37.6. "FrameWork" — Interactive application framework
*****************************************************

The "FrameWork" module contains classes that together provide a
framework for an interactive Macintosh application. The programmer
builds an application by creating subclasses that override various
methods of the bases classes, thereby implementing the functionality
wanted. Overriding functionality can often be done on various
different levels, i.e. to handle clicks in a single dialog window in a
non-standard way it is not necessary to override the complete event
handling.

Note: This module has been removed in Python 3.x.

Work on the "FrameWork" has pretty much stopped, now that "PyObjC" is
available for full Cocoa access from Python, and the documentation
describes only the most important functionality, and not in the most
logical manner at that. Examine the source or the examples for more
details.  The following are some comments posted on the MacPython
newsgroup about the strengths and limitations of "FrameWork":

   The strong point of "FrameWork" is that it allows you to break into
   the control-flow at many different places. "W", for instance, uses
   a different way to enable/disable menus and that plugs right in
   leaving the rest intact. The weak points of "FrameWork" are that it
   has no abstract command interface (but that shouldn’t be
   difficult), that its dialog support is minimal and that its
   control/toolbar support is non-existent.

The "FrameWork" module defines the following functions:

FrameWork.Application()

   An object representing the complete application. See below for a
   description of the methods. The default "__init__()" routine
   creates an empty window dictionary and a menu bar with an apple
   menu.

FrameWork.MenuBar()

   An object representing the menubar. This object is usually not
   created by the user.

FrameWork.Menu(bar, title[, after])

   An object representing a menu. Upon creation you pass the "MenuBar"
   the menu appears in, the *title* string and a position (1-based)
   *after* where the menu should appear (default: at the end).

FrameWork.MenuItem(menu, title[, shortcut, callback])

   Create a menu item object. The arguments are the menu to create,
   the item title string and optionally the keyboard shortcut and a
   callback routine. The callback is called with the arguments menu-
   id, item number within menu (1-based), current front window and the
   event record.

   Instead of a callable object the callback can also be a string. In
   this case menu selection causes the lookup of a method in the
   topmost window and the application. The method name is the callback
   string with "'domenu_'" prepended.

   Calling the "MenuBar" "fixmenudimstate()" method sets the correct
   dimming for all menu items based on the current front window.

FrameWork.Separator(menu)

   Add a separator to the end of a menu.

FrameWork.SubMenu(menu, label)

   Create a submenu named *label* under menu *menu*. The menu object
   is returned.

FrameWork.Window(parent)

   Creates a (modeless) window. *Parent* is the application object to
   which the window belongs. The window is not displayed until later.

FrameWork.DialogWindow(parent)

   Creates a modeless dialog window.

FrameWork.windowbounds(width, height)

   Return a "(left, top, right, bottom)" tuple suitable for creation
   of a window of given width and height. The window will be staggered
   with respect to previous windows, and an attempt is made to keep
   the whole window on-screen. However, the window will however always
   be the exact size given, so parts may be offscreen.

FrameWork.setwatchcursor()

   Set the mouse cursor to a watch.

FrameWork.setarrowcursor()

   Set the mouse cursor to an arrow.


37.6.1. Application Objects
===========================

Application objects have the following methods, among others:

Application.makeusermenus()

   Override this method if you need menus in your application. Append
   the menus to the attribute "menubar".

Application.getabouttext()

   Override this method to return a text string describing your
   application. Alternatively, override the "do_about()" method for
   more elaborate “about” messages.

Application.mainloop([mask[, wait]])

   This routine is the main event loop, call it to set your
   application rolling. *Mask* is the mask of events you want to
   handle, *wait* is the number of ticks you want to leave to other
   concurrent application (default 0, which is probably not a good
   idea). While raising *self* to exit the mainloop is still supported
   it is not recommended: call "self._quit()" instead.

   The event loop is split into many small parts, each of which can be
   overridden. The default methods take care of dispatching events to
   windows and dialogs, handling drags and resizes, Apple Events,
   events for non-FrameWork windows, etc.

   In general, all event handlers should return "1" if the event is
   fully handled and "0" otherwise (because the front window was not a
   FrameWork window, for instance). This is needed so that update
   events and such can be passed on to other windows like the Sioux
   console window. Calling "MacOS.HandleEvent()" is not allowed within
   *our_dispatch* or its callees, since this may result in an infinite
   loop if the code is called through the Python inner-loop event
   handler.

