#!/usr/bin/env python
######################################################################
# This module provides base classes for various shell classes.
#
# Mitch Chapman
#---------------------------------------------------------------------
# $Log: Shells.py,v $
# Revision 1.1  1996/12/01 22:58:54  mchapman
# Initial revision
#
######################################################################

__version__ = "$Revision: 1.1 $"

import Tkinter; Tk=Tkinter
import Cursors

######################################################################
# Make widget a transient for master.
# widget should be a Toplevel.
######################################################################
def makeTransientFor(widget, master):
    shell = master.winfo_toplevel()
    name = shell.group() or "."
    widget.group(name)
    widget.transient(widget._nametowidget(name))

######################################################################
# This is a Tk Frame which knows how to register itself for cursor
# stacking.  It is intended to serve as the main window of an
# application.
######################################################################
class Main(Tk.Frame, Cursors.Mixin):
    def __init__(self, master=None, **kw):
	apply(Tk.Frame.__init__, (self, master), kw)
	apply(Cursors.Mixin.__init__, (self,))

    def destroy(self):
	Tk.Frame.destroy(self)
	Cursors.Mixin.destroy(self)


######################################################################
# This is a Tk Toplevel which knows how to register itself for cursor
# stacking.
######################################################################
class Toplevel(Tk.Toplevel, Cursors.Mixin):
    ##################################################################
    # Initialize a new instance.
    ##################################################################
    def __init__(self, master=None, **kw):
	apply(Tk.Toplevel.__init__, (self, master), kw)
	apply(Cursors.Mixin.__init__, (self,))

    ##################################################################
    # Destroy an instance.
    ##################################################################
    def destroy(self):
	Tk.Toplevel.destroy(self)
	Cursors.Mixin.destroy(self)


######################################################################
# This is a modal dialog class.
######################################################################
class NonModal:
    ##################################################################
    # Initialize a new instance.  master should be a widget in front
    # of which self must appear.
    ##################################################################
    def __init__(self, master):
        self.master = master
	self.top = Toplevel(self.master)
	self.top.withdraw()
	self.isShowing = 0
	self.top.title(self.__class__.__name__)
	self.waitVar = `self.top` + 'EndDialogVar'

	# Indicate that the dialog has not been centered in front of
	# its master before.
	self.isCentered = 0

	# Modal dialogs may need to block input from other application
	# windows by setting a grab on them.  oldGrabber is where the
	# previous owner of the app grab (if any) is saved.
	self.oldGrabber = None
	
	# In case somebody manages to blow away self by underhanded
	# means, stop waiting for waitVar.
	self.top.protocol("WM_DELETE_WINDOW", self.deleteWindow)

	# A dialog has a result of arbitrary type.
	# The result should be considered valid after the dialog is
	# dismissed.
	# Modal dialogs can use this to return arbitrary
	# descriptions of what the user did.  For example, a file-
	# selection dialog might return either the pathname specified
	# by the user or, if the dialog was cancelled, None.
	self.result = None

    ##################################################################
    # Default response to an attempt to delete the window: ignore it.
    ##################################################################
    def deleteWindow(self):
        return

    ##################################################################
    # Show a dialog.
    ##################################################################
    def show(self):
	if self.isShowing:
	    # Dialog is already visible.  Raise it to the top.
	    self.top.tkraise()
	    return
	# Give us a chance to initialize contents.  Other program
	# state may have changed while the dialog was unmapped.
	self.initControls()

	self.center()
	# Remember the old grab owner, for modal subclasses.
	self.oldGrabber = self.top.grab_current()
	
	self.top.deiconify()

	# Here's where modal subclasses get a chance to set a grab.
	self.top.wait_visibility()
	self.modalGrab()
	
	self.top.focus()
	# Old results are invalid, now.
	self.result = None
	self.isShowing = 1

    ##################################################################
    # Initialize the contents of the dialog, e.g. put default values
    # into text fields.
    ##################################################################
    def initControls(self):
        return

    ##################################################################
    # Center the dialog in front of its master, if possible.
    ##################################################################
    def center(self):
	if self.isCentered:
	    # Center the dialog only the first time it is displayed.
	    # After that, just pop it up where the user left it.
	    return

