[cairo] [Fwd: Problem with stroke vs. fill]

[Duncan Mak]

Hello,

Carl asked me to post this question to the list so that we'll have
archived for others to see, he'll be posting his reply to me as well.

Duncan.

-----Forwarded Message-----
> From: Duncan Mak <duncan at ximian.com>
> To: Carl Worth <cworth at east.isi.edu>
> Cc: Ravindra Kumar <rkumar at novell.com>
> Subject: Problem with stroke vs. fill
> Date: Fri, 02 Apr 2004 02:09:11 -0500
> 
> Hello Carl,
> 
> Thanks so much for working on Cairo, I've been happily using it to
> implement the various 2D geometry drawing/filling functions in the GDI+
> Graphics class. We're making good progress!
> 
> I found an algorithm [1] from the comp.text.pdf FAQ for drawing
> elliptical arcs using bezier curves. Using this algorithm, I was able to
> implement the functions for drawing and filling arcs and pies.
> 
> I noticed tonight that my FillPie implementation is incorrect for cases
> where the sweep angle is equal or greater than 180, even though DrawPie
> works fine. Instead of drawing a line back to the absolute center, it
> draw a line to the center of the top/bottom edge (depending on the
> angle).
> 
> The code paths used by both functions (Draw and Fill) are identical,
> except FillPie calls cairo_fill, whereas DrawPie calls cairo_stroke.
> 
> All being the same, with stroke working and fill not working, I'm
> wondering, is this a Cairo bug?
> 
> Thanks,
> 
> Duncan.
> [1] http://www.stillhq.com/ctpfaq/2002/03/c1088.html#AEN1212