QTabWidget: Do not add tabbar size during sizeHint() when it is hidden

Since Qt 5.4 the QTabBar can be automatically hidden when it has less
then 2 tabs. Therefore the sizeHint should not consider the tabbars
size when the tabbar is hidden.

Task-number: QTBUG-64715
Change-Id: I2f248f88d9070de5354f7344c7628a78442ab499
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

2 files changed, 53 insertions, 12 deletions

diff --git a/src/widgets/widgets/qtabwidget.cpp b/src/widgets/widgets/qtabwidget.cpp
index 60a924510a..894053ec19 100644
--- a/src/widgets/widgets/qtabwidget.cpp
+++ b/src/widgets/widgets/qtabwidget.cpp
@@ -195,6 +195,11 @@ public:
     void _q_removeTab(int);
     void _q_tabMoved(int from, int to);
     void init();
+    bool isAutoHidden() const
+    {
+        // see QTabBarPrivate::autoHideTabs()
+        return (tabs->autoHide() && tabs->count() <= 1);
+    }
 
     void initBasicStyleOption(QStyleOptionTabWidgetFrame *option) const;
 
@@ -841,11 +846,14 @@ QSize QTabWidget::sizeHint() const
         that->setUpLayout(true);
     }
     QSize s(d->stack->sizeHint());
-    QSize t(d->tabs->sizeHint());
-    if(usesScrollButtons())
-        t = t.boundedTo(QSize(200,200));
-    else
-        t = t.boundedTo(QDesktopWidgetPrivate::size());
+    QSize t;
+    if (!d->isAutoHidden()) {
+        t = d->tabs->sizeHint();
+        if (usesScrollButtons())
+            t = t.boundedTo(QSize(200,200));
+        else
+            t = t.boundedTo(QDesktopWidgetPrivate::size());
+    }
 
     QSize sz = basicSize(d->pos == North || d->pos == South, lc, rc, s, t);
 
@@ -873,7 +881,9 @@ QSize QTabWidget::minimumSizeHint() const
         that->setUpLayout(true);
     }
     QSize s(d->stack->minimumSizeHint());
-    QSize t(d->tabs->minimumSizeHint());
+    QSize t;
+    if (!d->isAutoHidden())
+        t = d->tabs->minimumSizeHint();
 
     QSize sz = basicSize(d->pos == North || d->pos == South, lc, rc, s, t);
 
@@ -908,12 +918,14 @@ int QTabWidget::heightForWidth(int width) const
         QTabWidget *that = const_cast<QTabWidget*>(this);
         that->setUpLayout(true);
     }
-    QSize t(d->tabs->sizeHint());
-
-    if(usesScrollButtons())
-        t = t.boundedTo(QSize(200,200));
-    else
-        t = t.boundedTo(QDesktopWidgetPrivate::size());
+    QSize t;
+    if (!d->isAutoHidden()) {
+        t = d->tabs->sizeHint();
+        if (usesScrollButtons())
+            t = t.boundedTo(QSize(200,200));
+        else
+            t = t.boundedTo(QDesktopWidgetPrivate::size());
+    }
 
     const bool tabIsHorizontal = (d->pos == North || d->pos == South);
     const int contentsWidth = width - padding.width();
diff --git a/tests/auto/widgets/widgets/qtabwidget/tst_qtabwidget.cpp b/tests/auto/widgets/widgets/qtabwidget/tst_qtabwidget.cpp
index 2a2331c3bf..b5ffb90e42 100644
--- a/tests/auto/widgets/widgets/qtabwidget/tst_qtabwidget.cpp
+++ b/tests/auto/widgets/widgets/qtabwidget/tst_qtabwidget.cpp
@@ -98,6 +98,7 @@ private slots:
     void heightForWidth();
     void tabBarClicked();
     void moveCurrentTab();
+    void autoHide();
 
   private:
     int addPage();
@@ -713,5 +714,33 @@ void tst_QTabWidget::moveCurrentTab()
     QCOMPARE(tabWidget.currentWidget(), secondTab);
 }
 
+void tst_QTabWidget::autoHide()
+{
+    QTabWidget tabWidget;
+    QWidget* firstTab = new QWidget(&tabWidget);
+    tabWidget.addTab(firstTab, "0");
+    const auto sizeHint1 = tabWidget.sizeHint();
+    const auto minSizeHint1 = tabWidget.minimumSizeHint();
+    const auto heightForWidth1 = tabWidget.heightForWidth(20);
+
+    QWidget* secondTab = new QWidget(&tabWidget);
+    tabWidget.addTab(secondTab, "1");
+    const auto sizeHint2 = tabWidget.sizeHint();
+    const auto minSizeHint2 = tabWidget.minimumSizeHint();
+    const auto heightForWidth2 = tabWidget.heightForWidth(20);
+
+    tabWidget.setTabBarAutoHide(true);
+    // size should not change
+    QCOMPARE(sizeHint2, tabWidget.sizeHint());
+    QCOMPARE(minSizeHint2, tabWidget.minimumSizeHint());
+    QCOMPARE(heightForWidth2, tabWidget.heightForWidth(20));
+
+    tabWidget.removeTab(1);
+    // this size should change now since the tab should be hidden
+    QVERIFY(sizeHint1.height() > tabWidget.sizeHint().height());
+    QVERIFY(minSizeHint1.height() > tabWidget.sizeHint().height());
+    QVERIFY(heightForWidth1 > tabWidget.heightForWidth(20));
+}
+
 QTEST_MAIN(tst_QTabWidget)
 #include "tst_qtabwidget.moc"