Fix bug in QGraphicsItem::isVisibleTo().

Task-number: QTBUG-21612
Reviewed-by: James Perrett
Reviewed-by: Magne Pettersen Zachrisen

Merge-request: 1396
Reviewed-by: Jan-Arve Saether <jan-arve.saether@nokia.com>

2 files changed, 119 insertions, 9 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 9092593..f7ae045 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -2237,7 +2237,8 @@ bool QGraphicsItem::isVisible() const
     returned. \a parent can be 0, in which case this function will return
     whether the item is visible to the scene or not.
 
-    An item may not be visible to its ancestors even if isVisible() is true. If
+    An item may not be visible to its ancestors even if isVisible() is true. It
+    may also be visible to its ancestors even if isVisible() is false. If
     any ancestor is hidden, the item itself will be implicitly hidden, in which
     case this function will return false.
 
@@ -2245,15 +2246,16 @@ bool QGraphicsItem::isVisible() const
 */
 bool QGraphicsItem::isVisibleTo(const QGraphicsItem *parent) const
 {
-    if (!d_ptr->visible)
+    const QGraphicsItem *p = this;
+    if (d_ptr->explicitlyHidden)
         return false;
-    if (parent == this)
-        return true;
-    if (parentItem() && parentItem()->isVisibleTo(parent))
-        return true;
-    if (!parent && !parentItem())
-        return true;
-    return false;
+    do {
+        if (p == parent)
+            return true;
+        if (p->d_ptr->explicitlyHidden)
+            return false;
+    } while ((p = p->d_ptr->parent));
+    return parent == 0;
 }
 
 /*!
diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 9b834d5..b6a402e 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -306,6 +306,7 @@ private slots:
     void inputMethodHints();
     void toolTip();
     void visible();
+    void isVisibleTo();
     void explicitlyVisible();
     void enabled();
     void explicitlyEnabled();
@@ -1138,6 +1139,113 @@ void tst_QGraphicsItem::visible()
     QVERIFY(!item->hasFocus());
 }
 
