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>

2 files changed, 24 insertions, 0 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index c1167ad8a5..339e770910 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/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();
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index 61d57692a7..51804653f7 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/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,