	# Try to ensure any geometry requests have been processed.
	self.top.update_idletasks()

	w = self.master.winfo_width()
	h = self.master.winfo_height()
	x = self.master.winfo_rootx()
	y = self.master.winfo_rooty()
	reqw = self.top.winfo_reqwidth()
	reqh = self.top.winfo_reqheight()

	centerx = `x + (w - reqw)/2`
	centery = `y + (h - reqh)/2`
	geomStr = "+" + centerx + "+" + centery
	self.top.geometry(geomStr)
	self.isCentered = 1

    ##################################################################
    # This is a hook for modal dialog subclasses.  It gives them a
    # chance to do a grab_set on the dialog's Toplevel, to prevent
    # input from being delivered to other application windows.
    ##################################################################
    def modalGrab(self):
        return

    ##################################################################
    # This is another hook for modal dialog subclasses.  It allows
    # for the release of any grab set via modalGrab.
    ##################################################################
    def modalReleaseGrab(self):
        return

    ##################################################################
    # Terminate the dialog, returning its result.
    ##################################################################
    def terminate(self):
	# Set the wait variable, so modal dialogs will know they're
	# done.
	self.top.setvar(self.waitVar, 1)
	self.top.withdraw()
	self.isShowing = 0

	# Here's where modal subclasses get a chance to release any
	# grab they may have taken.
	self.modalReleaseGrab()
	
	self.master.focus()
        return self.result

    ##################################################################
    # Destroy the visuals.
    ##################################################################
    def destroy(self):
	self.top.destroy()


######################################################################
# This class represents an application-modal dialog.
######################################################################
class Modal(NonModal):
    ##################################################################
    # Initialize a new instance.
    ##################################################################
    def __init__(self, master):
	apply(NonModal.__init__, (self, master))

	# Make self a transient for its master.  This basically forces
	# self to remain in front of its master, and not to be
	# separately iconifiable. (Depends on the window manager?)
	#
	# Note this isn't done for non-modal dialogs.  Sorry,
	# OpenWindows fans, but I can't stand having to slide
	# non-modal dialogs out of the way just so I can see the
	# master window...
	makeTransientFor(self.top, master)
	
	# If somebody had an application-wide pointer grab,
	# remember them here.  When the dialog is dismissed, the
	# grab will be returned to the previous owner.
	self.oldGrabber = None

    ##################################################################
    # Show a modal dialog.
    ##################################################################
    def show(self):
	apply(NonModal.show, (self,))
	self.top.waitvar(self.waitVar)
	return self.result

    ##################################################################
    # Put an application-wide grab into effect, to block input from
    # other application windows.
    ##################################################################
    def modalGrab(self):
	# Display a do-not-enter cursor in front of all other toplevels
	# in the application.
	self.top.pushOtherCursors(Cursors.noEnterCursor)
	self.top.grab_set()

    ##################################################################
    # Release the grab obtained via modalGrab().
    ##################################################################
    def modalReleaseGrab(self):
	self.top.grab_release()
	# If somebody else owned the grab before we did, give it
	# back to them.
	if self.oldGrabber and (self.oldGrabber != self.top):
	    self.oldGrabber.grab_set()

	self.top.popOtherCursors()


######################################################################
# Main function for unit testing.
######################################################################
def main():
    global f, nonmodal, modal
    
    # Display a non-modal dialog.
    f = Main()
    nonmodal = None
    modal = None
    
    def showNonModal(event=None):
	global f, nonmodal

	if not nonmodal:
	    nonmodal = NonModal(f)
	    label = Tk.Label(nonmodal.top,
			     text="This is a non-modal dialog.")
	    label.pack()
	    
	    def quitCB(event=None, dlg=nonmodal):
		result = dlg.terminate()
		print "Dialog terminated with result", `result`
	    btn = Tk.Button(nonmodal.top, text="OK", command=quitCB)
	    btn.pack()
	    
	nonmodal.show()

    def showModal(event=None):
	global f, modal

	if not modal:
	    modal = Modal(f)
	    label = Tk.Label(modal.top, text="This is a modal dialog.")
	    label.pack()
	    
	    def quitCB(event=None, dlg=modal):
		result = dlg.terminate()
		print "Dialog terminated with result", `result`
	    btn = Tk.Button(modal.top, text="OK", command=quitCB)
	    btn.pack()
	    
	modal.show()

    for text, command in [("NonModal", showNonModal),
			  ("Modal", showModal),
			  ("Quit", f.quit)]:
	b = Tk.Button(f, text=text, width=10, command=command)
	b.pack()
    
    f.pack()
    f.mainloop()

if __name__ == "__main__":
    main()