Opal/CoreGraphics (was Re: UIKit?)

[Eric Wasylishen]

Hey,

As David mentioned, I implemented a bit more of Opal over the holidays 
(transparency layers, and CGLayer). I think Balaton's approach of implementing 
CoreGraphics as a thin wrapper over Cairo is the right choice in terms of 
performance (should be excellent, especially with Cairo's new OpenGL compositor 
backend under development), completeness/output quality (should closely match 
Apple's), and feasibility/minimal development effort. It currently implements a 
fairly large subset of CG and is under 4k lines of code. I'll move it to the 
/dev-libs directory in GNUstep SVN soon.

There are a few ways we could use Opal in GNUstep. The possibility I am 
currently exploring (planning to put in a branch in svn) is modifying -gui to 
use CoreGraphics directly. This would entail making Opal a dependency of -gui, 
eliminating the Display PostScript api between -gui and -back. -back would be 
reduced to the xlib and Win32 window server code. At the cost of not having a 
choice of graphics backend, this could make the code in -gui clearer, improve 
performance, and make possible a CoreAnimation implementation and porting a 
larger set of OS X applications. 

Regards,

Eric