[ui] add 'Message' structure to wrap high-level messages

* fix random segfault due to signals with 2+ arguments (PySide bug)
* group Connections to '_reconstruction' instance

meshroom/ui/qml/main.qml

@@ -197,22 +197,6 @@ ApplicationWindow {
         id: dialogsFactory
     }
 
-    // Bind log messages to DialogsFactory
-    Connections {
-        target: _reconstruction
-        function createDialog(func, args)
-        {
-            var dialog = func(_window)
-            // Set text afterwards to avoid dialog sizing issues
-            dialog.title = args[0]
-            dialog.text = args[1]
-            dialog.detailedText = args[2]
-        }
-        // onInfo: createDialog(dialogsFactory.info, arguments)
-        // onWarning: createDialog(dialogsFactory.warning, arguments)
-        // onError: createDialog(dialogsFactory.error, arguments)
-    }
-
     Action {
         id: undoAction
 
@@ -316,6 +300,20 @@ ApplicationWindow {
                                                  0,
                                                  graphEditor.boundingBox().height + graphEditor.gridSpacing
                                                  )
+
+        // Bind messages to DialogsFactory
+        function createDialog(func, message)
+        {
+            var dialog = func(_window)
+            // Set text afterwards to avoid dialog sizing issues
+            dialog.title = message.title
+            dialog.text = message.text
+            dialog.detailedText = message.detailedText
+        }
+
+        onInfo: createDialog(dialogsFactory.info, arguments[0])
+        onWarning: createDialog(dialogsFactory.warning, arguments[0])
+        onError: createDialog(dialogsFactory.error, arguments[0])
     }
 
     Controls1.SplitView {

meshroom/ui/reconstruction.py

@@ -10,6 +10,20 @@ from meshroom.core import graph
 from meshroom.ui.graph import UIGraph
 
 
+class Message(QObject):
+    """ Simple structure wrapping a high-level message. """
+
+    def __init__(self, title, text, detailedText="", parent=None):
+        super(Message, self).__init__(parent)
+        self._title = title
+        self._text = text
+        self._detailedText = detailedText
+
+    title = Property(str, lambda self: self._title, constant=True)
+    text = Property(str, lambda self: self._text, constant=True)
+    detailedText = Property(str, lambda self: self._detailedText, constant=True)
+
+
 class LiveSfmManager(QObject):
     """
     Manage a live SfM reconstruction by creating augmentation steps in the graph over time,
@@ -177,9 +191,13 @@ class Reconstruction(UIGraph):
         try:
             super(Reconstruction, self).load(filepath)
         except Exception as e:
-            self.error.emit("Error while loading {}".format(os.path.basename(filepath)),
+            self.error.emit(
+                Message(
+                    "Error while loading {}".format(os.path.basename(filepath)),
                     "An unexpected error has occurred",
-                            str(e))
+                    str(e)
+                )
+            )
 
     def onGraphChanged(self):
         """ React to the change of the internal graph. """
@@ -474,8 +492,7 @@ class Reconstruction(UIGraph):
     sfmReport = Property(bool, lambda self: len(self._poses) > 0, notify=sfmReportChanged)
     sfmAugmented = Signal(graph.Node, graph.Node)
 
-    # Signals to propagate high-level log messages
+    # Signals to propagate high-level messages
-    # Signal(title, text, detailedText)
+    error = Signal(Message)
-    error = Signal(str, str, str)
+    warning = Signal(Message)
-    warning = Signal(str, str, str)
+    info = Signal(Message)
-    info = Signal(str, str, str)