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      1 """Switchboard class.
      2 
      3 This class is used to coordinate updates among all Viewers.  Every Viewer must
      4 conform to the following interface:
      5 
      6     - it must include a method called update_yourself() which takes three
      7       arguments; the red, green, and blue values of the selected color.
      8 
      9     - When a Viewer selects a color and wishes to update all other Views, it
     10       should call update_views() on the Switchboard object.  Note that the
     11       Viewer typically does *not* update itself before calling update_views(),
     12       since this would cause it to get updated twice.
     13 
     14 Optionally, Viewers can also implement:
     15 
     16     - save_options() which takes an optiondb (a dictionary).  Store into this
     17       dictionary any values the Viewer wants to save in the persistent
     18       ~/.pynche file.  This dictionary is saved using marshal.  The namespace
     19       for the keys is ad-hoc; make sure you don't clobber some other Viewer's
     20       keys!
     21 
     22     - withdraw() which takes no arguments.  This is called when Pynche is
     23       unmapped.  All Viewers should implement this.
     24 
     25     - colordb_changed() which takes a single argument, an instance of
     26       ColorDB.  This is called whenever the color name database is changed and
     27       gives a chance for the Viewers to do something on those events.  See
     28       ListViewer for details.
     29 
     30 External Viewers are found dynamically.  Viewer modules should have names such
     31 as FooViewer.py.  If such a named module has a module global variable called
     32 ADDTOVIEW and this variable is true, the Viewer will be added dynamically to
     33 the `View' menu.  ADDTOVIEW contains a string which is used as the menu item
     34 to display the Viewer (one kludge: if the string contains a `%', this is used
     35 to indicate that the next character will get an underline in the menu,
     36 otherwise the first character is underlined).
     37 
     38 FooViewer.py should contain a class called FooViewer, and its constructor
     39 should take two arguments, an instance of Switchboard, and optionally a Tk
     40 master window.
     41 
     42 """
     43 
     44 import sys
     45 import marshal
     46 
     47 
     48 
     50 class Switchboard:
     51     def __init__(self, initfile):
     52         self.__initfile = initfile
     53         self.__colordb = None
     54         self.__optiondb = {}
     55         self.__views = []
     56         self.__red = 0
     57         self.__green = 0
     58         self.__blue = 0
     59         self.__canceled = 0
     60         # read the initialization file
     61         fp = None
     62         if initfile:
     63             try:
     64                 try:
     65                     fp = open(initfile, 'rb')
     66                     self.__optiondb = marshal.load(fp)
     67                     if not isinstance(self.__optiondb, dict):
     68                         print('Problem reading options from file:', initfile,
     69                               file=sys.stderr)
     70                         self.__optiondb = {}
     71                 except (IOError, EOFError, ValueError):
     72                     pass
     73             finally:
     74                 if fp:
     75                     fp.close()
     76 
     77     def add_view(self, view):
     78         self.__views.append(view)
     79 
     80     def update_views(self, red, green, blue):
     81         self.__red = red
     82         self.__green = green
     83         self.__blue = blue
     84         for v in self.__views:
     85             v.update_yourself(red, green, blue)
     86 
     87     def update_views_current(self):
     88         self.update_views(self.__red, self.__green, self.__blue)
     89 
     90     def current_rgb(self):
     91         return self.__red, self.__green, self.__blue
     92 
     93     def colordb(self):
     94         return self.__colordb
     95 
     96     def set_colordb(self, colordb):
     97         self.__colordb = colordb
     98         for v in self.__views:
     99             if hasattr(v, 'colordb_changed'):
    100                 v.colordb_changed(colordb)
    101         self.update_views_current()
    102 
    103     def optiondb(self):
    104         return self.__optiondb
    105 
    106     def save_views(self):
    107         # save the current color
    108         self.__optiondb['RED'] = self.__red
    109         self.__optiondb['GREEN'] = self.__green
    110         self.__optiondb['BLUE'] = self.__blue
    111         for v in self.__views:
    112             if hasattr(v, 'save_options'):
    113                 v.save_options(self.__optiondb)
    114         # save the name of the file used for the color database.  we'll try to
    115         # load this first.
    116         self.__optiondb['DBFILE'] = self.__colordb.filename()
    117         fp = None
    118         try:
    119             try:
    120                 fp = open(self.__initfile, 'wb')
    121             except IOError:
    122                 print('Cannot write options to file:', \
    123                       self.__initfile, file=sys.stderr)
    124             else:
    125                 marshal.dump(self.__optiondb, fp)
    126         finally:
    127             if fp:
    128                 fp.close()
    129 
    130     def withdraw_views(self):
    131         for v in self.__views:
    132             if hasattr(v, 'withdraw'):
    133                 v.withdraw()
    134 
    135     def canceled(self, flag=1):
    136         self.__canceled = flag
    137 
    138     def canceled_p(self):
    139         return self.__canceled
    140