Add mergePointerTargets to create pointer delivery list

This code joins lists of "target item" which are joins of where several
touch points should be delivered.

Change-Id: I15ab4b7f70b8930d15368bf4cba0893ab339fa2a
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

src/quick/items/qquickwindow.cpp

@@ -2169,6 +2169,28 @@ QVector<QQuickItem *> QQuickWindowPrivate::pointerTargets(QQuickItem *item, cons
     return targets;
 }
 
+// return the joined lists
+// list1 has priority, common items come last
+QVector<QQuickItem *> QQuickWindowPrivate::mergePointerTargets(const QVector<QQuickItem *> &list1, const QVector<QQuickItem *> &list2) const
+{
+    QVector<QQuickItem *> targets = list1;
+    // start at the end of list2
+    // if item not in list, append it
+    // if item found, move to next one, inserting before the last found one
+    int insertPosition = targets.length();
+    for (int i = list2.length() - 1; i >= 0; --i) {
+        int newInsertPosition = targets.lastIndexOf(list2.at(i), insertPosition);
+        if (newInsertPosition >= 0) {
+            Q_ASSERT(newInsertPosition <= insertPosition);
+            insertPosition = newInsertPosition;
+        }
+        // check for duplicates, only insert if the item isn't there already
+        if (insertPosition == targets.size() || list2.at(i) != targets.at(insertPosition))
+            targets.insert(insertPosition, list2.at(i));
+    }
+    return targets;
+}
+
 void QQuickWindowPrivate::deliverTouchEvent(QQuickPointerTouchEvent *event)
 {
     qCDebug(DBG_TOUCH) << " - delivering" << event->asTouchEvent();

src/quick/items/qquickwindow_p.h

@@ -175,6 +175,8 @@ public:
     bool sendFilteredTouchEvent(QQuickItem *target, QQuickItem *item, QTouchEvent *event, QSet<QQuickItem*> *filtered);
 
     QVector<QQuickItem *> pointerTargets(QQuickItem *, const QPointF &) const;
+    QVector<QQuickItem *> mergePointerTargets(const QVector<QQuickItem *> &list1, const QVector<QQuickItem *> &list2) const;
+
     // hover delivery
     bool deliverHoverEvent(QQuickItem *, const QPointF &scenePos, const QPointF &lastScenePos, Qt::KeyboardModifiers modifiers, bool &accepted);
     bool sendHoverEvent(QEvent::Type, QQuickItem *, const QPointF &scenePos, const QPointF &lastScenePos,

tests/auto/quick/qquickwindow/tst_qquickwindow.cpp

@@ -303,6 +303,9 @@ private slots:
     void touchEvent_reentrant();
     void touchEvent_velocity();
 
+    void mergeTouchPointLists_data();
+    void mergeTouchPointLists();
+
     void mouseFromTouch_basic();
 
     void clearWindow();
@@ -903,6 +906,63 @@ void tst_qquickwindow::touchEvent_velocity()
     delete item;
 }
 
+void tst_qquickwindow::mergeTouchPointLists_data()
+{
+    QTest::addColumn<QVector<QQuickItem*>>("list1");
+    QTest::addColumn<QVector<QQuickItem*>>("list2");
+    QTest::addColumn<QVector<QQuickItem*>>("expected");
+    QTest::addColumn<bool>("showItem");
+
+    // FIXME: do not leak all these items
+    auto item1 = new QQuickItem();
+    auto item2 = new QQuickItem();
+    auto item3 = new QQuickItem();
+    auto item4 = new QQuickItem();
+    auto item5 = new QQuickItem();
+
+    QTest::newRow("empty") << QVector<QQuickItem*>() << QVector<QQuickItem*>() << QVector<QQuickItem*>();
+    QTest::newRow("single list left")
+            << (QVector<QQuickItem*>() << item1 << item2 << item3)
+            << QVector<QQuickItem*>()
+            << (QVector<QQuickItem*>() << item1 << item2 << item3);
+    QTest::newRow("single list right")
+            << QVector<QQuickItem*>()
+            << (QVector<QQuickItem*>() << item1 << item2 << item3)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3);
+    QTest::newRow("two lists identical")
+            << (QVector<QQuickItem*>() << item1 << item2 << item3)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3);
+    QTest::newRow("two lists 1")
+            << (QVector<QQuickItem*>() << item1 << item2 << item5)
+            << (QVector<QQuickItem*>() << item3 << item4 << item5)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3 << item4 << item5);
+    QTest::newRow("two lists 2")
+            << (QVector<QQuickItem*>() << item1 << item2 << item5)
+            << (QVector<QQuickItem*>() << item3 << item4 << item5)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3 << item4 << item5);
+    QTest::newRow("two lists 3")
+            << (QVector<QQuickItem*>() << item1 << item2 << item3)
+            << (QVector<QQuickItem*>() << item1 << item4 << item5)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3 << item4 << item5);
+    QTest::newRow("two lists 3")
+            << (QVector<QQuickItem*>() << item1 << item3 << item4)
+            << (QVector<QQuickItem*>() << item2 << item3 << item5)
+            << (QVector<QQuickItem*>() << item1 << item2 << item3 << item4 << item5);
+}
+
+void tst_qquickwindow::mergeTouchPointLists()
+{
+    QFETCH(QVector<QQuickItem*>, list1);
+    QFETCH(QVector<QQuickItem*>, list2);
+    QFETCH(QVector<QQuickItem*>, expected);
+
+    QQuickWindow win;
+    auto windowPrivate = QQuickWindowPrivate::get(&win);
+    auto targetList = windowPrivate->mergePointerTargets(list1, list2);
+    QCOMPARE(targetList, expected);
+}
+
 void tst_qquickwindow::mouseFromTouch_basic()
 {
     // Turn off accepting touch events with acceptTouchEvents. This