qt - 在PyQt中覆盖QPaintEvents

Question

我正在尝试创建一个文本编辑器小部件，该小部件将有一个定界符行。首先，我创建了一个MyTextEdit类(作为QTextEdit的子类)，并覆盖了其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，我收到 很多的以下错误:

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

如果小部件具有viewport，则必须将其传递给QPainter构造函数:

painter = QPainter(self.viewport())