qt - 在 PyQt 中覆盖 QPaintEvents

Question

我正在尝试创建一个具有分隔线的 TextEdit 小部件。首先，我创建了一个MyTextEdit类（作为 a 的子类QTextEdit）并覆盖了它的paintEvent()方法：

import sys
from PyQt4.QtGui import QApplication, QTextEdit, QPainter

class MyTextEdit(QTextEdit):
    """A TextEdit widget derived from QTextEdit and implementing its
       own paintEvent"""

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawLine(0, 10, 10, 10)
        QTextEdit.paintEvent(self, event)

app = QApplication(sys.argv)
textEdit = MyTextEdit()
textEdit.show()

sys.exit(app.exec_())

尝试执行此代码时，我收到很多以下错误：

QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::begin: Widget painting can only begin as a result of a paintEvent
...

我究竟做错了什么？

Answer 1

如果小部件有viewport，则必须将其传递给QPainter构造函数：

painter = QPainter(self.viewport())