[cairo] Re: Notes on cairo/win32

[Owen Taylor]

On Wed, 2005-01-12 at 10:30 -0500, Owen Taylor wrote:
> On Wed, 2005-01-12 at 10:16 -0500, John Ehresman wrote:
> > Owen Taylor wrote:
> >  > ...
> > > If I had to take a guess at the right direction, it's to go on top of
> > > GDI+ for now (with heavy image fallbacks), and look at writing a
> > > Direct3D backend later.
> > 
> > How much of an advantage is GDI+ over GDI?  I agree that the need for 
> > printing favors GDI+/GDI over the other two.  My interest in cairo is 
> > mainly driven by the future use of it by gtk and its printing support. 
> > I don't anticipate that I'll be using many of the advanced graphics 
> > capabilities.
> 
> From rom what I've figured out so far, the main two things that GDI+ gives
> over GDI which are useful to us are anti-aliased paths and 
> alpha-composited primitives. 

Further question is handling of text ... 

 + for GDI+ : If GDI+ actually gives consistent rendering Win9x with
              later systems, then it is able to put text through
              arbitrary affines, something you can't do (AFAIK) with
              the Win9x GDI.

 - for GDI+ : There seems to be no way equivalent to ETO_GLYPH_INDEX
              in ExtTextOutW, so I don't see how we can draw Uniscribe
              output using GDI+

The latter point makes me think that even a "GDI+" backend is going to
need to use some GDI. I haven't found explicit information about mixing
GDI and GDI+, though it seems likely to be possible. 

(There's a Graphics::Flush() operation that might be needed when
switching betwen them. On the other hand, it might just be a wrapper
around GdiFlush(), and only needed for threading or accessing the
bits.)

Regards,
					Owen

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