undoable component movement

src/core.py

@@ -73,6 +73,7 @@ class Core:
             compPos = len(self.selectedComponents)
         if len(self.selectedComponents) > 50:
             return None
+
         if type(component) is int:
             # create component using module index in self.modules
             moduleIndex = int(component)

src/gui/actions.py

@@ -35,3 +35,42 @@ class RemoveComponent(QUndoCommand):
             )
         self.parent.drawPreview()
 
+
+class MoveComponent(QUndoCommand):
+    def __init__(self, parent, row, newRow, tag):
+        super().__init__("Move component %s" % tag)
+        self.parent = parent
+        self.row = row
+        self.newRow = newRow
+        self.id_ = ord(tag[0])
+
+    def id(self):
+        '''If 2 consecutive updates have same id, Qt will call mergeWith()'''
+        return self.id_
+
+    def mergeWith(self, other):
+        self.newRow = other.newRow
+        return True
+
+    def do(self, rowa, rowb):
+        componentList = self.parent.window.listWidget_componentList
+
+        page = self.parent.pages.pop(rowa)
+        self.parent.pages.insert(rowb, page)
+
+        item = componentList.takeItem(rowa)
+        componentList.insertItem(rowb, item)
+
+        stackedWidget = self.parent.window.stackedWidget
+        widget = stackedWidget.removeWidget(page)
+        stackedWidget.insertWidget(rowb, page)
+        componentList.setCurrentRow(rowb)
+        stackedWidget.setCurrentIndex(rowb)
+        self.parent.core.moveComponent(rowa, rowb)
+        self.parent.drawPreview(True)
+
+    def redo(self):
+        self.do(self.row, self.newRow)
+
+    def undo(self):
+        self.do(self.newRow, self.row)

src/gui/mainwindow.py

@@ -716,27 +716,19 @@ class MainWindow(QtWidgets.QMainWindow):
     def moveComponent(self, change):
         '''Moves a component relatively from its current position'''
         componentList = self.window.listWidget_componentList
+        tag = change
         if change == 'top':
             change = -componentList.currentRow()
         elif change == 'bottom':
             change = len(componentList)-componentList.currentRow()-1
-        stackedWidget = self.window.stackedWidget
+        else:
+            tag = 'down' if change == 1 else 'up'
 
         row = componentList.currentRow()
         newRow = row + change
         if newRow > -1 and newRow < componentList.count():
-            self.core.moveComponent(row, newRow)
-
-            # update widgets
-            page = self.pages.pop(row)
-            self.pages.insert(newRow, page)
-            item = componentList.takeItem(row)
-            newItem = componentList.insertItem(newRow, item)
-            widget = stackedWidget.removeWidget(page)
-            stackedWidget.insertWidget(newRow, page)
-            componentList.setCurrentRow(newRow)
-            stackedWidget.setCurrentIndex(newRow)
-            self.drawPreview(True)
+            action = MoveComponent(self, row, newRow, tag)
+            self.undoStack.push(action)
 
     def getComponentListMousePos(self, position):
         '''