Qtextedit边沿触发

如果您正在使用Qt中的QTextEdit，那么可以使用QTextCursor来检测文本编辑器中的边沿触发事件。以下是一个示例：

from PyQt5.QtWidgets import QTextEdit, QApplication

class MyTextEdit(QTextEdit):
    def __init__(self, parent=None):
        super(MyTextEdit, self).__init__(parent)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setLineWrapMode(QTextEdit.NoWrap)

    def event(self, event):
        if event.type() == QEvent.MouseMove:
            cursor = self.cursorForPosition(event.pos())
            if cursor.atStart() or cursor.atEnd():
                QApplication.setOverrideCursor(Qt.ArrowCursor)
                return True
        return super(MyTextEdit, self).event(event)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            cursor = self.cursorForPosition(event.pos())
            if cursor.atStart():
                self.setTextCursor(cursor)
                QApplication.setOverrideCursor(Qt.SizeHorCursor)
                self._drag_start_x = event.pos().x()
                return
            elif cursor.atEnd():
                self.setTextCursor(cursor)
                QApplication.setOverrideCursor(Qt.SizeHorCursor)
                self._drag_start_x = event.pos().x()
                return
        super(MyTextEdit, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if event.buttons() & Qt.LeftButton:
            diff = event.pos().x() - self._drag_start_x
            cursor = self.textCursor()
            if cursor.atStart():
                if diff < 0:
                    return
                cursor.movePosition(QTextCursor.Left, QTextCursor.KeepAnchor)
            elif cursor.atEnd():
                if diff > 0:
                    return
                cursor.movePosition(QTextCursor.Right, QTextCursor.KeepAnchor)
            else:
                return
            self.setTextCursor(cursor)
            self._drag_start_x = event.pos().x()
        else:
            super(MyTextEdit, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            QApplication.restoreOverrideCursor()
        super(MyTextEdit, self).mouseReleaseEvent(event)

这段代码会在鼠标移动到文本编辑器的边缘时显示一个箭头光标，并且在鼠标按下并拖动边缘时，会使文本编辑器的宽度相应地增加或减少。