Fix for issue #1370, Segfault using QImages due to not retaining the data

PIL/ImageQt.py

@@ -157,7 +157,6 @@ def _toqclass_helper(im):
     else:
         raise ValueError("unsupported image mode %r" % im.mode)
 
-    # must keep a reference, or Qt will crash!
     __data = data or align8to32(im.tobytes(), im.size[0], im.mode)
     return {
         'data': __data, 'im': im, 'format': format, 'colortable': colortable
@@ -175,8 +174,13 @@ if qt_is_installed:
                 string or a PyQt string object).
             """
             im_data = _toqclass_helper(im)
+            # must keep a reference, or Qt will crash!
+            # All QImage constructors that take data operate on an existing
+            # buffer, so this buffer has to hang on for the life of the image.
+            # Fixes https://github.com/python-pillow/Pillow/issues/1370
+            self.__data = im_data['data']
             QImage.__init__(self,
-                            im_data['data'], im_data['im'].size[0],
+                            self.__data, im_data['im'].size[0],
                             im_data['im'].size[1], im_data['format'])
             if im_data['colortable']:
                 self.setColorTable(im_data['colortable'])

Tests/test_image_toqimage.py

@@ -5,7 +5,17 @@ from PIL import ImageQt
 
 
 if ImageQt.qt_is_installed:
-    from PIL.ImageQt import QImage
+    from PIL.ImageQt import QImage, QPixmap
+
+    try:
+        from PyQt5 import QtGui
+    except (ImportError, RuntimeError):
+        try:
+            from PyQt4 import QtGui
+        except (ImportError, RuntimeError):
+            from PySide import QtGui
+            
+
 
 
 class TestToQImage(PillowQtTestCase, PillowTestCase):
@@ -23,5 +33,41 @@ class TestToQImage(PillowQtTestCase, PillowTestCase):
             data.save(tempfile)
 
 
+    def test_segfault(self):
+        PillowQtTestCase.setUp(self)
+
+        app = QtGui.QApplication([])
+        ex = Example()
+
+
+if ImageQt.qt_is_installed:
+    class Example(QtGui.QWidget):
+
+        def __init__(self):
+            super(Example, self).__init__()
+
+            img = hopper().resize((1000,1000))
+
+            qimage = ImageQt.ImageQt(img)
+
+            pixmap1 = QtGui.QPixmap.fromImage(qimage)
+
+            hbox = QtGui.QHBoxLayout(self)
+
+            lbl = QtGui.QLabel(self)
+            # Segfault in the problem
+            lbl.setPixmap(pixmap1.copy())
+
+
+
+
+def main():
+    app = QtGui.QApplication(sys.argv)
+    ex = Example()
+    sys.exit(app.exec_())
+
+
+
+
 if __name__ == '__main__':
     unittest.main()