qtextedit显示行号

要在QTextEdit中显示行号，可以通过以下步骤实现：

1. 创建一个新的QWidget，用于包含QTextEdit和显示行号的QLabel。

2. 将QTextEdit的verticalScrollBar()的valueChanged信号连接到一个槽函数，该槽函数将更新QLabel中的行号。

3. 在QTextEdit的paintEvent中绘制行号。

以下是示例代码：

from PyQt5.QtWidgets import QWidget, QTextEdit, QVBoxLayout, QLabel


class LineNumberArea(QWidget):
    def __init__(self, editor):
        super().__init__()
        self.editor = editor

    def sizeHint(self):
        return self.editor.sizeHint()

    def paintEvent(self, event):
        painter = QPainter(self)
        font_metrics = self.editor.fontMetrics()
        block = self.editor.firstVisibleBlock()
        line_number = block.blockNumber()
        top = self.editor.blockBoundingGeometry(block).translated(self.editor.contentOffset()).top()
        bottom = top + self.editor.blockBoundingRect(block).height()

        # Iterate over visible blocks
        while block.isValid() and top <= event.rect().bottom():
            if block.isVisible() and bottom >= event.rect().top():
                # Draw line number
                number_width = font_metrics.width(str(line_number))
                number_rect = QRect(0, top, self.width() - 5, font_metrics.height())
                painter.drawText(number_rect, Qt.AlignRight, str(line_number))

            block = block.next()
            top = bottom
            bottom = top + self.editor.blockBoundingRect(block).height()
            line_number += 1


class TextEditor(QWidget):
    def __init__(self):
        super().__init__()
        self.text_edit = QTextEdit(self)
        self.line_number_area = LineNumberArea(self.text_edit)
        self.init_ui()

    def init_ui(self):
        layout = QVBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self.text_edit)
        self.setLayout(layout)

        # Connect signal to update line number area
        self.text_edit.verticalScrollBar().valueChanged.connect(self.update_line_number_area)

    def update_line_number_area(self):
        rect = self.line_number_area.rect().intersected(self.text_edit.viewport().rect())
        self.line_number_area.update(0, rect.y(), self.line_number_area.width(), rect.height())

    def resizeEvent(self, event):
        super().resizeEvent(event)
        self.line_number_area.setGeometry(QRect(self.contentsRect().left(), self.contentsRect().top(),
                                                 self.line_number_area.width(), self.height()))

        self.text_edit.setGeometry(QRect(self.line_number_area.width(), self.contentsRect().top(),
                                          self.contentsRect().right() - self.line_number_area.width(),
                                          self.height()))

    def paintEvent(self, event):
        super().paintEvent(event)
        painter = QPainter(self)
        painter.fillRect(self.line_number_area.rect(), Qt.lightGray)

在这个示例中，我们创建了一个名为LineNumberArea的新QWidget，它使用QPainter在QTextEdit旁边显示行号。在TextEditor中，我们将QTextEdit和LineNumberArea组合在一起，并将QTextEdit的verticalScrollBar()的valueChanged信号连接到一个槽函数，该槽函数将更新LineNumberArea中的行号。我们还实现了resizeEvent和paintEvent函数来确保LineNumberArea与QTextEdit正确地对齐，并在文本编辑器旁边绘制一个灰色背景。