[Pythoncard-users] simple layout managers

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

I have written some code to reposition/resize
components with changes in Background (wxFrame) size.
There are 3 options. The only requirement for each is
that the anchors property is set for each component –
these indicate how the component should move/size with
respect to its environment. I have attached a simple
example GUI that can be run to demonstrate the 3
layout managers. The layout manager and anchors for
each component can be changed in
MyBackground.on_initialize.

1) Simple anchors are used in Delphi and .Net Forms.
See links below for description of this
http://euler.aero.iitb.ac.in/docs/Programming/wxPython-2.5.2.8/docs/api/wx.lib.anchors.LayoutAnchors-class.html
http://www.devx.com/dotnet/Article/6964/0/page/3
This layout manager does not work well if there is
more than one component to be resized in each
direction. Thus the example attached is not a good
example for this layout manager. By limiting the
number of components that resize, this method will
work Eg set tree anchors to ‘TRB’ (Top-Right-Bottom ->
only height change), and TextArea anchors to ‘LT’
(Left-Top -> no resizing).

2) Relative anchors are very similar to simple
anchors. However, components are constrained to be a
percentage distance to the container’s edge (relative
to container’s width/height). Ie instead of setting a
distance of 10 pixels, it is set to 10% (for a
container of width 100 pixels). This layout manager is
able to able to deal with multiple resizable
components. However, the distances between all
components changes as the window resizes. If the
resizable components do not take up the majority of
the window space, the increased spacing between
components as the window grows may look strange.

3) Advanced anchors allow for multiple resizable
components and absolute spacing by dividing the window
into a grid (based on position/size of all resizable
components) and the components are anchored relative
to the closest grid line in each direction. The grid
resizes with the window and the components are resized
to maintain their distance constraints to the grid
lines.  Each column/row in the grid has a different
weight which determines the extent that the row/col
size changes with container size. The col/row weights
are automatically calculated (there are multiple
options for how this can be automatically calculated
and obviously the option to manually set the weights).
The Background has a method showPartitions(True) that
can be used to show the grid lines.

I would be interested in comments and examples where
these layout managers do and do not work well.

Michael

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