StackView: allow choosing which transition to run

This is mostly useful for being able to use either push or pop
transition for replace operations, but there doesn't seem to be
any reason to limit the others. So, now it's able to run any of
the push/pop/replace transitions (or none with "immediate") for
any push/pop/replace operation.

[ChangeLog][StackView] Made it possible to choose the visual
transition type for any operation. This allows using for example
push and pop transitions with replace(), which allows implementing
an "infinite" back and forward navigation pattern while keeping
the amount of instantiated items constant.

Change-Id: I93b87cf854c3d6e2f33ef73ef25ffb3456ec27f4
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

4 files changed, 106 insertions, 25 deletions

diff --git a/src/quicktemplates2/qquickstackview.cpp b/src/quicktemplates2/qquickstackview.cpp
index 46c1d96e..6fd681c5 100644
--- a/src/quicktemplates2/qquickstackview.cpp
+++ b/src/quicktemplates2/qquickstackview.cpp
@@ -430,8 +430,11 @@ QQuickItem *QQuickStackView::find(const QJSValue &callback, LoadBehavior behavio
     An \a operation can be optionally specified as the last argument. Supported
     operations:
 
-    \value StackView.Transition An operation with transitions.
+    \value StackView.Transition An operation with default transitions (default).
     \value StackView.Immediate An immediate operation without transitions.
+    \value StackView.PushTransition An operation with push transitions (since QtQuick.Controls 2.1).
+    \value StackView.ReplaceTransition An operation with replace transitions (since QtQuick.Controls 2.1).
+    \value StackView.PopTransition An operation with pop transitions (since QtQuick.Controls 2.1).
 
     \sa initialItem
 */
@@ -447,7 +450,7 @@ void QQuickStackView::push(QQmlV4Function *args)
     QV4::ExecutionEngine *v4 = args->v4engine();
     QV4::Scope scope(v4);
 
-    Operation operation = d->elements.isEmpty() ? Immediate : Transition;
+    Operation operation = d->elements.isEmpty() ? Immediate : PushTransition;
     QV4::ScopedValue lastArg(scope, (*args)[args->length() - 1]);
     if (lastArg->isInt32())
         operation = static_cast<Operation>(lastArg->toInt32());
@@ -466,8 +469,8 @@ void QQuickStackView::push(QQmlV4Function *args)
     if (d->pushElements(elements)) {
         emit depthChanged();
         QQuickStackElement *enter = d->elements.top();
-        d->startTransition(QQuickStackTransition::enter(QQuickStackTransition::Push, enter, this),
-                           QQuickStackTransition::exit(QQuickStackTransition::Push, exit, this),
+        d->startTransition(QQuickStackTransition::pushEnter(operation, enter, this),
+                           QQuickStackTransition::pushExit(operation, exit, this),
                            operation == Immediate);
         d->setCurrentItem(enter->item);
     }
@@ -493,8 +496,11 @@ void QQuickStackView::push(QQmlV4Function *args)
     An \a operation can be optionally specified as the last argument. Supported
     operations:
 
-    \value StackView.Transition An operation with transitions.
+    \value StackView.Transition An operation with default transitions (default).
     \value StackView.Immediate An immediate operation without transitions.
+    \value StackView.PushTransition An operation with push transitions (since QtQuick.Controls 2.1).
+    \value StackView.ReplaceTransition An operation with replace transitions (since QtQuick.Controls 2.1).
+    \value StackView.PopTransition An operation with pop transitions (since QtQuick.Controls 2.1).
 
     Examples:
     \code
@@ -540,7 +546,7 @@ void QQuickStackView::pop(QQmlV4Function *args)
         }
     }
 
-    Operation operation = Transition;
+    Operation operation = PopTransition;
     if (argc > 0) {
         QV4::ScopedValue lastArg(scope, (*args)[argc - 1]);
         if (lastArg->isInt32())
@@ -555,8 +561,8 @@ void QQuickStackView::pop(QQmlV4Function *args)
             previousItem = exit->item;
         }
         emit depthChanged();
-        d->startTransition(QQuickStackTransition::exit(QQuickStackTransition::Pop, exit, this),
-                           QQuickStackTransition::enter(QQuickStackTransition::Pop, enter, this),
+        d->startTransition(QQuickStackTransition::popExit(operation, exit, this),
+                           QQuickStackTransition::popEnter(operation, enter, this),
                            operation == Immediate);
         d->setCurrentItem(enter->item);
     }
@@ -612,8 +618,39 @@ void QQuickStackView::pop(QQmlV4Function *args)
     An \a operation can be optionally specified as the last argument. Supported
     operations:
 
