PyQt4 - Image Watermark

Question

I'm trying to open a PNG image and write some text to it (a watermark) via QImage and QPainter. The code works 100% on Linux but when I run it on Windows XP (haven't tested with any other versions of Windows) the text is never written to the image. I have the code in a try/except block, but no errors are returned.

image = QtGui.QImage('demo.png')

painter = QtGui.QPainter()
painter.begin(image)
painter.setOpacity(0.8)
painter.setPen(QtCore.Qt.blue)
painter.setFont(QtGui.QFont('arial', 12))
painter.drawText(image.rect(), QtCore.Qt.AlignCenter, 'Watermark')
painter.end()

image.save('demo.png')

Using Python 2.6.2, PyQt 4.5.4

Any ideas?

Answer 1

First thing that comes to my mind is maybe it isn't finding the specified font on Windows.

Answer 2

My guess would be that whatever png lib you are using on Windows doesn't do tranparency (properly)