Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!hsdndev!think.com!mintaka!geech.ai.mit.edu!rjc
From: rjc@geech.ai.mit.edu (Ray Cromwell)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: Hooks into the OS vs doing it all yourself (Was Re: Clueless Mac<>)
Message-ID: <1991Jan31.044116.25645@mintaka.lcs.mit.edu>
Date: 31 Jan 91 04:41:16 GMT
References: <1991Jan25.075446.716@Neon.Stanford.EDU> <7658@sugar.hackercorp.com> <1991Jan31.011702.12095@Neon.Stanford.EDU>
Sender: daemon@mintaka.lcs.mit.edu (Lucifer Maleficius)
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In article <1991Jan31.011702.12095@Neon.Stanford.EDU> torrie@cs.stanford.edu (Evan J Torrie) writes:
>peter@sugar.hackercorp.com (Peter da Silva) writes:
>
>>In article <1991Jan25.075446.716@Neon.Stanford.EDU> torrie@cs.stanford.edu (Evan J Torrie) writes:

>>>   Can your program get its hooks into this event BEFORE the OS gets
>>> hold of it and "do its own thing"?
>
>>Nope. You can tell Intuition the bounds you're willing to let the user manage
>>the window within, but that's it.
>
>  Well this will probably cause some flames, but this is an example of
>where the Mac is MORE customizable than the Amiga... i.e. where the
>user can make things work the way he wants, not the way the OS wants.
>  I am reminded of a quote in Steve Chernicoff's Macintosh Revealed
>book... paraphrasing, he said something like "When Apple released the
>Macintosh 128K, critics pounded it for being a closed system.  While
>their criticisms of the hardware were well-founded, what they didn't
>realise was that the Macintosh had an almost completely open software
>design".
>  For example, all the hooks into window definition functions, menu
>definition functions, etc... where you can roll your own code, and
>make your own windows/menus etc... this is how the Mac gets all those
>nice NeXT/Motif type windows without having to rewrite existing
>program code.

   Well the Amiga can do this too, but its not officially supported.
Programs can use input handlers to get mouse/key events before
intuition gets them, programs can SetFunction() OpenWindow, programs
can open their own screen and uses layer's to implement their own 
windowing system. There are many ways to customize the interface.
For instance, there are programs like Exploding Windows, PopUpMenu,
Snap, NewLook, NeXTWindows that do a good job of enhancing the Amiga's
look. In the area of enhancing the Amiga's environment, users can choose
from a wide variety of Shells, Replacement Workbenchs, Mouse Accelerators,
Pointer Animators, Screen blankers, Clocks, Gadget Replacements, Screen
hacks, input handlers, etc. Look at the Fish collection, over 400 megabytes
of Freeware, and atleast 6-10% of it is in the format of user enhancements.


>  While it means you may have to write more code to handle the general
>case, it gives you more control over the final result as well.   
>
>>Amiga scrollbars (proportional gadgets) don't have arrows. If you see an arrow
>>the application is managing two gadgets together. But if you want to know how
>>Intuition (which, by the way, is not the O/S, it's just another task) knows how
>>far you can frag a scrollbar with the mouse, I can tell you that: the
>>application tells it how far it can move the knob.
>
>  Can you have callback functions.. i.e. get Intuition to call your
>function while it's moving the knob?

  Not that I know of. I wouldn't want it. Consider a heavy loaded system
with the user causing lots of input events. Your call-back function
better be damn FAST or your going to suck up lots of CPU. Instead, the
Amiga sends messages and you can service these messages at your
own leisure, a benefit is that calls to Wait()/GetMsg() can yield the
CPU to other tasks while your waiting for a message. If you want
the OS to call your functions, install an input handler and have it 
parse a list and call the appropriate functions, or spawn a task
to Wait for messages, and have that task translate those messages into
calls to other tasks. Hard? No. Not as easy as call back, but any 
fairly good Amiga programmer can emulate them with an input handler
in a few hours. My question would be, why? I like the message system
better.

 Also, some of the graphics.library functions are call-back (the animation
and collision routines)

Since when does the Mac have a NeXT/Motif look? If so, is it a  PD hack
and where can I get it? I want to try it on my friends Amax. I think
plain old finder looks horrible, and so do many of the Mac requestors.
AmigaDOS 2.0 makes the Mac look like C64 GEOS.

>-- 
>------------------------------------------------------------------------------
>Evan Torrie.  Stanford University, Class of 199?       torrie@cs.stanford.edu   
>Today's maxim:  All socialists are failed capitalists