Fixed positioning of map view when switching between maps in a world

When the new map has not previously been open the "fit map in view"
logic kicked in, overriding the synchronization of the scale and
position for the current world.

Fixed by never doing "fit map in view" when a "forceCenterOn" call
happened.

src/tiled/mapeditor.cpp

@@ -640,7 +640,7 @@ void MapEditor::restoreDocumentState(MapDocument *mapDocument) const
         mapView->zoomable()->setScale(scale);
 
     const QPointF viewCenter = fromSettingsValue<QPointF>(fileState.value(QLatin1String("viewCenter")));
-    mapView->setInitialCenterPos(viewCenter);
+    mapView->forceCenterOn(viewCenter);
 
     const int layerIndex = fileState.value(QLatin1String("selectedLayer")).toInt();
     if (Layer *layer = layerAtGlobalIndex(mapDocument->map(), layerIndex))

src/tiled/mapview.cpp

@@ -263,6 +263,14 @@ void MapView::setHandScrolling(bool handScrolling)
  */
 void MapView::forceCenterOn(const QPointF &pos)
 {
+    // Let's wait until the initial paint event before we position the view,
+    // otherwise layout changes may still affect the position.
+    if (!mViewInitialized) {
+        mInitialCenterPos = pos;
+        mHasInitialCenterPos = true;
+        return;
+    }
+
     // This is only to make it update QGraphicsViewPrivate::lastCenterPoint,
     // just in case this is important.
     QGraphicsView::centerOn(pos);

src/tiled/mapview.h

@@ -61,8 +61,6 @@ class MapView : public QGraphicsView
     MapView(QWidget *parent = nullptr, Mode mode = StaticContents);
     ~MapView() override;
 
-    void setInitialCenterPos(const QPointF &center);
-
     void setScene(MapScene *scene);
     MapScene *mapScene() const;
 
@@ -125,13 +123,6 @@ class MapView : public QGraphicsView
     Zoomable *mZoomable;
 };
 
-
-inline void MapView::setInitialCenterPos(const QPointF &center)
-{
-    mInitialCenterPos = center;
-    mHasInitialCenterPos = true;
-}
-
 } // namespace Tiled
 
 Q_DECLARE_METATYPE(Tiled::MapView*)