Flags in the tree updated slowly

Question

I implemented a cutom model for treeview to have checkboxes inside treeview. If I check the parent node, all child nodes should be tickled automatically. This basically works, but der is the lack of time between checking the parent node and updating the subnodes.

from PyQt4 import QtCore, QtGui import sys class Node(object): def __init__(self, name, parent=None, checked=False): self._name = name self._children = [] self._parent = parent self._checked = checked if parent is not None: parent.addChild(self) def addChild(self, child): self._children.append(child) def insertChild(self, position, child): if position < 0 or position > len(self._children): return False self._children.insert(position, child) child._parent = self return True def name(self): return self._name def checked(self): return self._checked def setChecked(self, state): self._checked = state for c in self._children: c.setChecked(state) def child(self, row): return self._children[row] def childCount(self): return len(self._children) def parent(self): return self._parent def row(self): if self._parent is not None: return self._parent._children.index(self) class TreeModel(QtCore.QAbstractItemModel): def __init__(self, root, parent=None): super().__init__(parent) self._rootNode = root def rowCount(self, parent): if not parent.isValid(): parentNode = self._rootNode else: parentNode = parent.internalPointer() return parentNode.childCount() def columnCount(self, parent): return 1 def data(self, index, role): if not index.isValid(): return None node = index.internalPointer() if role == QtCore.Qt.DisplayRole: if index.column() == 0: return node.name() if role == QtCore.Qt.CheckStateRole: if node.checked(): return QtCore.Qt.Checked else: return QtCore.Qt.Unchecked def setData(self, index, value, role=QtCore.Qt.EditRole): if index.isValid(): if role == QtCore.Qt.CheckStateRole: node = index.internalPointer() node.setChecked(not node.checked()) return True return False def headerData(self, section, orientation, role): if role == QtCore.Qt.DisplayRole: return "Nodes" def flags(self, index): return QtCore.Qt.ItemIsEnabled | QtCore.Qt.ItemIsSelectable| QtCore.Qt.ItemIsUserCheckable def parent(self, index): node = self.getNode(index) parentNode = node.parent() if parentNode == self._rootNode: return QtCore.QModelIndex() return self.createIndex(parentNode.row(), 0, parentNode) def index(self, row, column, parent): parentNode = self.getNode(parent) childItem = parentNode.child(row) if childItem: return self.createIndex(row, column, childItem) else: return QtCore.QModelIndex() def getNode(self, index): if index.isValid(): node = index.internalPointer() if node: return node return self._rootNode def removeRows(self, position, rows, parent=QtCore.QModelIndex()): parentNode = self.getNode(parent) self.beginRemoveRows(parent, position, position + rows - 1) for row in range(rows): success = parentNode.removeChild(position) self.endRemoveRows() return success def main_simple(): app = QtGui.QApplication(sys.argv) rootNode = Node("Root") n1 = Node("Node1", rootNode) n2 = Node("Node2", rootNode) n3 = Node("Node3", rootNode) n1_1 = Node("Node1 1", n1) n1_2 = Node("Node1 2", n1) n1_3 = Node("Node1 3", n1) n2_1 = Node("Node2 1", n2) n2_2 = Node("Node2 2", n2) n2_3 = Node("Node2 3", n2) n3_1 = Node("Node3 1", n3) n3_2 = Node("Node3 2", n3) n3_3 = Node("Node3 3", n3) model = TreeModel(rootNode) treeView = QtGui.QTreeView() treeView.show() treeView.setModel(model) sys.exit(app.exec_()) if __name__ == '__main__': main_simple() 

How can I avoid this drawback so that the user interface is smoother?

Answer 1

The model should emit a dataChanged() signal for children when they switch so that the view can instantly update its flags. According to the documentation , setData should also highlight dataChanged for an element that has been explicitly modified.

This should work:

 def setData(self, index, value, role=QtCore.Qt.EditRole): if index.isValid(): if role == QtCore.Qt.CheckStateRole: node = index.internalPointer() node.setChecked(not node.checked()) self.dataChanged.emit(index, index) self.emitDataChangedForChildren(index) return True return False def emitDataChangedForChildren(self, index): count = self.rowCount(index) if count: self.dataChanged.emit(index.child(0, 0), index.child(count-1, 0)) for child in range(count): self.emitDataChangedForChildren(index.child(child, 0))