python - keyPressEvent 不适用于 PyQt5 中的 Enter 键(但适用于其他所有键)
问题描述
我有一个 PyQt5 GUI,它有一个带有按钮的主窗口和一个 QLineEdit。
我制作了 keyPressEvent 函数并在键盘上设置了某些键来做不同的事情。我设置的所有键都可以使用,而不是 Enter 按钮。当您按下 Enter 键时,如果未单击屏幕按钮,则会触发数字 7 屏幕按钮(这是 GUI 中制作的第一个按钮)。单击按钮后,Enter 键将始终触发最后一次单击的屏幕按钮。所有其他事件工作正常。有谁知道为什么会这样?
MRE:
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QDialog, QPushButton
from PyQt5.QtCore import*
from PyQt5.QtWidgets import*
if hasattr(QtCore.Qt, 'AA_EnableHighDpiScaling'):
QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling, True)
if hasattr(QtCore.Qt, 'AA_UseHighDpiPixmaps'):
QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_UseHighDpiPixmaps, True)
# I know global variables is bad programming. Just doing this for the example
outputText = ""
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName("MainWindow")
MainWindow.setFixedSize(331, 411)
self.centralwidget = QtWidgets.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.button_7 = QtWidgets.QPushButton(self.centralwidget)
self.button_7.setGeometry(QtCore.QRect(20, 190, 71, 41))
self.button_7.setStyleSheet("QPushButton\n"
"{\n"
"border: none;\n"
"background-color: rgb(255, 255, 255);\n"
"font: 20pt \"Arial\";\n"
"}\n"
"QPushButton:hover{\n"
"background-color: rgb(220, 220, 220);\n"
"}\n"
"QPushButton:pressed\n"
"{\n"
"background-color: rgb(212, 212, 212);\n"
"}\n"
"\n"
"")
self.button_7.setAutoDefault(True)
self.button_7.setDefault(False)
self.button_7.setFlat(True)
self.button_7.setObjectName("button_7")
self.button_7.clicked.connect(self.click_and_update)
self.screenOutput = QtWidgets.QLineEdit(self.centralwidget)
self.screenOutput.setGeometry(QtCore.QRect(20, 30, 291, 20))
self.screenOutput.setStyleSheet("border: none; background: transparent;"
"font: 12pt \"MS Shell Dlg 2\";\n""color: rgb(190, 190, 190);")
self.screenOutput.setAlignment(QtCore.Qt.AlignCenter)
self.screenOutput.setObjectName("eqInput")
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtWidgets.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 331, 22))
self.menubar.setObjectName("menubar")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtWidgets.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
def retranslateUi(self, MainWindow):
_translate = QtCore.QCoreApplication.translate
MainWindow.setWindowTitle(_translate("MainWindow", " MRE"))
self.button_7.setText(_translate("MainWindow", "7"))
self.screenOutput.setText(_translate("MainWindow", "Do Something"))
# set keyPressEvent to current widgets that we'd like it to be overridden
self.centralwidget.keyPressEvent = self.keyPressEvent
self.screenOutput.keyPressEvent = self.keyPressEvent
def keyPressEvent(self,e):
if e.key() == Qt.Key_Enter:
self.equal_click()
if e.key() == Qt.Key_Equal:
self.equal_click()
def update_screen(self):
self.screenOutput.setText(outputText)
return
def equal_click(self):
global outputText
outputText = "Pressed Key"
self.update_screen()
return
def click_and_update(self):
global outputText
outputText+=" 7"
self.update_screen()
return
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
Equal 键工作正常,Enter 键不行。
解决方案
问题是 Enter 密钥与 Qt.Key_Return 相关联,并且仅在键盘中是 Qt.Key_Enter。所以一个通用的解决方案是检查两个键:
if e.key() in (Qt.Key_Return, Qt.Key_Enter):
self.equal_click()
但是,它并不能纠正真正的错误,因为问题在于按钮具有焦点,因此 keypress 事件不会传播到其父级。
此外,不建议这样做,foo.keyPressEvent = bar
因为在许多情况下它可能会失败,如果您有“n”个小部件,您将不得不为所有这些小部件实现该逻辑。更优雅的解决方案是在窗口上使用事件过滤器。所以你必须恢复 .py 文件,因为不建议修改它(参见这篇文章:QtDesigner changes will be lost after redesign User Interface),我假设它被称为 main_ui.py
from PyQt5 import QtCore, QtWidgets
from main_ui import Ui_MainWindow
class KeyHelper(QtCore.QObject):
keyPressed = QtCore.pyqtSignal(QtCore.Qt.Key)
def __init__(self, window):
super().__init__(window)
self._window = window
self.window.installEventFilter(self)
@property
def window(self):
return self._window
def eventFilter(self, obj, event):
if obj is self.window and event.type() == QtCore.QEvent.KeyPress:
self.keyPressed.emit(event.key())
return super().eventFilter(obj, event)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
def handle_key_pressed(self, key):
if key in (QtCore.Qt.Key_Enter, QtCore.Qt.Key_Return):
self.update_text()
def update_text(self):
text = self.ui.screenOutput.text() + "7"
self.ui.screenOutput.setText(text)
if hasattr(QtCore.Qt, "AA_EnableHighDpiScaling"):
QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling, True)
if hasattr(QtCore.Qt, "AA_UseHighDpiPixmaps"):
QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_UseHighDpiPixmaps, True)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
helper = KeyHelper(w.windowHandle())
helper.keyPressed.connect(w.handle_key_pressed)
sys.exit(app.exec_())
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