[Python知识库]Python 使用installEventFilter(filterObj)方法实现QTextEdit输入内容keyPressEvent的过滤

实现QTextEdit输入内容的过滤有两种方法，一种是通过重载QTextEdit的keyPressEvent()方法实现，简单举个例子实现只能在QTextEdit中只能输入16进制的数：：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QTextEdit
from PyQt5.QtGui import QKeyEvent
import string


class KeyEventDemo(QWidget):
	def __init__(self):
		super(KeyEventDemo, self).__init__()
		self.resize(500, 500)
		self.setMouseTracking(False)
		self.te = TextEdit()
		self.te.setParent(self)


class TextEdit(QTextEdit):
	def __init__(self):
		super(TextEdit, self).__init__()

	def keyPressEvent(self, e: QKeyEvent) -> None:
		QTextEdit.keyPressEvent(self, e)
		# 下面写自己需要过滤的代码
		if e.text() not in string.hexdigits:  # 只有当输入的字符为a时才能显示在QTextEdit中
			if e.key() != 16777219:
				self.textCursor().deletePreviousChar()


if __name__ == "__main__":
	app = QApplication(sys.argv)
	window = KeyEventDemo()
	window.show()
	sys.exit(app.exec_())

还可以通过installEventFilter(filterObj)方法实现，推荐这种，下面的例子是实现只能在QTextEdit中只能输入16进制的数：
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import sys
import string
from PyQt5.QtWidgets import QApplication, QWidget, QTextEdit
from PyQt5.QtCore import QEvent, QObject


# 首先创建一个KeyPressEster类，用于拦截监控对象的按键
class KeyPressEster(QObject):
	def eventFilter(self, a0: 'QObject', a1: 'QEvent') -> bool:  # a0为当前监控的对象，a1为触发的事件
		if a1.type() == QEvent.KeyPress:
			print("按键：", a1.text())
			if a1.text() in string.hexdigits:  # 只能输入16进制的数
				a0.textCursor().insertText(a1.text())
			if a1.key() == 16777219:  # 当按下推个键时，删除字符
				a0.textCursor().deletePreviousChar()
			return True
		else:
			return QObject.eventFilter(self, a0, a1)


class FilterDemo(QWidget):
	def __init__(self):
		super(FilterDemo, self).__init__()
		self.resize(500, 500)
		self.te = QTextEdit(self)
		keyPressEster = KeyPressEster(self)  # 实例化按键拦截实例
		self.te.installEventFilter(keyPressEster)  # 安装过滤器


if __name__ == "__main__":
	app = QApplication(sys.argv)
	window = FilterDemo()
	window.show()
	sys.exit(app.exec_())

其他控件也可以设置过滤器，这种方法个人感觉很好用。