[PyQt] Performance of QTreeView
Virgil Dupras
hsoft at hardcoded.net
Sun Oct 10 12:01:09 BST 2010
It probably has something to do with the bazillions of parent() call
that are made to your model. I asked a similar question on stack
overflow a while ago. I profiled the example, so the bottleneck is
evident.
http://stackoverflow.com/questions/841096/slow-selection-in-qtreeview-why
So the answer is: In some respects, Qt sucks balls.
Regards,
--
Virgil Dupras
Hardcoded Software
http://www.hardcoded.net
On Sun, Oct 10, 2010 at 11:08 AM, Knacktus <knacktus at googlemail.com> wrote:
> import sys
> import PyQt4.QtGui as QtGui
> import PyQt4.QtCore as QtCore
>
>
> #########################################################################
> # Underlying data
> # ----------------
> # - RuntimeItems hold the data. They come from a database.
> # - ViewItems are the objects, that are given to the model indexes of Qt.
> # They are constructed according to some rules like filters and
> # configuration.
> # - DummieViewItemFactory processes the rules and configurations.
> # The example here is simplfied. An instance of the factory is given
> # to each ViewItem.
> # The view item calls the
> # DummieViewItemFactory.get_view_item_children method
> # to request calculation of its children on demand.
> # - For this demo-version, the number of items is controlled by
> # DummieViewItemFactory.max_items. It's passed in by the constructor.
> # - Nesting as high as possible: One child per parent.
> #########################################################################
>
>
> class RuntimeItem(object):
> """Represent the real world business items. These objects
> have a lot of relations.
> """
>
> def __init__(self, name, ident, item_type):
> self.name = name
> self.ident = ident
> self.item_type = item_type
>
>
> class ViewItem(object):
> """Represent items that are to be shown to the user in a QTreeView.
> Those items do only occur one time in a view. They have a
> corresponding runtime_item.
> The children are calculated by the view_item_factory on demand.
> """
>
> def __init__(self, view_item_factory, runtime_item=None, parent=None,
> hidden_runtime_items=None):
> self.view_item_factory = view_item_factory
> self.runtime_item = runtime_item
> self.parent = parent
> self.hidden_runtime_items = hidden_runtime_items
>
> @property
> def children(self):
> try:
> return self._children
> except AttributeError:
> self._children = \
> self.view_item_factory.get_view_item_children(self)
> return self._children
>
> @children.setter
> def children(self, children):
> self._children = children
>
>
> class DummieViewItemFactory(object):
> """Creates the view_items. This is a dumb dummie as a simple
> example. Normally a lot of things happen here like filtering
> and configuration. But once the view_item hierachy is build,
> this shouldn't be called at all.
> """
>
> def __init__(self, runtime_item, max_items):
> self.runtime_item = runtime_item
> self.max_items = max_items
> self.item_counter = 0
> self.aux_root_view_item = ViewItem(self)
>
> def get_view_item_children(self, view_item_parent):
> if self.item_counter > self.max_items:
> return []
> self.item_counter += 1
> view_item = ViewItem(self, self.runtime_item, view_item_parent)
> return [view_item]
>
>
> #########################################################################
> # Qt classes
> # ----------------
> # - This should be standard stuff. I've got most of it from the Rapid
> # GUI Programming book.
> # - The ActiveColums class tells the model which colums to use.
> # - The TreeView has a context menu with navigation actions.
> # - The expand_all calls the Qt slot. Here the surprise for the
> # performance.
> #########################################################################
>
>
> class ActiveColumns(object):
>
> def __init__(self, columns):
> self.columns = columns
>
>
> class TreeView(QtGui.QTreeView):
>
> def __init__(self, aux_root_view_item, active_columns, parent=None,
> header_hidden=False):
> super(TreeView, self).__init__(parent)
> self.setIndentation(10)
> self.active_columns = active_columns
> self.setAlternatingRowColors(True)
> self.setHeaderHidden(header_hidden)
> self.setAllColumnsShowFocus(True)
> self.setUniformRowHeights(True)
> self.setContextMenuPolicy(QtCore.Qt.ActionsContextMenu)
>
> model = TreeModel(aux_root_view_item, self)
> self.setModel(model)
>
> e_a_action = QtGui.QAction("Expand all", self)
> e_a_action.setToolTip("Expands all items of the tree.")
