QGraphicsItem discard updates when it shouldn't.

Once a _q_processDirtyItems call is queued, it means we at least have
one item that is marked as dirty and we must reset it when the
_q_processDirtyItems slot is called. The problem however, was that
we didn't reset the item's dirty state if a full scene update occurred
in between, i.e. item->update(); scene.update();

We don't have to calculate the item's dirty rect if a full scene update
occurs in between, but we still have to reset its state.

Auto-test included.

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 427ecf3..5b297f6 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -219,6 +219,7 @@ private slots:
     void updateCachedItemAfterMove();
     void deviceTransform_data();
     void deviceTransform();
+    void update();
 
     // task specific tests below me
     void task141694_textItemEnsureVisible();
@@ -6427,5 +6428,32 @@ void tst_QGraphicsItem::deviceTransform()
     QCOMPARE(rect3->deviceTransform(deviceX).map(QPointF(50, 50)), mapResult3);
 }
 
+void tst_QGraphicsItem::update()
+{
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+    view.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&view);
+#endif
+    QTest::qWait(100);
+
+    EventTester *item = new EventTester;
+    scene.addItem(item);
+    QTest::qWait(100); // Make sure all pending updates are processed.
+    item->repaints = 0;
+
+    item->update(); // Item marked as dirty
+    scene.update(); // Entire scene marked as dirty
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 1);
+
+    // Make sure the dirty state from the previous update is reset so that
+    // the item don't think it is already dirty and discards this update.
+    item->update();
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 2);
+}
+
 QTEST_MAIN(tst_QGraphicsItem)
 #include "tst_qgraphicsitem.moc"