NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/sys/atari/st/tech/6285

Internet Message Format | 1992-12-15 | 1.7 KB

Path: sparky!uunet!pipex!demon!cix.compulink.co.uk!apelled
Newsgroups: comp.sys.atari.st.tech
From: [e-mail] (Adam Pelled)
Subject: Re: Sending objc_draw to a memory buffer rather than screen
Reply-To: [e-mail]
Date: Wed, 16 Dec 1992 02:16:00 +0000
Message-ID: <[e-mail]>
Sender: [e-mail]
Lines: 28


In article <[e-mail]>, [e-mail] (Howard Chu) writes:
>I've got a question of my own tho (which shows my own inexperience with
>GEM, sigh) - how do you update a window that is partially obscured, and
>make sure that you only redraw the area that is exposed? (I'm not talking
>about fielding a redraw event from AES, but when you want to draw new stuff
>into a window and it is no longer the top window. Is that rectangle list
>always valid, so I should just treat these two cases the same way?)
>--
>  -- Howard Chu @ Jet Propulsion Laboratory, Pasadena, CA
>
>All true wisdom is conveyed in one-line witticisms.

    Ah, yes, that's a goody. Took me a while to find out that the rectangle
list is maintained valid at all times. Just walk it even without the redraw
event.
    Incidentally. Has anyone else noticed that when a window is moved back
into full view that the redaw is for all the work area. A bit lazy of the
AES methinks.
    Also the rectangle list is not exactly optimum. i realise it must be
recursive and that there must be some kind of inheritance, but it seems a
shame that it couldn't be merged by the OS and save the overhead for all the
apps having to redraw too many rectangles. With losts of windows this gets to
be quite drastic. Try an experiment and draw a box outline in a  multi window
environment you'll see what i mean.


    Adam.