Package Gnumed :: Package wxpython :: Module gmRegetMixin
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Source Code for Module Gnumed.wxpython.gmRegetMixin

  1  """gmRegetMixin - GNUmed data change callback mixin. 
  2   
  3  Widget code can mix in this class as a base class and 
  4  thus gain the infrastructure to update it's display 
  5  when data changes. If the widget is not visible it will 
  6  only schedule refetching data from the business layer. 
  7  If it *is* visible it will immediately fetch and redisplay. 
  8   
  9  You must call cRegetOnPaintMixin.__init__() in your own 
 10  __init__() after calling __init__() on the appropriate 
 11  wx.Widgets class your widget inherits from. 
 12   
 13  You must then make sure to call _schedule_data_reget() 
 14  whenever you learn of backend data changes. This will 
 15  in most cases happen after you receive a gmDispatcher 
 16  signal indicating a change in the backend. 
 17   
 18  The _populate_with_data(self) method must be overriden in the 
 19  including class and must return True if the UI was successfully 
 20  repopulated with content. 
 21   
 22  @copyright: authors 
 23   
 24  Template for users: 
 25   
 26          #----------------------------------------------------- 
 27          # reget-on-paint mixin API 
 28          # 
 29          # remember to call 
 30          #       self._schedule_data_reget() 
 31          # whenever you learn of data changes from database 
 32          # listener threads, dispatcher signals etc. 
 33          #----------------------------------------------------- 
 34          def _populate_with_data(self): 
 35                  # fill the UI with data 
 36                  print "need to implement _populate_with_data" 
 37                  return False 
 38                  return True 
 39          #----------------------------------------------------- 
 40  """ 
 41  #=========================================================================== 
 42  __author__ = "K.Hilbert <Karsten.Hilbert@gmx.net>" 
 43  __license__ = 'GPL v2 or later (details at http://www.gnu.org)' 
 44   
 45  import wx 
 46   
 47  #=========================================================================== 
48 -class cRegetOnPaintMixin:
49 """Mixin to add redisplay_data-on-wx.EVT_PAINT aspect. 50 51 Any code mixing in this class will gain the mechanism 52 to reget data on wxPaint events. The code must be an 53 instance of a wx.Window and must implement a 54 _populate_with_data() method. It must also call 55 _schedule_data_reget() at appropriate times. 56 """
57 - def __init__(self):
58 self._data_stale = True 59 try: 60 wx.EVT_PAINT(self, self.__on_paint_event) 61 except: 62 print 'you likely need to call "cRegetOnPaintMixin.__init__(self)" later in %s__init__()' % self.__class__.__name__ 63 raise
64 #-----------------------------------------------------
65 - def __on_paint_event(self, event):
66 """Called just before the widget is repainted. 67 68 Checks whether data needs to be refetched. 69 """ 70 self.__repopulate_ui() 71 event.Skip()
72 #-----------------------------------------------------
73 - def __repopulate_ui(self):
74 """Checks whether data must be refetched and does so 75 76 Called on different occasions such as "notebook page 77 raised" or "paint event received". 78 """ 79 if not self._data_stale: 80 return True 81 repopulated = self._populate_with_data() 82 self._data_stale = (repopulated is False) 83 return repopulated
84 #----------------------------------------------------- 85 # API for child classes 86 #-----------------------------------------------------
87 - def _populate_with_data(self):
88 """Actually fills the UI with data. 89 90 This must be overridden in child classes ! 91 92 Must return True/False. 93 """ 94 raise NotImplementedError, "[%s] _populate_with_data() not implemented" % self.__class__.__name__
95 #-----------------------------------------------------
96 - def _schedule_data_reget(self):
97 """Flag data as stale and schedule refetch/redisplay. 98 99 - if not visible schedules refetch only 100 - if visible redisplays immediately (virtue of Refresh() 101 calling __on_paint_event() if visible) thereby invoking 102 the actual data refetch 103 104 Called by the child class whenever it learns of data changes 105 such as from database listener threads, dispatcher signals etc. 106 """ 107 self._data_stale = True 108 109 # Master Robin Dunn sayeth this is The Way(tm) but 110 # neither this: 111 #wx.GetApp().GetTopWindow().Refresh() 112 # nor this: 113 #top_parent = wx.GetTopLevelParent(self) 114 #top_parent.Refresh() 115 # appear to work as expected :-( 116 # The issues I have with them are: 117 # 1) It appears to cause refreshes "too often", eg whenever 118 # *any* child of self calls this method - but this may 119 # not matter much as only those that have self._data_stale 120 # set to True will trigger backend refetches. 121 # 2) Even this does not in all cases cause a proper redraw 122 # of the visible widgets - likely because nothing has 123 # really changed in them, visually. 124 125 # further testing by Hilmar revealed that the 126 # following appears to work: 127 self.Refresh() 128 # the logic should go like this: 129 # database insert -> after-insert trigger 130 # -> notify 131 # -> middleware listener 132 # -> flush optional middleware cache 133 # -> dispatcher signal to frontend listener*s* 134 # -> frontend listeners schedule a data reget and a Refresh() 135 # problem: those that are not visible are refreshed, too 136 # FIXME: is this last assumption true ? 137 return True
138 #----------------------------------------------------- 139 # notebook plugin API if needed 140 #-----------------------------------------------------
141 - def repopulate_ui(self):
142 """Just a glue method to make this compatible with notebook plugins.""" 143 self.__repopulate_ui()
144 #=========================================================================== 145 # main 146 #--------------------------------------------------------------------------- 147 if __name__ == '__main__': 148 print "no unit test available" 149