A partial QGraphicsItem update causes a full update to be discarded.

E.g. item->update(QRectF(0, 0, 5, 5)); item->update();

The problem was that we discarded all update requests whenever the item
was already marked as dirty. The dirty bit only means it has pending
updates (which might be a full update). However, we have a separate bit
for full updates (fullUpdatePending) so we have to check against that
bit instead.

Makes tst_QGraphicsProxyWidget::paintEvent happy.

Another auto-test included.

2 files changed, 32 insertions, 3 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 80ad19d..2a062ab 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -3907,7 +3907,7 @@ bool QGraphicsItemPrivate::discardUpdateRequest(bool ignoreClipping, bool ignore
     // No scene, or if the scene is updating everything, means we have nothing
     // to do. The only exception is if the scene tracks the growing scene rect.
     return (!visible && !ignoreVisibleBit)
-           || (!ignoreDirtyBit && dirty)
+           || (!ignoreDirtyBit && fullUpdatePending)
            || !scene
            || (scene->d_func()->updateAll && scene->d_func()->hasSceneRect)
            || (!ignoreClipping && (childrenClippedToShape() && isClippedAway()))
@@ -4163,7 +4163,7 @@ void QGraphicsItem::update(const QRectF &rect)
             }
         }
         // Only invalidate cache; item is already dirty.
-        if (d_ptr->dirty)
+        if (d_ptr->fullUpdatePending)
             return;
     }
 
diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 5b297f6..41593b5 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -6428,10 +6428,25 @@ void tst_QGraphicsItem::deviceTransform()
     QCOMPARE(rect3->deviceTransform(deviceX).map(QPointF(50, 50)), mapResult3);
 }
 
+class MyGraphicsView : public QGraphicsView
+{
+public:
+    int repaints;
+    QRegion paintedRegion;
+    MyGraphicsView(QGraphicsScene *scene) : QGraphicsView(scene), repaints(0) {}
+    void paintEvent(QPaintEvent *e)
+    {
+        paintedRegion += e->region();
+        ++repaints;
+        QGraphicsView::paintEvent(e);
+    }
+    void reset() { repaints = 0; paintedRegion = QRegion(); }
+};
+
 void tst_QGraphicsItem::update()
 {
     QGraphicsScene scene;
-    QGraphicsView view(&scene);
+    MyGraphicsView view(&scene);
     view.show();
 #ifdef Q_WS_X11
     qt_x11_wait_for_window_manager(&view);
@@ -6453,6 +6468,20 @@ void tst_QGraphicsItem::update()
     item->update();
     qApp->processEvents();
     QCOMPARE(item->repaints, 2);
+
+    // Make sure a partial update doesn't cause a full update to be discarded.
+    view.reset();
+    item->repaints = 0;
+    item->update(QRectF(0, 0, 5, 5));
+    item->update();
+    qApp->processEvents();
+    QCOMPARE(item->repaints, 1);
+    QCOMPARE(view.repaints, 1);
+    const QRect itemDeviceBoundingRect = item->deviceTransform(view.viewportTransform())
+                                         .mapRect(item->boundingRect()).toRect();
+    const QRegion expectedRegion = itemDeviceBoundingRect.adjusted(-2, -2, 2, 2);
+    // The entire item's bounding rect (adjusted for antialiasing) should have been painted.
+    QCOMPARE(view.paintedRegion, expectedRegion);
 }
 
 QTEST_MAIN(tst_QGraphicsItem)