如何让 QLineEdit 检测到 Tab Key Pressing 事件

Posted 2023-03-29

【中文标题】如何让 QLineEdit 检测到 Tab Key Pressing 事件

【英文标题】：How to allow QLineEdit detects Tab Key Pressing event

【发布时间】：2018-12-19 17:23:50

【问题描述】：

这篇文章是为了以不同的方式改写我在here 发布的问题。我想让 QlineEdit 检测到Tab Key 按调用一个名为do_something() 的方法。我从 Qt Designer 生成了以下 pyqt5 代码，其中包括名为 lineEdit 的 QlineEdit 实例。当我输入SSN 数字并按 Tab 键时，应该调用该方法。我该怎么做？

from PyQt5.QtWidgets import QApplication
from PyQt5 import QtCore, QtGui, QtWidgets
import sys

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(348, 68)
        self.label = QtWidgets.QLabel(Dialog)
        self.label.setGeometry(QtCore.QRect(40, 20, 41, 16))
        self.label.setObjectName("label")
        self.lineEdit = QtWidgets.QLineEdit(Dialog)
        self.lineEdit.setGeometry(QtCore.QRect(80, 20, 201, 21))
        self.lineEdit.setObjectName("lineEdit")

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

    def do_something():
        print('Success!')

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.label.setText(_translate("Dialog", "SSN"))

【参考方案1】：

更简单地说，我成功地继承了 QLineEdit 并覆盖了它的事件方法，如下所示：

class EditSpec(QLineEdit):
    def event(self,event):
        if event.type() == QEvent.KeyPress and event.key() == Qt.Key_Tab:
            self.tabFollow()
            return True
        else:
            return QLineEdit.event(self,event)          
    def tabFollow(self):
        print("tab-key pressed!")

任何非制表键按下都会正常进行，而制表键按下会触发 tabFollow 方法。要添加（这很重要），重写 keyPressEvent 方法不会阻止事件通过应用程序的事件系统被触发。仅以与上述类似的方式覆盖事件方法。

【参考方案2】：

我之前的回答中指出的最简单的选项是使用QShorcut，您必须作为小部件传递给QLineEdit，并且在这种情况下必须是Qt::WidgetWithChildrenShortcut的上下文

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(348, 68)
        self.label = QtWidgets.QLabel(Dialog)
        self.label.setGeometry(QtCore.QRect(40, 20, 41, 16))
        self.label.setObjectName("label")
        self.lineEdit = QtWidgets.QLineEdit(Dialog)
        self.lineEdit.setGeometry(QtCore.QRect(80, 20, 201, 21))
        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.label.setText(_translate("Dialog", "SSN"))

class Dialog(QtWidgets.QDialog, Ui_Dialog):
    def __init__(self, parent=None):
        super(Dialog, self).__init__(parent)
        self.setupUi(self)
        shortcut = QtWidgets.QShortcut(
            QtGui.QKeySequence(QtCore.Qt.Key_Tab), 
            self.lineEdit, 
            context= QtCore.Qt.WidgetWithChildrenShortcut,
            activated=self.do_something)

    @QtCore.pyqtSlot()
    def do_something(self):
        print('Success!')

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Dialog()
    w.show()
    sys.exit(app.exec_())