重写QTextEdit的paintEvent以在单词周围绘制矩形

为了在QTextEdit中的单词周围绘制矩形，需要重写其paintEvent方法并使用QTextLayout类来确定单词的文本位置和范围。

以下是一个实现示例：

from PyQt5.QtWidgets import QTextEdit
from PyQt5.QtGui import QPainter, QTextLayout, QPen


class MyTextEdit(QTextEdit):

    def paintEvent(self, event):
        # 调用父类的paintEvent以保留QTextEdit的默认行为
        super().paintEvent(event)

        # 获取QTextEdit的文本内容
        doc = self.document()
        cursor = self.textCursor()
        text = doc.toPlainText()

        # 创建QPainter对象并设置画笔样式
        painter = QPainter(self.viewport())
        painter.setPen(QPen(Qt.red))

        # 使用QTextLayout类来确定每个单词的位置和范围
        layout = QTextLayout(text, painter.font())
        pos = cursor.position() - 1
        line = doc.findBlock(cursor.position()).text()
        x = 0
        y = 0
        for word in line.split():
            index = line.find(word, pos)
            if index != -1:
                pos = index + len(word)
                layout.setText(line[index:pos])
                layout.setPos(x, y)
                rects = layout.glyphRuns()[0].glyphsBoundingRects()
                for rect in rects:
                    painter.drawRect(rect.translated(x, y))

            x += layout.glyphRuns()[0].advanceWidth(len(word)) + layout.font().pixelSize()

            if x >= self.viewport().width():
                x = 0
                y += painter.fontMetrics().height()

        painter.end()

此代码重写了QTextEdit的paintEvent方法，使用QTextLayout类来确定每个单词的文本位置和范围，并使用QPainter.drawRect方法在单词周围绘制红色矩形。