组合框函数currentIndexChanged无法正常工作

小编典典

组合框函数currentIndexChanged无法正常工作

python

我接受了两个comboBoxes，即comboBox1和comboBox_2以及两个函数test和test1，并使用currentIndexChanged（self.comboBOx1.currentIndexChanged和self.comboBOx_2.currentIndexChanged）调用它们。从comboBox1中选择一个值时，将调用其对应的函数（self.comboBOx1.currentIndexChanged），并且对于comboBox_2也是如此。在从comboBox1中选择值时，将更改comboBox_2中的值及其正常工作。但是我遇到的问题是，首先当我从comboBox1和comboBox_2中选择一个值时，我从调用的函数中得到了期望的值（打印’hello’）。第二次，当我从comboBox1中选择一个值时，仅应调用测试函数，但此处两个函数（test和test1）都被调用，第二个函数（test1）被调用两次（打印’
你好’两次），第三次被调用四次（打印’你好’四次）。请任何人可以帮助我解决这个问题。

码：

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(800, 600)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.comboBox1 = QtGui.QComboBox(self.centralwidget)
        self.comboBox1.setGeometry(QtCore.QRect(310, 150, 171, 31))
        self.comboBox1.setObjectName(_fromUtf8("comboBox1"))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox_2 = QtGui.QComboBox(self.centralwidget)
        self.comboBox_2.setGeometry(QtCore.QRect(310, 240, 171, 41))
        self.comboBox_2.setObjectName(_fromUtf8("comboBox_2"))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
        self.menubar.setObjectName(_fromUtf8("menubar"))
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName(_fromUtf8("statusbar"))
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
        self.comboBox1.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox1.setItemText(1, _translate("MainWindow", "a", None))
        self.comboBox1.setItemText(2, _translate("MainWindow", "b", None))
        self.comboBox1.setItemText(3, _translate("MainWindow", "c", None))
        self.comboBox_2.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox_2.setItemText(1, _translate("MainWindow", "p", None))
        self.comboBox_2.setItemText(2, _translate("MainWindow", "q", None))
        self.comboBox_2.setItemText(3, _translate("MainWindow", "r", None))
        self.comboBox_2.setEnabled(0)
        self.comboBox1.currentIndexChanged.connect(self.test)

    def test(self):
        s = str(self.comboBox1.currentText())
        res=['aa','bb','cc','dd']

        if (s == "- - select - -"):
            self.comboBox_2.setEnabled(0)
            self.comboBox_2.setCurrentIndex(0)
        elif(len(s)== 0):
            self.comboBox_2.setEnabled(1)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
        else:
            self.comboBox_2.setEnabled(1)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
            self.comboBox_2.addItems(res)
            self.comboBox_2.currentIndexChanged.connect(self.test1)

    def test1(self):
        print ("Hello")

if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    MainWindow = QtGui.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

阅读 214

2020-12-20

共1个答案

小编典典

要了解行为，我们将使用以下示例：

范例1 ：

from PyQt4 import QtCore, QtGui


def on_clicked():
    print("clicked")


if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    button = QtGui.QPushButton("Press me")
    for _ in range(4):
        button.clicked.connect(on_clicked)
    button.show()
    sys.exit(app.exec_())

当您按下按钮时，它将打印4次，因为Qt不会记住信号和函数之间是否已经存在连接，因此，如果同一信号和函数之间存在n个连接，则在发出信号时它们将被调用n次。。

范例2 ：

from PyQt4 import QtCore, QtGui


def on_currentIndexChanged(ix):
    print("currentIndex:", ix)


if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    combo = QtGui.QComboBox()
    print("currentIndex:", combo.currentIndex())
    combo.currentIndexChanged.connect(on_currentIndexChanged)
    button_add = QtGui.QPushButton("Add Items")
    button_add.clicked.connect(lambda: combo.addItems("1 2 3".split()))
    button_clear = QtGui.QPushButton("Clear")
    button_clear.clicked.connect(combo.clear)
    w = QtGui.QWidget()
    lay = QtGui.QVBoxLayout(w)
    for widget in (combo, button_add, button_clear):
        lay.addWidget(widget)
    w.show()
    sys.exit(app.exec_())

QComboBox的默认currentIndex为-1，当您添加项目时，该值将变为currentIndex为0，而当您清洁QComboBox时，currentIndex将恢复为-1。因此，当您添加或清洁项目时，会发出currentIndexChanged信号。

