Cassowary anyone?!

Andreas Raab andreas.raab at
Thu Jan 9 19:11:31 UTC 2003


Thanks - by now I got various copies from people (thanks to all of you!)
but this is the kind of thing that really _ought_ to be on SqueakMap
(hint, hint!).

> What are you thinking of doing with it?

I'm looking into different ways of end-user friendly specification of
"object compositions" (aka: layouts). Since I know that Cassowary was
used for CSVG and other things I was wondering if it might be a good
starting base for some more end-user friendly model than we have right

This problem bugged me for a long time now - the AlignmentMorph's in
Squeak used to require compositions of compositions of compositions of
nested things and they just got in the way of "seeing the thing you are
interested in" (namely some object of the composition). So I tried to
generalize this into the layouts we have today but while they are more
general they are also much harder to understand (lots of very generic
properties with lots of unclear compositional effects).

So what I am essentially looking for is some way of specifying "lots of
dog-simple constraints" (like: make the left edge of one guy follow the
right edge of some other guy) and provide some interactive means for
specifying it - so that rather than having a set of generic properties
the user gets a (possibly large) number of very concrete
mini-constraints. Those need to be solved efficiently and that's when I
got into thinking about the various constraint solvers.

BTW, do you know if Cassowary can give feedback about constraints that
cannot be resolved (perhaps even potentially)?! I'm interested in this
because what I would like to do is give constant feedback about the
composition you are building - so that when you add a constraint which
"won't work" the system could indicate this by some means.

  - Andreas

> -----Original Message-----
> From: squeak-dev-admin at 
> [mailto:squeak-dev-admin at] On 
> Behalf Of Joshua 'Schwa' Gargus
> Sent: Thursday, January 09, 2003 7:32 PM
> To: Andreas Raab; Squeak Mailing List
> Subject: Re: Cassowary anyone?!
> Hi Andreas,
> My message to the list seems to have been lost, so I'm resending
> to you and the list.
> You can get Cassowary from:
> What are you thinking of doing with it?
> Joshua

More information about the Squeak-dev mailing list