[PyQt] Segfaults on MacOS

[Michael Held]

hi,

I am building an image viewer with PyQt and wanted to display the pixel
color under the cursor for mouseMoveEvent - everything fine so far.
using the eventFilter I was able circumvent QLabel sub-classing.

*BUT* printing the pixel value crashes my program with a seg fault (I am
just moving a bit over the image and BANG...)
my silly attempt to delay the event-response with time.sleep(0.5) did
also not work.

I was using Stackless Python 2.6.2 before but the same error happened
for the normal Python 2.6.2
MacOS 10.5.7
PyQt-mac-gpl-4.5.2-snapshot-20090627
sip-4.8.1

thanks a lot!
michael


class ImageViewer(QScrollArea):

    def __init__(self, parent):
        super(ImageViewer, self).__init__(parent)
        self.setBackgroundRole(QPalette.Dark)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAsNeeded)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)
        self.label = QLabel(self)
        self.label.setBackgroundRole(QPalette.Base)
        self.setAlignment(Qt.AlignHCenter|Qt.AlignVCenter)
        self.label.installEventFilter(self)
        self.label.show()
        self.label.setMouseTracking(True)
        self.setWidget(self.label)
        self._qimage = None
        self.connect(self, SIGNAL('MouseMovedOverImage'),
                     self._on_move)

    def from_numpy(self, data):
        self._qimage = numpy_to_qimage(data)
        self._update()

    def from_qimage(self, qimage):
        self._qimage = qimage
        self._update()

    def _on_move(self, pos):
        print pos, self._qimage.pixel(pos)
        time.sleep(0.5)

    def eventFilter(self, obj, ev):
        if ev.type() == QEvent.MouseMove and obj == self.label:
            self.emit(SIGNAL('MouseMovedOverImage'),
                      ev.pos())
            return True
        else:
            return False

    def _update(self):
        self.label.setPixmap(QPixmap.fromImage(self._qimage))
        self.label.resize(self.label.pixmap().size())