.e. codes >= 256) in their pathnames.

       This behaviour is all completely transparent to users, with the 
exception of those calling the gsapi functions with strings including 
'extended ascii' (i.e. characters with codes >= 128 and <= 255). These 
characters include accented latin characters, such as u + umlaut, a + 
grave etc. The changes required for code that is affected by this are 
relatively minor, but as this is a change to the current API, we are 
announcing it in advance, and inviting comments.

       As of the 9.04 release, the code is disabled. For those who wish 
to experiment you will need to build Ghostscript from source, and either 
pass USEUNICODE=1 when you invoke nmake or edit psi/msvc.mak to remove 
the /DWINDOWS_NO_UNICODE option from CFLAGS.

       WARNING: Our intention, subject to feedback, is to enable this by 
default in near-future releases (hopefully, the next major release). If 
you make use of the affected APIs you should be prepared for the change 
to occur - be aware, however, that the current code is experimental and, 
depending on the feedback we get, maybe subject to change.

       NOTE: this whole change refers to file paths, command line 
parameters and so on - it does not imply that we have unilaterally 
extended Postscript to understand UNICODE.

       More details:

       To give an example, suppose we have a file 'EXAMPLE' we'd like to 
invoke ghostscript on, where 'EXAMPLE' is actually a string that 
contains some characters with codes >= 128.

       On Linux (or MacOS X), when ghostscript is called from a shell, e.g.

       gs EXAMPLE

       the command is UTF8 encoded; this means that characters with 
codes < 128 are left unchanged, and characters >= 128 are encoded into 
multiple bytes. This encoded string is then passed to the standard 
'main' entrypoint in the gs executable.

       Ghostscript proceeds internally without any special handling of 
these multibyte characters at all. When it comes to access files it 
therefore passes out the UTF8 encoded strings to the standard OS file 
handling routines. These routines are designed to take pathnames in UTF8 
format, and thus the files are accessed as normal.

       If the Ghostscript executable outputs these (or other) strings to 
its stdout, the shell again converts the output from UTF8 back to 
unicode in order to display it.

       The net effect is that the caller can seamlessly pass in unicode 
filenames, has his fileaccesses work out and gets unicode output without 
the core of ghostscript ever having to worry about it.

       The code change discussed here endeavours to make Windows follow 
the same pattern as closely as possible.

       When Windows executables are invoked, they can either be called 
through an 'ascii' entrypoint (main), or through a unicode ('wide') 
entrypoint (wmain). The difference is invisible to the caller, except 
that unicode executables can accept characters >= 256 in their invocations.

       The new code changes ghostscript from being an ascii executable 
to being a unicode one. The Windows specific outer layer takes the 
unicode command string and UTF8 encodes it before passing it to the 
ghostscript core.

       Similarly, the Windows specific filing system calls are updated 
to accept utf8 encoded strings from the core, and to convert them to 
unicode before operating on them.

       The Windows gui app (gswin32.exe, NOT gswin32c.exe) is also 
updated to convert stdin/stdout between unicode and utf8 as appropriate, 
allowing unicode strings to be copied/pasted to/from other apps.

       All of this should be completely transparent to the user, and no 
code changes should be required. The one area where changes may be 
required are where ghostscript is invoked through the gsapi functions.

       Currently, on Linux (and MacOS X) any strings sent over the gsapi 
are assumed to be utf8 encoded (and thus can represent any Unicode 
character). On Windows, they are assumed simply to be in extended ASCII 
(and can therefore represent any character < 256 in the current 
codepage). With the proposed change, Windows will move to be in step 
with Linux. No differences will be caused to anyone who only uses chars 
<= 128, but those people using character codes between 128 and 256 (or 
indeed wanting to use higher codes) will need to utf8 encode the strings 
before calling gsapi functions.

       Such encoding/decoding is a very simple process, and code for 
both directions can be found in psi/dwmain.c, psi/dwmainc.c and 
psi/dwtext.c.

       Again, we welcome feedback on this feature, in this case problems 
or suggestions about the implementation can be submitted via Bugzilla 
but for detailed discussion about the approach for which we opted, it 
would be more beneficial discuss it (preferably) on our IRC channel 
#ghostscript on freenode.net, or on the gs-devel mailing list.




For a list of open issues, or to report problems, please visit 
bugs.ghostscript.com.

Incompatible changes

Deprecated file "gs/base/errors.h" removed, psi/ierrors.h should be used 
instead.

The eXternal Fonts (XFonts) functionality, marked as deprecated in 9.02 
has now been fully removed.

No other recorded incompatible changes.


Thanks to everyone whose hard work made this release possible!



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