Painting artifacts when moving an item with partial updates.

Found during manual testing (dndrobotinproxy). The problem was that the
paintedViewBoundingRect was set to an empty rect because the partial
update area didn't intersect with the viewport. The item itself was
partially inside the viewport. Then, when the item was moved, its old
area was not repainted due to this empty paintedViewBoundingRect.

Auto-test included.

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index d689293..2dbd5f1 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -6580,6 +6580,7 @@ public:
 void tst_QGraphicsItem::update()
 {
     QGraphicsScene scene;
+    scene.setSceneRect(-100, -100, 200, 200);
     MyGraphicsView view(&scene);
 
     view.show();
@@ -6636,6 +6637,52 @@ void tst_QGraphicsItem::update()
     QCOMPARE(view.repaints, 1);
     // The entire item's bounding rect (adjusted for antialiasing) should have been painted.
     QCOMPARE(view.paintedRegion, expectedRegion);
+
+    // Make sure item is repainted when shown (after being hidden).
+    view.reset();
+    item->repaints = 0;
+    item->show();
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 1);
+    QCOMPARE(view.repaints, 1);
+    // The entire item's bounding rect (adjusted for antialiasing) should have been painted.
+    QCOMPARE(view.paintedRegion, expectedRegion);
+
+    item->repaints = 0;
+    item->hide();
+    qApp->processEvents();
+    view.reset();
+    const QPointF originalPos = item->pos();
+    item->setPos(5000, 5000);
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 0);
+    QCOMPARE(view.repaints, 0);
+    qApp->processEvents();
+
+    item->setPos(originalPos);
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 0);
+    QCOMPARE(view.repaints, 0);
+    item->show();
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 1);
+    QCOMPARE(view.repaints, 1);
+    // The entire item's bounding rect (adjusted for antialiasing) should have been painted.
+    QCOMPARE(view.paintedRegion, expectedRegion);
+
+    QGraphicsViewPrivate *viewPrivate = static_cast<QGraphicsViewPrivate *>(qt_widget_private(&view));
+    item->setPos(originalPos + QPoint(50, 50));
+    viewPrivate->updateAll();
+    QVERIFY(viewPrivate->fullUpdatePending);
+    QTest::qWait(50);
+    item->repaints = 0;
+    view.reset();
+    item->setPos(originalPos);
+    QTest::qWait(50);
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 1);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(view.paintedRegion, expectedRegion + expectedRegion.translated(50, 50));
 }
 
 void tst_QGraphicsItem::setTransformProperties_data()