Properly track the selection center and use it for the tool handle po…

…sition

Fixes #34

UM/Scene/Selection.py

@@ -9,12 +9,16 @@ class Selection:
     def add(cls, object):
         if object not in cls.__selection:
             cls.__selection.append(object)
+            object.transformationChanged.connect(cls._onTransformationChanged)
+            cls._onTransformationChanged(object)
             cls.selectionChanged.emit()
 
     @classmethod
     def remove(cls, object):
         if object in cls.__selection:
             cls.__selection.remove(object)
+            object.transformationChanged.disconnect(cls._onTransformationChanged)
+            cls._onTransformationChanged(object)
             cls.selectionChanged.emit()
 
     @classmethod
@@ -44,29 +48,14 @@ def hasSelection(cls):
 
     selectionChanged = Signal()
 
-    ##  Calculate the average position of the selection.
+    selectionCenterChanged = Signal()
+
     @classmethod
-    def getAveragePosition(cls):
+    def getSelectionCenter(cls):
         if not cls.__selection:
-            return Vector(0, 0, 0)
-
-        if len(cls.__selection) == 1:
-            node = cls.__selection[0]
-            if node.getBoundingBox() and node.getBoundingBox().isValid():
-                return node.getBoundingBox().center
-            else:
-                return node.getWorldPosition()
-
-        pos = Vector()
-        for node in cls.__selection:
-            if node.getBoundingBox() and node.getBoundingBox().isValid():
-                pos += node.getBoundingBox().center
-            else:
-                pos += node.getWorldPosition()
-
-        pos /= len(cls.__selection)
+            cls.__selection_center = Vector(0, 0, 0)
 
-        return pos
+        return cls.__selection_center
 
     ##  Apply an operation to the entire selection
     #
@@ -96,4 +85,16 @@ def applyOperation(cls, operation, *args, **kwargs):
 
         op.push()
 
+    @classmethod
+    def _onTransformationChanged(cls, node):
+        cls.__selection_center = Vector(0, 0, 0)
+
+        for object in cls.__selection:
+            cls.__selection_center += object.getWorldPosition()
+
+        cls.__selection_center /= len(cls.__selection)
+
+        cls.selectionCenterChanged.emit()
+
     __selection = []
+    __selection_center = Vector(0, 0, 0)

UM/Scene/ToolHandle.py

@@ -10,6 +10,8 @@
 from UM.Math.Color import Color
 from UM.Math.Vector import Vector
 
+from UM.Scene.Selection import Selection
+
 class ToolHandle(SceneNode.SceneNode):
     NoAxis = 1
     XAxis = 2
@@ -39,6 +41,8 @@ def __init__(self, parent = None):
 
         self.setCalculateBoundingBox(False)
 
+        Selection.selectionCenterChanged.connect(self._onSelectionCenterChanged)
+
     def getLineMesh(self):
         return self._line_mesh
 
@@ -114,3 +118,6 @@ def isAxis(cls, value):
         ZAxis: ZAxisColor,
         AllAxis: AllAxisColor
     }
+
+    def _onSelectionCenterChanged(self):
+        self.setPosition(Selection.getSelectionCenter())

UM/Tool.py

@@ -43,7 +43,6 @@ def event(self, event):
         if event.type == Event.ToolActivateEvent:
             if Selection.hasSelection() and self._handle:
                 self._handle.setParent(self.getController().getScene().getRoot())
-                self._handle.setPosition(Selection.getAveragePosition())
 
         if event.type == Event.MouseMoveEvent and self._handle:
             if self._locked_axis:
@@ -61,12 +60,6 @@ def event(self, event):
 
         return False
 
-    ##  Update the position of the ToolHandle
-    #   \sa ToolHandle
-    def updateHandlePosition(self):
-        if Selection.hasSelection():
-            self._handle.setPosition(Selection.getAveragePosition())
-
     ##  Convenience function 
     def getController(self):
         return self._controller

plugins/Tools/RotateTool/RotateTool.py

@@ -112,7 +112,6 @@ def event(self, event):
             Selection.applyOperation(RotateOperation, rotation)
 
             self.setDragStart(event.x, event.y)
-            self.updateHandlePosition()
 
         if event.type == Event.MouseReleaseEvent:
             if self.getDragPlane():

plugins/Tools/ScaleTool/ScaleTool.py

@@ -124,7 +124,6 @@ def event(self, event):
                     Selection.applyOperation(ScaleOperation, scale)
 
                 self._drag_length = (handle_position - drag_position).length()
-                self.updateHandlePosition()
                 return True
 
         if event.type == Event.MouseReleaseEvent:

plugins/Tools/TranslateTool/TranslateTool.py

@@ -87,7 +87,6 @@ def event(self, event):
                 Selection.applyOperation(TranslateOperation, drag)
 
             self.setDragStart(event.x, event.y)
-            self.updateHandlePosition()
             return True
 
         if event.type == Event.MouseReleaseEvent: