first: wow I did not expect such a deep problem when reporting this. I am glad you found it (I was about to repart that my new tests, with Cairo 1.3.14 as you advised, presented the same problem, obviously...)
On 2007-February-25 , at 17:10 , bulia byak wrote:
Last night, with the help of Carl Worth, the issue of cairo/inkscape not working on mac was more or less clarified. Here's how I understand it.
When drawing into a memory buffer, cairo uses a fixed byte order of the R, G, B, A bytes regardless of the platform.
Inkscape and GDK (which is used by Inkscape for drawing to screen), however, both use system-dependent byte order, i.e. the order of R, G, B, A is determined by the hardware and is different on PC and Mac platforms.
And it so happens that the fixed order of cairo coincides with the hardware order on PC but not on Mac. Hence, painting by cairo directly into Inkscape/GDK buffers worked on PC but on Mac, all colors are wrong and (in case of outline) black color gets zero opacity, i.e. becomes invisible.
Is this a problem in the hardware in terms of the physical pieces in the computer or in the way the hardware is handled by the system, deeply inside? I don't know if this is relevant but then, is there a difference between PowerPC and Intel based Macs (I am on a PPC)? Indeed those new Macs are really more like PCs inside and the difference with PCs is more and more at the system level. In which case the future looks brighter because PPC macs will progresively disappear. Meanwhile the old code would be conserved and wraped under a configure option (like --with-old-rendering) we would use only on PPC macs while Cairoification continues on the rest.
Essentially, this means that Inkscape and cairo are not compatible as is, and that a gradual switching of parts of our display engine to cairo is not possible. (Unless we ditch Macs, of course.)
I hope this won't be the case! Notify me, I'll buy a PC then ;-)
Not sure I really understand the details of the rest so:
[...]
Thank you again for your efficient investigation. Too bad it yielded such a result. I think it deserves a news item on the website though.
JiHO --- http://jo.irisson.free.fr/