Path: utzoo!attcan!uunet!husc6!think!ames!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga.tech
Subject: Re: CloseScreen internals
Keywords: closescreen 1.4
Message-ID: <3102@amiga.UUCP>
Date: 14 Nov 88 21:24:31 GMT
References: <4996@garfield.MUN.EDU>
Reply-To: jimm@cloyd.UUCP (Jim Mackraz)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 33

In article <4996@garfield.MUN.EDU> john13@garfield.MUN.EDU (John Russell) writes:
)I'm curious as to whether the inner workings of CloseScreen could be
)changed for the better without breaking anything. I think they could.
)
)Why not make the screen structure's presence dependent on a semaphore?

In V1.4, CloseScreen (and OpenWindow, CloseWindow, OpenScreen, and some new ones) will
support "Public Screens" which do All You Want and More.

Although there is a count of "visitor windows," the mechanism isn't exactly
a semaphore, although critical sections of the processing are protected by
an internal Intuition semaphore.

One of the tricky parts for a visitor window is determining if a screen exists, then 
adjusting for the screen's mode, font, depth and so on.  Sound familiar?  That's
what GetScreenData() was all about.  Well, that approach turned out kind of lame,
and a more general function LockPublicScreen() gets you a pointer to the
actual open screen, and a guarantee that that screen won't be closed until
you unlock it and close any windows you opened while it was locked.

I agree with John: this will be pretty useful.  It provides, as a side effect,
the ability to open workbench applications on various screens.  You can
have an editor, for example, which "jumps" from screen to screen, taking you
with it ;^)

)John

	jimm
-- 
	Jim Mackraz, I and I Computing	  
	amiga!jimm	BIX:jmackraz
Opinions are my own.  Comments regarding the Amiga operating system, and
all others, are not to be taken as Commodore official policy.