Add StackView::empty for convenience

"stack.empty" looks cleaner in bindings than "stack.depth === 0"

Change-Id: Ia99ea8ff2a8cf76a752917c239874d24d2103312
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

4 files changed, 33 insertions, 5 deletions

diff --git a/src/quicktemplates2/qquickstackview.cpp b/src/quicktemplates2/qquickstackview.cpp
index e1740273..ee975056 100644
--- a/src/quicktemplates2/qquickstackview.cpp
+++ b/src/quicktemplates2/qquickstackview.cpp
@@ -517,7 +517,7 @@ void QQuickStackView::push(QQmlV4Function *args)
         exit = d->elements.top();
 
     if (d->pushElements(elements)) {
-        emit depthChanged();
+        d->depthChange();
         QQuickStackElement *enter = d->elements.top();
         d->startTransition(QQuickStackTransition::pushEnter(operation, enter, this),
                            QQuickStackTransition::pushExit(operation, exit, this),
@@ -612,7 +612,7 @@ void QQuickStackView::pop(QQmlV4Function *args)
             d->removing.insert(exit);
             previousItem = exit->item;
         }
-        emit depthChanged();
+        d->depthChange();
         d->startTransition(QQuickStackTransition::popExit(operation, exit, this),
                            QQuickStackTransition::popEnter(operation, enter, this),
                            operation == Immediate);
@@ -759,7 +759,7 @@ void QQuickStackView::replace(QQmlV4Function *args)
 
     if (exit != target ? d->replaceElements(target, elements) : d->pushElements(elements)) {
         if (depth != d->elements.count())
-            emit depthChanged();
+            d->depthChange();
         if (exit) {
             exit->removal = true;
             d->removing.insert(exit);
@@ -780,6 +780,21 @@ void QQuickStackView::replace(QQmlV4Function *args)
 }
 
 /*!
+    \since QtQuick.Controls 2.3
+    \qmlproperty bool QtQuick.Controls::StackView::empty
+    \readonly
+
+    This property holds whether the stack is empty.
+
+    \sa depth
+*/
+bool QQuickStackView::isEmpty() const
+{
+    Q_D(const QQuickStackView);
+    return d->elements.isEmpty();
+}
+
+/*!
     \qmlmethod void QtQuick.Controls::StackView::clear(transition)
 
     Removes all items from the stack.
@@ -808,7 +823,7 @@ void QQuickStackView::clear(Operation operation)
     d->setCurrentItem(nullptr);
     qDeleteAll(d->elements);
     d->elements.clear();
-    emit depthChanged();
+    d->depthChange();
 }
 
 /*!
@@ -1012,7 +1027,7 @@ void QQuickStackView::componentComplete()
     if (!error.isEmpty()) {
         d->warn(error);
     } else if (d->pushElement(element)) {
-        emit depthChanged();
+        d->depthChange();
         d->setCurrentItem(element);
         element->setStatus(QQuickStackView::Active);
     }
diff --git a/src/quicktemplates2/qquickstackview_p.cpp b/src/quicktemplates2/qquickstackview_p.cpp
index 3c983d6b..69ad7848 100644
--- a/src/quicktemplates2/qquickstackview_p.cpp
+++ b/src/quicktemplates2/qquickstackview_p.cpp
@@ -297,4 +297,12 @@ void QQuickStackViewPrivate::setBusy(bool b)
     emit q->busyChanged();
 }
 
+void QQuickStackViewPrivate::depthChange()
+{
+    Q_Q(QQuickStackView);
+    emit q->depthChanged();
+    if (elements.count() <= 1)
+        emit q->emptyChanged();
+}
+
 QT_END_NAMESPACE
diff --git a/src/quicktemplates2/qquickstackview_p.h b/src/quicktemplates2/qquickstackview_p.h
index 22392698..21c20f3a 100644
--- a/src/quicktemplates2/qquickstackview_p.h
+++ b/src/quicktemplates2/qquickstackview_p.h
@@ -72,6 +72,7 @@ class Q_QUICKTEMPLATES2_PRIVATE_EXPORT QQuickStackView : public QQuickControl
     Q_PROPERTY(QQuickTransition *pushExit READ pushExit WRITE setPushExit NOTIFY pushExitChanged FINAL)
     Q_PROPERTY(QQuickTransition *replaceEnter READ replaceEnter WRITE setReplaceEnter NOTIFY replaceEnterChanged FINAL)
     Q_PROPERTY(QQuickTransition *replaceExit READ replaceExit WRITE setReplaceExit NOTIFY replaceExitChanged FINAL)
+    Q_PROPERTY(bool empty READ isEmpty NOTIFY emptyChanged FINAL REVISION 3)
 
 public:
     explicit QQuickStackView(QQuickItem *parent = nullptr);
@@ -134,6 +135,8 @@ public:
     Q_INVOKABLE void pop(QQmlV4Function *args);
     Q_INVOKABLE void replace(QQmlV4Function *args);
 
+    bool isEmpty() const;
+
 public Q_SLOTS:
     void clear(Operation operation = Immediate);
 
@@ -147,6 +150,7 @@ Q_SIGNALS:
     void pushExitChanged();
     void replaceEnterChanged();
     void replaceExitChanged();
+    Q_REVISION(3) void emptyChanged();
 
 protected:
     void componentComplete() override;
diff --git a/src/quicktemplates2/qquickstackview_p_p.h b/src/quicktemplates2/qquickstackview_p_p.h
index 81ca9164..871891aa 100644
--- a/src/quicktemplates2/qquickstackview_p_p.h
+++ b/src/quicktemplates2/qquickstackview_p_p.h
@@ -92,6 +92,7 @@ public:
 
     void viewItemTransitionFinished(QQuickItemViewTransitionableItem *item) override;
     void setBusy(bool busy);
+    void depthChange();
 
     bool busy;
     QString operation;