Add widgetAdded signal for QStackedWidget and QStackedLayout

Currently, there is no signal provided when a widget is added
or inserted into QStackedWidget or QStackedLayout.

Emit a signal whenever a widget is added or inserted into
QStackedWidget or QStackedLayout.

[ChangeLog][QtWidgets][QStackedWidget] The widgetAdded() signal
emits whenever a widget is added or inserted into QStackedWidget
or QStackedLayout.

Fixes: QTBUG-122748
Change-Id: I3bf658346a5881665214a8d8f77975aa10e497c0
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/widgets/kernel/qstackedlayout.cpp

@@ -113,6 +113,17 @@ QLayoutItem* QStackedLayoutPrivate::replaceAt(int idx, QLayoutItem *newitem)
     \sa removeWidget()
 */
 
+/*!
+    \fn void QStackedLayout::widgetAdded(int index)
+
+    \since 6.9
+
+    This signal is emitted whenever a widget is added or inserted.
+    The widget's \a index is passed as parameter.
+
+    \sa addWidget(), insertWidget()
+*/
+
 /*!
     Constructs a QStackedLayout with no parent.
 
@@ -204,6 +215,7 @@ int QStackedLayout::insertWidget(int index, QWidget *widget)
             widget->hide();
         widget->lower();
     }
+    emit widgetAdded(index);
     return index;
 }
 

src/widgets/kernel/qstackedlayout.h

@@ -57,6 +57,7 @@ public:
 Q_SIGNALS:
     void widgetRemoved(int index);
     void currentChanged(int index);
+    void widgetAdded(int index);
 
 public Q_SLOTS:
     void setCurrentIndex(int index);

src/widgets/widgets/qstackedwidget.cpp

@@ -88,6 +88,18 @@ public:
     \sa removeWidget()
 */
 
+/*!
+    \fn void QStackedWidget::widgetAdded(int index)
+
+    \since 6.9
+
+    This signal is emitted whenever a widget is added or inserted.
+    The widget's \a index is passed as parameter.
+
+    \sa addWidget(), insertWidget()
+*/
+
+
 /*!
     Constructs a QStackedWidget with the given \a parent.
 
@@ -102,6 +114,8 @@ QStackedWidget::QStackedWidget(QWidget *parent)
             this, &QStackedWidget::widgetRemoved);
     connect(d->layout, &QStackedLayout::currentChanged,
             this, &QStackedWidget::currentChanged);
+    connect(d->layout, &QStackedLayout::widgetAdded,
+            this, &QStackedWidget::widgetAdded);
 }
 
 /*!

src/widgets/widgets/qstackedwidget.h

@@ -41,6 +41,7 @@ public Q_SLOTS:
 Q_SIGNALS:
     void currentChanged(int);
     void widgetRemoved(int index);
+    void widgetAdded(int index);
 
 protected:
     bool event(QEvent *e) override;

tests/auto/widgets/kernel/qstackedlayout/tst_qstackedlayout.cpp

@@ -31,6 +31,7 @@ private slots:
     void keepFocusAfterSetCurrent();
     void heigthForWidth();
     void replaceWidget();
+    void widgetAdded();
 
 private:
     QWidget *testWidget;
@@ -353,6 +354,27 @@ void tst_QStackedLayout::replaceWidget()
     QCOMPARE(stackLayout->currentWidget(), replaceTo);
 }
 
+
+void tst_QStackedLayout::widgetAdded()
+{
+    QStackedLayout stackedLayout;
+    QSignalSpy addSpy(&stackedLayout, &QStackedLayout::widgetAdded);
+    QVERIFY(addSpy.isValid());
+
+    stackedLayout.addWidget(new QWidget);
+    QCOMPARE(addSpy.count(), 1);
+    QCOMPARE(addSpy.at(0).at(0).toInt(), 0);
+
+    stackedLayout.insertWidget(1, new QWidget);
+    QCOMPARE(addSpy.count(), 2);
+    QCOMPARE(addSpy.at(1).at(0).toInt(), 1);
+
+    stackedLayout.insertWidget(100, new QWidget);
+    QCOMPARE(addSpy.count(), 3);
+    QCOMPARE(addSpy.at(2).at(0).toInt(), 2);
+}
+
+
 QTEST_MAIN(tst_QStackedLayout)
 #include "tst_qstackedlayout.moc"
 

tests/auto/widgets/widgets/qstackedwidget/tst_qstackedwidget.cpp

@@ -10,6 +10,7 @@
 #include <qpushbutton.h>
 #include <QHBoxLayout>
 #include <qlineedit.h>
+#include <QSignalSpy>
 
 #include <QtWidgets/private/qapplication_p.h>
 
@@ -25,6 +26,7 @@ private slots:
     void getSetCheck();
     void testMinimumSize();
     void dynamicPages();
+    void widgetAdded();
 };
 
 tst_QStackedWidget::tst_QStackedWidget()
@@ -172,5 +174,24 @@ void tst_QStackedWidget::dynamicPages()
 
 }
 
+void tst_QStackedWidget::widgetAdded()
+{
+    QStackedWidget stackedWidget;
+    QSignalSpy addSpy(&stackedWidget, &QStackedWidget::widgetAdded);
+    QVERIFY(addSpy.isValid());
+
+    stackedWidget.addWidget(new QWidget);
+    QCOMPARE(addSpy.count(), 1);
+    QCOMPARE(addSpy.at(0).at(0).toInt(), 0);
+
+    stackedWidget.insertWidget(1, new QWidget);
+    QCOMPARE(addSpy.count(), 2);
+    QCOMPARE(addSpy.at(1).at(0).toInt(), 1);
+
+    stackedWidget.insertWidget(100, new QWidget);
+    QCOMPARE(addSpy.count(), 3);
+    QCOMPARE(addSpy.at(2).at(0).toInt(), 2);
+}
+
 QTEST_MAIN(tst_QStackedWidget)
 #include "tst_qstackedwidget.moc"