Path: utzoo!mnetor!uunet!husc6!bbn!uwmcsd1!ig!jade!ucbvax!hoser.berkeley.edu!bryce
From: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Newsgroups: comp.sys.amiga
Subject: Re: Dealing with lots of messages
Message-ID: <22427@ucbvax.BERKELEY.EDU>
Date: 7 Jan 88 13:39:49 GMT
References: <4346@garfield.UUCP>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Distribution: na
Organization: The Logic Foundation
Lines: 52
Keywords: messages IDCMP MOUSEMOVE

In article <4346@garfield.UUCP> john13@garfield.UUCP (John Russell) writes:
>None of the messages on dealing with many messages (esp. mousemove) from one
>or more ports has mentioned a very simple technique that can speed up
>response time greatly.
>
>It goes something like this...
>
>	msg = GetMsg(window->UserPort);
>	....
>		case MOUSEMOVE:
>			if (window->MouseX != x || window->MouseY != y)
>			/* user has moved the mouse since this message
>			   so I will ignore it */
>				break;
>			else
>			<normal routine to deal with mouse movements>

*YUCK!* This technique combines a timestamped mouse message and compares it
syncronously as a crude aproximation of the current mouse position! This
also has the potential of getting out of sync.  Either method alone is
ok.  Combining them is asking for problems.

The much better way is just to eat all of the mouse messages you don't
want.  I'll drag an example out of my bag of disks and post it as AmigaLine
#5.

(Note: anyone is welcome to write an AmigaLine... just send it to me first
so the numbers stay straight).

The Intuition manual has an example like this, but I consider it defective.
It processes "normal" messages before the mouse moves.  This means that the
user might use the mouse, then pull down a menu.  Both messages will be
queued to the port.  The Intuition manual code would handle the menu THEN
handle the mouse move.	Potential problems abound.


<By doing this you can minimize the number of redraws (say when rubberbanding
<a line).

Yes. It is a valuable technique.  (-: (-: One Intuition should use :-) :-)
It also keeps piles of unwanted mouse messages from piling up at your
ports.


BTW: I would not recommend depending on the Window's relative mouse
co-ordinates always getting updated (unless the window is the active one).
Not a problem for your code, of course.

|\ /|  . Ack! (NAK, SOH, EOT)
{o O} . bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce (or try "cogsci")
 (")
  U	"Your theory is crazy... but not crazy enought to be true." -Niels Bohr