Moved emits after all method state updates since PySide2 immediately executes signals.

Pull request #907 addressed a specific case where a signal was emitted before a state update.
If an application's slot then calls back into the instance, the instance was in an inconsistent
state.  This commit audits and fixes similar issues throughout the pyqtgraph library.  This
commit fixes several latent issues:

* SignalProxy: flush -> sigDelayed -> signalReceived would have incorrectly resulted in timer.stop().
* ViewBox: resizeEvent -> sigStateChange -> background state
* ViewBox: setRange -> sigStateChange -> autoranging not updated correctly
* ViewBox: updateMatrix -> sigTransformChanged -> any _matrixNeedsUpdate = True -> ignored
* Parameter: Child may have missed state tree messages on insert or received extra on remove
* GraphicsView: updateMatrix -> sigDeviceRangeChanged/sigDeviceTransformChange -> before propagated to locked viewports.

pyqtgraph/SignalProxy.py

@@ -67,11 +67,11 @@ class SignalProxy(QtCore.QObject):
         """If there is a signal queued up, send it now."""
         if self.args is None or self.block:
             return False
-        #self.emit(self.signal, *self.args)
+        args, self.args = self.args, None
-        self.sigDelayed.emit(self.args)
-        self.args = None
         self.timer.stop()
         self.lastFlushTime = time()
+        #self.emit(self.signal, *self.args)
+        self.sigDelayed.emit(args)
         return True
         
     def disconnect(self):

pyqtgraph/dockarea/Dock.py

@@ -346,9 +346,9 @@ class DockLabel(VerticalLabel):
         ev.accept()
             
     def mouseReleaseEvent(self, ev):
+        ev.accept()
         if not self.startedDrag:
             self.sigClicked.emit(self, ev)
-        ev.accept()
         
     def mouseDoubleClickEvent(self, ev):
         if ev.button() == QtCore.Qt.LeftButton:

pyqtgraph/flowchart/Flowchart.py

@@ -503,8 +503,8 @@ class Flowchart(Node):
         finally:
             self.blockSignals(False)
             
-        self.sigChartLoaded.emit()
         self.outputChanged()
+        self.sigChartLoaded.emit()
         self.sigStateChanged.emit()
             
     def loadFile(self, fileName=None, startDir=None):

pyqtgraph/graphicsItems/HistogramLUTItem.py

@@ -205,8 +205,8 @@ class HistogramLUTItem(GraphicsWidget):
     def regionChanging(self):
         if self.imageItem() is not None:
             self.imageItem().setLevels(self.getLevels())
-        self.sigLevelsChanged.emit(self)
         self.update()
+        self.sigLevelsChanged.emit(self)
 
     def imageChanged(self, autoLevel=False, autoRange=False):
         if self.imageItem() is None:

pyqtgraph/graphicsItems/ROI.py

@@ -711,10 +711,10 @@ class ROI(GraphicsObject):
                 
         if hover:
             self.setMouseHover(True)
-            self.sigHoverEvent.emit(self)
             ev.acceptClicks(QtCore.Qt.LeftButton)  ## If the ROI is hilighted, we should accept all clicks to avoid confusion.
             ev.acceptClicks(QtCore.Qt.RightButton)
             ev.acceptClicks(QtCore.Qt.MidButton)
+            self.sigHoverEvent.emit(self)
         else:
             self.setMouseHover(False)
 

pyqtgraph/graphicsItems/ScatterPlotItem.py

@@ -834,8 +834,8 @@ class ScatterPlotItem(GraphicsObject):
             pts = self.pointsAt(ev.pos())
             if len(pts) > 0:
                 self.ptsClicked = pts
-                self.sigClicked.emit(self, self.ptsClicked)
                 ev.accept()
+                self.sigClicked.emit(self, self.ptsClicked)
             else:
                 #print "no spots"
                 ev.ignore()

pyqtgraph/graphicsItems/ViewBox/ViewBox.py

@@ -427,8 +427,8 @@ class ViewBox(GraphicsWidget):
         self.updateAutoRange()
         self.updateViewRange()
         self._matrixNeedsUpdate = True
-        self.sigStateChanged.emit(self)
         self.background.setRect(self.rect())
+        self.sigStateChanged.emit(self)
         self.sigResized.emit(self)
 
     def viewRange(self):
@@ -561,18 +561,18 @@ class ViewBox(GraphicsWidget):
 
         # If nothing has changed, we are done.
         if any(changed):
-            self.sigStateChanged.emit(self)
-
             # Update target rect for debugging
             if self.target.isVisible():
                 self.target.setRect(self.mapRectFromItem(self.childGroup, self.targetRect()))
 
