Add QQuickItemParticle give() method body

The current version of QQuickItemParticle give() method was not
implemented and a simple TODO comment was present instead.
I added a working body and add also a reparent feature when an
added item is released.

Fixes: QTBUG-76827
Change-Id: Ib7d289cad2ff0cd166e766eb7f07e92437e7681b
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 21 insertions, 6 deletions

diff --git a/src/particles/qquickitemparticle.cpp b/src/particles/qquickitemparticle.cpp
index fc28864746..740d0f60f3 100644
--- a/src/particles/qquickitemparticle.cpp
+++ b/src/particles/qquickitemparticle.cpp
@@ -159,8 +159,15 @@ void QQuickItemParticle::take(QQuickItem *item, bool prioritize)
 
 void QQuickItemParticle::give(QQuickItem *item)
 {
-    //TODO: This
-    Q_UNUSED(item);
+    for (auto groupId : groupIds()) {
+        for (QQuickParticleData* data : qAsConst(m_system->groupData[groupId]->data)) {
+            if (data->delegate == item){
+                m_deletables << item;
+                data->delegate = nullptr;
+                return;
+            }
+        }
+    }
 }
 
 void QQuickItemParticle::initialize(int gIdx, int pIdx)
@@ -179,8 +186,11 @@ void QQuickItemParticle::processDeletables()
             item->setOpacity(0.);
         item->setVisible(false);
         QQuickItemParticleAttached* mpa;
-        if ((mpa = qobject_cast<QQuickItemParticleAttached*>(qmlAttachedPropertiesObject<QQuickItemParticle>(item))))
-            mpa->detach();//reparent as well?
+        if ((mpa = qobject_cast<QQuickItemParticleAttached*>(qmlAttachedPropertiesObject<QQuickItemParticle>(item)))) {
+            if (mpa->m_parentItem != nullptr)
+                item->setParentItem(mpa->m_parentItem);
+            mpa->detach();
+        }
         int idx = -1;
         if ((idx = m_managed.indexOf(item)) != -1) {
             m_managed.takeAt(idx);
@@ -205,9 +215,12 @@ void QQuickItemParticle::tick(int time)
             m_deletables << d->delegate;
             d->delegate = nullptr;
         }
+        QQuickItem* parentItem = nullptr;
         if (!m_pendingItems.isEmpty()){
-            d->delegate = m_pendingItems.front();
+            QQuickItem *item = m_pendingItems.front();
             m_pendingItems.pop_front();
+            parentItem = item->parentItem();
+            d->delegate = item;
         }else if (m_delegate){
             d->delegate = qobject_cast<QQuickItem*>(m_delegate->create(qmlContext(this)));
             if (d->delegate)
@@ -218,6 +231,7 @@ void QQuickItemParticle::tick(int time)
             d->delegate->setY(d->curY(m_system) - d->delegate->height() / 2);
             QQuickItemParticleAttached* mpa = qobject_cast<QQuickItemParticleAttached*>(qmlAttachedPropertiesObject<QQuickItemParticle>(d->delegate));
             if (mpa){
+                mpa->m_parentItem = parentItem;
                 mpa->m_mp = this;
                 mpa->attach();
             }
diff --git a/src/particles/qquickitemparticle_p.h b/src/particles/qquickitemparticle_p.h
index 70cfe2a446..ea46c67db7 100644
--- a/src/particles/qquickitemparticle_p.h
+++ b/src/particles/qquickitemparticle_p.h
@@ -130,13 +130,14 @@ class QQuickItemParticleAttached : public QObject
     Q_PROPERTY(QQuickItemParticle* particle READ particle CONSTANT);
 public:
     QQuickItemParticleAttached(QObject* parent)
-        : QObject(parent), m_mp(0)
+        : QObject(parent), m_mp(0), m_parentItem(nullptr)
     {;}
     QQuickItemParticle* particle() const { return m_mp; }
     void detach(){Q_EMIT detached();}
     void attach(){Q_EMIT attached();}
 private:
     QQuickItemParticle* m_mp;
+    QPointer<QQuickItem> m_parentItem;
     friend class QQuickItemParticle;
 Q_SIGNALS:
     void detached();