assembly: support for derived assembly

Deriving assembly directly contains all parts from derived assembly.
And all derived parts are added as fixed part. The intention is mostly
for user to customize visibilities of the derived parts as a way of
controling the level of details.

assembly.py

@@ -179,8 +179,53 @@ class ViewProviderAsmGroupOnTop(ViewProviderAsmGroup):
 class AsmPartGroup(AsmGroup):
     def __init__(self,parent):
         self.parent = getProxy(parent,Assembly)
+        self.derivedParts = set()
         super(AsmPartGroup,self).__init__()
 
+    def getLinkedObject(self,obj,recursive,mat,transform,depth):
+        if not isTypeOf(getattr(obj,'DerivedFrom',None),Assembly,True):
+            return
+        if not recursive:
+            return (obj.DerivedFrom,mat)
+        return obj.DerivedFrom.getLinkedObject(True,mat,transform,depth+1)
+
+    def canLinkProperties(self,_obj):
+        return False
+
+    def linkSetup(self,obj):
+        super(AsmPartGroup,self).linkSetup(obj)
+        if not hasattr(obj,'DerivedFrom'):
+            obj.addProperty('App::PropertyLink','DerivedFrom','Base','')
+        self.derivedParts = set()
+
+    def checkDerivedParts(self):
+        if self.getAssembly().Object.Freeze:
+            return
+
+        obj = self.Object
+        if not isTypeOf(obj.DerivedFrom,Assembly,True):
+            self.derivedParts = set()
+            return
+
+        parts = set(obj.Group)
+        derived = obj.DerivedFrom.getLinkedObject(True).Proxy.getPartGroup()
+        derivedParts = derived.Group
+        self.derivedParts = set(derivedParts)
+        newParts = obj.Group
+        vis = list(obj.VisibilityList)
+        touched = False
+        for o in derivedParts:
+            if o in parts:
+                continue
+            touched = True
+            newParts.append(o)
+            vis.append(True if derived.isElementVisible(o.Name) else False)
+        if touched:
+            obj.Group = newParts
+            obj.setPropertyStatus('VisibilityList','-Immutable')
+            obj.VisibilityList = vis
+            obj.setPropertyStatus('VisibilityList','Immutable')
+
     def getAssembly(self):
         return self.parent
 
@@ -193,7 +238,9 @@ class AsmPartGroup(AsmGroup):
     def onChanged(self,obj,prop):
         if obj.Removing or FreeCAD.isRestoring():
             return
-        if prop == 'Group':
+        if prop == 'DerivedFrom':
+            self.checkDerivedParts()
+        elif prop == 'Group':
             parent = getattr(self,'parent',None)
             if parent and not self.parent.Object.Freeze:
                 relationGroup = parent.getRelationGroup()
@@ -2205,24 +2252,26 @@ class Assembly(AsmGroup):
             del partMap[part]
 
     def execute(self,obj):
+        if self.frozen:
+            return True
+
         parts = set()
         partArrays = set()
         self.constraints = None
 
-        if not self.frozen:
-            self.buildShape()
-            System.touch(obj)
-            obj.ViewObject.Proxy.onExecute()
+        self.buildShape()
+        System.touch(obj)
+        obj.ViewObject.Proxy.onExecute()
 
-            # collect the part objects of this assembly
-            for cstr in self.getConstraints():
-                for element in cstr.Proxy.getElements():
-                    info = element.Proxy.getInfo()
-                    if isinstance(info.Part,tuple):
-                        partArrays.add(info.Part[0])
-                        parts.add(info.Part[0])
-                    else:
-                        parts.add(info.Part)
+        # collect the part objects of this assembly
+        for cstr in self.getConstraints():
+            for element in cstr.Proxy.getElements():
+                info = element.Proxy.getInfo()
+                if isinstance(info.Part,tuple):
+                    partArrays.add(info.Part[0])
+                    parts.add(info.Part[0])
+                else:
+                    parts.add(info.Part)
 
         # Update the global part object list for auto solving
         #
@@ -2441,9 +2490,9 @@ class Assembly(AsmGroup):
             obj.addProperty("App::PropertyLinkSubHidden",
                     "ColoredElements","Base",'')
         obj.setPropertyStatus('ColoredElements',('Hidden','Immutable'))
+        obj.configLinkProperty('ColoredElements')
         if not hasattr(obj,'Freeze'):
             obj.addProperty('App::PropertyBool','Freeze','Base','')
-        obj.configLinkProperty('ColoredElements')
         super(Assembly,self).linkSetup(obj)
         obj.setPropertyStatus('Group','Output')
         System.attach(obj)
@@ -2571,6 +2620,7 @@ class Assembly(AsmGroup):
             parent = getattr(ret.Proxy,'parent',None)
             if not parent:
                 ret.Proxy.parent = self
+                ret.Proxy.checkDerivedParts()
             elif parent!=self:
                 raise RuntimeError(
                         'invalid parent of part group {}'.format(objName(ret)))

mover.py

@@ -215,8 +215,8 @@ def checkFixedPart(info):
         return
     assembly = resolveAssembly(info.Parent)
     cstrs = assembly.getConstraints()
-    parts = assembly.getPartGroup().Group
-    if info.Part in Constraint.getFixedParts(None,cstrs,parts):
+    partGroup = assembly.getPartGroup()
+    if info.Part in Constraint.getFixedParts(None,cstrs,partGroup):
         raise RuntimeError('cannot move fixed part')
 
 def getMovingElementInfo():

solver.py

@@ -56,8 +56,8 @@ class Solver(object):
         roty = FreeCAD.Rotation(FreeCAD.Vector(1,0,0),90)
         self.ny = self.system.addNormal3dV(*utils.getNormal(roty))
 
-        parts = assembly.Proxy.getPartGroup().Group
-        self._fixedParts = Constraint.getFixedParts(self,cstrs,parts)
+        partGroup = assembly.Proxy.getPartGroup()
+        self._fixedParts = Constraint.getFixedParts(self,cstrs,partGroup)
         for part in self._fixedParts:
             self._fixedElements.add((part,None))