pyatspi/accessiblecache.py

   1 #Copyright (C) 2008 Codethink Ltd
   2
   3 #This library is free software; you can redistribute it and/or
   4 #modify it under the terms of the GNU Lesser General Public
   5 #License version 2 as published by the Free Software Foundation.
   6
   7 #This program is distributed in the hope that it will be useful,
   8 #but WITHOUT ANY WARRANTY; without even the implied warranty of
   9 #MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10 #GNU General Public License for more details.
  11 #You should have received a copy of the GNU Lesser General Public License
  12 #along with this program; if not, write to the Free Software
  13 #Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14
  15 import dbus as _dbus
  16
  17 from event import Event as _Event
  18
  19 #------------------------------------------------------------------------------
  20
  21 class _CacheData(object):
  22         __slots__ = [
  23                         'parent',
  24                         'interfaces',
  25                         'children',
  26                         'role',
  27                         'name',
  28                         'description',
  29                         'state',
  30                     ]
  31
  32         def __init__(self, data):
  33                 self._update(data)
  34
  35         def _update(self, data):
  36                 #Don't cache the path here, used as lookup in cache object dict.
  37                 (path,
  38                 self.parent,
  39                 self.children,
  40                 self.interfaces,
  41                 self.name,
  42                 self.role,
  43                 self.description,
  44                 self.state) = data
  45
  46 #------------------------------------------------------------------------------
  47
  48 def _list_items_added_removed (l1, l2):
  49         """
  50         Returns a tuple (boolean, boolean).
  51         The first value indicates if, when
  52         moving from l1 to l2, any items have been added.
  53         The second value indicates whether any items have
  54         been removed.
  55         """
  56         l1notl2 = [item for item in l1 if item not in l2]
  57         l2notl1 = [item for item in l2 if item not in l1]
  58         return ((len(l1notl2) > 0), (len(l2notl1) > 0))
  59
  60 #------------------------------------------------------------------------------
  61
  62 class AccessibleCache(object):
  63         """
  64         There is one accessible cache per application.
  65         For each application the accessible cache stores
  66         data on every accessible object within the app.
  67
  68         It also acts as the factory for creating client
  69         side proxies for these accessible objects.
  70
  71         connection - DBus connection.
  72         busName    - Name of DBus connection where cache interface resides.
  73         """
  74
  75         _PATH = '/org/freedesktop/atspi/tree'
  76         _INTERFACE = 'org.freedesktop.atspi.Tree'
  77         _GET_METHOD = 'getTree'
  78         _UPDATE_SIGNAL = 'updateAccessible'
  79         _REMOVE_SIGNAL = 'removeAccessible'
  80
  81         def __init__(self, registry, connection, bus_name):
  82                 """
  83                 Creates a cache.
  84
  85                 connection - DBus connection.
  86                 busName    - Name of DBus connection where cache interface resides.
  87                 """
  88                 self._registry = registry
  89                 self._connection = connection
  90                 self._bus_name = bus_name
  91
  92                 obj = connection.get_object(bus_name, self._PATH, introspect=False)
  93                 itf = _dbus.Interface(obj, self._INTERFACE)
  94
  95                 self._objects = {}
  96
  97                 get_method = itf.get_dbus_method(self._GET_METHOD)
  98                 self._update_objects(get_method())
  99
 100                 self._updateMatch = itf.connect_to_signal(self._UPDATE_SIGNAL, self._update_objects)
 101                 self._removeMatch = itf.connect_to_signal(self._REMOVE_SIGNAL, self._remove_object)
 102
 103                 obj = connection.get_object(self._bus_name, self._PATH, introspect=False)
 104                 itf = _dbus.Interface(obj, self._INTERFACE)
 105
 106                 self._root = itf.getRoot()
 107
 108         def __getitem__(self, key):
 109                 return self._objects[key]
 110
 111         def __contains__(self, key):
 112                 return key in self._objects
 113
 114         def _dispatch_event(self, olddata, newdata):
 115                 if olddata.name != newdata.name:
 116                         event = _Event(self._registry.cache,
 117                                        path,
 118                                        self._bus_name,
 119                                        "org.freedesktop.atspi.Event.Object",
 120                                        "property-change",
 121                                        ("name", 0, 0, newdata.name))
 122                         self._registry._notifyNameChange(event)
 123
 124                 if olddata.description != newdata.description:
 125                         event = _Event(self._registry.cache,
 126                                        path,
 127                                        self._bus_name,
 128                                        "org.freedesktop.atspi.Event.Object",
 129                                        "property-change",
 130                                        ("description", 0, 0, description))
 131                         self._registry._notifyDescriptionChange(event)
 132
 133                 if olddata.parent != newdata.parent:
 134                         event = _Event(self._registry.cache,
 135                                        path,
 136                                        self._bus_name,
 137                                        "org.freedesktop.atspi.Event.Object",
 138                                        "property-change",
 139                                        ("parent", 0, 0, ""))
 140                         self._registry._notifyParentChange(event)
 141
 142                 added, removed = _list_items_added_removed (olddata.children, newdata.children)
 143
 144                 if added:
 145                         event = _Event(self._registry.cache,
 146                                        path,
 147                                        self._bus_name,
 148                                        "org.freedesktop.atspi.Event.Object",
 149                                        "children-changed",
 150                                        ("add", 0, 0, ""))
 151                         self._registry._notifyChildrenChange(event)
 152
 153                 if removed:
 154                         event = _Event(self._registry.cache,
 155                                        path,
 156                                        self._bus_name,
 157                                        "org.freedesktop.atspi.Event.Object",
 158                                        "children-changed",
 159                                        ("remove", 0, 0, ""))
 160                         self._registry._notifyChildrenChange(event)
 161
 162         def _update_objects(self, objects):
 163                 cache_update_objects = []
 164                 for data in objects:
 165                         #First element is the object path.
 166                         path = data[0]
 167                         if path in self._objects:
 168                                 olddata = self._objects[path]
 169                                 newdata = _CacheData(data)
 170                                 cache_update_objects.append((olddata, newdata))
 171                                 self._objects[path] = newdata
 172                         else:
 173                                 self._objects[path] = _CacheData(data)
 174                 for old, new in cache_update_objects:
 175                         self._dispatch_event(old, new)
 176
 177         def _remove_object(self, paths):
 178                 # TODO I'm squashing a possible error here
 179                 # I've seen things appear to be deleted twice
 180                 # which needs investigation
 181                 try:
 182                         del(self._objects[path])
 183                 except KeyError:
 184                         pass
 185
 186         def _get_root(self):
 187                 return self._root
 188
 189         root = property(fget=_get_root)
 190
 191 #END---------------------------------------------------------------------------