PyQt5中Tamil99键盘布局下QLineEdit实时输入异常解决问询

问题背景 #

在Windows 10上开发PyQt5应用，包含3个QLineEdit和1个QListWidget：

• 第一个QLineEdit：英语（美国）输入
• 第二个QLineEdit：泰米尔语拼音输入法
• 第三个QLineEdit：Tamil99键盘布局

当使用Tamil99键盘布局输入时（比如同时按j+Q输入“பா”，n+q输入“லா”），QLineEdit的textChanged信号无法在每次按键时触发，导致QListWidget的过滤列表不能实时更新。

解决方案 #

Tamil99这类依赖组合键输入的键盘布局会延迟发送textChanged信号，直到完整的字符输入序列完成。我们需要通过事件过滤器捕获所有按键事件，并主动触发过滤逻辑，确保列表实时更新。

关键修改点 #

1. 扩展事件过滤器，添加对KeyPress事件的处理，针对Tamil99输入框强制触发过滤
2. 新增filter_list_for_textbox方法，专门处理指定输入框的文本过滤
3. 优化过滤逻辑，区分英语和泰米尔语的文本匹配规则（泰米尔语无需转小写）
4. 用QTimer.singleShot延迟获取文本，确保输入法完成组合键的字符转换

修改后的完整代码 #

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import win32api
import py_win_keyboard_layout

class Diff_Language(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Input Different Languages in Different Textboxes")

        self.lbl1 = QLabel("Input Language - English (US)")
        self.tbox1 = QLineEdit()
        self.tbox1.setFont(QFont('Arial Unicode MS', 10, QFont.Bold))
        self.tbox1.installEventFilter(self)
        self.tbox1.setMaxLength(25)
        self.tbox1.textChanged.connect(self.filter_list)

        self.lbl2 = QLabel("Input Language - Tamil Phonetic")
        self.tbox2 = QLineEdit()
        self.tbox2.setFont(QFont('Arial Unicode MS', 30, QFont.Bold))
        self.tbox2.installEventFilter(self)
        self.tbox2.setMaxLength(25)
        self.tbox2.textChanged.connect(self.filter_list)

        self.lbl3 = QLabel("Input Language - Tamil99 Keyboard")
        self.tbox3 = QLineEdit()
        self.tbox3.setFont(QFont('Arial Unicode MS', 12, QFont.Bold))
        self.tbox3.installEventFilter(self)
        self.tbox3.setMaxLength(25)
        self.tbox3.textChanged.connect(self.filter_list)

        self.listbox = QListWidget()
        add_items = ["பாலாஜி","பாலா","பால்","Red", "Dark red", "Light Red", "Redish Blue", "Redish Green", "Green","Blue","Dark Blue", "Dark Green"]
        self.original_items = add_items.copy()
        self.listbox.addItems(add_items)

        self.vbox = QVBoxLayout()
        self.vbox.addWidget(self.lbl1)
        self.vbox.addWidget(self.tbox1)
        self.vbox.addWidget(self.lbl2)
        self.vbox.addWidget(self.tbox2)
        self.vbox.addWidget(self.lbl3)
        self.vbox.addWidget(self.tbox3)
        self.vbox.addWidget(self.listbox)

        self.setLayout(self.vbox)
        self.current_layout = 0x409

    def eventFilter(self, obj, event):
        if event.type() == QEvent.FocusIn:
            self.handle_focus_in(obj)
        elif event.type() == QEvent.KeyPress:
            QTimer.singleShot(10, lambda: self.filter_list_for_textbox(obj))
        return super().eventFilter(obj, event)

    def filter_list_for_textbox(self, textbox):
        if textbox in [self.tbox1, self.tbox2, self.tbox3]:
            text = textbox.text()
            filtered_items = []
            for item in self.original_items:
                if text.lower() in item.lower() if item.isascii() else text in item:
                    filtered_items.append(item)
            self.listbox.clear()
            self.listbox.addItems(filtered_items)

    def handle_focus_in(self, textbox):
        if textbox == self.tbox1:
            self.current_layout = win32api.LoadKeyboardLayout("00020409")
        elif textbox == self.tbox2:
            self.current_layout = 0x449
        elif textbox == self.tbox3:
            self.current_layout = win32api.LoadKeyboardLayout("00020449")

        py_win_keyboard_layout.change_foreground_window_keyboard_layout(self.current_layout)
        self.listbox.clear()
        self.listbox.addItems(self.original_items)
        
    def filter_list(self):
        text = self.sender().text()
        filtered_items = []
        for item in self.original_items:
            if text.lower() in item.lower() if item.isascii() else text in item:
                filtered_items.append(item)
        self.listbox.clear()
        self.listbox.addItems(filtered_items)

    def handle_focus_out(self, textbox):
        self.current_layout = win32api.LoadKeyboardLayout("00020409")
        py_win_keyboard_layout.change_foreground_window_keyboard_layout(self.current_layout)

    def closeEvent(self, event):
        self.current_layout = win32api.LoadKeyboardLayout("00020409")
        py_win_keyboard_layout.change_foreground_window_keyboard_layout(self.current_layout)
        event.accept()

def main():
    app = QApplication(sys.argv)
    mainscreen = Diff_Language()
    app.setStyle("Fusion")
    mainscreen.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

内容的提问来源于stack exchange，提问作者Bala