Don't re-parent ShaderEffect source items.

ShaderEffect and ShaderEffectSource used to set themselves as
parent of and hide source items that don't already have a parent.
This was done in order to make sure the source items got a canvas.
This patch sets the canvas of the source items without re-parenting.

Task-number: QTBUG-23069
Change-Id: I24d56e6eb970590bca3adff7a61459d25e4983a0
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

src/quick/items/qquickcanvas.cpp

@@ -1415,8 +1415,10 @@ void QQuickCanvasPrivate::cleanupNodesOnShutdown(QQuickItem *item)
 void QQuickCanvasPrivate::cleanupNodesOnShutdown()
 {
     cleanupNodes();
-
     cleanupNodesOnShutdown(rootItem);
+    QSet<QQuickItem *>::const_iterator it = parentlessItems.begin();
+    for (; it != parentlessItems.end(); ++it)
+        cleanupNodesOnShutdown(*it);
 }
 
 void QQuickCanvasPrivate::updateDirtyNodes()

src/quick/items/qquickcanvas_p.h

@@ -107,6 +107,7 @@ class QQuickCanvasPrivate : public QWindowPrivate
     void initRootItem();//Currently only used if items added in QML
 
     QQuickRootItem *rootItem;
+    QSet<QQuickItem *> parentlessItems;
     QDeclarativeListProperty<QObject> data();
 
     QQuickItem *activeFocusItem;

src/quick/items/qquickitem.cpp

@@ -1892,6 +1892,8 @@ void QQuickItem::setParentItem(QQuickItem *parentItem)
                                                                 QQuickCanvasPrivate::DontChangeFocusProperty);
 
         op->removeChild(this);
+    } else if (d->canvas) {
+        QQuickCanvasPrivate::get(d->canvas)->parentlessItems.remove(this);
     }
 
     d->parentItem = parentItem;
@@ -2119,6 +2121,8 @@ void QQuickItemPrivate::initCanvas(InitializationState *state, QQuickCanvas *c)
             c->hoverItems.removeAll(q);
         if (itemNodeInstance)
             c->cleanup(itemNodeInstance);
+        if (!parentItem)
+            c->parentlessItems.remove(q);
     }
 
     canvas = c;
@@ -2142,6 +2146,9 @@ void QQuickItemPrivate::initCanvas(InitializationState *state, QQuickCanvas *c)
         childState = &_dummy;
     }
 
+    if (!parentItem && canvas)
+        QQuickCanvasPrivate::get(canvas)->parentlessItems.insert(q);
+
     for (int ii = 0; ii < childItems.count(); ++ii) {
         QQuickItem *child = childItems.at(ii);
         QQuickItemPrivate::get(child)->initCanvas(childState, c);

src/quick/items/qquickshadereffect.cpp

@@ -388,14 +388,17 @@ void QQuickShaderEffect::setSource(const QVariant &var, int index)
 
     source.sourceObject = item;
 
-
-    // TODO: Find better solution.
-    // 'item' needs a canvas to get a scenegraph node.
-    // The easiest way to make sure it gets a canvas is to
-    // make it a part of the same item tree as 'this'.
-    if (item && item->parentItem() == 0) {
-        item->setParentItem(this);
-        item->setVisible(false);
+    if (item) {
+        QQuickItemPrivate *d = QQuickItemPrivate::get(item);
+        // 'item' needs a canvas to get a scene graph node. It usually gets one through its
+        // parent, but if the source item is "inline" rather than a reference -- i.e.
+        // "property variant source: Image { }" instead of "property variant source: foo" -- it
+        // will not get a parent. In those cases, 'item' should get the canvas from 'this'.
+        if (!d->parentItem && canvas() && !d->canvas) {
+            QQuickItemPrivate::InitializationState initState;
+            initState.clear();
+            d->initCanvas(&initState, canvas());
+        }
     }
 }
 
@@ -454,9 +457,6 @@ void QQuickShaderEffect::reset()
     for (int i = 0; i < m_sources.size(); ++i) {
         const SourceData &source = m_sources.at(i);
         delete source.mapper;
-        QQuickItem *item = qobject_cast<QQuickItem *>(source.sourceObject);
-        if (item && item->parentItem() == this)
-            item->setParentItem(0);
     }
     m_sources.clear();
 
