From 58e43f85adf131395c21db3925ae350bb7a380be Mon Sep 17 00:00:00 2001
From: Volker Hilsheimer <volker.hilsheimer@qt.io>
Date: Fri, 18 Nov 2022 14:20:20 +0100
Subject: [PATCH 20/30] QQuickItem: Fix effective visibility for items without
 parent

Items are visible if they are children of a visible parent, and not
explicitly hidden. The effectiveVisible member stores the state and is
updated when conditions that impact the item visibility changes.

The old code returned true for items outside a visual hierarchy, which
broke signal emission when items were removed from a parent, e.g.
because the parent got destroyed. With this change, items removed from
a visual hierarchy will emit the visibleChanged signal.

Note: QQuickItem initializes the effectiveVisible member to true, even
if the item was created without parent item. Visual items are required
to be added to a visual hierarchy via setParentItem. For this reason,
newly created items never emit visibleChanged when they are added to
a parent.

Adjust the QQuickItem::visible test - it creates an item hierarchy
without window. Such items are never visible, so add a window and
parent the test item hierarchy to the window's content item.

This fixes the expected failures in the tests. It does introduce an
incompatibility with QGraphicsView and QGraphicsItem, which continue
to return true from QGraphicsItem::isVisible for items that are not
in an item hierarchy.

[ChangeLog][Qt Quick][QQuickItem] The visible property of Items without
a parent now always returns false, and the visibleChanged signal gets
emitted when the parent item of a visible item becomes null.

Fixes: QTBUG-108213
Change-Id: If4b2947cefd1407853f0f29e6c3fdbd49fc9af65
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit d1b9a4cacfb966cf0a37983d8f8044f3aedf5de3)

CCBUG: 467909
CCBUG: 396359
---
 src/quick/items/qquickitem.cpp                 | 6 ++----
 tests/auto/quick/qquickitem/tst_qquickitem.cpp | 2 ++
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index c370d6e5c3..0d421349d7 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -6081,10 +6081,8 @@ void QQuickItem::setEnabled(bool e)
 
 bool QQuickItemPrivate::calcEffectiveVisible() const
 {
-    // XXX todo - Should the effective visible of an element with no parent just be the current
-    // effective visible?  This would prevent pointless re-processing in the case of an element
-    // moving to/from a no-parent situation, but it is different from what graphics view does.
-    return explicitVisible && (!parentItem || QQuickItemPrivate::get(parentItem)->effectiveVisible);
+    // An item is visible if it is a child of a visible parent, and not explicitly hidden.
+    return explicitVisible && parentItem && QQuickItemPrivate::get(parentItem)->effectiveVisible;
 }
 
 bool QQuickItemPrivate::setEffectiveVisibleRecur(bool newEffectiveVisible)
diff --git a/tests/auto/quick/qquickitem/tst_qquickitem.cpp b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
index 42348d8dd1..34eefd85e6 100644
--- a/tests/auto/quick/qquickitem/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
@@ -989,7 +989,9 @@ void tst_qquickitem::setParentItem()
 
 void tst_qquickitem::visible()
 {
+    QQuickWindow window;
     QQuickItem *root = new QQuickItem;
+    root->setParentItem(window.contentItem());
 
     QQuickItem *child1 = new QQuickItem;
     child1->setParentItem(root);
-- 
2.44.0