-    \value StackView.Transition An operation with transitions.
+    \value StackView.Transition An operation with default transitions (default).
     \value StackView.Immediate An immediate operation without transitions.
+    \value StackView.PushTransition An operation with push transitions (since QtQuick.Controls 2.1).
+    \value StackView.ReplaceTransition An operation with replace transitions (since QtQuick.Controls 2.1).
+    \value StackView.PopTransition An operation with pop transitions (since QtQuick.Controls 2.1).
+
+    The following example illustrates the use of push and pop transitions with replace().
+
+    \code
+    StackView {
+        id: stackView
+
+        initialItem: Component {
+            id: page
+
+            Page {
+                Row {
+                    spacing: 20
+                    anchors.centerIn: parent
+
+                    Button {
+                        text: "<"
+                        onClicked: stackView.replace(page, StackView.PopTransition)
+                    }
+                    Button {
+                        text: ">"
+                        onClicked: stackView.replace(page, StackView.PushTransition)
+                    }
+                }
+            }
+        }
+    }
+    \endcode
 
     \sa push()
 */
@@ -629,7 +666,7 @@ void QQuickStackView::replace(QQmlV4Function *args)
     QV4::ExecutionEngine *v4 = args->v4engine();
     QV4::Scope scope(v4);
 
-    Operation operation = d->elements.isEmpty() ? Immediate : Transition;
+    Operation operation = d->elements.isEmpty() ? Immediate : ReplaceTransition;
     QV4::ScopedValue lastArg(scope, (*args)[args->length() - 1]);
     if (lastArg->isInt32())
         operation = static_cast<Operation>(lastArg->toInt32());
@@ -659,8 +696,8 @@ void QQuickStackView::replace(QQmlV4Function *args)
         if (exit)
             exit->removal = true;
         QQuickStackElement *enter = d->elements.top();
-        d->startTransition(QQuickStackTransition::exit(QQuickStackTransition::Replace, exit, this),
-                           QQuickStackTransition::enter(QQuickStackTransition::Replace, enter, this),
+        d->startTransition(QQuickStackTransition::replaceExit(operation, exit, this),
+                           QQuickStackTransition::replaceEnter(operation, enter, this),
                            operation == Immediate);
         d->setCurrentItem(enter->item);
     }
diff --git a/src/quicktemplates2/qquickstackview_p.cpp b/src/quicktemplates2/qquickstackview_p.cpp
index c021ba77..5d25793e 100644
--- a/src/quicktemplates2/qquickstackview_p.cpp
+++ b/src/quicktemplates2/qquickstackview_p.cpp
@@ -501,7 +501,7 @@ void QQuickStackViewPrivate::setBusy(bool b)
     emit q->busyChanged();
 }
 
-QQuickStackTransition QQuickStackTransition::exit(Operation operation, QQuickStackElement *element, QQuickStackView *view)
+static QQuickStackTransition exitTransition(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
 {
     QQuickStackTransition st;
     st.status = QQuickStackView::Deactivating;
@@ -511,21 +511,21 @@ QQuickStackTransition QQuickStackTransition::exit(Operation operation, QQuickSta
     const QQuickItemViewTransitioner *transitioner = QQuickStackViewPrivate::get(view)->transitioner;
 
     switch (operation) {
-    case Push:
+    case QQuickStackView::PushTransition:
         st.target = false;
         st.type = QQuickItemViewTransitioner::AddTransition;
         st.viewBounds = QRectF();
         if (transitioner)
             st.transition = transitioner->addDisplacedTransition;
         break;
-    case Replace:
+    case QQuickStackView::ReplaceTransition:
         st.target = false;
         st.type = QQuickItemViewTransitioner::MoveTransition;
         st.viewBounds = QRectF();
         if (transitioner)
             st.transition = transitioner->moveDisplacedTransition;
         break;
-    case Pop:
+    case QQuickStackView::PopTransition:
         st.target = true;
         st.type = QQuickItemViewTransitioner::RemoveTransition;
         st.viewBounds = view->boundingRect();
@@ -540,7 +540,7 @@ QQuickStackTransition QQuickStackTransition::exit(Operation operation, QQuickSta
     return st;
 }
 
