Hi debian-devel, As we all know, squeeze is frozen now. This was a long awaited event, although for some importans software that we have in the distro it would be beneficial if this moment could happen later. One of such examples is libcairo2.
The last release by ustream [1] is 1.8.10. At the moment we have this version in both testing and unstable. We also have 1.9.14 in experimental, one of the very important features of which is a proper support of fontconfig's attribute "lcdfilter" [2]. To those who are not familiar with this: this setting allows to tune the final stage of subpixel rendering [3] that is a filtering stage, the purpose of which is to reduce the visual color fringes around a character. Unfortunately, there is no filter that could perform equaly well with all available fonts. Fonts that have bytecode and are full-hinted with the native hinter usually look better (i.e., give less strain to the eyes) with the so-called "intrapixel" filters, while the autohinted fonts with hintstyle = hintslight look better with the so-called "interpixel" filters (or FIR lilters) [4, 5]. I am writing this to make it clear that it is important to have this filtering configurable. The lcdfilter setting with possible values of lcdnone, lcddefault, lcdlight (FIR filters), and lcdlegacy (itrapixel) has been supported by fontconfig since version 2.6.0. Freetype has provided respective filters since 2.3.0 (i.e., both were already available in lenny). Qt-based applcations respected these settings since Qt 4.5 [6]. The current situation with GTK applications in squeeze is the following. GTK aplications use cairo to render fonts. Cairo 1.8.10 has its own intrapixel filter (which is equivalent to freetype's lcdlegacy filter). It is impossible to redefine or tune this filter besides setting subpixel order. This significantly reduces the set of fonts that one can daily use with this filter without putting too much strain on her eyes. Even worse: one is usually forced to use only non-free fonts with this filter because the glyphs must be very well hinted in order for this filter to be efficient. For a long time there have been patches [7] that make cairo lcdfilter-aware and let it use freetype's internal filters. Untill recently (the commit [2] is dated June, 17th) the upstream was reluctant to accept them, therefore many distributions applied these patches on their own (so did Ubuntu; in the internet one may find many guides of how to build and install these Ubuntu packages on Debian to get "decent fonts"; we have also bugreports like [8]). Thus, getting to the main point of this long e-mail: what are we going to do with libcairo2 in squeeze? If we keep it at 1.8.10, I think it makes sense to apply the above mentioned patch, because it has been accepted by upstream and tested for quite a long time by other distributions. Or are we going to wait for the next release of cairo that might happen any time before squeeze releases, and then push it into testig? This sounds less probable, knowing the usual Debian practices. References ========== [1] http://cairographics.org/releases/ [2] http://cgit.freedesktop.org/cairo/commit/?id=7a023a62f7517ad0d54f4d59c99909fadcc05e82 [3] http://en.wikipedia.org/wiki/Subpixel_rendering [4] http://en.wikipedia.org/wiki/Intrapixel_and_Interpixel_processing [5] http://freddie.witherden.org/pages/font-rasterisation/ [6] http://labs.trolltech.com/blogs/2008/09/01/subpixel-antialiasing-on-x11/ [7] http://bugs.freedesktop.org/show_bug.cgi?id=10301 [8] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=555722 -- Stanislav -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20100809142701.ga8...@kaiba.homelan
