Rework item creation UI as an item param editor

bliss/flint/widgets/curve_plot_property.py

@@ -270,13 +270,13 @@ class _AddItemAction(qt.QWidgetAction):
         menu: qt.QMenu = self.sender()
         menu.clear()
 
-        availableItemFactory = {
+        availableItemParamEditor = {
             MaxCurveItem: None,
             MinCurveItem: None,
             DerivativeItem: None,
             NegativeItem: None,
             GaussianFitItem: None,
-            NormalizedCurveItem: self.__createNormalized,
+            NormalizedCurveItem: self.__editNormalizedParams,
             NormalizedZeroOneItem: None,
         }
 
@@ -284,14 +284,14 @@ class _AddItemAction(qt.QWidgetAction):
         if isinstance(item, plot_item_model.CurveMixIn):
             menu.addSection("Statistics")
 
-            for className, chassFactory in availableItemFactory.items():
+            for className, editor in availableItemParamEditor.items():
                 try:
                     name = className.NAME
                 except Exception:
                     name = className.__name__
-
-                if chassFactory is None:
-                    chassFactory = functools.partial(self.__createChildItem, className)
+                chassFactory = functools.partial(
+                    self.__createChildItem, className, editor
+                )
                 action = qt.QAction(self)
                 action.setText(name)
                 icon = icons.getQIcon("flint:icons/item-stats")
@@ -307,23 +307,39 @@ class _AddItemAction(qt.QWidgetAction):
     def __selectionChanged(self, current: plot_model.Item):
         self.defaultWidget().setEnabled(current is not None)
 
-    def __createChildItem(self, itemClass):
+    def __createChildItem(self, itemClass, itemEditor):
         parentItem = self.parent().selectedPlotItem()
-        if parentItem is not None:
-            plotModel = parentItem.plot()
-            newItem = itemClass(plotModel)
-            newItem.setSource(parentItem)
-            with plotModel.transaction():
-                plotModel.addItem(newItem)
-            # FIXME: It would be better to make it part of the model
-            plotModel.tagUserEditTime()
+        if parentItem is None:
+            return
+        plotModel = parentItem.plot()
+        newItem = itemClass(plotModel)
+        if itemEditor is not None:
+            result = itemEditor(newItem)
+            if not result:
+                newItem.deleteLater()
+                return
 
-    def __createNormalized(self):
+        # Sanity check as we did a user selection in between it is not atomic
         parentItem = self.parent().selectedPlotItem()
         if parentItem is None:
+            newItem.deleteLater()
             return
-        # Avoid strong reference
-        parentItem = None
+        plotModel = parentItem.plot()
+        if plotModel is None:
+            newItem.deleteLater()
+            return
+
+        newItem.setSource(parentItem)
+        with plotModel.transaction():
+            plotModel.addItem(newItem)
+        # FIXME: It would be better to make it part of the model
+        plotModel.tagUserEditTime()
+
+    def __editNormalizedParams(self, item: NormalizedCurveItem):
+        """Edit NormalizedCurveItem parameters.
+
+        Returns true if the edition succeeded, else false.
+        """
         parentWidget = self.parent()
         scan = parentWidget.scan()
         dialog = SelectChannelDialog(parentWidget)
@@ -333,22 +349,11 @@ class _AddItemAction(qt.QWidgetAction):
             return
         monitorName = dialog.selectedChannelName()
         if monitorName is None:
-            return
-        # As we did a user selection make sure the item is still there
-        parentItem = self.parent().selectedPlotItem()
-        if parentItem is None:
-            return
-        plotModel = parentItem.plot()
-        if plotModel is None:
-            return
-        newItem = NormalizedCurveItem(plotModel)
+            return False
+        plotModel = item.plot()
         channel = plot_model.ChannelRef(plotModel, monitorName)
-        newItem.setMonitorChannel(channel)
-        newItem.setSource(parentItem)
-        with plotModel.transaction():
-            plotModel.addItem(newItem)
-        # FIXME: It would be better to make it part of the model
-        plotModel.tagUserEditTime()
+        item.setMonitorChannel(channel)
+        return True
 
 
 class _DataItem(_property_tree_helper.ScanRowItem):