-QQuickStackTransition QQuickStackTransition::enter(Operation operation, QQuickStackElement *element, QQuickStackView *view)
+static QQuickStackTransition enterTransition(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
 {
     QQuickStackTransition st;
     st.status = QQuickStackView::Activating;
@@ -550,21 +550,21 @@ QQuickStackTransition QQuickStackTransition::enter(Operation operation, QQuickSt
     const QQuickItemViewTransitioner *transitioner = QQuickStackViewPrivate::get(view)->transitioner;
 
     switch (operation) {
-    case Push:
+    case QQuickStackView::PushTransition:
         st.target = true;
         st.type = QQuickItemViewTransitioner::AddTransition;
         st.viewBounds = view->boundingRect();
         if (transitioner)
             st.transition = transitioner->addTransition;
         break;
-    case Replace:
+    case QQuickStackView::ReplaceTransition:
         st.target = true;
         st.type = QQuickItemViewTransitioner::MoveTransition;
         st.viewBounds = view->boundingRect();
         if (transitioner)
             st.transition = transitioner->moveTransition;
         break;
-    case Pop:
+    case QQuickStackView::PopTransition:
         st.target = false;
         st.type = QQuickItemViewTransitioner::RemoveTransition;
         st.viewBounds = QRectF();
@@ -579,4 +579,41 @@ QQuickStackTransition QQuickStackTransition::enter(Operation operation, QQuickSt
     return st;
 }
 
+static QQuickStackView::Operation operationTransition(QQuickStackView::Operation operation, QQuickStackView::Operation transition)
+{
+    if (operation == QQuickStackView::Immediate || operation == QQuickStackView::Transition)
+        return transition;
+    return operation;
+}
+
+QQuickStackTransition QQuickStackTransition::popExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return exitTransition(operationTransition(operation, QQuickStackView::PopTransition), element, view);
+}
+
+QQuickStackTransition QQuickStackTransition::popEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return enterTransition(operationTransition(operation, QQuickStackView::PopTransition), element, view);
+}
+
+QQuickStackTransition QQuickStackTransition::pushExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return exitTransition(operationTransition(operation, QQuickStackView::PushTransition), element, view);
+}
+
+QQuickStackTransition QQuickStackTransition::pushEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return enterTransition(operationTransition(operation, QQuickStackView::PushTransition), element, view);
+}
+
+QQuickStackTransition QQuickStackTransition::replaceExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return exitTransition(operationTransition(operation, QQuickStackView::ReplaceTransition), element, view);
+}
+
+QQuickStackTransition QQuickStackTransition::replaceEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view)
+{
+    return enterTransition(operationTransition(operation, QQuickStackView::ReplaceTransition), element, view);
+}
+
 QT_END_NAMESPACE
diff --git a/src/quicktemplates2/qquickstackview_p.h b/src/quicktemplates2/qquickstackview_p.h
index 579a6c7f..c76f8167 100644
--- a/src/quicktemplates2/qquickstackview_p.h
+++ b/src/quicktemplates2/qquickstackview_p.h
@@ -121,8 +121,11 @@ public:
     Q_INVOKABLE QQuickItem *find(const QJSValue &callback, LoadBehavior behavior = DontLoad);
 
     enum Operation {
-        Transition,
-        Immediate
+        Transition = -1, // deprecated
+        Immediate = 0,
+        PushTransition = 1,
+        ReplaceTransition = 2,
+        PopTransition = 3,
     };
     Q_ENUM(Operation)
 
diff --git a/src/quicktemplates2/qquickstackview_p_p.h b/src/quicktemplates2/qquickstackview_p_p.h
index 7fe7f005..c7691c40 100644
--- a/src/quicktemplates2/qquickstackview_p_p.h
+++ b/src/quicktemplates2/qquickstackview_p_p.h
@@ -140,10 +140,14 @@ public:
 
 struct QQuickStackTransition
 {
-    enum Operation { Push, Replace, Pop };
+    static QQuickStackTransition popExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
+    static QQuickStackTransition popEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
 
-    static QQuickStackTransition exit(Operation operation, QQuickStackElement *element, QQuickStackView *view);
-    static QQuickStackTransition enter(Operation operation, QQuickStackElement *element, QQuickStackView *view);
+    static QQuickStackTransition pushExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
+    static QQuickStackTransition pushEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
+
+    static QQuickStackTransition replaceExit(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
+    static QQuickStackTransition replaceEnter(QQuickStackView::Operation operation, QQuickStackElement *element, QQuickStackView *view);
 
     bool target;
     QQuickStackView::Status status;