如何在PyQt4中为QTreeWidget实现itemChecked和itemUnchecked信号？

Question

QTreeWidget上的信号itemChecked和itemUncheсked在哪里？

Qt Signals: (quote from PyQt4 QTreeWidget documentation page)

void currentItemChanged (QTreeWidgetItem *,QTreeWidgetItem *)
void itemActivated (QTreeWidgetItem *,int)
void itemChanged (QTreeWidgetItem *,int)
void itemClicked (QTreeWidgetItem *,int)
void itemCollapsed (QTreeWidgetItem *)
void itemDoubleClicked (QTreeWidgetItem *,int)
void itemEntered (QTreeWidgetItem *,int)
void itemExpanded (QTreeWidgetItem *)
void itemPressed (QTreeWidgetItem *,int)
void itemSelectionChanged ()

目前我解决了这个问题:

self.treeWidget.itemClicked.connect (self.handle)

def handle (item, column): 
    print 'emitted!', item.text(column)
    if item.checkState(column) == QtCore.Qt.Checked:
        # there are a lot of my functions inside which work with item data
        self.handleChecked(item, column)
    elif item.checkState(column) == QtCore.Qt.Unchecked:
        self.handleUnchecked(item, column)

但对我来说这是一个糟糕的解决方案,因为在很多情况下都会发出itemClicked.它发出的左/右鼠标点击的项目文本,这是绝对不必要(我有内self.handleChecked重功能,并在上下文菜单中打开这些不必要的调用是非常糟糕)的情况.

好吧,我也试过使用itemChanged:

self.treeWidget.itemChanged.connect (self.handle)

但这种情况更糟糕!self.handle函数将自己递归调用到无穷大和更远,因为我在self.handleChecked中的函数更改了项目数据,并且此信号一次又一次地发出.此外,我需要信号只发出项目复选框切换.

有人能告诉我,我做错了什么？

Answer 1

为避免在使用itemChanged信号时出现递归问题,请尝试暂时阻止信号,直到处理程序完成:

def handle(self, item, column):
    self.treeWidget.blockSignals(True)
    if item.checkState(column) == QtCore.Qt.Checked:
        self.handleChecked(item, column)
    elif item.checkState(column) == QtCore.Qt.Unchecked:
        self.handleUnchecked(item, column)
    self.treeWidget.blockSignals(False)

UPDATE

问题的另一部分询问仅在检查项目时发出信号.

一种方法是将QTreeWidgetItem子类化并重新实现它的setData函数:

class TreeWidgetItem(QtGui.QTreeWidgetItem):
    def setData(self, column, role, value):
        state = self.checkState(column)
        QtGui.QTreeWidgetItem.setData(self, column, role, value)
        if (role == QtCore.Qt.CheckStateRole and
            state != self.checkState(column)):
            treewidget = self.treeWidget()
            if treewidget is not None:
                treewidget.itemChecked.emit(self, column)

class Window(QtGui.QTreeWidget):
    itemChecked = QtCore.pyqtSignal(object, int)

    def __init__(self, rows, columns):
        QtGui.QTreeWidget.__init__(self)
        self.itemChecked.connect(self.handleItemChecked)

    def handleItemChecked(self, item, column):
        print 'ItemChecked', int(item.checkState(column))