monday, 11 february 2008

posted at 09:07

AROS work has slowed down over the last week. There's been a lot of email to reply to (I won't mention the topic :P), and I've doing some web work on the side, but I've still had a little time to work on cairo, which I'm now calling finished, at least for the moment.

The big thing I was trying to get going was the shared library stuff; ie having a shared cairo.library. I got this working, but programs are crashing because cairo has globals, a fact that I'd overlooked. It only has a couple, but they're rather important. Once again, I'm not willing to make the large changes required to remove the globals because I want to keep the changes to upstream to an absolute minimum. Once AROS has proper support for global data, then this code can be resurrected.

So cairo works, but is noticably slow. That mostly comes from it doing all its rendering in software and then blitting the results into the AROS graphics subsystem. Working slowly is good enough for me at this stage.

Fonts work, with the following issues:

  • Non-scale transformations (rotate, shear, etc) don't work as the necessary API is not exposed via bullet. Scaling work, buts only vertically - again, missing API. Basically the only cairo API that is of any use for glyph transformation is cairo_set_font_size().
  • The font tests don't pass. The first reason for this is that font sizing on AROS is not the same as on other systems. As far as I can tell the bullet interface to FreeType is recalculating the metrics to better match the traditional Amiga way of talking about metrics, with the downside that it makes the glyphs smaller than they should be. Additionally, there's no way to get the display device DPI under AROS, making it quite impossible to have FreeType adjust the scale appropriately.
  • The other reason the tests don't pass is that spacing between glyphs is wrong. A typical line of test rendered on Linux will have pretty much even spacing between each glyph. The same text rendered on AROS has uneven widths. I haven't been able to determine the cause of this yet.

The font problems shouldn't be an issue for WebKit as it does its own font work, though it will still hit the underlying font system so its likely the same issues will appear in other contexts. Again, I'll just do the best I can.

So this afternoon its back to WebKit! There's been many many changes there in the last month, so the first step will be to just get my stuff building again.