[Pythoncard-users] Sizers for PythonCard

[Hugh K. <ma...@hu...>]

I found PythonCard some time ago while looking for a way to write 'real 
programmes' for Windows.  Its simplicity and logical structure appealed 
to me.  Through it I have learnt a huge amount about both Python and 
wxWidgets.  In particular the ability to adapt, amend and extend the 
tools is very satisfying.

Like others I found the inability to use sizers easily was a drawback.  
Not so much of a drawback as to make me want to learn C++ and code in 
wxWidgets, or to give up PythonCard, but at the same time I objected to 
mixing programmatic generation of sizers into my code - it is also a 
hard way to learn.

Inspiration for a solution came with Alex Tweedly's simplesizer and I 
set off with the aim of making sizers work for PythonCard while 
maintaining what seem to be its two key characteristics:  the separation 
of layout and processing, and the use of visual drag-and-drop tools for 
layout.  A secondary aim was to develop the routines in a way which did 
not break existing tools or code.

I now have something which is firmly an alpha version and a work in 
progress, but it does work in several regards.  I'd be happy to share my 
code for comment and improvement but the mailing list rejected the zip 
file (even if it was only 106Kb).  So I'd be glad if someone could 
explain how to get round that.

The elements are:
(a) additions to the existing Layout Editor to create a visual Sizer 
Editor which manipulates sizers and allows components to be dropped into 
them and re-arranged at will; the effect of different settings can be 
seen immediately;
(b) the final sizer details are saved into the current .rsrc.py file;
(b) a short routine, called autoSizer, which processes the sizer data in 
the .rsrc file when a main application is initialized.

The routines handle BoxSizers, GridSizers and StaticBoxSizers;  
FlexGridSizers are implemented but I am not 100% convinced I've got them 
right. The biggest omission is the ability to override manually the 
sizer engine's calculation of minimum dimensions for components.

There is an option to ease the conversion of existing .rsrc.py layouts 
to a sizer-based format.  A menu option creates a single vertical sizer 
containing all the components in the .rsrc file (effectively an 
on-screen list).  You can then define your desired sizer configuration 
and drag and drop the components into the right places.  Eventually the 
temporary vertical sizer can be deleted when it is empty.  Slightly 
tedious but it works and it beats re-typing all your components.

I have had  trouble with setting minimum sizes, so I've parked that for 
now.  I have also yet to master re-drawing the screen properly, dealing 
with the sizing handles when they get misplaced, and the impact of the 
MenuBar on the editor display.  Nor have I tested the interaction of my 
sizer-based solutions with all the elements of Layout Editor, especially 
multiple selections.  The GridBagSizer is a joy to come, as are global 
and multiple edits of sizers, drag-and-drop in the sizer tree etc, etc!

Thanks, Hugh Kernohan