Bug 691103

Summary:	CIDFont with atypical FontMatrix get wrong spacing after distilled by pdfwrite
Product:	Ghostscript	Reporter:	Masaki Ushizaka <masaki.ushizaka>
Component:	PDF Writer	Assignee:	Masaki Ushizaka <masaki.ushizaka>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	P4
Version:	master
Hardware:	All
OS:	All
Customer:		Word Size:	---
Attachments:	Bug691103.ps Bug691103_2.ps b691103_b2.patch

Description Masaki Ushizaka 2010-02-11 01:18:03 UTC

Ralph found this during 8.71 release test using Bug687832.pdf.

Procedure:
$ bin/gs -sDEVICE=pdfwrite -o Bug687832.pdf.pdf Bug687832.pdf
$ bin/gs -sDEVICE=png16m -o Bug687832.pdf.pdf.png Bug687832.pdf.pdf

This results large spaced letters in Bug687832.pdf.pdf.png.  Acrobat 9 renders Bug687832.pdf.pdf same 
as gs.
With gs 8.70, this doesn't make wrong output.  With r10602, this resulted 4 times larger spacing, and with 
r10603 (which was a fix for bug #687832), this resulted double spaced letters (same as current).

I am working on reduced and openable test code.

Comment 1 Masaki Ushizaka 2010-02-12 00:33:42 UTC

Fist of all, please forget what I said about r10602 yesterday.  Today r10602 renders exactly same image 
with r10603.   I must have done something wrong yesterday.

Second, I wrote a test code about what I believe the cause of this isssue, which is 2048x2048 grid designed 
CIDFont.  It displayed similar symptom with current head, while it also went wrong even with gs 8.70.  I 
think my code might have discovered another issue.  I will attach that code later, or I may open another bug 
about it.

Last, search-svn-revs (what a nice tool!) told me that this symptom first introduced with r10476.  I will look 
further to find the cause of this issue.

Comment 2 Masaki Ushizaka 2010-02-12 03:10:30 UTC

Created attachment 5947 [details]
Bug691103.ps

Before r10476, pdfwrite converted CIDFont letters in Bug687832.pdf into graphic
objects (not a font).  I think the change in r10476 fixed a problem that had
been covering this problem which have been there for a long time.

So I consider this file must be the simplest case to exhibit this issue.

Procedure to reproduce:
$ bin/gs -sDEVICE=pdfwrite -o Bug691103.ps.pdf Bug691103.ps
$ bin/gs -sDEVICE=pngmono -o Bug691103.ps.pdf.png Bug691103.ps.pdf

Comment 3 Masaki Ushizaka 2010-02-14 19:17:08 UTC

Bug691103.ps.pdf generated in above command line contains a 'W' array which says:

/W [0 [2048]]

The number 2048 is in glyph space (this is a CIDFont with 2048x2048 glyph space) and this is wrong.
It should be 1000, which is in 1000th of text space.

Comment 4 Masaki Ushizaka 2010-02-17 17:12:07 UTC

The problem is not just that pdfwrite is ignoring FDArray font's FontMatrix,
but also that orig_FontMatrix is not working for CIDFont at all.
I need to fix that too.

Comment 5 Masaki Ushizaka 2010-02-23 03:59:49 UTC

Created attachment 5979 [details]
Bug691103_2.ps

A new test file.  First line is with same CIDFont with minor fix,  second line
is a Type 1 Font with 2048x2048 glyph space.  I found it useful while
debugging.

Comment 6 Masaki Ushizaka 2010-02-24 03:43:04 UTC

Created attachment 5986 [details]
b691103_b2.patch

A patch.
Bug687832.pdf and Bug690834.ps show differences but those are improvements.

Comment 7 Ken Sharp 2010-02-24 05:53:38 UTC

The patch looks good to me, you've obviously done regression tests so I think
you should go ahead and commit it. Thanks for working on this one!

Comment 8 Masaki Ushizaka 2010-03-10 02:29:52 UTC

The patch had been committed r10810 at Feb 25.  Closing this bug as fixed.

---
r10810 | masaki | 2010-02-25 17:21:46 +0900 (Thu, 25 Feb 2010) | 3 lines

Fix for bug 691103.  The pdfwrite device now considers FDArray fonts' FontMatrix and writes correct W/W2/DW/DW2 widths for CIDFont with unusual FontMatrix.  This also fixes a problem gs_font::orig_FontMatrix not being initialized for CIDFont.
Bug687832.pdf and Bug690834.ps will show differences which are improvements.