[ui] Graph: Node selection refactor (1)

Switch selection management backend to a QItemSelectionModel,
while keeping the current 'selectedNodes' API for now.
Use DelegateSectionBox for node selection in the graph, and
rewrite the handling of node selection / displacement.

meshroom/ui/graph.py

@@ -7,8 +7,19 @@
 from enum import Enum
 from threading import Thread, Event, Lock
 from multiprocessing.pool import ThreadPool
-
-from PySide6.QtCore import Slot, QJsonValue, QObject, QUrl, Property, Signal, QPoint
+from typing import Iterator
+
+from PySide6.QtCore import (
+    Slot,
+    QJsonValue,
+    QObject,
+    QUrl,
+    Property,
+    Signal,
+    QPoint,
+    QItemSelectionModel,
+    QItemSelection,
+)
 
 from meshroom.core import sessionUid
 from meshroom.common.qt import QObjectListModel
@@ -359,6 +370,8 @@ def __init__(self, undoStack, taskManager, parent=None):
         self._layout = GraphLayout(self)
         self._selectedNode = None
         self._selectedNodes = QObjectListModel(parent=self)
+        self._nodeSelection = QItemSelectionModel(self._graph.nodes, parent=self)
+        self._nodeSelection.selectionChanged.connect(self.onNodeSelectionChanged)
         self._hoveredNode = None
 
         self.submitLabel = "{projectName}"
@@ -395,6 +408,8 @@ def setGraph(self, g):
                 self._layout.reset()
                 # clear undo-stack after layout
                 self._undoStack.clear()
+
+        self._nodeSelection.setModel(self._graph.nodes)
         self.graphChanged.emit()
 
     def onGraphUpdated(self):
@@ -642,27 +657,24 @@ def filterNodes(self, nodes):
             nodes = [nodes]
         return [ n for n in nodes if n in self._graph.nodes.values() ]
 
-    @Slot(Node, QPoint, QObject)
-    def moveNode(self, node, position, nodes=None):
+    def moveNode(self, node: Node, position: Position):
         """
-        Move 'node' to the given 'position' and also update the positions of 'nodes' if necessary.
+        Move `node` to the given `position`.
 
         Args:
-            node (Node): the node to move
-            position (QPoint): the target position
-            nodes (list[Node]): the nodes to update the position of
+            node: The node to move.
+            position: The target position.
         """
-        if not nodes:
-            nodes = [node]
-        nodes = self.filterNodes(nodes)
-        if isinstance(position, QPoint):
-            position = Position(position.x(), position.y())
-        deltaX = position.x - node.x
-        deltaY = position.y - node.y
+        self.push(commands.MoveNodeCommand(self._graph, node, position))
+
+    @Slot(QPoint)
+    def moveSelectedNodesBy(self, offset: QPoint):
+        """Move all the selected nodes by the given `offset`."""
+
         with self.groupedGraphModification("Move Selected Nodes"):
-            for n in nodes:
-                position = Position(n.x + deltaX, n.y + deltaY)
-                self.push(commands.MoveNodeCommand(self._graph, n, position))
+            for node in self.iterSelectedNodes():
+                position = Position(node.x + offset.x(), node.y + offset.y())
+                self.moveNode(node, position)
 
     @Slot(QObject)
     def removeNodes(self, nodes):
@@ -934,62 +946,83 @@ def removeImagesFromAllGroups(self):
         with self.groupedGraphModification("Remove Images From All CameraInit Nodes"):
             self.push(commands.RemoveImagesCommand(self._graph, list(self.cameraInits)))
 
-    @Slot(Node)
-    def appendSelection(self, node):
-        """ Append 'node' to the selection if it is not already part of the selection. """
-        if not self._selectedNodes.contains(node):
-            self._selectedNodes.append(node)
-
-    @Slot("QVariantList")
-    def selectNodes(self, nodes):
-        """ Append 'nodes' to the selection. """
-        for node in nodes:
-            self.appendSelection(node)
+    def onNodeSelectionChanged(self, selected, deselected):
+        # Update internal cache of selected Node instances.
+        self._selectedNodes.setObjectList(list(self.iterSelectedNodes()))
         self.selectedNodesChanged.emit()
 