+void tst_QGraphicsItem::isVisibleTo()
+{
+    QGraphicsScene scene;
+    QGraphicsItem *parent = scene.addRect(QRectF(0, 0, 100, 100));
+    QGraphicsItem *child = scene.addRect(QRectF(25, 25, 50, 50));
+    QGraphicsItem *grandChild = scene.addRect(QRectF(50, 50, 50, 50));
+    QGraphicsItem *stranger = scene.addRect(100, 100, 100, 100);
+
+    child->setParentItem(parent);
+    grandChild->setParentItem(child);
+
+    QVERIFY(grandChild->isVisible());
+    QVERIFY(grandChild->isVisibleTo(grandChild));
+    QVERIFY(grandChild->isVisibleTo(child));
+    QVERIFY(grandChild->isVisibleTo(parent));
+    QVERIFY(grandChild->isVisibleTo(0));
+    QVERIFY(child->isVisible());
+    QVERIFY(child->isVisibleTo(child));
+    QVERIFY(child->isVisibleTo(parent));
+    QVERIFY(child->isVisibleTo(0));
+    QVERIFY(parent->isVisible());
+    QVERIFY(parent->isVisibleTo(parent));
+    QVERIFY(parent->isVisibleTo(0));
+    QVERIFY(!parent->isVisibleTo(child));
+    QVERIFY(!child->isVisibleTo(grandChild));
+    QVERIFY(!grandChild->isVisibleTo(stranger));
+    QVERIFY(!child->isVisibleTo(stranger));
+    QVERIFY(!parent->isVisibleTo(stranger));
+    QVERIFY(!stranger->isVisibleTo(grandChild));
+    QVERIFY(!stranger->isVisibleTo(child));
+    QVERIFY(!stranger->isVisibleTo(parent));
+
+    // Case 1: only parent is explicitly hidden
+    parent->hide();
+
+    QVERIFY(!grandChild->isVisible());
+    QVERIFY(grandChild->isVisibleTo(grandChild));
+    QVERIFY(grandChild->isVisibleTo(child));
+    QVERIFY(grandChild->isVisibleTo(parent));
+    QVERIFY(!grandChild->isVisibleTo(0));
+    QVERIFY(!child->isVisible());
+    QVERIFY(child->isVisibleTo(child));
+    QVERIFY(child->isVisibleTo(parent));
+    QVERIFY(!child->isVisibleTo(0));
+    QVERIFY(!parent->isVisible());
+    QVERIFY(!parent->isVisibleTo(parent));
+    QVERIFY(!parent->isVisibleTo(0));
+    QVERIFY(!parent->isVisibleTo(child));
+    QVERIFY(!child->isVisibleTo(grandChild));
+    QVERIFY(!grandChild->isVisibleTo(stranger));
+    QVERIFY(!child->isVisibleTo(stranger));
+    QVERIFY(!parent->isVisibleTo(stranger));
+    QVERIFY(!stranger->isVisibleTo(grandChild));
+    QVERIFY(!stranger->isVisibleTo(child));
+    QVERIFY(!stranger->isVisibleTo(parent));
+
+    // Case 2: only child is hidden
+    parent->show();
+    child->hide();
+
+    QVERIFY(!grandChild->isVisible());
+    QVERIFY(grandChild->isVisibleTo(grandChild));
+    QVERIFY(grandChild->isVisibleTo(child));
+    QVERIFY(!grandChild->isVisibleTo(parent));
+    QVERIFY(!grandChild->isVisibleTo(0));
+    QVERIFY(!child->isVisible());
+    QVERIFY(!child->isVisibleTo(child));
+    QVERIFY(!child->isVisibleTo(parent));
+    QVERIFY(!child->isVisibleTo(0));
+    QVERIFY(parent->isVisible());
+    QVERIFY(parent->isVisibleTo(parent));
+    QVERIFY(parent->isVisibleTo(0));
+    QVERIFY(!parent->isVisibleTo(child));
+    QVERIFY(!child->isVisibleTo(grandChild));
+    QVERIFY(!grandChild->isVisibleTo(stranger));
+    QVERIFY(!child->isVisibleTo(stranger));
+    QVERIFY(!parent->isVisibleTo(stranger));
+    QVERIFY(!stranger->isVisibleTo(grandChild));
+    QVERIFY(!stranger->isVisibleTo(child));
+    QVERIFY(!stranger->isVisibleTo(parent));
+
+    // Case 3: only grand child is hidden
+    child->show();
+    grandChild->hide();
+
+    QVERIFY(!grandChild->isVisible());
+    QVERIFY(!grandChild->isVisibleTo(grandChild));
+    QVERIFY(!grandChild->isVisibleTo(child));
+    QVERIFY(!grandChild->isVisibleTo(parent));
+    QVERIFY(!grandChild->isVisibleTo(0));
+    QVERIFY(child->isVisible());
+    QVERIFY(child->isVisibleTo(child));
+    QVERIFY(child->isVisibleTo(parent));
+    QVERIFY(child->isVisibleTo(0));
+    QVERIFY(parent->isVisible());
+    QVERIFY(parent->isVisibleTo(parent));
+    QVERIFY(parent->isVisibleTo(0));
+    QVERIFY(!parent->isVisibleTo(child));
+    QVERIFY(!child->isVisibleTo(grandChild));
+    QVERIFY(!grandChild->isVisibleTo(stranger));
+    QVERIFY(!child->isVisibleTo(stranger));
+    QVERIFY(!parent->isVisibleTo(stranger));
+    QVERIFY(!stranger->isVisibleTo(grandChild));
+    QVERIFY(!stranger->isVisibleTo(child));
+    QVERIFY(!stranger->isVisibleTo(parent));
+}
+
 void tst_QGraphicsItem::explicitlyVisible()
 {
     QGraphicsScene scene;