[Pythoncard-devel] Simple anchors for window resizing

[Michael S. <mik...@ya...>]

Hi,

I have written some simple code to allow for anchoring
of components to edges of containers. This corresponds
fairly closely to a past discussion on the list
http://aspn.activestate.com/ASPN/Mail/Message/pythoncard/1183899.
Attached are a few files that can be run to
demonstrate the concept. The code is very short and
simple. I have written it based on PythonCard v0.8.1

testAnchors.py has all the layout code included in the
file. You should be able to run this application
without any changes to the PythonCard installation.

If you update model.py, widget.py, and
propertyEditor.py in your PythonCard distribution, you
will be able to get testAnchors2.py to run. This
should display the same example application. The
anchors variable is now stored in the rsrc file (and
can be set/viewed in the resource editor). The
testAnchors2.py file is now nothing more than the
standard file automatically created with a new
application. You should be able to test your own
examples – simply make a new application and set the
anchors property in the property editor (there should
be a list of options with default of ‘LT’ –ie left and
top- and thus if you don’t change the property it will
continue to act as it did before this update).
Alternatively, load an existing rsrc file and alter
the anchors property and save.

testAnchors.py is an example that demonstrates the
limitations of this approach. Components set to expand
with an expanding container are greedy – their
increase in size is equivalent to the increase in size
of the container. Hence when there are multiple
components that are to change size this may cause
problems. A mechanism of sharing the container size
change between multiple components is necessary to
deal with this. I am unsure what the simplest way of
doing this is. I think it is rather confusing to set
the sharing on a component by component basis. A
simpler approach may be to partition the container
into segments (by rows or columns), with a simple
mechanism for sharing the container size changes. The
components would then reference the sub containers
(using anchors). 

I hope this is useful. If so, feel free to use the
code under the same license as pythoncard. 

Michael

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