engine/scene: preserve fixture order when saving on XML

This might be a bit less efficient than before, but it is more consistent in terms of user experience,
especially when empty fixtures are left in a Scene

engine/src/scene.cpp

@@ -364,37 +364,37 @@ bool Scene::saveXML(QXmlStreamWriter *doc)
     }
 
     /* Scene contents */
-    QList<quint32> writtenFixtures;
-    QMapIterator <SceneValue, uchar> it(m_values);
-    qint32 currFixID = -1;
-    QStringList currFixValues;
-    while (it.hasNext() == true)
+    // make a copy of the Scene values cause we need to empty it in the process
+    QList<SceneValue> values = m_values.keys();
+
+    // loop through the Scene Fixtures in the order they've been added
+    foreach (quint32 fxId, m_fixtures)
     {
-        SceneValue sv = it.next().key();
-        if (currFixID == -1) currFixID = sv.fxi;
-        if ((qint32)sv.fxi != currFixID)
+        QStringList currFixValues;
+        bool found = false;
+
+        // look for the values that match the current Fixture ID
+        for (int j = 0; j < values.count(); j++)
         {
-            saveXMLFixtureValues(doc, currFixID, currFixValues);
-            writtenFixtures << currFixID;
-            currFixValues.clear();
-            currFixID = sv.fxi;
-        }
-        currFixValues.append(QString::number(sv.channel));
-        // IMPORTANT: if a Scene is hidden, so used as a container by some Sequences,
-        // it must be saved with values set to zero
-        currFixValues.append(QString::number(isVisible() ? sv.value : 0));
-    }
-    /* write last element */
-    saveXMLFixtureValues(doc, currFixID, currFixValues);
-    writtenFixtures << currFixID;
+            SceneValue scv = values.at(j);
+            if (scv.fxi != fxId)
+            {
+                if (found == true)
+                    break;
+                else
+                    continue;
+            }
 
-    // Write fixtures with no scene value
-    foreach(quint32 fixtureID, m_fixtures)
-    {
-        if (writtenFixtures.contains(fixtureID))
-            continue;
+            found = true;
+            currFixValues.append(QString::number(scv.channel));
+            // IMPORTANT: if a Scene is hidden, so used as a container by some Sequences,
+            // it must be saved with values set to zero
+            currFixValues.append(QString::number(isVisible() ? scv.value : 0));
+            values.removeAt(j);
+            j--;
+        }
 
-        saveXMLFixtureValues(doc, fixtureID, QStringList());
+        saveXMLFixtureValues(doc, fxId, currFixValues);
     }
 
     /* End the <Function> tag */