node_selection_changed signal

Author: jchanvfx

NodeGraphQt/base/graph.py

@@ -90,6 +90,14 @@ class NodeGraph(QtCore.QObject):
     :parameters: :class:`NodeGraphQt.NodeObject`
     :emits: selected node
     """
+    node_selection_changed = QtCore.Signal(list, list)
+    """
+    Signal triggered when the node selection has changed.
+
+    :parameters: list[:class:`NodeGraphQt.NodeObject`], 
+                 list[:class:`NodeGraphQt.NodeObject`]
+    :emits: previous node selection, new selection.
+    """
     node_double_clicked = QtCore.Signal(NodeObject)
     """
     Signal triggered when a node is double clicked and emits the node.
@@ -167,6 +175,8 @@ def _wire_signals(self):
 
         # pass through signals.
         self._viewer.node_selected.connect(self._on_node_selected)
+        self._viewer.node_selection_changed.connect(
+            self._on_node_selection_changed)
         self._viewer.data_dropped.connect(self._on_node_data_dropped)
 
     def _insert_node(self, pipe, node_id, prev_node_pos):
@@ -260,6 +270,19 @@ def _on_node_selected(self, node_id):
         node = self.get_node_by_id(node_id)
         self.node_selected.emit(node)
 
+    def _on_node_selection_changed(self, prev_ids, node_ids):
+        """
+        called when the node selection changes in the viewer.
+        (emits node objects <un-selected nodes>, <selected nodes>)
+
+        Args:
+            prev_ids (list[str]): previous selection.
+            node_ids (list[str]): current selection.
+        """
+        prev_nodes = [self.get_node_by_id(nid) for nid in prev_ids]
+        new_nodes = [self.get_node_by_id(nid) for nid in node_ids]
+        self.node_selection_changed.emit(prev_nodes, new_nodes)
+
     def _on_node_data_dropped(self, data, pos):
         """
         called when data has been dropped on the viewer.

NodeGraphQt/constants.py

@@ -122,6 +122,9 @@
 
 # === NODE LAYOUT DIRECTION ===
 
+#: Mode for vertical node layout.
 NODE_LAYOUT_VERTICAL = 0
+#: Mode for horizontal node layout.
 NODE_LAYOUT_HORIZONTAL = 1
+#: Variable for setting the node layout direction.
 NODE_LAYOUT_DIRECTION = NODE_LAYOUT_HORIZONTAL

NodeGraphQt/qgraphics/node_abstract.py

@@ -23,7 +23,7 @@ def __init__(self, name='node', parent=None):
             'type_': 'AbstractBaseNode',
             'selected': False,
             'disabled': False,
-            'visible' : False,
+            'visible': False,
         }
         self._width = NODE_WIDTH
         self._height = NODE_HEIGHT
@@ -135,7 +135,9 @@ def disabled(self, state=False):
 
     @property
     def selected(self):
-        return self.isSelected()
+        if self._properties['selected'] != self.isSelected():
+            self._properties['selected'] = self.isSelected()
+        return self._properties['selected']
 
     @selected.setter
     def selected(self, selected=False):

NodeGraphQt/widgets/viewer.py

@@ -36,6 +36,7 @@ class NodeViewer(QtWidgets.QGraphicsView):
 
     # pass through signals
     node_selected = QtCore.Signal(str)
+    node_selection_changed = QtCore.Signal(list, list)
     node_double_clicked = QtCore.Signal(str)
     data_dropped = QtCore.Signal(QtCore.QMimeData, QtCore.QPoint)
 
@@ -306,11 +307,25 @@ def mouseReleaseEvent(self, event):
                 self._rubber_band.hide()
 
                 rect = QtCore.QRect(self._origin_pos, event.pos()).normalized()
-                for item in self.scene().items(self.mapToScene(rect).boundingRect()):
+                rect_items = self.scene().items(
+                    self.mapToScene(rect).boundingRect()
+                )
+                node_ids = []
+                for item in rect_items:
                     if isinstance(item, AbstractNodeItem):
-                        self.node_selected.emit(item.id)
-                        return
+                        node_ids.append(item.id)
+
+                # emit the node selection signals.
+                if node_ids:
+                    prev_ids = [
+                        n.id for n in self._prev_selection_nodes
+                        if not n.selected
+                    ]
+                    self.node_selected.emit(node_ids[0])
+                    self.node_selection_changed.emit(prev_ids, node_ids)
+
                 self.scene().update(map_rect)
+                return
 
