Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!lll-winken!uunet!wugate!wuibc!beard
From: beard@wuibc.UUCP (James Beard MD)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: using fields with scroll bars
Message-ID: <364@wuibc.UUCP>
Date: 23 Jun 89 04:50:58 GMT
References: <4161@emory.mathcs.emory.edu>
Reply-To: beard@wuibc.UUCP (James Beard MD)
Organization: Washington University in St. Louis
Lines: 42

[in response to a query about how to make a click in the scroll bar of
a scrolling field un-highlight a button overlying a line of text in
the field.]

I can't be certain I understand what you are trying to do, but I would
suggest the following:

1) Perhaps you could dispense with the button entirely, if its sole
purpose is to highlight the selected line.  Version 1.2 allows you to
highlight a chunk of a field from within a script.  You can first
deduce what line of the field was clicked in.  Apple gives some
examples of this, which requires using the mouseloc at clicking time,
the height of a line of text (one of the fld properties), and how far
scrolled the field is (a fld property).  Assume that you have deduced
that the line clicked was line x.  Then you could write
  ...
  select line x of fld myField
  ... 

Besides being faster than moving a button around, this has the
advantage that the highlighted line remains highlighted (even during
scrolling out of and into view) until you do something to un-highlight it.

2) Version 1.2 has a new operator, Within, that lets you ask
whether a given point is within a certain rectangle.  An expression
of the form "<point> is within <rect>" will return a value of either
true or false.  Thus you could include something like the following in
the script of the scrolling field, assuming that you had previously
put the rect of the scroll bar into scrollzone:

on mousedown
  global scrollzone
  get the mouseloc
  if it is within scrollzone 
  then select empty  -- this undoes the highlighting
  pass mousedown  -- this lets the scroll bar do its scrolling work
end mousedown

(Not having tried the above, I can't guarantee it will work.  But I
think something very like it will.)

James C. Beard  (beard@wuibc2.wustl.edu)