racket/collects/frtime/gui/doc.txt

> FrEd (Functional Reactive Editor library)
  
MACROS
-------
To get the basic macros:
(require frtime/demos/gui/mixin-macros)

> (events->callbacks field-name update-call)
Generates a mixin for allowing an event stream to drive
callbacks. When an event stream is given as the init value
for field-name, that event stream is stored, and whenever an
event occurs on that stream,  update-call is invoked on the
value of the event. The one argument to the resulting mixin
is the class being extended

> (callbacks->args-evts stream-name callback)
Generates a mixin that sends an event on stream-name when
callback is called. The class has an init field called
[stream-name]-event-processor, whose value is a function.
The public method (get-[stream-name]) of the resulting class
gets the result of applying [stream-name]-event-processor 
to the stream of args-evts. The events on the stream are
lists of the arguments to the callback. The default value 
for [stream-name]-event-processor is given as the first
argument to the mixin, and the class being extended is the
second argument to the mixin.

FtA provides event-is-val, split-mouse-events/type, and
split-key-events/type for use as initialization arguments.
event-is-val can be used for [stream-name]-event-processor
when the event should just be the value of the first 
argument of the callback. split-*-events/type sets up an
appropriate split (see FrTime docs for split information,
MrEd docs for key-event codes and mouse-event types) over
the type of event occurence.

                                                    
events->callbacks and callbacks->args-evts are the backbone
of the transition between an object-oriented library and an
event-stream based library.




AUXILIARY MACROS
------------------

Some common utility macros provided from:
(lib "aux-mixin-macros.ss" "frtime" "demo" "gui")
                                                    
> (behavior->callbacks field-name update-call)
Generates a mixin for allowing a behavior to control a
widget. The mixin has two arguments. The mixin's first
argument is the default value for field-name, and the
seconds argument is the class being mixed. Whenever a
behavior is supplied as the value for field-name, the
value-now of that behavior is used as the super-new argument
for filed-name, and whenever there is a change in that
behavior, update-call is invoked with the current value of
the behavior.

> (mixin-merge-e new-stream-name stream-getter1 stream-getter2)
Generates a mixin that provides access to the merge-e of two
event streams. The first argument is the name of the merged
stream. The merged stream can be accessed by the public
method (get-[new-stream-name]). The method stream-getter1
and stream-getter2 are assumed to be inherited public
methods that return event streams.

> (embed-processor processed-member-name getter ...)

embed-processor is a macro for creating a mixin that embeds
a signal processing step into the object. For example,
mixin-merge-e is written in terms of  embed-processor as: 

(embed-processor new-stream-name
		(lambda (ev1 ev2)
		(merge-e ev1 ev2))
		stream-getter1
		stream-getter2).
		
The mixin created has one argument, which is the class being
mixed. embed-processor is in aux-mixin-macros.ss

For examples of how to use behavior->callbacks,
mixin-merge-e, events->callbacks, and callbacks->args-evts,
consult the tutorial file "instr.ss" in 
collects/frtime/demos/gui/demo.



MIXINS
------
Some common mixins have already been defined and applied.
To get these: 
(require "fred.ss" "frtime" "demos" "gui")

> (add-mouse-access super-class)
Derived from callbacks->args-evts.
 stream-name: mouse-events
 
> (add-focus-access super-class)
Derived from callbacks->args-evts
 stream-name: focus-events

> (add-keypress-split super-class)
Derived from callbacks->args-evts.
 stream-name: key-events
 
> (add-callback-access value-extractor default-value super-class)
value-extractor is a method of two arguments (a widget and a
control event) that gets a value for the widget.
default-value is the default value for the widget. Adds
(get-value-e) and (get-value-b) to super-class, where
get-value-e returns an event stream representing the value
of the widget, and get-value-b returns a behavior
representing the value of the widget.

> (add-callback-access/loop value-extractor default-value super-class)
does the work of add-callback-access, but also adds an
initialization argument value-set, which is an event stream
that sets the value of the widget at each event.

> (add-focus-on-event super-class)
Derived from events->callbacks.
 field-name: focus-when
 


UTILITY
-------

> (standard-lift widget value-method value-default)

standard-lift applys a common set of mixins to the widget.
It applies add-mouse-access, add-focus-access, and it applys
the result of behavior->callback for label, enabled,
min-width, and min-height. It also applies
add-callback-access with value-method as the
value-extractor, and value-default as the default-value.
Widgets that have been standard-lift'ed:

ft-button%
ft-radio-box%
ft-choice%
ft-list-box%


> (standard-lift/loop widget value-method value-default)
standard-lift/loop is the same as standard-lift, except
thatit applies add-callback-access/loop instead of
add-callback-access.
Widgets that have been standard-lift/loop'ed:
ft-check-box%
ft-slider%
ft-text-field%


simple.ss
---------

Many useful utilities have been put in
(require "simple.ss" "frtime" "demos" "gui")
feel free to look around and use the ones you think are
useful.