python - PySide2 引发错误， "QPaintDevice: Cannot destroy paint device that is being painted"

Question

这个问题在这里已经有了答案:

Error printing image in PyQt (1 个回答)

PyQt print QWidget (1 个回答)

关闭 2 年前。

我试图在 QPixmap 上绘制一些东西，但它在清理过程中抛出了一个错误。

from PySide2.QtGui import QPixmap, QPainter
from PySide2.QtWidgets import QApplication

app = QApplication()
width = 200
height = 100
pixmap = QPixmap(width, height)
painter = QPainter(pixmap)
painter.drawLine(0, 0, 100, 100)
print('Done.')

当我运行它时，我看到“完成”消息，然后是一个错误。

Done.
QPaintDevice: Cannot destroy paint device that is being painted

Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)

我看到一些类似的问题有同样的错误，但不清楚是什么导致错误或如何避免错误。

Answer 1

经过实验，似乎 painter 必须在 pixmap 之前清理，否则会出现错误。例如，这可以正常工作。

from PySide2.QtGui import QPixmap, QPainter
from PySide2.QtWidgets import QApplication

app = QApplication()
width = 200
height = 100
pixmap = QPixmap(width, height)
painter = QPainter(pixmap)
painter.drawLine(0, 0, 100, 100)
print('Done.')

del painter
del pixmap

你也可以告诉painter 清理而不破坏它。只需调用 end() 告诉它您已完成绘画。

from PySide2.QtGui import QPixmap, QPainter
from PySide2.QtWidgets import QApplication

app = QApplication()
width = 200
height = 100
pixmap = QPixmap(width, height)
painter = QPainter(pixmap)
painter.drawLine(0, 0, 100, 100)
print('Done.')

painter.end()

还有一些其他的东西由于神秘的原因避免了错误。例如，这避免了错误。

from PySide2.QtGui import QPixmap, QPainter
from PySide2.QtWidgets import QApplication

app = QApplication()
width = 200
height = 100
pixmap = QPixmap(width, height)
painter = QPainter(pixmap)
painter.device()  # <-- No idea why this helps!
painter.drawLine(0, 0, 100, 100)
print('Done.')

总而言之，只要确保画家在像素图之前清理干净即可。我建议在比像素图更小的范围内使用 painter，或者显式调用 painter.end()。