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Re: RXVT and Bitstream Vera Sans Mono


On Thu, 6 Dec 2007 22:41:06 -0000, Thorsten Kampe <thorsten at
thorstenkampe dot de> wrote:

>If you like Bitstream fonts then you will like DejaVu fonts - who are 
>based on Bitstream - even more. But beware that your issue might be a 
>issue similar to this:
>
>https://bugs.freedesktop.org/show_bug.cgi?id=10693
>
>Thorsten

Thanks for the link. My issue is similar, in that it seems to occur at
one size only, but what actually happens at that size is very
different.

I read the conversation in this bug report with considerable interest.
There are a few items that I would like to comment upon:

 ------- Comment #3 From Thorsten Kampe 2007-04-21 05:53:19 PST -------

>I think, this /might/ be a Cygwin/rxvt bug. Unfortunately I can't
>convince rxvt under Linux to use DejaVu Fonts ("can't load DejaVu Sans
>Mono-17") - so I can't tell whether it's just a Cygwin/rxvt thingy).

How strange... I had no problems getting my copy of rxvt to accept
'DejaVu Sans Mono-17', and found the "underscore not displaying" bug
you reported to be immediately reproducable. Note that the the issue I
described in my initial post to this list is identical when using the
DejaVu Sans Mono font. One only needs to read the status.txt file in
the DejaVu package to realize that a significant portion of the
original Bitstream Vera 1.10 font remains unchanged.

 ------- Comment #4 From Thorsten Kampe 2007-04-21 06:02:29 PST -------

>I wouldn't have a problem reporting the bug to the Cygwin rxvt
>maintainer - but as rxvt is AFAIK not actively maintained

Charles Wilson, the current maintainer of the Cygwin rxvt, appears to
be active on this list. According to the archive search engine, his
most recent post concerning rxvt was in response to the thread "[rxvt
packaging bug?] New rxvt introduces broken font default," which was
posted on Sun, 16 Sep 2007:
http://sourceware.org/ml/cygwin/2007-09/threads.html#00373

Then again, there is this, which describes both Cygwin rxvt and the
underlying W11 library as "moribund":
http://cygwin.com/ml/cygwin-announce/2006-05/msg00004.html
However... "But don't worry: I've taken over maintainership of the
split-personality rxvt package, and it's not going anywhere. In fact, I
currently use 'rxvt' when native mode is good enough, and
'rxvt-unicode-X' when I want X support."

In /usr/share/doc/Cygwin/rxvt-20050409.README, Charles requests that we
"Please address all questions to the Cygwin mailing list ..."; in
respect of his wishes, I posted my issue here in the hopes that he
would see and respond to it.

>and other fonts (Fixedsys) don't show the behaviour I think he will
>classify this as "NOTOURBUG", too...

It is quite possible that the bug may not be in either rxvt or the
Bitstream/DejaVu fonts per se, but may very well be an interoperability
issue instead. The release notes for the Bitstream Vera fonts at
http://www.gnome.org/fonts/ include a comment that underscores this
complexity: "Font rendering in Gnome or KDE is the combination of
algorithms in Xft2 and Freetype, along with hinting in the fonts
themselves. It is vital to have sufficient information to disentangle
problems that you may observe."

It is a common human problem when interoperability issues occur,
fostered by our usual blame-based, CYA mode of problem solving, for the
involved parties to declare "NOTOURBUG" in chorus, and then point an
index finger at the developers of "that other product over there."
Under these circumstances, getting the developers of separate products
that are showing interoperability problems to cooperate toward finding
a uniform solution can be a serious challenge. The current situation,
where the DejaVu fonts seem to work well in any other application
(including native Windows GUI apps like MS Word) and rxvt seems to have
no problem rendering other monospaced fonts (such as Lucida Console and
Courier New) at any size, sounds to me very much like an
interoperability issue.

Then again, the bug may be in the underlying code bases and/or
development tools used to create these products. For example, the
release notes for the Bitstream Vera fonts at
http://www.gnome.org/fonts/ contain a detailed discussion of font
rendering setup in Gnome (including comments concerning the features
that the various font rendering components offer), and an advisory that
a partucular version of Freetype (one of the font rendering components
in Gnome) contains serious bugs. (At the top of this page is the
request that users "Please read the release notes before reporting
problems with the fonts," which in a sense is a step toward the
situation just described in the preceeding paragraph.)

This raises some questions with respect to Cygwin rxvt when run in
native mode: Does it rely on Windows font rendering, or does it have
its own font rendering engine (part of the W11 library, or-)? If the
former, why does a font that seems to display fine in native Windows
GUI apps have problems in rxvt? If the latter, is font rendering in
rxvt possibly provided by the buggy Freetype code mentioned above?
Finally, if the problem is with rxvt and/or W11, is there any
possibility of a fix?

I don't really want to think about this possibility, but the problem
could even be in FontForge, the app used to create the DejaVu (and
probably the Bitstream Vera) fonts...

 ------- Comment #13 From Thorsten Kampe 2007-04-21 07:45:28 PST -------

>(In reply to comment #12)
>> Then Denis was right, rxvt doesn't display the lowest pixel line at
>>that size 17 (15 ppem). But I have no idea why it would do that...
>
>Hm.
>
>I tried Fixedsys and Lucida Console (both size 17). If rxvt doesn't
>display the "lowest pixel line at that size 17 (15 ppem)" - then why
>only with DejaVu Sans Mono?!

 ------- Comment #16 From Ben Laenen 2007-04-21 08:02:46 PST -------

>So rxvt fixes the line height at 17 pixels there, and tries to select
>the appropriate font size to match it, but I have the impression it
>chooses wrongly, as the line height at that font size for DejaVu is 18
>pixels.
>
>Other fonts may only need 17 pixels at that size, or their underscore
>may be higher than in DejaVu...

So, they focused on line height (which is probably natural, given the
specifics of your report), and ignored your questions that raised
interoperability issues (which is also natural, though for different
reasons). Though my issue also involves the DejaVu/Bitstream font at
one specific size in Cygwin rxvt, it has, so far as I can determine,
nothing to do with line height. I'm thinking of posting a bug report,
which will hopefully stir up further discussion and investigation. I'm
not sure whether it would be better to add my information to this
report, or to create a seperate report and link it to this one (or--
other possibilities). Recommendations?

Thanks,

Jeff

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