[Measure] Add features, viewproviders and preferences for unified measurement facility

src/Mod/Measure/MeasureCOM.py

@@ -0,0 +1,152 @@
+# /***************************************************************************
+#  *   Copyright (c) 2023 David Friedli <david[at]friedli-be.ch>             *
+#  *                                                                         *
+#  *   This file is part of FreeCAD.                                         *
+#  *                                                                         *
+#  *   FreeCAD is free software: you can redistribute it and/or modify it    *
+#  *   under the terms of the GNU Lesser General Public License as           *
+#  *   published by the Free Software Foundation, either version 2.1 of the  *
+#  *   License, or (at your option) any later version.                       *
+#  *                                                                         *
+#  *   FreeCAD is distributed in the hope that it will be useful, but        *
+#  *   WITHOUT ANY WARRANTY; without even the implied warranty of            *
+#  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      *
+#  *   Lesser General Public License for more details.                       *
+#  *                                                                         *
+#  *   You should have received a copy of the GNU Lesser General Public      *
+#  *   License along with FreeCAD. If not, see                               *
+#  *   <https://www.gnu.org/licenses/>.                                      *
+#  *                                                                         *
+#  **************************************************************************/
+
+import FreeCAD
+from FreeCAD import Units, Placement
+from UtilsMeasure import MeasureBasePython
+from PySide.QtCore import QT_TRANSLATE_NOOP
+
+
+
+__title__="Measure Center of Mass Object"
+__author__ = "David Friedli"
+__url__ = "http://www.freecad.org"
+
+
+
+""" 
+    The Measure cpp object defines a result and a placement property. The Python measure type
+    adds it's own specific properties. Once the object is recomputed the parent properties are updated
+    based on the specific python properties. 
+
+    We'll need some kind of interface for the measure command which exposes "parseSelection", "isValidSelection" etc.
+
+"""
+
+
+
+def makeMeasureCOM(name="CenterOfMass"):
+    '''makeMeasureCOM(name): make a CenterofMass measurement'''
+    obj = FreeCAD.ActiveDocument.addObject("Measure::MeasurePython", name)
+    MeasureCOM(obj)
+    return obj
+
+
+class MeasureCOM(MeasureBasePython):
+    "The MeasureCOM object"
+    
+    def __init__(self, obj):
+        obj.Proxy = self
+
+        obj.addProperty("App::PropertyLinkSubGlobal", "Element", "", QT_TRANSLATE_NOOP("App::Property", "Element to measure"))
+        obj.addProperty("App::PropertyPosition", "Result", "", QT_TRANSLATE_NOOP("App::PropertyVector", "The result location"))
+
+    @classmethod
+    def isValidSelection(cls, selection):
+        if not len(selection) == 1:
+            return False
+
+        element = selection[0]
+        ob = element["object"]
+        subName = element["subName"]
+
+        if not ob:
+            return
+        
+        sub = ob.getSubObject(subName)
+        if not sub:
+            return
+
+        if not hasattr(sub, "CenterOfMass"):
+            return
+
+        return True
+
+    @classmethod
+    def isPrioritySelection(cls, selection):
+        return False
+
+    @classmethod
+    def getInputProps(cls):
+        return ("Element",)
+
+    def getSubject(self, obj):
+        if not obj:
+            return ()
+
+        element = obj.Element
+        if not element:
+            return ()
+
+        ob = element[0]
+        if not ob:
+            return ()
+        return (ob,)
+
+
+    def parseSelection(self, obj, selection):
+        item = selection[0]
+        o = item["object"]
+        obj.Element = (o, item["subName"])
+
+
+    def getResultString(self, obj):
+        values = [Units.Quantity(v, Units.Length).getUserPreferred()[0] for v in obj.Result]
+        return "COM\nX: {}\nY: {}\nZ: {}".format(*values)
+
+    def execute(self, obj):
+        element = obj.Element
+        if not element:
+            return
+
+        ob = element[0]
+        subElements = element[1]
+
+        if subElements:
+            subName = subElements[0]
+            sub = ob.getSubObject(subName)
+
+            if not sub or not hasattr(sub, "CenterOfMass"):
+                return
+            com = sub.CenterOfMass
+
+        else:
+            # Get Center of Mass of the object
+            if not hasattr(ob, "Shape"):
+                return
+
+            shape = ob.Shape
+            if not hasattr(shape, "CenterOfMass"):
+                return
+
+            com = shape.CenterOfMass
+
+        obj.Result = com
+        placement = Placement()
+        placement.Base = com
+        obj.Placement = placement
+
+
+    def onChanged(self, obj, prop):
+        '''Do something when a property has changed'''
+
+        if prop == "Element":
+            self.execute(obj)