Fixes broken BSP lookup in QGraphicsSceneBspTreeIndex.

The chip demo was unbelievable slow, so I investigated and found out
the bsp always returned almost all items in the tree (40 000 in this
particular case). It did so because the tree was initialized with
an empty sceneRect. The sceneRect was empty due to a lacking signal-slot
connection, resulting in QGraphicsSceneBspTreeIndex::updateSceneRect
never being invoked.

Auto-test included.

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/auto/qgraphicssceneindex/tst_qgraphicssceneindex.cpp b/tests/auto/qgraphicssceneindex/tst_qgraphicssceneindex.cpp
index ac21e201a8..9d0675d7a7 100644
--- a/tests/auto/qgraphicssceneindex/tst_qgraphicssceneindex.cpp
+++ b/tests/auto/qgraphicssceneindex/tst_qgraphicssceneindex.cpp
@@ -64,6 +64,7 @@ private slots:
     void overlappedItems();
     void movingItems_data();
     void movingItems();
+    void connectedToSceneRectChanged();
 
 private:
     void common_data();
@@ -214,6 +215,18 @@ void tst_QGraphicsSceneIndex::movingItems()
     QCOMPARE(scene.items(QRectF(0, 0, 1000, 1000)).count(), 11);
 }
 
+void tst_QGraphicsSceneIndex::connectedToSceneRectChanged()
+{
+
+    class MyScene : public QGraphicsScene
+    { public: using QGraphicsScene::receivers; };
+
+    MyScene scene; // Uses QGraphicsSceneBspTreeIndex by default.
+    QCOMPARE(scene.receivers(SIGNAL(sceneRectChanged(const QRectF&))), 1);
+
+    scene.setItemIndexMethod(QGraphicsScene::NoIndex); // QGraphicsSceneLinearIndex
+    QCOMPARE(scene.receivers(SIGNAL(sceneRectChanged(const QRectF&))), 1);
+}
 
 QTEST_MAIN(tst_QGraphicsSceneIndex)
 #include "tst_qgraphicssceneindex.moc"