Application.asyncevents(onoff)

   Call this method with a nonzero parameter to enable asynchronous
   event handling. This will tell the inner interpreter loop to call
   the application event handler *async_dispatch* whenever events are
   available. This will cause FrameWork window updates and the user
   interface to remain working during long computations, but will slow
   the interpreter down and may cause surprising results in non-
   reentrant code (such as FrameWork itself). By default
   *async_dispatch* will immediately call *our_dispatch* but you may
   override this to handle only certain events asynchronously. Events
   you do not handle will be passed to Sioux and such.

   The old on/off value is returned.

Application._quit()

   Terminate the running "mainloop()" call at the next convenient
   moment.

Application.do_char(c, event)

   The user typed character *c*. The complete details of the event can
   be found in the *event* structure. This method can also be provided
   in a "Window" object, which overrides the application-wide handler
   if the window is frontmost.

Application.do_dialogevent(event)

   Called early in the event loop to handle modeless dialog events.
   The default method simply dispatches the event to the relevant
   dialog (not through the "DialogWindow" object involved). Override
   if you need special handling of dialog events (keyboard shortcuts,
   etc).

Application.idle(event)

   Called by the main event loop when no events are available. The
   null-event is passed (so you can look at mouse position, etc).


37.6.2. Window Objects
======================

Window objects have the following methods, among others:

Window.open()

   Override this method to open a window. Store the Mac OS window-id
   in "self.wid" and call the "do_postopen()" method to register the
   window with the parent application.

Window.close()

   Override this method to do any special processing on window close.
   Call the "do_postclose()" method to cleanup the parent state.

Window.do_postresize(width, height, macoswindowid)

   Called after the window is resized. Override if more needs to be
   done than calling "InvalRect".

Window.do_contentclick(local, modifiers, event)

   The user clicked in the content part of a window. The arguments are
   the coordinates (window-relative), the key modifiers and the raw
   event.

Window.do_update(macoswindowid, event)

   An update event for the window was received. Redraw the window.

Window.do_activate(activate, event)

   The window was activated ("activate == 1") or deactivated
   ("activate == 0"). Handle things like focus highlighting, etc.


37.6.3. ControlsWindow Object
=============================

ControlsWindow objects have the following methods besides those of
"Window" objects:

ControlsWindow.do_controlhit(window, control, pcode, event)

   Part *pcode* of control *control* was hit by the user. Tracking and
   such has already been taken care of.


37.6.4. ScrolledWindow Object
=============================

ScrolledWindow objects are ControlsWindow objects with the following
extra methods:

ScrolledWindow.scrollbars([wantx[, wanty]])

   Create (or destroy) horizontal and vertical scrollbars. The
   arguments specify which you want (default: both). The scrollbars
   always have minimum "0" and maximum "32767".

ScrolledWindow.getscrollbarvalues()

   You must supply this method. It should return a tuple "(x, y)"
   giving the current position of the scrollbars (between "0" and
   "32767"). You can return "None" for either to indicate the whole
   document is visible in that direction.

ScrolledWindow.updatescrollbars()

   Call this method when the document has changed. It will call
   "getscrollbarvalues()" and update the scrollbars.

ScrolledWindow.scrollbar_callback(which, what, value)

   Supplied by you and called after user interaction. *which* will be
   "'x'" or "'y'", *what* will be "'-'", "'--'", "'set'", "'++'" or
   "'+'". For "'set'", *value* will contain the new scrollbar
   position.

ScrolledWindow.scalebarvalues(absmin, absmax, curmin, curmax)

   Auxiliary method to help you calculate values to return from
   "getscrollbarvalues()". You pass document minimum and maximum value
   and topmost (leftmost) and bottommost (rightmost) visible values
   and it returns the correct number or "None".

ScrolledWindow.do_activate(onoff, event)

   Takes care of dimming/highlighting scrollbars when a window becomes
   frontmost. If you override this method, call this one at the end of
   your method.

ScrolledWindow.do_postresize(width, height, window)

   Moves scrollbars to the correct position. Call this method
   initially if you override it.

ScrolledWindow.do_controlhit(window, control, pcode, event)

   Handles scrollbar interaction. If you override it call this method
   first, a nonzero return value indicates the hit was in the
   scrollbars and has been handled.


37.6.5. DialogWindow Objects
============================

DialogWindow objects have the following methods besides those of
"Window" objects:

DialogWindow.open(resid)

   Create the dialog window, from the DLOG resource with id *resid*.
   The dialog object is stored in "self.wid".

DialogWindow.do_itemhit(item, event)

   Item number *item* was hit. You are responsible for redrawing
   toggle buttons, etc.
