Rendering artifacts when hiding a QGraphicsItem.

The problem was that update() followed by hide() didn't work as
expected because the update() caused all sub-sequent update requests
to be discareded. This is correct, however, we have to make sure the
ignoreVisible/ignoreOpacity bit is set properly; we won't process a
hidden item otherwise.

Auto-test included.

2 files changed, 21 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index ae6c53c..0ca72b7 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4358,6 +4358,16 @@ void QGraphicsScenePrivate::markDirty(QGraphicsItem *item, const QRectF &rect, b
                                           /*ignoreVisibleBit=*/force,
                                           /*ignoreDirtyBit=*/removingItemFromScene || invalidateChildren,
                                           /*ignoreOpacity=*/ignoreOpacity)) {
+        if (item->d_ptr->dirty) {
+            // The item is already marked as dirty and will be processed later. However,
+            // we have to make sure ignoreVisible and ignoreOpacity are set properly;
+            // otherwise things like: item->update(); item->hide() (force is now true)
+            // won't work as expected.
+            if (force)
+                item->d_ptr->ignoreVisible = 1;
+            if (ignoreOpacity)
+                item->d_ptr->ignoreOpacity = 1;
+        }
         return;
     }
 
diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 3f7a50b..d689293 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -6625,6 +6625,17 @@ void tst_QGraphicsItem::update()
     qApp->processEvents();
     QCOMPARE(item->repaints, 0);
     QCOMPARE(view.repaints, 0);
+
+    // Make sure the area occupied by an item is repainted when hiding it.
+    view.reset();
+    item->repaints = 0;
+    item->update(); // Full update; all sub-sequent update requests are discarded.
+    item->hide(); // visible set to 0. ignoreVisible must be set to 1; the item won't be processed otherwise.
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 0);
+    QCOMPARE(view.repaints, 1);
+    // The entire item's bounding rect (adjusted for antialiasing) should have been painted.
+    QCOMPARE(view.paintedRegion, expectedRegion);
 }
 
 void tst_QGraphicsItem::setTransformProperties_data()