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From: av@woo.oulu.fi.oulu.fi (Ari Vaulo, LuTK/TOL)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: if there is ... at [xx,yy]
Message-ID: <1991Mar30.180433.17363@ousrvr.oulu.fi>
Date: 30 Mar 91 18:04:33 GMT
References: <12497@pt.cs.cmu.edu>
Sender: news@ousrvr.oulu.fi
Organization: University of Oulu, Finland
Lines: 84

From article <12497@pt.cs.cmu.edu>, by kem@h.gp.cs.cmu.edu (Kenneth Mohnkern):
> I guess HC2.0's "there is" doesn't have the ability to check if 
> there's an object at a certain point. The manual doesn't cover
> "there is" very well. I think it's only mentioned in a table of
> functions (or commands? properties?) I tried "If there is a bg 
> btn at 442,42 then beep". I got an error message.
> 
> Is there another way around this? I'd like to look at a specific 
> location and see if there's a button there without looking at
> every button and comparing its loc with the desired loc.
> 
> I know if there's a cool way to do this I'll find it here.
> 
> Thanks,
> 	ken
> 
> -- 
> 
> ken mohnkern#the robotics institute#carnegie mellon univ#pittsburgh pa

I solved that kind of problem by clicking at the point where I supposed 
that there could be a button or something else. But it requires special
code on every possible target. First I tried (with HC 2.0) the following
command:
    click at xloc,yloc
It was easy to look using TARGET function which object was at location
(xloc,yloc), but it was a bit harmful because it executes all the mouse*
command handlers and I should modify the command with shift,command, and
option keys:
    click at xloc,yloc with cmdkey

and in possible targets

  on mouseUp
     if the cmdKey is "down" then
        exit mouseUp
     else
        {code what the button should normally do}
     end if
  end mouseUp

And at last I found that the possible solution isn't elegant, but it works.
You should put the following code in your script where you want to find
other objects:
   
    ...
    global KLIKATTU,OSUMA
    put empty into OSUMA
    put "Joo" into KLIKATTU
    click at xloc,yloc
    put empty into KLIKATTU
    if OSUMA is not empty then
       {the name of the object located at xloc,yloc is in variable OSUMA}
       {and it could be anything card, button, field, and so on.
    ...

And in every object where is either some mouse* handlers or are your
possible targets you should put the following code:

   on mouseUp
      global KLIKATTU
      if KLIKATTU is empty then
         {code what the object should normally do}
      else
         global OSUMA
         put the name of me into OSUMA
         exit mouseUp 
      end if
   end mouseUp

I don't like global with object oriented like code, but sometimes it is MUST.
I'm trying to do draughts (or checkers) game with HC (I'm not sure that it
will be ever ready) and there I need this kind of scripts.

Ari





Ari Vaulo ---------------------------------------- eMail: av@tolsun.oulu.fi
University of Oulu --------------------------------------------------------
Department of Information Processing Science ------------------------------
Finland --------------------------------------------- voice: +358-81-352647