qt6-declarative/0001-QQuickItem-map-To-From-Item-Account-for-not-having-a.patch

From 0ae3697cf40bcd3ae1de20621abad17cf6c5f52d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Wed, 2 Oct 2024 17:04:25 +0200
Subject: [PATCH] QQuickItem::map{To,From}Item: Account for not having a window
 yet

Prior to 06ace3e226b2394362e27d1bc4743c1170777af1 we would not
account for items in different scenes, and would map them as if
they were part of the same scene.

After 06ace3e226b2394362e27d1bc4743c1170777af1 we took the scenes
into account, but failed to guard against one or both of the items
not having a scene (yet), causing potential crashes.

We now properly check that both items have a scene before trying
any scene to scene mapping.

The semantics if one or both of the items are not in a scene is
kept as it was before 06ace3e226b2394362e27d1bc4743c1170777af1,
where we assume the two items are part of the same scene, and an
item without a parent is assumed to be the root of its scene.

Fixes: QTBUG-129500
Change-Id: I897faf73d04dddd68a7a8797e5238743efdd4f73
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit 08b0e3e39e899bea013057a7ac038b8878809712)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/quick/items/qquickitem.cpp                | 14 +++++-----
 .../data/mapCoordinatesWithWindows.qml        | 11 ++++++++
 .../auto/quick/qquickitem2/tst_qquickitem.cpp | 27 +++++++++++++++++++
 3 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 9288df17a4..802f4dad55 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -8755,9 +8755,10 @@ QPointF QQuickItem::mapToItem(const QQuickItem *item, const QPointF &point) cons
 {
     QPointF p = mapToScene(point);
     if (item) {
-        const QQuickWindow *itemWindow = item->window();
-        if (itemWindow != nullptr && itemWindow != window())
-            p = itemWindow->mapFromGlobal(window()->mapToGlobal(p));
+        const auto *itemWindow = item->window();
+        const auto *thisWindow = window();
+        if (thisWindow && itemWindow && itemWindow != thisWindow)
+            p = itemWindow->mapFromGlobal(thisWindow->mapToGlobal(p));
 
         p = item->mapFromScene(p);
     }
@@ -8862,9 +8863,10 @@ QPointF QQuickItem::mapFromItem(const QQuickItem *item, const QPointF &point) co
     QPointF p = point;
     if (item) {
         p = item->mapToScene(point);
-
-        if (item->window() != window())
-            p = window()->mapFromGlobal(item->window()->mapToGlobal(p));
+        const auto *itemWindow = item->window();
+        const auto *thisWindow = window();
+        if (thisWindow && itemWindow && itemWindow != thisWindow)
+            p = thisWindow->mapFromGlobal(itemWindow->mapToGlobal(p));
     }
     return mapFromScene(p);
 }
diff --git a/tests/auto/quick/qquickitem2/data/mapCoordinatesWithWindows.qml b/tests/auto/quick/qquickitem2/data/mapCoordinatesWithWindows.qml
index 98fc0e77af..1696699a75 100644
--- a/tests/auto/quick/qquickitem2/data/mapCoordinatesWithWindows.qml
+++ b/tests/auto/quick/qquickitem2/data/mapCoordinatesWithWindows.qml
@@ -48,4 +48,15 @@ QtObject {
             color: "cyan"
         }
     }
+
+    property Item itemWithoutWindowA: Item {
+        x: 20; y: 20
+    }
+    property Item itemWithoutWindowB: Item {
+        x: 40; y: 40
+        Item {
+            objectName: "childItemWithoutWindow"
+            x: 30; y: 30
+        }
+    }
 }
diff --git a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
index 154c4a661f..eb4f62e65f 100644
--- a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
@@ -2945,6 +2945,33 @@ void tst_QQuickItem::mapCoordinatesWithWindows()
         globalItemOffset(childItemInChildWindow, childItemInOtherWindow));
     QCOMPARE(childItemInChildWindow->mapFromItem(childItemInOtherWindow, {0, 0}),
         globalItemOffset(childItemInOtherWindow, childItemInChildWindow));
+
+    // If one or both of the items are not in a scene (yet), they are assumed
+    // to eventually be in the same scene.
+
+    auto *itemWithoutWindowA = root->property("itemWithoutWindowA").value<QQuickItem*>();
+    QVERIFY(itemWithoutWindowA);
+    auto *itemWithoutWindowB = root->property("itemWithoutWindowB").value<QQuickItem*>();
+    QVERIFY(itemWithoutWindowB);
+    auto *childItemWithoutWindow = itemWithoutWindowB->findChild<QQuickItem*>("childItemWithoutWindow");
+    QVERIFY(childItemWithoutWindow);
+
+    QPoint itemWithoutWindowAPos = itemWithoutWindowA->position().toPoint();
+    QPoint itemWithoutWindowBPos = itemWithoutWindowB->position().toPoint();
+
+    QCOMPARE(itemWithoutWindowA->mapToItem(childItemWithoutWindow, {0, 0}),
+        itemWithoutWindowAPos - (itemWithoutWindowBPos + childItemWithoutWindow->position()));
+    QCOMPARE(itemWithoutWindowA->mapFromItem(childItemWithoutWindow, {0, 0}),
+        (itemWithoutWindowBPos + childItemWithoutWindow->position()) - itemWithoutWindowAPos);
+
+    QCOMPARE(itemWithoutWindowA->mapToItem(childItem, {0, 0}),
+        itemWithoutWindowAPos - itemPos);
+    QCOMPARE(itemWithoutWindowA->mapFromItem(childItem, {0, 0}),
+        itemPos - itemWithoutWindowAPos);
+    QCOMPARE(childItem->mapToItem(itemWithoutWindowA, {0, 0}),
+        itemPos - itemWithoutWindowAPos);
+    QCOMPARE(childItem->mapFromItem(itemWithoutWindowA, {0, 0}),
+        itemWithoutWindowAPos - itemPos);
 }
 
 void tst_QQuickItem::transforms_data()
-- 
2.47.0