+    @Slot(list)
+    @Slot(list, int)
+    def selectNodes(self, nodes, command=QItemSelectionModel.SelectionFlag.ClearAndSelect):
+        """Update selection with `nodes` using the specified `command`."""
+        indices = [self._graph._nodes.indexOf(node) for node in nodes]
+        self.selectNodesByIndices(indices, command)
+
     @Slot(Node)
-    def selectFollowing(self, node):
-        """ Select all the nodes the depend on 'node'. """
+    def selectFollowing(self, node: Node):
+        """Select all the nodes that depend on `node`."""
         self.selectNodes(self._graph.dfsOnDiscover(startNodes=[node], reverse=True, dependenciesOnly=True)[0])
-
-    @Slot(QObject, QObject)
-    def boxSelect(self, selection, draggable):
-        """
-        Select nodes that overlap with 'selection'.
-        Takes into account the zoom and position of 'draggable'.
-
+        self.selectedNode = node
+
+    @Slot(int)
+    @Slot(int, int)
+    def selectNodeByIndex(self, index: int, command=QItemSelectionModel.SelectionFlag.ClearAndSelect):
+        """Update selection with node at the given `index` using the specified `command`."""
+        if isinstance(command, int):
+            command = QItemSelectionModel.SelectionFlag(command)
+
+        self.selectNodesByIndices([index], command)
+
+        if self._nodeSelection.isRowSelected(index):
+            self.selectedNode = self._graph.nodes.at(index)
+
+    @Slot(list)
+    @Slot(list, int)
+    def selectNodesByIndices(
+        self, indices: list[int], command=QItemSelectionModel.SelectionFlag.ClearAndSelect
+    ):
+        """Update selection with node at given `indices` using the specified `command`.
+        
         Args:
-            selection: the rectangle selection widget.
-            draggable: the parent widget that has position and scale data.
+            indices: The list of indices to select.
+            command: The selection command to use.
         """
-        x = selection.x() - draggable.x()
-        y = selection.y() - draggable.y()
-        otherX = x + selection.width()
-        otherY = y + selection.height()
-        x, y, otherX, otherY = [ i / draggable.scale() for i in [x, y, otherX, otherY] ]
-        if x == otherX or y == otherY:
-            return
-        for n in self._graph.nodes:
-            bbox = self._layout.boundingBox([n])
-            # evaluate if the selection and node intersect
-            if not (x > bbox[2] + bbox[0] or otherX < bbox[0] or y > bbox[3] + bbox[1] or otherY < bbox[1]):
-                self.appendSelection(n)
-        self.selectedNodesChanged.emit()
+        if isinstance(command, int):
+            command = QItemSelectionModel.SelectionFlag(command)
+
+        itemSelection = QItemSelection()
+        for index in indices:
+            itemSelection.select(
+                self._graph.nodes.index(index), self._graph.nodes.index(index)
+            )
+
+        self._nodeSelection.select(itemSelection, command)
+
+        if self.selectedNode and not self.isSelected(self.selectedNode):
+            self.selectedNode = None
+
+    def iterSelectedNodes(self) -> Iterator[Node]:
+        """Iterate over the currently selected nodes."""
+        for idx in self._nodeSelection.selectedRows():
+            yield self._graph.nodes.at(idx.row())
+
+    @Slot(Node, result=bool)
+    def isSelected(self, node: Node) -> bool:
+        """Whether `node` is part of the current selection."""
+        return self._nodeSelection.isRowSelected(self._graph.nodes.indexOf(node))
 
     @Slot()
     def clearNodeSelection(self):
-        """ Clear all node selection. """
-        self._selectedNode = None
-        self._selectedNodes.clear()
-        self.selectedNodeChanged.emit()
-        self.selectedNodesChanged.emit()
+        """Clear all node selection."""
+        self.selectedNode = None
+        self._nodeSelection.clear()
 
     def clearNodeHover(self):
         """ Reset currently hovered node to None. """
         self.hoveredNode = None
 
     @Slot(result=str)
-    def getSelectedNodesContent(self):
+    def getSelectedNodesContent(self) -> str:
         """
         Return the content of the currently selected nodes in a string, formatted to JSON.
         If no node is currently selected, an empty string is returned.
@@ -1144,6 +1177,8 @@ def pasteNodes(self, clipboardContent, position=None, centerPosition=False):
     # Currently selected nodes
     selectedNodes = makeProperty(QObject, "_selectedNodes", selectedNodesChanged, resetOnDestroy=True)
 
+    nodeSelection = makeProperty(QObject, "_nodeSelection")
+
     hoveredNodeChanged = Signal()
     # Currently hovered node
     hoveredNode = makeProperty(QObject, "_hoveredNode", hoveredNodeChanged, resetOnDestroy=True)