QGraphicsItem::setOpacity(0.0) does not trigger an update.

The problem was that we discarded update requests for fully
transparent items, which is correct, but we even did that
when the update was issued from QGraphicsItem::setOpacity.
We don't have to, and shouldn't, consider the opacity in
that case. Whenever we reach the fullUpdateHelper call in
setOpacity it means we have to do an update regardless of
the current opacity (oldOpacity was not 0.0 if the
currentOpacity is 0.0).

Auto-test included.

Task-number: 252913
Reviewed-by: Andreas

1 files changed, 87 insertions, 2 deletions

diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 77b7948..6d150cb 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -78,8 +78,7 @@ Q_DECLARE_METATYPE(QRectF)
 class EventTester : public QGraphicsItem
 {
 public:
-    EventTester()
-        : repaints(0)
+    EventTester(QGraphicsItem *parent = 0) : QGraphicsItem(parent), repaints(0)
     { br = QRectF(-10, -10, 20, 20); }
 
     void setGeometry(const QRectF &rect)
@@ -207,6 +206,7 @@ private slots:
     void itemTransform_unrelated();
     void opacity_data();
     void opacity();
+    void opacity2();
     void itemStacksBehindParent();
     void nestedClipping();
     void nestedClippingTransforms();
@@ -5570,6 +5570,91 @@ void tst_QGraphicsItem::opacity()
     QCOMPARE(c3->effectiveOpacity(), c3_effectiveOpacity);
 }
 
+void tst_QGraphicsItem::opacity2()
+{
+    EventTester *parent = new EventTester;
+    EventTester *child = new EventTester(parent);
+    EventTester *grandChild = new EventTester(child);
+
+    QGraphicsScene scene;
+    scene.addItem(parent);
+
+    class MyGraphicsView : public QGraphicsView
+    { public:
+        int repaints;
+        MyGraphicsView(QGraphicsScene *scene) : QGraphicsView(scene), repaints(0) {}
+        void paintEvent(QPaintEvent *e) { ++repaints; QGraphicsView::paintEvent(e); }
+    };
+
+    MyGraphicsView view(&scene);
+    view.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&view);
+#endif
+    QTest::qWait(250);
+
+#define RESET_REPAINT_COUNTERS \
+    parent->repaints = 0; \
+    child->repaints = 0; \
+    grandChild->repaints = 0; \
+    view.repaints = 0;
+
+    RESET_REPAINT_COUNTERS
+
+    child->setOpacity(0.0);
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(parent->repaints, 1);
+    QCOMPARE(child->repaints, 0);
+    QCOMPARE(grandChild->repaints, 0);
+
+    RESET_REPAINT_COUNTERS
+
+    child->setOpacity(1.0);
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(parent->repaints, 1);
+    QCOMPARE(child->repaints, 1);
+    QCOMPARE(grandChild->repaints, 1);
+
+    RESET_REPAINT_COUNTERS
+
+    parent->setOpacity(0.0);
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(parent->repaints, 0);
+    QCOMPARE(child->repaints, 0);
+    QCOMPARE(grandChild->repaints, 0);
+
+    RESET_REPAINT_COUNTERS
+
+    parent->setOpacity(1.0);
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(parent->repaints, 1);
+    QCOMPARE(child->repaints, 1);
+    QCOMPARE(grandChild->repaints, 1);
+
+    grandChild->setFlag(QGraphicsItem::ItemIgnoresParentOpacity);
+    RESET_REPAINT_COUNTERS
+
+    child->setOpacity(0.0);
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 1);
+    QCOMPARE(parent->repaints, 1);
+    QCOMPARE(child->repaints, 0);
+    QCOMPARE(grandChild->repaints, 1);
+
+    RESET_REPAINT_COUNTERS
+
+    child->setOpacity(0.0); // Already 0.0; no change.
+    QTest::qWait(100);
+    QCOMPARE(view.repaints, 0);
+    QCOMPARE(parent->repaints, 0);
+    QCOMPARE(child->repaints, 0);
+    QCOMPARE(grandChild->repaints, 0);
+}
+
 void tst_QGraphicsItem::itemStacksBehindParent()
 {
     QGraphicsRectItem *parent1 = new QGraphicsRectItem(QRectF(0, 0, 100, 50));