[Bug 5946] text rendering using vsfilter doesn't properly display (affects Flash Pro 8)

http://bugs.winehq.org/show_bug.cgi?id=5946

--- Comment #14 from Niels Martin Hansen   2009-01-24 10:58:42 ---
I don't know how common this technique is for getting text paths. (The more
"sanctioned" method I believe should be to repeatedly call GetGlyphOutlineW().)
But it can affect various kinds of graphical applications that need to draw
text in more advanced ways than GDI is able of.

I have looked a bit further into the Wine GDI32 source and found some things I
think look strange.

First of all, Wine's GetPath() will return -1 on error. Microsoft doesn't seem
to document the actual return on error, but it seems that TextSub expects a 0
return to signal error. I don't think this is the cause however.

Looking further, it appears that PATH_ExtTextOut() will abort if
GetGlyphOutlineW() returns zero. I don't know if this applies to Wine, but in
my own experiments, on Windows GetGlyphOutlineW() will return zero for space
characters. This might be the cause of the bug. However
WineEngGetGlyphOutline() seems to return GDI_ERROR (which is (~0d) ie.
non-zero) on error. I believe it may also return 0 if the glyph requires an
empty path to draw, such as I would expect space characters to do.