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README -- Presto Tool Box
 
% Copyright (C) 1999 Dr. Charles R. Denham, ZYDECO.
%  All Rights Reserved.
%   Disclosure without explicit written consent from the
%    copyright owner does not constitute publication.
 
% Version of 03-Nov-1999 08:17:54.
% Updated    14-Dec-1999 14:34:50.

The "PS" Class

Presto's "ps" class provides a framework for handling
events generated by interactive graphical components
in Matlab-5.  Users are expected to derive their own
class from the "ps" class and then provide a
"doevent" method to overload the basic "ps" behavior,
as needed.  Methods for creating menus, controls, and
user-defined properties are included.

How Presto Works

The "ps" constructor writes a "ps" object into
the "UserData" of the graphical entity to which it
will be attached, typically a "figure".  Key callbacks
of the associated graphical components are forced to
invoke "psevent the_callback_name" whenever they are
manipulated with the mouse.  The "ps" object itself
is extracted from the GUI, and its "doevent" method is
called as "doevent(self, the_callback_name)".  In the
case of menus and controls, the callback-name is
translated to the tag of the particular item
before the "doevent" method is invoked.

The basic "doevent" method is a "switch" ladder, which
uses the names of the callbacks to decide how to act
upon any request.

User-Defined Properties

Users may set and get additional properties of their own
choosing for each "ps" object, using the standard
"dot" syntax associated with Matlab "struct" entities.
Interestingly, if the requested property happens to be
an actual graphical property, it is instituted directly.
Thus, whether dealing with a GUI property, or a user-defined
property, the same "dot" syntax works for both.  Indeed, the
"ps" subscripting abilities are versatile, unlike the
Matlab "set/get" commands.

Example:

p = ps(anyFigure)
p.myColor = [0 1 1]
p.color = p.myColor

Menus

In "ps", uimenus are created with the "menu" method, whose
second argument is the name of the menu-item, suitably prefixed
with an indication of where it lies in the menu heirarchy.
When enables, these menus call the "event" method, which cleans
up the name before deciding what to do.  For example, "Open..."
is translated into "open" before the switch-ladder is executed.

Controls

The "control" method allocates uicontrols, whose layout is defined
in normalized units, plus pixel offsets.  Whenever a "ResizeFcn"
event occurs in "presto", all such controls are themselves
resized to fit the new figure geometry.  This scheme is very
important for preserving the appearance of the figure, an
ability not otherwise available in Matlab.

Standard scrollbars are created using the keywords "right", "bottom",
"left", and "top" as the style-name in the "control" method.  This
facilitates immensely the otherwise difficult burden of positioning
Matlab scrollbars (sliders).