Use signals to avoid hard dependancy between component graphic items and scene

python/gui/auto_generated/processing/models/qgsmodelcomponentgraphicitem.sip.in

@@ -48,6 +48,21 @@ Returns the model component associated with this item.
     QgsProcessingModelAlgorithm *model();
 %Docstring
 Returns the model associated with this item.
+%End
+
+  signals:
+
+
+    void requestModelRepaint();
+%Docstring
+Emitted by the item to request a repaint of the parent model scene.
+%End
+
+
+    void changed();
+%Docstring
+Emitted when the definition of the associated component is changed
+by the item.
 %End
 
 };

python/plugins/processing/modeler/ModelerGraphicItem.py

@@ -56,9 +56,8 @@ class ModelerGraphicItem(QgsModelComponentGraphicItem):
     BUTTON_WIDTH = 16
     BUTTON_HEIGHT = 16
 
-    def __init__(self, element, model, scene=None):
+    def __init__(self, element, model):
         super().__init__(element, model, None)
-        self.scene = scene
         self.box_width = ModelerGraphicItem.BOX_WIDTH
         self.box_height = ModelerGraphicItem.BOX_HEIGHT
         self.item_font = QFont()
@@ -223,11 +222,11 @@ class ModelerGraphicItem(QgsModelComponentGraphicItem):
 
     def deactivateAlgorithm(self):
         self.model().deactivateChildAlgorithm(self.component().childId())
-        self.scene.dialog.repaintModel()
+        self.requestModelRepaint.emit()
 
     def activateAlgorithm(self):
         if self.model().activateChildAlgorithm(self.component().childId()):
-            self.scene.dialog.repaintModel()
+            self.requestModelRepaint.emit()
         else:
             QMessageBox.warning(None, 'Could not activate Algorithm',
                                 'The selected algorithm depends on other currently non-active algorithms.\n'
@@ -272,7 +271,7 @@ class ModelerGraphicItem(QgsModelComponentGraphicItem):
                 self.component().setDescription(new_param.name())
                 self.model().addModelParameter(new_param, self.component())
                 self.text = new_param.description()
-                self.scene.dialog.repaintModel()
+                self.requestModelRepaint.emit()
         elif isinstance(self.component(), QgsProcessingModelChildAlgorithm):
             elemAlg = self.component().algorithm()
             dlg = ModelerParametersDialog(elemAlg, self.model(), self.component().childId(), self.component().configuration())
@@ -280,7 +279,7 @@ class ModelerGraphicItem(QgsModelComponentGraphicItem):
                 alg = dlg.createAlgorithm()
                 alg.setChildId(self.component().childId())
                 self.updateAlgorithm(alg)
-                self.scene.dialog.repaintModel()
+                self.requestModelRepaint.emit()
 
         elif isinstance(self.component(), QgsProcessingModelOutput):
             child_alg = self.model().childAlgorithm(self.component().childId())
@@ -318,21 +317,21 @@ class ModelerGraphicItem(QgsModelComponentGraphicItem):
                                     'Remove them before trying to remove it.')
             else:
                 self.model().removeModelParameter(self.component().parameterName())
-                self.scene.dialog.haschanged = True
-                self.scene.dialog.repaintModel()
+                self.changed.emit()
+                self.requestModelRepaint.emit()
         elif isinstance(self.component(), QgsProcessingModelChildAlgorithm):
             if not self.model().removeChildAlgorithm(self.component().childId()):
                 QMessageBox.warning(None, 'Could not remove element',
                                     'Other elements depend on the selected one.\n'
                                     'Remove them before trying to remove it.')
             else:
-                self.scene.dialog.haschanged = True
-                self.scene.dialog.repaintModel()
+                self.changed.emit()
+                self.requestModelRepaint.emit()
         elif isinstance(self.component(), QgsProcessingModelOutput):
             self.model().childAlgorithm(self.component().childId()).removeModelOutput(self.component().name())
             self.model().updateDestinationParameters()
-            self.scene.dialog.haschanged = True
-            self.scene.dialog.repaintModel()
+            self.changed.emit()
+            self.requestModelRepaint.emit()
 
     def getAdjustedText(self, text):
         fm = QFontMetricsF(self.item_font)

python/plugins/processing/modeler/ModelerScene.py

@@ -88,18 +88,25 @@ class ModelerScene(QgsModelGraphicsScene):
                         items.extend(self.getItemsFromParamValue(variables[v].source, child_id, context))
         return items
 
+    def requestModelRepaint(self):
+        self.dialog.repaintModel()
+
+    def componentChanged(self):
+        self.dialog.haschanged = True
+
     def paintModel(self, model):
         self.model = model
         context = createContext()
         # Inputs
         for inp in list(model.parameterComponents().values()):
-            item = ModelerGraphicItem(inp.clone(), model, scene=self)
-            item.setFlag(QGraphicsItem.ItemIsMovable, True)
-            item.setFlag(QGraphicsItem.ItemIsSelectable, True)
+            item = ModelerGraphicItem(inp.clone(), model)
             self.addItem(item)
             item.setPos(inp.position().x(), inp.position().y())
             self.paramItems[inp.parameterName()] = item
 
+            item.requestModelRepaint.connect(self.requestModelRepaint)
+            item.changed.connect(self.componentChanged)
+
         # Input dependency arrows
         for input_name in list(model.parameterComponents().keys()):
             idx = 0
@@ -128,13 +135,14 @@ class ModelerScene(QgsModelGraphicsScene):
 
         # We add the algs
         for alg in list(model.childAlgorithms().values()):
-            item = ModelerGraphicItem(alg.clone(), model, scene=self)
-            item.setFlag(QGraphicsItem.ItemIsMovable, True)
-            item.setFlag(QGraphicsItem.ItemIsSelectable, True)
+            item = ModelerGraphicItem(alg.clone(), model)
             self.addItem(item)
             item.setPos(alg.position().x(), alg.position().y())
             self.algItems[alg.childId()] = item
 
+            item.requestModelRepaint.connect(self.requestModelRepaint)
+            item.changed.connect(self.componentChanged)
+
         # And then the arrows
 
         for alg in list(model.childAlgorithms().values()):
@@ -169,9 +177,10 @@ class ModelerScene(QgsModelGraphicsScene):
 
             for key, out in outputs.items():
                 if out is not None:
-                    item = ModelerGraphicItem(out.clone(), model, scene=self)
-                    item.setFlag(QGraphicsItem.ItemIsMovable, True)
-                    item.setFlag(QGraphicsItem.ItemIsSelectable, True)
+                    item = ModelerGraphicItem(out.clone(), model)
+                    item.requestModelRepaint.connect(self.requestModelRepaint)
+                    item.changed.connect(self.componentChanged)
+
                     self.addItem(item)
                     pos = out.position()
 

src/gui/processing/models/qgsmodelcomponentgraphicitem.h

@@ -63,6 +63,23 @@ class GUI_EXPORT QgsModelComponentGraphicItem : public QGraphicsObject
      */
     QgsProcessingModelAlgorithm *model();
 
+  signals:
+
+    // TEMPORARY ONLY during refactoring
+
+    /**
+     * Emitted by the item to request a repaint of the parent model scene.
+     */
+    void requestModelRepaint();
+
+    // TEMPORARY ONLY during refactoring
+
+    /**
+     * Emitted when the definition of the associated component is changed
+     * by the item.
+     */
+    void changed();
+
   private:
 
     std::unique_ptr< QgsProcessingModelComponent > mComponent;