From 65b5b6a7bc40a88e6eea75cbe488406f5861c1db Mon Sep 17 00:00:00 2001
From: Luke Campagnola <ausqualius@yahoo.com>
Date: Wed, 13 Sep 2017 21:04:04 -0700
Subject: [PATCH] Add CanvasItem.saveState/restoreState

---
 pyqtgraph/canvas/Canvas.py     |  9 +++++----
 pyqtgraph/canvas/CanvasItem.py | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/pyqtgraph/canvas/Canvas.py b/pyqtgraph/canvas/Canvas.py
index a9f1d918..2ebc2ba1 100644
--- a/pyqtgraph/canvas/Canvas.py
+++ b/pyqtgraph/canvas/Canvas.py
@@ -19,9 +19,11 @@ elif QT_LIB == 'PyQt5':
 import numpy as np
 from .. import debug
 import weakref
+import gc
 from .CanvasManager import CanvasManager
 from .CanvasItem import CanvasItem, GroupCanvasItem
 
+
 class Canvas(QtGui.QWidget):
     
     sigSelectionChanged = QtCore.Signal(object, object)
@@ -417,25 +419,24 @@ class Canvas(QtGui.QWidget):
             ctrl = item.ctrlWidget()
             ctrl.hide()
             self.ui.ctrlLayout.removeWidget(ctrl)
+            ctrl.setParent(None)
         else:
             if hasattr(item, '_canvasItem'):
                 self.removeItem(item._canvasItem)
             else:
                 self.view.removeItem(item)
-        
-        ## disconnect signals, remove from list, etc..
+                
+        gc.collect()
         
     def clear(self):
         while len(self.items) > 0:
             self.removeItem(self.items[0])
-        
 
     def addToScene(self, item):
         self.view.addItem(item)
         
     def removeFromScene(self, item):
         self.view.removeItem(item)
-
     
     def listItems(self):
         """Return a dictionary of name:item pairs"""
diff --git a/pyqtgraph/canvas/CanvasItem.py b/pyqtgraph/canvas/CanvasItem.py
index eb6d0a61..c406256c 100644
--- a/pyqtgraph/canvas/CanvasItem.py
+++ b/pyqtgraph/canvas/CanvasItem.py
@@ -453,6 +453,25 @@ class CanvasItem(QtCore.QObject):
     def isVisible(self):
         return self.opts['visible']
 
+    def saveState(self):
+        return {
+            'type': self.__class__.__name__,
+            'name': self.name,
+            'visible': self.isVisible(),
+            'alpha': self.alpha(),
+            'userTransform': self.saveTransform(), 
+            'z': self.zValue(),
+            'scalable': self.opts['scalable'],
+            'rotatable': self.opts['rotatable'],
+            'movable': self.opts['movable'],
+        }
+    
+    def restoreState(self, state):
+        self.setVisible(state['visible'])
+        self.setAlpha(state['alpha'])
+        self.restoreTransform(state['userTransform'])
+        self.setZValue(state['z'])
+
 
 class GroupCanvasItem(CanvasItem):
     """