@@ -760,4 +760,21 @@ QSGNode *QQuickShaderEffect::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeDa
     return node;
 }
 
+void QQuickShaderEffect::itemChange(ItemChange change, const ItemChangeData &value)
+{
+    if (change == QQuickItem::ItemSceneChange) {
+        // See comment in QQuickShaderEffect::setSource().
+        for (int i = 0; i < m_sources.size(); ++i) {
+            QQuickItemPrivate *d = QQuickItemPrivate::get(m_sources.at(i).sourceObject);
+            if (!d->parentItem && value.canvas != d->canvas) {
+                QQuickItemPrivate::InitializationState initState;
+                initState.clear();
+                d->initCanvas(&initState, value.canvas);
+            }
+        }
+    }
+    QQuickItem::itemChange(change, value);
+}
+
+
 QT_END_NAMESPACE

src/quick/items/qquickshadereffect_p.h

@@ -110,6 +110,7 @@ class Q_AUTOTEST_EXPORT QQuickShaderEffect : public QQuickItem
 protected:
     virtual void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry);
     virtual QSGNode *updatePaintNode(QSGNode *, UpdatePaintNodeData *);
+    virtual void itemChange(ItemChange change, const ItemChangeData &value);
 
 private Q_SLOTS:
     void changeSource(int index);

src/quick/items/qquickshadereffectsource.cpp

@@ -601,16 +601,18 @@ void QQuickShaderEffectSource::setSourceItem(QQuickItem *item)
         d->removeItemChangeListener(this, QQuickItemPrivate::Geometry);
     }
     m_sourceItem = item;
-    if (m_sourceItem) {
-        // TODO: Find better solution.
-        // 'm_sourceItem' needs a canvas to get a scenegraph node.
-        // The easiest way to make sure it gets a canvas is to
-        // make it a part of the same item tree as 'this'.
-        if (m_sourceItem->parentItem() == 0) {
-            m_sourceItem->setParentItem(this);
-            m_sourceItem->setVisible(false);
+
+    if (item) {
+        QQuickItemPrivate *d = QQuickItemPrivate::get(item);
+        // 'item' needs a canvas to get a scene graph node. It usually gets one through its
+        // parent, but if the source item is "inline" rather than a reference -- i.e.
+        // "sourceItem: Item { }" instead of "sourceItem: foo" -- it will not get a parent.
+        // In those cases, 'item' should get the canvas from 'this'.
+        if (!d->parentItem && canvas() && !d->canvas) {
+            QQuickItemPrivate::InitializationState initState;
+            initState.clear();
+            d->initCanvas(&initState, canvas());
         }
-        QQuickItemPrivate *d = QQuickItemPrivate::get(m_sourceItem);
         d->refFromEffectItem(m_hideSource);
         d->addItemChangeListener(this, QQuickItemPrivate::Geometry);
     }
@@ -918,4 +920,18 @@ QSGNode *QQuickShaderEffectSource::updatePaintNode(QSGNode *oldNode, UpdatePaint
     return node;
 }
 
+void QQuickShaderEffectSource::itemChange(ItemChange change, const ItemChangeData &value)
+{
+    if (change == QQuickItem::ItemSceneChange && m_sourceItem) {
+        // See comment in QQuickShaderEffectSource::setSourceItem().
+        QQuickItemPrivate *d = QQuickItemPrivate::get(m_sourceItem);
+        if (!d->parentItem && value.canvas != d->canvas) {
+            QQuickItemPrivate::InitializationState initState;
+            initState.clear();
+            d->initCanvas(&initState, value.canvas);
+        }
+    }
+    QQuickItem::itemChange(change, value);
+}
+
 QT_END_NAMESPACE

src/quick/items/qquickshadereffectsource_p.h

@@ -232,6 +232,7 @@ class Q_QUICK_EXPORT QQuickShaderEffectSource : public QQuickItem, public QQuick
     virtual QSGNode *updatePaintNode(QSGNode *, UpdatePaintNodeData *);
 
     virtual void itemGeometryChanged(QQuickItem *item, const QRectF &newRect, const QRectF &oldRect);
+    virtual void itemChange(ItemChange change, const ItemChangeData &value);
 
 private:
     void ensureTexture();