Pango Status Report #2 9 Feb 2000 ====================================== General news: http://www.pango.org is now online. Thanks to Raph for hosting the site on his machine. What's up there now is mostly what was on my older pages, but with nicer formatting, a more complete design section, and updated API docs. Recent progress: In the last few weeks, I've been concentrating my efforts on the font system, both for the rendering-independent interfaces and for X. The general design for the font independent stuff is pretty similar to lots of existing systems ... whether Java or gnome-font. The exact set of properties is based most closely on the font properties from CSS2. You can check out the API for this at: http://www.pango.org/api/pango-fonts.html The X work I've done is mostly implementing this API for the X platform, and also improving the selection algorithms for finding XLFDs to match a particular PangoFontDescription and size. (I'm now just listing all fonts from the X server with XListFonts() and doing all the matching client side.) The other thing I've been working on is getting fonts to report their own coverage maps. This will allow better handling of selecting fonts with fallbacks to other fonts for character points not handled by the first font. The implementation of this is pretty much complete, though it isn't yet used by the shaping core. Releases: Pango-0.6 is on available from www.pango.org. The big change is the font stuff. I've also (with Tom Tromey's permission) made a release of libunicode from CVS and put it there to make it easier to get Pango compiling. TODO highlights: The projects I intend to tackle next are: - Finish up the font stuff API by adding list_families() and list_sizes() calls. - Make the shaping core use the font coverage code; this will involve attributing the text fed into the pango_itemize() with font information as well as the current language tags. - Change the engine lookup code to be a bit more general than the current mechanism which hard-codes the types of engines available. After that, I intend to move on to working on Pango in a GUI enviroment. I'll probably simply make a branch of GTK+, start pushing in Pango and see what happens. Some interesting projects that other people might want to consider: - Write a libart based font-system and renderer to go along with the X based one. It would be good to have an idea about how well the interfaces work with something other than X before we get too far along. - Write an Arabic shaping module. A simple one shouldn't be too bad. With the Tamil and Korean modules, we are already doing more sophisticated stuff than are necessary for shaping Arabic characters for X, and the basic module already does simple bidirectional reordering for glyphs. (caveat: the module interfaces are not currently very documented, so this would involve lots of reading code and exploration) - Write a shaping engine for whatever language you are interested in. Misc stuff: Another interesting development is that Havoc Pennington has started working on a port of the TkText widget to GTK+. (We needed a more sophisticated text widget for various things we are working on here at the Red Hat.) Initially I thought that a port of that widget wouldn't be appropriate for a Pango-based system, and I'd also be starting over on a new text widget for Pango/GTK+. But having talked to Havoc a bunch about the design, it looks like moving that code base to Pango would work pretty well: There is a pretty clean separation between text storage - which would be done before shaping and reordering, and text display, which would be done after shaping and reordering. Also, the text storage is essentially paragraph-based, which works well as a unit for bidectional reordering. Finally, the text storage is already in UTF-8, so no conversion would be needed there. Owen Taylor
Last modified 31-May-2000 Owen Taylor <otaylor@redhat.com>