Add benchmarks for QGraphicsItem::setParenItem().

Ensure we test simple and deep constructs of setParentItem(). These
benchmarks don't cover slowness in ancestor flag updating.

QVariant is already identified as a contributor to this slowness, as is
updating of the depth value (a deep tree crawl).

Reviewed-by: Aaron Kennedy

2 files changed, 26 insertions, 1 deletions

diff --git a/tests/benchmarks/qgraphicsitem/qgraphicsitem.pro b/tests/benchmarks/qgraphicsitem/qgraphicsitem.pro
index c8fc07b..726bb96 100644
--- a/tests/benchmarks/qgraphicsitem/qgraphicsitem.pro
+++ b/tests/benchmarks/qgraphicsitem/qgraphicsitem.pro
@@ -3,4 +3,3 @@ TEMPLATE = app
 TARGET = tst_qgraphicsitem
 
 SOURCES += tst_qgraphicsitem.cpp
-
diff --git a/tests/benchmarks/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/benchmarks/qgraphicsitem/tst_qgraphicsitem.cpp
index 42f2e6b..62a5b5c 100644
--- a/tests/benchmarks/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/benchmarks/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -25,6 +25,8 @@ public slots:
     void cleanup();
 
 private slots:
+    void setParentItem();
+    void setParentItem_deep();
     void setPos_data();
     void setPos();
     void setTransform_data();
@@ -52,6 +54,30 @@ void tst_QGraphicsItem::cleanup()
 {
 }
 
+void tst_QGraphicsItem::setParentItem()
+{
+    QBENCHMARK {
+        QGraphicsRectItem rect;
+        QGraphicsRectItem *childRect = new QGraphicsRectItem;
+        childRect->setParentItem(&rect);
+    }
+}
+
+void tst_QGraphicsItem::setParentItem_deep()
+{
+    QBENCHMARK {
+        QGraphicsRectItem rect;
+        QGraphicsRectItem *lastRect = ▭
+        for (int i = 0; i < 10; ++i) {
+            QGraphicsRectItem *childRect = new QGraphicsRectItem;
+            childRect->setParentItem(lastRect);
+            lastRect = childRect;
+        }
+        QGraphicsItem *first = rect.children().first();
+        first->setParentItem(0);
+    }
+}
+
 void tst_QGraphicsItem::setPos_data()
 {
     QTest::addColumn<QPointF>("pos");