Mac OS X Window Server vs. X11: the insane task

Question

Dedicated to all who likes low-level Window Server (CoreGraphicsPrivate.h, etc), X11 on Mac, SIMBL and other crazy stuff :)

There\'s a simple X11-emulated application on

Answer 1

All the X11.app sources and other stuff (Xquartz) are available at Apple's official site (current version 2.3.5 (server 85.2)). The core of windows creation lies in xpr subdirectory.

To manipulate windows Xquartz uses Xplugin library (/usr/lib/libXplugin.dylib). Its header, /usr/include/Xplugin.h, defines functions like xp_create_surface() and others, which create windows using private CoreGraphics API, like CGSNewWindowWithOpaqueShape(). Undocumented CoreGraphicsPrivate.h or CSGPrivate.h, the result of reverse engineering, can be found over the Web. Xplugin remembers ids of such Quartz windows in its own hash and returns an opaque integer (i.e., xp_resource_id) for them. Then Xquartz associates a particular XID with this xp_resource_id and returns it to a client.

Xplugin is closed source and has no API to return native Quartz drawable by xp_resource_id or XID.

In order to draw upon a window which was created with private CoreGraphics API you have to use those private API. There's a function, named CGWindowContextCreate(), which returns CGContextRef for a particular native window by its Quartz id. It is possible to draw on the window using this context. But to receive the real context instead of NULL, you must be in a process, which created the window.