root/trunk/RBRapier/RBRapier/Renderer/ChangeBaseMgr.py

#!/usr/bin/env python
##~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
##~ License 
##~ 
##- The RuneBlade Foundation library is intended to ease some 
##- aspects of writing intricate Jabber, XML, and User Interface (wxPython, etc.) 
##- applications, while providing the flexibility to modularly change the 
##- architecture. Enjoy.
##~ 
##~ Copyright (C) 2002  TechGame Networks, LLC.
##~ 
##~ This library is free software; you can redistribute it and/or
##~ modify it under the terms of the BSD style License as found in the 
##~ LICENSE file included with this distribution.
##~ 
##~ TechGame Networks, LLC can be reached at:
##~ 3578 E. Hartsel Drive #211
##~ Colorado Springs, Colorado, USA, 80920
##~
##~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#~ Imports 
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

from RBFoundation.SubObs.Basic import SubjectList
from RBFoundation.Objects.Properties import LazyProperty

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#~ Definitions 
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class ChangeElementBase(object):
    pass

class DynamicChangeElementBase(ChangeElementBase):
    Trackers = LazyProperty(SubjectList)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class ChangeTrackerBase(object):
    def __init__(self):
        self.TrackedElements = {}

    def SequenceAdd(self, Sequence):
        Sequence.OnAddElement.Add(self.OnAddElement)
        Sequence.OnRemoveElement.Add(self.OnRemoveElement)

    def OnAddElement(self, Element):
        Change = getattr(Element, self._ElementAttributeName, None)
        if Change is not None:
            self.TrackedElements[Change] = self.TrackedElements.get(Change, 0) + 1
            if self.TrackedElements[Change] == 1:
                Change.AddTracker(self.OnTrackedChange)

    def OnRemoveElement(self, Element):
        Change = getattr(Element, self._ElementAttributeName, None)
        if Change is not None:
            self.TrackedElements[Change] -= 1
            if self.TrackedElements[Change] == 0:
                del self.TrackedElements[Change]
                Change.RemoveTracker(self.OnTrackedChange)
    
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class BitmaskChangeElement(ChangeElementBase):
    """Encapsulates a single collection of bitmask changes"""

    Bitmask = 0

    def __init__(self, Bitmask=0):
        if Bitmask:
            self.Bitmask |= Bitmask

    def AddTracker(self, OnChange):
        OnChange('add', self.Bitmask)

    def RemoveTracker(self, OnChange):
        OnChange('remove', self.Bitmask)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class BitmaskChangeTracker(ChangeTrackerBase):
    """Collects many attribute changes into a single change"""

    #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    #~ Constants / Variables / Etc. 
    #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Bitmask = 0
    BitmaskDefault = 0
    _BitmaskNeedUpdate = True

    def __init__(self, BitmaskDefault=None):
        ChangeTrackerBase.__init__(self)
        if BitmaskDefault is not None:
            self.Bitmask = self.BitmaskDefault = BitmaskDefault

    def OnTrackedChange(self, ChangeType, Change):
        if ChangeType == 'add':
            self.Bitmask |= Change
        elif ChangeType == 'update':
            self.Bitmask |= Change # this might overestimate the needed attribute saves
            # self._BitmaskNeedUpdate = True # this might force unneeded updates.  life is so unfair ;)
        elif ChangeType == 'remove':
            self._BitmaskNeedUpdate = True
        else: 
            raise ValueError, "ChangeType is expected to be one of ['add', 'update', 'remove'], but is '%s'" % ChangeType

    def _UpdateBitmask(self, force=False):
        if self._BitmaskNeedUpdate or force:
            Bitmask = self.BitmaskDefault
            for each in self.TrackedELements:
                Bitmask |= each.Bitmask
            self.Bitmask = Bitmask
            self._BitmaskNeedUpdate = False

    def GLExecute(self, context):
        pass
    
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class DynamicBitmaskChangeElement(DynamicChangeElementBase):
    """Encapsulates a single collection of attribute changes"""

    _Bitmask = 0

    def __init__(self, Bitmask=0):
        if Bitmask:
            self.Bitmask |= Bitmask

    def AddTracker(self, OnChange):
        self.Trackers.Add(OnChange)
        OnChange('add', self.Bitmask)

    def RemoveTracker(self, OnChange):
        self.Trackers.Remove(OnChange)
        OnChange('remove', self.Bitmask)

    #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    def _getBitmask(self):
        self._UpdateBitmask()
        return self._Bitmask
    def _setBitmask(self, value):
        self._Bitmask = value
        self.Trackers.Update('update', self._Bitmask)
    def _delBitmask(self):
        del self._Bitmask
        self.Trackers.Update('update', self._Bitmask)
    def _UpdateBitmask(self, force=False):
        pass
    Bitmask = property(_getBitmask, _setBitmask)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class DynamicBitmaskChangeTracker(BitmaskChangeTracker, DynamicBitmaskChangeElement):
    def SequenceAdd(self, Sequence):
        result = BitmaskChangeTracker.SequenceAdd(self, Sequence)
        setattr(Sequence, self._ElementAttributeName, self)
        return result