[ui] Work around PySide2 bug affecting property decorators

PySide 5.15.1 and newer have a bug
(https://bugreports.qt.io/browse/PYSIDE-1426) which results in the
following error emitted on certain @Property decorators:

TypeError: A constant property cannot have a WRITE method or a NOTIFY
signal.

Until the bug is fixed on PySide2 side workaround is to not use Property
as a decorator, but as a simple function wrapper emitting the property
as a class member.

Fixes #1239.

Author: p12tic

meshroom/ui/app.py

@@ -284,17 +284,17 @@ def markdownToHtml(self, md):
             return md
         return markdown(md)
 
-    @Property(QJsonValue, constant=True)
-    def systemInfo(self):
+    def _systemInfo(self):
         import platform
         import sys
         return {
             'platform': '{} {}'.format(platform.system(), platform.release()),
             'python': 'Python {}'.format(sys.version.split(" ")[0])
         }
 
-    @Property("QVariantList", constant=True)
-    def licensesModel(self):
+    systemInfo = Property(QJsonValue, _systemInfo, constant=True)
+
+    def _licensesModel(self):
         """
         Get info about open-source licenses for the application.
         Model provides:
@@ -316,6 +316,7 @@ def licensesModel(self):
             }
         ]
 
+    licensesModel = Property("QVariantList", _licensesModel, constant=True)
     recentProjectFilesChanged = Signal()
     recentProjectFiles = Property("QVariantList", _recentProjectFiles, notify=recentProjectFilesChanged)
 

meshroom/ui/reconstruction.py

@@ -249,10 +249,8 @@ def _updateDenseSceneParams(self):
             self._undistortedImagePath = os.path.join(self._activeNode_PrepareDenseScene.node.output.value, filename)
         self.denseSceneParamsChanged.emit()
 
-    @Property(type=QObject, constant=True)
-    def attribute(self):
-        """ Get the underlying Viewpoint attribute wrapped by this Viewpoint. """
-        return self._viewpoint
+    # Get the underlying Viewpoint attribute wrapped by this Viewpoint.
+    attribute = Property(QObject, lambda self: self._viewpoint, constant=True)
 
     @Property(type="QVariant", notify=initialParamsChanged)
     def initialIntrinsics(self):