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"""Switchboard class. This class is used to coordinate updates among all Viewers. Every Viewer must conform to the following interface: - it must include a method called update_yourself() which takes three arguments; the red, green, and blue values of the selected color. - When a Viewer selects a color and wishes to update all other Views, it should call update_views() on the Switchboard object. Note that the Viewer typically does *not* update itself before calling update_views(), since this would cause it to get updated twice. Optionally, Viewers can also implement: - save_options() which takes an optiondb (a dictionary). Store into this dictionary any values the Viewer wants to save in the persistent ~/.pynche file. This dictionary is saved using marshal. The namespace for the keys is ad-hoc; make sure you don't clobber some other Viewer's keys! - withdraw() which takes no arguments. This is called when Pynche is unmapped. All Viewers should implement this. - colordb_changed() which takes a single argument, an instance of ColorDB. This is called whenever the color name database is changed and gives a chance for the Viewers to do something on those events. See ListViewer for details. External Viewers are found dynamically. Viewer modules should have names such as FooViewer.py. If such a named module has a module global variable called ADDTOVIEW and this variable is true, the Viewer will be added dynamically to the `View' menu. ADDTOVIEW contains a string which is used as the menu item to display the Viewer (one kludge: if the string contains a `%', this is used to indicate that the next character will get an underline in the menu, otherwise the first character is underlined). FooViewer.py should contain a class called FooViewer, and its constructor should take two arguments, an instance of Switchboard, and optionally a Tk master window. """ import sys from types import DictType import marshal  class Switchboard: def __init__(self, initfile): self.__initfile = initfile self.__colordb = None self.__optiondb = {} self.__views = [] self.__red = 0 self.__green = 0 self.__blue = 0 self.__canceled = 0 # read the initialization file fp = None if initfile: try: try: fp = open(initfile) self.__optiondb = marshal.load(fp) if not isinstance(self.__optiondb, DictType): print >> sys.stderr, \ 'Problem reading options from file:', initfile self.__optiondb = {} except (IOError, EOFError, ValueError): pass finally: if fp: fp.close() def add_view(self, view): self.__views.append(view) def update_views(self, red, green, blue): self.__red = red self.__green = green self.__blue = blue for v in self.__views: v.update_yourself(red, green, blue) def update_views_current(self): self.update_views(self.__red, self.__green, self.__blue) def current_rgb(self): return self.__red, self.__green, self.__blue def colordb(self): return self.__colordb def set_colordb(self, colordb): self.__colordb = colordb for v in self.__views: if hasattr(v, 'colordb_changed'): v.colordb_changed(colordb) self.update_views_current() def optiondb(self): return self.__optiondb def save_views(self): # save the current color self.__optiondb['RED'] = self.__red self.__optiondb['GREEN'] = self.__green self.__optiondb['BLUE'] = self.__blue for v in self.__views: if hasattr(v, 'save_options'): v.save_options(self.__optiondb) # save the name of the file used for the color database. we'll try to # load this first. self.__optiondb['DBFILE'] = self.__colordb.filename() fp = None try: try: fp = open(self.__initfile, 'w') except IOError: print >> sys.stderr, 'Cannot write options to file:', \ self.__initfile else: marshal.dump(self.__optiondb, fp) finally: if fp: fp.close() def withdraw_views(self): for v in self.__views: if hasattr(v, 'withdraw'): v.withdraw() def canceled(self, flag=1): self.__canceled = flag def canceled_p(self): return self.__canceled