基于以上内容，我将解释您指出的行为：在QCombobox
1中选择新的currentIndex时，将调用测试方法，并且在清理并添加了第一个连接的项目后，如果该方法进入 else
语句，则现在重复相同的事情，因为有一个连接，currentIndexChanged信号被发射两次（一个用于clear（），另一个用于addItems（）），并且您还创建了第二个连接，如果再次重复，则发射信号4次（1个clear（）x
2个连接+ 1个addItems（）x 2个连接）。

解：

在仅调用一次的函数中建立连接。
为了使clear（）信号和addItems（）不会发出currentIndexChanged信号，您必须使用blockSignals（）。
另外，建议不要修改Qt Designer生成的代码，除使用修饰@ QtCore.pyqtSlot（）外，建议创建另一个使用初始类作为接口的类。

from PyQt4 import QtCore, QtGui

try:
_fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
def _fromUtf8(s):
return s

try:
_encoding = QtGui.QApplication.UnicodeUTF8
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName(_fromUtf8(“MainWindow”))
MainWindow.resize(800, 600)
self.centralwidget = QtGui.QWidget(MainWindow)
self.centralwidget.setObjectName(_fromUtf8(“centralwidget”))
self.comboBox1 = QtGui.QComboBox(self.centralwidget)
self.comboBox1.setGeometry(QtCore.QRect(310, 150, 171, 31))
self.comboBox1.setObjectName(_fromUtf8(“comboBox1”))
self.comboBox1.addItem(_fromUtf8(“”))
self.comboBox1.addItem(_fromUtf8(“”))
self.comboBox1.addItem(_fromUtf8(“”))
self.comboBox1.addItem(_fromUtf8(“”))
self.comboBox_2 = QtGui.QComboBox(self.centralwidget)
self.comboBox_2.setGeometry(QtCore.QRect(310, 240, 171, 41))
self.comboBox_2.setObjectName(_fromUtf8(“comboBox_2”))
self.comboBox_2.addItem(_fromUtf8(“”))
self.comboBox_2.addItem(_fromUtf8(“”))
self.comboBox_2.addItem(_fromUtf8(“”))
self.comboBox_2.addItem(_fromUtf8(“”))
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtGui.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
self.menubar.setObjectName(_fromUtf8(“menubar”))
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtGui.QStatusBar(MainWindow)
self.statusbar.setObjectName(_fromUtf8(“statusbar”))
MainWindow.setStatusBar(self.statusbar)
```
    self.retranslateUi(MainWindow)
    QtCore.QMetaObject.connectSlotsByName(MainWindow)

def retranslateUi(self, MainWindow):
    MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
    self.comboBox1.setItemText(0, _translate("MainWindow", "select", None))
    self.comboBox1.setItemText(1, _translate("MainWindow", "a", None))
    self.comboBox1.setItemText(2, _translate("MainWindow", "b", None))
    self.comboBox1.setItemText(3, _translate("MainWindow", "c", None))
    self.comboBox_2.setItemText(0, _translate("MainWindow", "select", None))
    self.comboBox_2.setItemText(1, _translate("MainWindow", "p", None))
    self.comboBox_2.setItemText(2, _translate("MainWindow", "q", None))
    self.comboBox_2.setItemText(3, _translate("MainWindow", "r", None))
```
class MainWindow(QtGui.QMainWindow, Ui_MainWindow):
def init(self, parent=None):
super(MainWindow, self).init(parent)
self.setupUi(self)
```
    self.comboBox_2.setEnabled(False)
    self.comboBox1.currentIndexChanged[str].connect(self.test)
    self.comboBox_2.currentIndexChanged.connect(self.test1)

@QtCore.pyqtSlot(str)
def test(self, s):
    res=['aa','bb','cc','dd']

    if s == "- - select - -":
        self.comboBox_2.setEnabled(False)
        self.comboBox_2.setCurrentIndex(0)
    elif not s:
        self.comboBox_2.setEnabled(True)
        self.comboBox_2.blockSignals(True)
        self.comboBox_2.clear()
        self.comboBox_2.addItem("- - select - -")
        self.comboBox_2.addItem("New Checklist")
        self.comboBox_2.blockSignals(False)
    else:
        self.comboBox_2.setEnabled(True)
        self.comboBox_2.blockSignals(True)
        self.comboBox_2.clear()
        self.comboBox_2.addItem("- - select - -")
        self.comboBox_2.addItem("New Checklist")
        self.comboBox_2.addItems(res)
        self.comboBox_2.blockSignals(False)

@QtCore.pyqtSlot(int)
def test1(self, ix):
    print("Hello", ix)
```
if name == “main”:
import sys
app = QtGui.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())

2020-12-20