         # find position changed nodes and emit signal.
         moved_nodes = {
@@ -326,11 +341,16 @@ def mouseReleaseEvent(self, event):
 
         # emit signal if selected node collides with pipe.
         # Note: if collide state is true then only 1 node is selected.
+        nodes, pipes = self.selected_items()
         if self.COLLIDING_state:
-            nodes, pipes = self.selected_items()
             if nodes and pipes:
                 self.insert_node.emit(pipes[0], nodes[0].id, moved_nodes)
 
+        # emit node selection changed signal.
+        prev_ids = [n.id for n in self._prev_selection_nodes if not n.selected]
+        node_ids = [n.id for n in nodes if n not in self._prev_selection_nodes]
+        self.node_selection_changed.emit(prev_ids, node_ids)
+
         super(NodeViewer, self).mouseReleaseEvent(event)
 
     def mouseMoveEvent(self, event):
@@ -544,6 +564,7 @@ def sceneMousePressEvent(self, event):
     def sceneMouseReleaseEvent(self, event):
         """
         triggered mouse release event for the scene.
+
         Args:
             event (QtWidgets.QGraphicsSceneMouseEvent):
                 The event handler from the QtWidgets.QGraphicsScene
@@ -556,7 +577,9 @@ def sceneMouseReleaseEvent(self, event):
     def apply_live_connection(self, event):
         """
         triggered mouse press/release event for the scene.
-         - verify to make a the connection Pipe.
+        - verifies the live connection pipe.
+        - makes a connection pipe if valid.
+        - emits the "connection changed" signal.
 
         Args:
             event (QtWidgets.QGraphicsSceneMouseEvent):

README.md

@@ -37,6 +37,9 @@ applications that supports PySide2.
 #### Properties Bin
 <img src="/docs/_images/prop_bin.png" width="600" title="Properties Bin">
 
+#### Vertical Layout
+<img src="/docs/_images/vertical_layout.png" width="600" title="Vertical Layout">
+
 #### Example
 
 ```python

docs/_images/example_subgraph.gif

@@ -4,7 +4,7 @@ Port Examples
 Creating Custom Shapes
 **********************
 
-*(Implemented on NodeGraphQt* ``v0.1.1`` *or above)*
+(*Implemented on* ``v0.1.1``)
 
 To have custom port shapes the :meth:`NodeGraphQt.BaseNode.add_input` and
 :meth:`NodeGraphQt.BaseNode.add_output` functions now have a ``painter_func``
@@ -16,7 +16,7 @@ argument where you specify you custom port painter function.
 Example Triangle Port
 *********************
 
-Here's an example function for drawing a triangle shaped port.
+Here's an example function for drawing a triangle port.
 
 .. code-block:: python
     :linenos:
@@ -40,12 +40,14 @@ Here's an example function for drawing a triangle shaped port.
         """
         painter.save()
 
+        # create triangle polygon.
         size = int(rect.height() / 2)
         triangle = QtGui.QPolygonF()
         triangle.append(QtCore.QPointF(-size, size))
         triangle.append(QtCore.QPointF(0.0, -size))
         triangle.append(QtCore.QPointF(size, size))
 
+        # map polygon to port position.
         transform = QtGui.QTransform()
         transform.translate(rect.center().x(), rect.center().y())
         port_poly = transform.map(triangle)
@@ -76,19 +78,21 @@ The ``draw_triangle_port`` painter function can then be passed to the ``painter_
 
 .. code-block:: python
     :linenos:
+    :emphasize-lines: 8
 
     from NodeGraphQt import BaseNode
 
     class MyListNode(BaseNode):
 
         def __init__(self):
             super(MyListNode, self).__init__()
+            # create a input port with custom painter function.
             self.add_input('triangle', painter_func=draw_triangle_port)
 
 Example Square Port
 *******************
 
-Here's simpler example function for drawing a Square shaped port.
+And here's another example function for drawing a Square port.
 
 .. code-block:: python
     :linenos: