populate transition for positioners

Fix positioners to apply a "populate" transition for initially added
items. This is consistent with ListView and GridView and also fixes the
behaviour from QtQuick 1.x where the positioners were instead running
the "move" transition for initially added items.

Change-Id: Ib43f1141ce3e7379df085c178b684f89b8567403
Reviewed-by: Alan Alpert <alan.alpert@nokia.com>

3 files changed, 133 insertions, 21 deletions

diff --git a/src/quick/items/qquickitemviewtransition.cpp b/src/quick/items/qquickitemviewtransition.cpp
index c680945e04..c1f1e515ff 100644
--- a/src/quick/items/qquickitemviewtransition.cpp
+++ b/src/quick/items/qquickitemviewtransition.cpp
@@ -577,8 +577,8 @@ QQuickViewTransitionAttached::QQuickViewTransitionAttached(QObject *parent)
     operations:
 
     \list
-    \li \c populate - the transition to run when a view is created, or when the model changes
-    \li \c add - the transition to apply to items that are added to the view
+    \li \c populate - the transition to apply to the items created initially for the view, or when the model changes
+    \li \c add - the transition to apply to items that are added to the view after it has been created
     \li \c remove - the transition to apply to items that are removed from the view
     \li \c move - the transition to apply to items that are moved within the view (i.e. as a result
        of a move operation in the model)
@@ -593,7 +593,9 @@ QQuickViewTransitionAttached::QQuickViewTransitionAttached(QObject *parent)
     items rather than data models, the following properties are used instead:
 
     \list
-    \li \c add - the transition to apply to items that are created for the positioner, added to
+    \li \c populate - the transition to apply to items that have been added to the positioner at the
+       time of its creation
+    \li \c add - the transition to apply to items that are added to
        or reparented to the positioner, or items that have become \l {Item::}{visible}
     \li \c move - the transition to apply to items that have moved within the positioner, including
        when they are displaced due to the addition or removal of other items, or when items are otherwise
diff --git a/src/quick/items/qquickpositioners.cpp b/src/quick/items/qquickpositioners.cpp
index 97a74c6765..37c3ef1224 100644
--- a/src/quick/items/qquickpositioners.cpp
+++ b/src/quick/items/qquickpositioners.cpp
@@ -195,6 +195,23 @@ void QQuickBasePositioner::setSpacing(qreal s)
     emit spacingChanged();
 }
 
+QQuickTransition *QQuickBasePositioner::populate() const
+{
+    Q_D(const QQuickBasePositioner);
+    return d->transitioner ? d->transitioner->populateTransition : 0;
+}
+
+void QQuickBasePositioner::setPopulate(QQuickTransition *transition)
+{
+    Q_D(QQuickBasePositioner);
+    if (!d->transitioner)
+        d->transitioner = new QQuickItemViewTransitioner;
+    if (d->transitioner->populateTransition != transition) {
+        d->transitioner->populateTransition = transition;
+        emit populateChanged();
+    }
+}
+
 QQuickTransition *QQuickBasePositioner::move() const
 {
     Q_D(const QQuickBasePositioner);
@@ -233,9 +250,14 @@ void QQuickBasePositioner::setAdd(QQuickTransition *add)
 
 void QQuickBasePositioner::componentComplete()
 {
+    Q_D(QQuickBasePositioner);
     QQuickItem::componentComplete();
+    if (d->transitioner)
+        d->transitioner->setPopulateTransitionEnabled(true);
     positionedItems.reserve(childItems().count());
     prePositioning();
+    if (d->transitioner)
+        d->transitioner->setPopulateTransitionEnabled(false);
 }
 
 void QQuickBasePositioner::itemChange(ItemChange change, const ItemChangeData &value)
@@ -301,7 +323,10 @@ void QQuickBasePositioner::prePositioning()
                     if (addedIndex < 0)
                         addedIndex = posItem.index;
                     PositionedItem *theItem = &positionedItems[positionedItems.count()-1];
-                    theItem->transitionNextReposition(d->transitioner, QQuickItemViewTransitioner::AddTransition, true);
+                    if (d->transitioner->canTransition(QQuickItemViewTransitioner::PopulateTransition, true))
+                        theItem->transitionNextReposition(d->transitioner, QQuickItemViewTransitioner::PopulateTransition, true);
+                    else if (!d->transitioner->populateTransitionEnabled())
+                        theItem->transitionNextReposition(d->transitioner, QQuickItemViewTransitioner::AddTransition, true);
                 }
             }
         } else {
@@ -354,7 +379,7 @@ void QQuickBasePositioner::prePositioning()
     }
 
     if (d->transitioner) {
-        QRectF viewBounds;
+        QRectF viewBounds(QPointF(), contentSize);
         for (int i=0; i<positionedItems.count(); i++)
             positionedItems[i].prepareTransition(d->transitioner, viewBounds);
         for (int i=0; i<positionedItems.count(); i++)
@@ -602,13 +627,27 @@ void QQuickPositionerAttached::setIsLastItem(bool isLastItem)
     \sa Row, Grid, Flow, Positioner, {qml/positioners}{Positioners example}
 */
 /*!
+    \qmlproperty Transition QtQuick2::Column::populate
+
+    This property holds the transition to be run for items that are part of
+    this positioner at the time of its creation. The transition is run when the positioner
+    is first created.
+
+    The transition can use the \l ViewTransition property to access more details about
+    the item that is being added. See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
+
+    \sa add, ViewTransition, {declarative/positioners}{Positioners example}
+*/
+/*!
     \qmlproperty Transition QtQuick2::Column::add
 
     This property holds the transition to be run for items that are added to this
     positioner. For a positioner, this applies to:
 
     \list
-    \li Items that are created or reparented as a child of the positioner
+    \li Items that are created or reparented as a child of the positioner after the
+        positioner has been created
     \li Child items that change their \l visible property from false to true, and thus
        are now visible
     \endlist
@@ -617,7 +656,10 @@ void QQuickPositionerAttached::setIsLastItem(bool isLastItem)
     the item that is being added. See the \l ViewTransition documentation for more details
     and examples on using these transitions.
 
-    \sa move, ViewTransition, {declarative/positioners}{Positioners example}
+    \note This transition is not applied to the items that already part of the positioner
+    at the time of its creation. In this case, the \l populate transition is applied instead.
+
+    \sa populate, ViewTransition, {declarative/positioners}{Positioners example}
 */
 /*!
     \qmlproperty Transition QtQuick2::Column::move
@@ -635,9 +677,12 @@ void QQuickPositionerAttached::setIsLastItem(bool isLastItem)
     the item that is being moved. Note, however, that for this move transition, the
     ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
     this transition is triggered by the addition of other items in the positioner; in other
-    cases, these lists will be empty.
+    cases, these lists will be empty.  See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
 
-    See the \l ViewTransition documentation for more details and examples on using these transitions.
+    \note In QtQuick 1, this transition was applied to all items that were part of the
+    positioner at the time of its creation. From QtQuick 2 onwards, positioners apply the
+    \l populate transition to these items instead.
 
     \sa add, ViewTransition, {qml/positioners}{Positioners example}
 */
@@ -735,13 +780,27 @@ void QQuickColumn::reportConflictingAnchors()
     \sa Column, Grid, Flow, Positioner, {qml/positioners}{Positioners example}
 */
 /*!
+    \qmlproperty Transition QtQuick2::Row::populate
+
+    This property holds the transition to be run for items that are part of
+    this positioner at the time of its creation. The transition is run when the positioner
+    is first created.
+
+    The transition can use the \l ViewTransition property to access more details about
+    the item that is being added. See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
+
+    \sa add, ViewTransition, {declarative/positioners}{Positioners example}
+*/
+/*!
     \qmlproperty Transition QtQuick2::Row::add
 
     This property holds the transition to be run for items that are added to this
     positioner. For a positioner, this applies to:
 
     \list
-    \li Items that are created or reparented as a child of the positioner
+    \li Items that are created or reparented as a child of the positioner after the
+        positioner has been created
     \li Child items that change their \l visible property from false to true, and thus
        are now visible
     \endlist
@@ -750,7 +809,10 @@ void QQuickColumn::reportConflictingAnchors()
     the item that is being added. See the \l ViewTransition documentation for more details
     and examples on using these transitions.
 
-    \sa move, ViewTransition, {declarative/positioners}{Positioners example}
+    \note This transition is not applied to the items that already part of the positioner
+    at the time of its creation. In this case, the \l populate transition is applied instead.
+
+    \sa populate, ViewTransition, {declarative/positioners}{Positioners example}
 */
 /*!
     \qmlproperty Transition QtQuick2::Row::move
@@ -768,9 +830,12 @@ void QQuickColumn::reportConflictingAnchors()
     the item that is being moved. Note, however, that for this move transition, the
     ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
     this transition is triggered by the addition of other items in the positioner; in other
-    cases, these lists will be empty.
+    cases, these lists will be empty.  See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
 
-    See the \l ViewTransition documentation for more details and examples on using these transitions.
+    \note In QtQuick 1, this transition was applied to all items that were part of the
+    positioner at the time of its creation. From QtQuick 2 onwards, positioners apply the
+    \l populate transition to these items instead.
 
     \sa add, ViewTransition, {qml/positioners}{Positioners example}
 */
@@ -947,13 +1012,27 @@ void QQuickRow::reportConflictingAnchors()
     \sa Flow, Row, Column, Positioner, {qml/positioners}{Positioners example}
 */
 /*!
+    \qmlproperty Transition QtQuick2::Grid::populate
+
+    This property holds the transition to be run for items that are part of
+    this positioner at the time of its creation. The transition is run when the positioner
+    is first created.
+
+    The transition can use the \l ViewTransition property to access more details about
+    the item that is being added. See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
+
+    \sa add, ViewTransition, {declarative/positioners}{Positioners example}
+*/
+/*!
     \qmlproperty Transition QtQuick2::Grid::add
 
     This property holds the transition to be run for items that are added to this
     positioner. For a positioner, this applies to:
 
     \list
-    \li Items that are created or reparented as a child of the positioner
+    \li Items that are created or reparented as a child of the positioner after the
+        positioner has been created
     \li Child items that change their \l visible property from false to true, and thus
        are now visible
     \endlist
@@ -962,7 +1041,10 @@ void QQuickRow::reportConflictingAnchors()
     the item that is being added. See the \l ViewTransition documentation for more details
     and examples on using these transitions.
 
-    \sa move, ViewTransition, {declarative/positioners}{Positioners example}
+    \note This transition is not applied to the items that already part of the positioner
+    at the time of its creation. In this case, the \l populate transition is applied instead.
+
+    \sa populate, ViewTransition, {declarative/positioners}{Positioners example}
 */
 /*!
     \qmlproperty Transition QtQuick2::Grid::move
@@ -980,9 +1062,12 @@ void QQuickRow::reportConflictingAnchors()
     the item that is being moved. Note, however, that for this move transition, the
     ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
     this transition is triggered by the addition of other items in the positioner; in other
-    cases, these lists will be empty.
+    cases, these lists will be empty.  See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
 
-    See the \l ViewTransition documentation for more details and examples on using these transitions.
+    \note In QtQuick 1, this transition was applied to all items that were part of the
+    positioner at the time of its creation. From QtQuick 2 onwards, positioners apply the
+    \l populate transition to these items instead.
 
     \sa add, ViewTransition, {qml/positioners}{Positioners example}
 */
@@ -1360,13 +1445,27 @@ void QQuickGrid::reportConflictingAnchors()
   \sa Column, Row, Grid, Positioner, {qml/positioners}{Positioners example}
 */
 /*!
+    \qmlproperty Transition QtQuick2::Flow::populate
+
+    This property holds the transition to be run for items that are part of
+    this positioner at the time of its creation. The transition is run when the positioner
+    is first created.
+
+    The transition can use the \l ViewTransition property to access more details about
+    the item that is being added. See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
+
+    \sa add, ViewTransition, {declarative/positioners}{Positioners example}
+*/
+/*!
     \qmlproperty Transition QtQuick2::Flow::add
 
     This property holds the transition to be run for items that are added to this
     positioner. For a positioner, this applies to:
 
     \list
-    \li Items that are created or reparented as a child of the positioner
+    \li Items that are created or reparented as a child of the positioner after the
+        positioner has been created
     \li Child items that change their \l visible property from false to true, and thus
        are now visible
     \endlist
@@ -1375,7 +1474,10 @@ void QQuickGrid::reportConflictingAnchors()
     the item that is being added. See the \l ViewTransition documentation for more details
     and examples on using these transitions.
 
-    \sa move, ViewTransition, {declarative/positioners}{Positioners example}
+    \note This transition is not applied to the items that already part of the positioner
+    at the time of its creation. In this case, the \l populate transition is applied instead.
+
+    \sa populate, ViewTransition, {declarative/positioners}{Positioners example}
 */
 /*!
     \qmlproperty Transition QtQuick2::Flow::move
@@ -1393,9 +1495,12 @@ void QQuickGrid::reportConflictingAnchors()
     the item that is being moved. Note, however, that for this move transition, the
     ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
     this transition is triggered by the addition of other items in the positioner; in other
-    cases, these lists will be empty.
+    cases, these lists will be empty.  See the \l ViewTransition documentation for more details
+    and examples on using these transitions.
 
-    See the \l ViewTransition documentation for more details and examples on using these transitions.
+    \note In QtQuick 1, this transition was applied to all items that were part of the
+    positioner at the time of its creation. From QtQuick 2 onwards, positioners apply the
+    \l populate transition to these items instead.
 
     \sa add, ViewTransition, {qml/positioners}{Positioners example}
 */
diff --git a/src/quick/items/qquickpositioners_p.h b/src/quick/items/qquickpositioners_p.h
index c13d9975af..7463d0db7e 100644
--- a/src/quick/items/qquickpositioners_p.h
+++ b/src/quick/items/qquickpositioners_p.h
@@ -93,6 +93,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickBasePositioner : public QQuickImplicitSizeIte
     Q_OBJECT
 
     Q_PROPERTY(qreal spacing READ spacing WRITE setSpacing NOTIFY spacingChanged)
+    Q_PROPERTY(QQuickTransition *populate READ populate WRITE setPopulate NOTIFY populateChanged)
     Q_PROPERTY(QQuickTransition *move READ move WRITE setMove NOTIFY moveChanged)
     Q_PROPERTY(QQuickTransition *add READ add WRITE setAdd NOTIFY addChanged)
 public:
@@ -104,6 +105,9 @@ public:
     qreal spacing() const;
     void setSpacing(qreal);
 
+    QQuickTransition *populate() const;
+    void setPopulate(QQuickTransition *);
+
     QQuickTransition *move() const;
     void setMove(QQuickTransition *);
 
@@ -123,6 +127,7 @@ protected:
 
 Q_SIGNALS:
     void spacingChanged();
+    void populateChanged();
     void moveChanged();
     void addChanged();