Enable connecting multiple list Attributes

Author: Fabien Servant

meshroom/ui/graph.py

@@ -1231,11 +1231,37 @@ def clearDataFrom(self, nodes: list[Node]):
     @Slot(Attribute, Attribute)
     def addEdge(self, src, dst):
         if isinstance(src, ListAttribute) and not isinstance(dst, ListAttribute):
+            # Source is a list, Destination is not a list
+            # Connect first attribute of the list to the destination
             self._addEdge(src.at(0), dst)
         elif isinstance(dst, ListAttribute) and not isinstance(src, ListAttribute):
+            # Source is not a list, Destination is a list
+            # Append the source to the destination's list attributes
             with self.groupedGraphModification(f"Insert and Add Edge on {dst.fullName}"):
                 self.appendAttribute(dst)
                 self._addEdge(src, dst.at(-1))
+        elif isinstance(src, ListAttribute) and isinstance(dst, ListAttribute):
+            # Both Source and Destination attributes are listAttributes
+            with self.groupedGraphModification(f"Insert and Add Edges on {dst.fullName}"):
+                
+                if dst.isLink:
+                    # Destination link is only a *view* on the listAttributes provided 
+                    # by the connected node. Therefore there is no meaning modifying the 
+                    # ListAttribute. We will therefore remove the existing link and create
+                    # links for each attributes of the list. The listAttribute will be owned
+                    # by the destination node and contains *views* on source individual attributes
+                    existingEdge = self._graph.edge(dst)
+                    existingSrc = existingEdge.src  # the previously connected ListAttribute
+                    self.push(commands.RemoveEdgeCommand(self._graph, existingEdge))
+                    for j in range(len(existingSrc)):
+                        self.appendAttribute(dst)
+                        self._addEdge(existingSrc.at(j), dst.at(-1))
+
+                # Add connections betweens the element of the source listAttribute
+                # and newly created items of the destination listAttribute
+                for i in range(len(src)):
+                    self.appendAttribute(dst)
+                    self._addEdge(src.at(i), dst.at(-1))
         else:
             self._addEdge(src, dst)
 

meshroom/ui/qml/GraphEditor/AttributePin.qml

@@ -130,12 +130,11 @@ RowLayout {
                         || drag.source.objectName != inputDragTarget.objectName  // Not an edge connector
                         || !validIncomingConnection                              // Connection is not allowed
                         || drag.source.nodeItem === inputDragTarget.nodeItem     // Connection between attributes of the same node
-                        || drag.source.isList && childrenRepeater.count          // Source/target are lists but target already has children
                         || drag.source.connectorType === "input"                 // Refuse to connect an "input pin" on another one (input attr can be connected to input attr, but not the graphical pin)
                     ) {
                         // Refuse attributes connection
                         drag.accepted = false
-                    } else if (inputDragTarget.attribute.isLink) {  // Already connected attribute
+                    } else if (inputDragTarget.attribute.isLink && !(drag.source.isList && root.isList)) {  // Already connected attribute (not list-to-list, which is additive)
                         root.edgeAboutToBeRemoved(inputDragTarget.attribute)
                     }
                     inputDropArea.acceptableDrop = drag.accepted
@@ -367,12 +366,11 @@ RowLayout {
                     || !validIncomingConnection                             // Connection is not allowed
                     || drag.source.nodeItem === outputDragTarget.nodeItem   // Connection between attributes of the same node
                     || (!drag.source.isList && outputDragTarget.isList)     // Connection between a list and a simple attribute
-                    || (drag.source.isList && childrenRepeater.count)       // Source/target are lists but target already has children
                     || drag.source.connectorType === "output"               // Refuse to connect an output pin on another one
                    ) {
                     // Refuse attributes connection
                     drag.accepted = false
-                } else if (drag.source.attribute.isLink) {  // Already connected attribute
+                } else if (drag.source.attribute.isLink && !(drag.source.isList && root.isList)) {  // Already connected attribute (not list-to-list, which is additive)
                     root.edgeAboutToBeRemoved(drag.source.attribute)
                 }
                 outputDropArea.acceptableDrop = drag.accepted