QBuffer does not fill QByteArray problem

So, I try to fill QByteArray with data (and then save it to database). I use QFileDialog to obtain picture, QPixmap to paint it in a grid, and it works fine, but QByteArray, that is intende开发者_StackOverflow中文版d to be stored in db through sqlalchemy is empty after QPixmap::save(). Beside, signals, connected to bytesWritten and readyRead doesn't fire too. Pixmap is ok, grid contains a valid image after setData.

        ba = QtCore.QByteArray()
        buffer = QtCore.QBuffer(ba)
        buffer.bytesWritten.connect(self.b)
        buffer.readyRead.connect(self.c)
        buffer.open(QtCore.QIODevice.WriteOnly)
        pixmap.save(buffer)
        buffer.close()
        ba = buffer.data()

So, what am I doing wrong?

I think you need to specify the image file format when calling pixmap.save(), smth like this:

pixmap.save(buffer, 'PNG')

hope this helps, regards