Fix bug with undo redo and empty selections.

Author: hsorby

src/mapclient/view/workflow/workflowcommands.py

@@ -60,23 +60,27 @@ class CommandSelection(QtGui.QUndoCommand):
     don't end up in a recursive loop.
     """
 
-    def __init__(self, scene, selection, previous):
+    def __init__(self, scene, current, previous):
         super(CommandSelection, self).__init__()
-        logger.debug("Selection Command created ...")
         self._scene = scene
-        self._selection = selection
-        self._previousSelection = previous
+        self._current = list(current)
+        self._previous = list(previous)
 
     def redo(self):
-        self._scene.blockSignals(True)
-        for item in list(self._scene.items()):
-            item.setSelected(item in self._selection)
-        self._scene.blockSignals(False)
+        self._apply_selection(self._current)
 
     def undo(self):
+        self._apply_selection(self._previous)
+
+    def _apply_selection(self, items_to_select):
         self._scene.blockSignals(True)
-        for item in list(self._scene.items()):
-            item.setSelected(item in self._previousSelection)
+
+        self._scene.clearSelection()
+        for item in items_to_select:
+            # Check if item still belongs to scene (handle deleted items)
+            if item.scene() == self._scene:
+                item.setSelected(True)
+
         self._scene.blockSignals(False)
 
 

src/mapclient/view/workflow/workflowgraphicsview.py

@@ -129,11 +129,10 @@ def connectNodes(self, src_port, dest_port):
                 self._errorIconTimer.start()
 
     def selectionChanged(self):
-        currentSelection = self.scene().selectedItems()
-        previousSelection = self.scene().previouslySelectedItems()
-        command = CommandSelection(self.scene(), currentSelection, previousSelection)
-        self._undoStack.push(command)
-        self.scene().setPreviouslySelectedItems(currentSelection)
+        current_selection = self.scene().selectedItems()
+        previous_selection = self.scene().previouslySelectedItems()
+        self._undoStack.push(CommandSelection(self.scene(), current_selection, previous_selection))
+        self.scene().setPreviouslySelectedItems(current_selection)
 
     def nodeSelected(self, node, state):
         if state and node not in self._selectedNodes:
@@ -370,9 +369,10 @@ def mouseReleaseEvent(self, event):
             QtWidgets.QGraphicsView.mouseReleaseEvent(self, event)
             if self._selectionStartPos:
                 diff = event.pos() - self._selectionStartPos
-                if diff.x() != 0 and diff.y() != 0:
+                selected_items = self.scene().selectedItems()
+                if diff.x() != 0 and diff.y() != 0 and selected_items:
                     self._undoStack.beginMacro('Move Step(s)')
-                    for item in self.scene().selectedItems():
+                    for item in selected_items:
                         if item.type() == Node.Type:
                             self._undoStack.push(CommandMove(item, item.pos() - diff, item.pos()))
                     self._undoStack.endMacro()