QWidget: add overload to set tab order as a list of widgets

The "two widgets at a time" API to set the tab order is awkward and
easily misused (as the documentation explicitly explains). Add an inline
overload that takes an initializer_list, and call the existing function
for each consecutive pair of widgets in the list.

Add documentation with snippet, and a test.

Change-Id: I8e6f14a242866e3ee7cfb8ecade4697d6bdfb4d4
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

src/widgets/doc/snippets/code/src_gui_kernel_qwidget.cpp

@@ -61,6 +61,11 @@ setTabOrder(c, d); // a to b to c to d
 //! [9]
 
 
+//! [9.list]
+setTabOrder({a, b, c, d}); // a to b to c to d
+//! [9.list]
+
+
 //! [10]
 // WRONG
 setTabOrder(c, d); // c to d

src/widgets/kernel/qwidget.cpp

@@ -6918,6 +6918,30 @@ bool QWidget::isActiveWindow() const
     return false;
 }
 
+/*!
+    \fn void QWidget::setTabOrder(std::initializer_list<QWidget *> widgets)
+    \overload
+    \since 6.6
+
+    Sets the tab order for the widgets in the \a widgets list by calling
+    \l{QWidget::setTabOrder(QWidget *, QWidget *)} for each consecutive
+    pair of widgets.
+
+    Instead of setting up each pair manually like this:
+
+    \snippet code/src_gui_kernel_qwidget.cpp 9
+
+    you can call:
+
+    \snippet code/src_gui_kernel_qwidget.cpp 9.list
+
+    The call does not create a closed tab focus loop. If there are more widgets
+    with \l{Qt::TabFocus} focus policy, tabbing on \c{d} will move focus to one
+    of those widgets, not back to \c{a}.
+
+    \sa setFocusPolicy(), setFocusProxy(), {Keyboard Focus in Widgets}
+*/
+
 /*!
     Puts the \a second widget after the \a first widget in the focus order.
 

src/widgets/kernel/qwidget.h

@@ -432,6 +432,7 @@ public:
     void setFocusPolicy(Qt::FocusPolicy policy);
     bool hasFocus() const;
     static void setTabOrder(QWidget *, QWidget *);
+    static inline void setTabOrder(std::initializer_list<QWidget *> widgets);
     void setFocusProxy(QWidget *);
     QWidget *focusProxy() const;
     Qt::ContextMenuPolicy contextMenuPolicy() const;
@@ -916,6 +917,18 @@ inline bool QWidget::testAttribute(Qt::WidgetAttribute attribute) const
     return testAttribute_helper(attribute);
 }
 
+inline void QWidget::setTabOrder(std::initializer_list<QWidget *> widgets)
+{
+    QWidget *prev = nullptr;
+    for (const auto &widget : widgets) {
+        if (!prev) {
+            prev = widget;
+        } else {
+            QWidget::setTabOrder(prev, widget);
+            prev = widget;
+        }
+    }
+}
 
 #define QWIDGETSIZE_MAX ((1<<24)-1)
 

tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp

@@ -173,6 +173,7 @@ private slots:
     void appFocusWidgetWhenLosingFocusProxy();
     void explicitTabOrderWithComplexWidget();
     void explicitTabOrderWithSpinBox_QTBUG81097();
+    void tabOrderList();
 #if defined(Q_OS_WIN)
     void activation();
 #endif
@@ -1929,6 +1930,26 @@ public:
     QLineEdit *lineEdit3;
 };
 
+static QList<QWidget *> getFocusChain(QWidget *start, bool bForward)
+{
+    QList<QWidget *> ret;
+    QWidget *cur = start;
+    // detect infinite loop
+    int count = 100;
+    auto loopGuard = qScopeGuard([]{
+        QFAIL("Inifinite loop detected in focus chain");
+    });
+    do {
+        ret += cur;
+        auto widgetPrivate = static_cast<QWidgetPrivate *>(qt_widget_private(cur));
+        cur = bForward ? widgetPrivate->focus_next : widgetPrivate->focus_prev;
+        if (!--count)
+            return ret;
+    } while (cur != start);
+    loopGuard.dismiss();
+    return ret;
+}
+
 void tst_QWidget::defaultTabOrder()
 {
     if (QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive))
@@ -2048,6 +2069,17 @@ void tst_QWidget::reverseTabOrder()
     QVERIFY(firstEdit->hasFocus());
 }
 
+void tst_QWidget::tabOrderList()
+{
+    Composite c;
+    QCOMPARE(getFocusChain(&c, true),
+             QList<QWidget *>({&c, c.lineEdit1, c.lineEdit2, c.lineEdit3}));
+    QWidget::setTabOrder({c.lineEdit3, c.lineEdit2, c.lineEdit1});
+    // not starting with 3 like one would maybe expect, but still 3, 2, 1
+    QCOMPARE(getFocusChain(&c, true),
+             QList<QWidget *>({&c, c.lineEdit1, c.lineEdit3, c.lineEdit2}));
+}
+
 void tst_QWidget::tabOrderWithProxy()
 {
     if (QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive))
@@ -2269,26 +2301,6 @@ void tst_QWidget::tabOrderWithCompoundWidgets()
     QVERIFY(lastEdit->hasFocus());
 }
 
-static QList<QWidget *> getFocusChain(QWidget *start, bool bForward)
-{
-    QList<QWidget *> ret;
-    QWidget *cur = start;
-    // detect infinite loop
-    int count = 100;
-    auto loopGuard = qScopeGuard([]{
-        QFAIL("Inifinite loop detected in focus chain");
-    });
-    do {
-        ret += cur;
-        auto widgetPrivate = static_cast<QWidgetPrivate *>(qt_widget_private(cur));
-        cur = bForward ? widgetPrivate->focus_next : widgetPrivate->focus_prev;
-        if (!--count)
-            return ret;
-    } while (cur != start);
-    loopGuard.dismiss();
-    return ret;
-}
-
 void tst_QWidget::tabOrderWithProxyOutOfOrder()
 {
     Container container;