> e_a_action.triggered.connect(self.expand_all)
>
> e_a_b_action = QtGui.QAction("Expand all below", self)
> e_a_b_action.setToolTip("Expands all items under the selection.")
> e_a_b_action.triggered.connect(self.expand_all_below)
>
> c_a_action = QtGui.QAction("Collapse all", self)
> c_a_action.setToolTip("Collapses all items of the tree.")
> c_a_action.triggered.connect(self.collapse_all)
>
> c_a_b_action = QtGui.QAction("Collapse all below", self)
> c_a_b_action.setToolTip("Collapses all items under the selection.")
> c_a_b_action.triggered.connect(self.collapse_all_below)
>
> for action in (e_a_action, c_a_action, e_a_b_action, c_a_b_action):
> self.addAction(action)
>
> def expand_all(self):
> self.expandAll()
>
> def collapse_all(self):
> self.collapseAll()
>
> def expand_all_below(self):
> def expand_all_below_recursive(parent_index):
> self.expand(parent_index)
> children_indexes = \
> self.tree_itemmodel.get_children_indexes(parent_index)
> for child_index in children_indexes:
> expand_all_below_recursive(child_index)
>
> indexes = self.selectedIndexes()
> if indexes:
> index = indexes[0]
> expand_all_below_recursive(index)
>
> def collapse_all_below(self):
> def collapse_all_below_recursive(parent_index):
> self.collapse(parent_index)
> children_indexes = \
> self.tree_itemmodel.get_children_indexes(parent_index)
> for child_index in children_indexes:
> collapse_all_below_recursive(child_index)
>
> indexes = self.selectedIndexes()
> if indexes:
> index = indexes[0]
> collapse_all_below_recursive(index)
>
> class TreeModel(QtCore.QAbstractItemModel):
>
> def __init__(self, aux_root_view_item, parent):
> super(TreeModel, self).__init__(parent)
> self.aux_root_view_item = aux_root_view_item
> self.active_columns = parent.active_columns
>
> def rowCount(self, parent_index):
> parent_view_item = self.view_item_from_index(parent_index)
> if parent_view_item is None:
> return 0
> return len(parent_view_item.children)
>
> def get_children_indexes(self, parent_index):
> children_indexes = []
> for row_no in range(self.rowCount(parent_index)):
> children_indexes.append(self.index(row_no, 0, parent_index))
> return children_indexes
>
> def columnCount(self, parent):
> return len(self.active_columns.columns)
>
> def data(self, index, role):
> if role == QtCore.Qt.TextAlignmentRole:
> return int(QtCore.Qt.AlignTop|QtCore.Qt.AlignLeft)
> if role != QtCore.Qt.DisplayRole:
> return None
> view_item = self.view_item_from_index(index)
> try:
> data = getattr(view_item.runtime_item,
> self.active_columns.columns[index.column()])
> except AttributeError:
> data = ""
> return data
>
> def headerData(self, section, orientation, role):
> if (orientation == QtCore.Qt.Horizontal and
> role == QtCore.Qt.DisplayRole):
> assert 0 <= section <= len(self.active_columns.columns)
> return self.active_columns.columns[section]
> return QtCore.QVariant()
>
> def index(self, row, column, parent_index):
> view_item_parent = self.view_item_from_index(parent_index)
> return self.createIndex(row, column,
> view_item_parent.children[row])
>
> def parent(self, child_index):
> child_view_item = self.view_item_from_index(child_index)
> if child_view_item is None:
> return QtCore.QModelIndex()
> parent_view_item = child_view_item.parent
> if parent_view_item is None:
> return QtCore.QModelIndex()
> grandparent_view_item = parent_view_item.parent
> if grandparent_view_item is None:
> return QtCore.QModelIndex()
> grandparent_view_item
> row = grandparent_view_item.children.index(parent_view_item)
> assert row != -1
> return self.createIndex(row, 0, parent_view_item)
>
> def view_item_from_index(self, index):
> return (index.internalPointer()
> if index.isValid() else self.aux_root_view_item)
>
>
> if __name__ == "__main__":
>
> run_time_item = RuntimeItem("Test", "test_12", "Test Item")
> view_factory = DummieViewItemFactory(run_time_item, max_items=5000)
> active_colums = ActiveColumns(["name", "id", "item_type"])
>
> app = QtGui.QApplication(sys.argv)
> tree_view = TreeView(view_factory.aux_root_view_item, active_colums)
> app.setApplicationName("IPDM")
> tree_view.show()
> app.exec_()
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