-        # If ortho axes have auto-visible-only, update them now
+            # If ortho axes have auto-visible-only, update them now
-        # Note that aspect ratio constraints and auto-visible probably do not work together..
+            # Note that aspect ratio constraints and auto-visible probably do not work together..
-        if changed[0] and self.state['autoVisibleOnly'][1] and (self.state['autoRange'][0] is not False):
+            if changed[0] and self.state['autoVisibleOnly'][1] and (self.state['autoRange'][0] is not False):
-            self._autoRangeNeedsUpdate = True
+                self._autoRangeNeedsUpdate = True
-        elif changed[1] and self.state['autoVisibleOnly'][0] and (self.state['autoRange'][1] is not False):
+            elif changed[1] and self.state['autoVisibleOnly'][0] and (self.state['autoRange'][1] is not False):
-            self._autoRangeNeedsUpdate = True
+                self._autoRangeNeedsUpdate = True
+                
+            self.sigStateChanged.emit(self)
 
     def setYRange(self, min, max, padding=None, update=True):
         """
@@ -1156,8 +1156,8 @@ class ViewBox(GraphicsWidget):
 
         self._resetTarget()
         self.scaleBy(s, center)
-        self.sigRangeChangedManually.emit(mask)
         ev.accept()
+        self.sigRangeChangedManually.emit(mask)
 
     def mouseClickEvent(self, ev):
         if ev.button() == QtCore.Qt.RightButton and self.menuEnabled():
@@ -1498,14 +1498,8 @@ class ViewBox(GraphicsWidget):
 
         if any(changed):
             self._matrixNeedsUpdate = True
-            # emit range change signals
-            if changed[0]:
-                self.sigXRangeChanged.emit(self, tuple(self.state['viewRange'][0]))
-            if changed[1]:
-                self.sigYRangeChanged.emit(self, tuple(self.state['viewRange'][1]))
-            self.sigRangeChanged.emit(self, self.state['viewRange'])
             self.update()
-
+            
             # Inform linked views that the range has changed
             for ax in [0, 1]:
                 if not changed[ax]:
@@ -1514,6 +1508,13 @@ class ViewBox(GraphicsWidget):
                 if link is not None:
                     link.linkedViewChanged(self, ax)
 
+            # emit range change signals
+            if changed[0]:
+                self.sigXRangeChanged.emit(self, tuple(self.state['viewRange'][0]))
+            if changed[1]:
+                self.sigYRangeChanged.emit(self, tuple(self.state['viewRange'][1]))
+            self.sigRangeChanged.emit(self, self.state['viewRange'])
+
     def updateMatrix(self, changed=None):
         if not self._matrixNeedsUpdate:
             return
@@ -1541,9 +1542,9 @@ class ViewBox(GraphicsWidget):
         m.translate(-st[0], -st[1])
 
         self.childGroup.setTransform(m)
+        self._matrixNeedsUpdate = False
 
         self.sigTransformChanged.emit(self)  ## segfaults here: 1
-        self._matrixNeedsUpdate = False
 
     def paint(self, p, opt, widget):
         self.checkSceneChange()

pyqtgraph/parametertree/Parameter.py

@@ -559,8 +559,8 @@ class Parameter(QtCore.QObject):
             self.childs.insert(pos, child)
             
             child.parentChanged(self)
-            self.sigChildAdded.emit(self, child, pos)
             child.sigTreeStateChanged.connect(self.treeStateChanged)
+            self.sigChildAdded.emit(self, child, pos)
         return child
         
     def removeChild(self, child):
@@ -571,11 +571,11 @@ class Parameter(QtCore.QObject):
         del self.names[name]
         self.childs.pop(self.childs.index(child))
         child.parentChanged(None)
-        self.sigChildRemoved.emit(self, child)
         try:
             child.sigTreeStateChanged.disconnect(self.treeStateChanged)
         except (TypeError, RuntimeError):  ## already disconnected
             pass
+        self.sigChildRemoved.emit(self, child)
 
     def clearChildren(self):
         """Remove all child parameters."""

pyqtgraph/widgets/ColorButton.py

@@ -50,11 +50,11 @@ class ColorButton(QtGui.QPushButton):
     def setColor(self, color, finished=True):
         """Sets the button's color and emits both sigColorChanged and sigColorChanging."""
         self._color = functions.mkColor(color)
+        self.update()
         if finished:
             self.sigColorChanged.emit(self)
         else:
             self.sigColorChanging.emit(self)
-        self.update()
         
     def selectColor(self):
         self.origColor = self.color()

pyqtgraph/widgets/GraphicsView.py

@@ -227,12 +227,12 @@ class GraphicsView(QtGui.QGraphicsView):
             else:
                 self.fitInView(self.range, QtCore.Qt.IgnoreAspectRatio)
             
-        self.sigDeviceRangeChanged.emit(self, self.range)
-        self.sigDeviceTransformChanged.emit(self)
-        
         if propagate:
             for v in self.lockedViewports:
                 v.setXRange(self.range, padding=0)
+
+        self.sigDeviceRangeChanged.emit(self, self.range)
+        self.sigDeviceTransformChanged.emit(self)
         
     def viewRect(self):
         """Return the boundaries of the view in scene coordinates"""
@@ -262,7 +262,6 @@ class GraphicsView(QtGui.QGraphicsView):
         h = self.range.height() / scale[1]
         self.range = QtCore.QRectF(center.x() - (center.x()-self.range.left()) / scale[0], center.y() - (center.y()-self.range.top())  /scale[1], w, h)
         
-        
         self.updateMatrix()
         self.sigScaleChanged.emit(self)