Path: utzoo!attcan!uunet!lll-winken!ames!ncar!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!stadler
From: stadler@Apple.COM (Andy Stadler)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: opaque paint problem
Message-ID: <24809@apple.Apple.COM>
Date: 26 Jan 89 23:03:47 GMT
References: <584@gould.doc.ic.ac.uk>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 32

In article <584@gould.doc.ic.ac.uk> np@doc.ic.ac.uk (Nigel Perry) writes:
>
>Opaque paint doesn't seem to work properly, can anybody suggest a solution
>or is this a real bug? Scenario: background picture of keyboard, background
>transparent buttons over some of the keys including "return", card picture
>of ']' button painted opaque. This is done so when the return button is
>highlighted it looks "L" shaped. Now this works fine, but leave the card
>and come back again and the card picture has gone transparent! I've
>temporarily fixed the problem by using an "openCard" handler to
>select the card picture and make it opaque again, but this is slow.
>Any ideas, have I misunderstood opaque paint?
>

Hypercard has a 'feature' which was designed to remove spurious opaque areas
which tend to clutter up a painted card.  If hypercard determines that the
opaque areas of a card aren't doing anything (that is, if you removed the
opaqueness, would the image still come out the same?) then it will -remove-
the opaque bits.  This speeds up hypercard for a number of reasons, incl.
smaller file, less bits to worry about, etc.

But the problem is when you are using opaque to obscure a button.  If you need
opaque to 'stick', you must convince hypercard not to remove this.  There are
two ways to do this...

(1) Put a black dot in the background image of your ']' key.  The opaque will
    cover it up so the end user won't see it;  And hypercard will say 'the
    opaque is doing something, I better not remove it!'

(2) Use opaque somewhere else in the card.  Hypercard will only remove opaque
    if it can -completely- remove the opaque.

--Andy        stadler@apple.com