From a1cd9a62d1d68d74c059d12c4f2e90b514f36206 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@digia.com>
Date: Tue, 3 Dec 2013 16:24:23 +0100
Subject: [PATCH] Fix QDockAreaLayoutInfo::updateTabBar() to handle rearranged
 tabs.

Search tabs by id instead of assuming they are in order of
the dock widgets. Previously, the algorithm got confused
if QTabBar::moveTabs() was called on the QTabBar.

Task-number: QTBUG-35148
Change-Id: I5946f0e865623049ee243ff99be07d7015288c15
---
 src/widgets/widgets/qdockarealayout.cpp            | 62 ++++++++++------------
 .../widgets/qmainwindow/tst_qmainwindow.cpp        | 26 +++++++++
 2 files changed, 55 insertions(+), 33 deletions(-)

diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 72a463b..832c247 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -1117,17 +1117,23 @@ void QDockAreaLayoutInfo::setCurrentTab(QWidget *widget)
     setCurrentTabId(reinterpret_cast<quintptr>(widget));
 }
 
+static inline int indexOfTabId(const QTabBar *tb, quintptr id)
+{
+    const int tabCount = tb->count();
+    for (int i = 0; i < tabCount; ++i) {
+        if (qvariant_cast<quintptr>(tb->tabData(i)) == id)
+            return i;
+    }
+    return -1;
+}
+
 void QDockAreaLayoutInfo::setCurrentTabId(quintptr id)
 {
     if (!tabbed || tabBar == 0)
         return;
-
-    for (int i = 0; i < tabBar->count(); ++i) {
-        if (qvariant_cast<quintptr>(tabBar->tabData(i)) == id) {
-            tabBar->setCurrentIndex(i);
-            return;
-        }
-    }
+    const int i = indexOfTabId(tabBar, id);
+    if (i != -1)
+        tabBar->setCurrentIndex(i);
 }
 
 #endif // QT_NO_TABBAR
@@ -2099,7 +2105,7 @@ bool QDockAreaLayoutInfo::updateTabBar() const
     bool blocked = tabBar->blockSignals(true);
     bool gap = false;
 
-    int tab_idx = 0;
+    QVector<bool> seenTabs(tabBar->count(), false);
     for (int i = 0; i < item_list.count(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
         if (item.skip())
@@ -2113,39 +2119,29 @@ bool QDockAreaLayoutInfo::updateTabBar() const
 
         QDockWidget *dw = qobject_cast<QDockWidget*>(item.widgetItem->widget());
         QString title = dw->d_func()->fixedWindowTitle;
-        quintptr id = tabId(item);
-        if (tab_idx == tabBar->count()) {
-            tabBar->insertTab(tab_idx, title);
-#ifndef QT_NO_TOOLTIP
-            tabBar->setTabToolTip(tab_idx, title);
-#endif
-            tabBar->setTabData(tab_idx, id);
-        } else if (qvariant_cast<quintptr>(tabBar->tabData(tab_idx)) != id) {
-            if (tab_idx + 1 < tabBar->count()
-                    && qvariant_cast<quintptr>(tabBar->tabData(tab_idx + 1)) == id)
-                tabBar->removeTab(tab_idx);
-            else {
-                tabBar->insertTab(tab_idx, title);
+        const quintptr id = tabId(item);
+        const int tabIdx = indexOfTabId(tabBar, id); // Match the tab by id in case they were rearranged by QTabBar::moveTab()
+        if (tabIdx >= 0) {
+            seenTabs[tabIdx] = true;
+            if (title != tabBar->tabText(tabIdx)) {
+                tabBar->setTabText(tabIdx, title);
 #ifndef QT_NO_TOOLTIP
-                tabBar->setTabToolTip(tab_idx, title);
+                tabBar->setTabToolTip(tabIdx, title);
 #endif
-                tabBar->setTabData(tab_idx, id);
             }
-        }
-
-        if (title != tabBar->tabText(tab_idx)) {
-            tabBar->setTabText(tab_idx, title);
+        } else {
+            const int tabPos = tabBar->count();
+            tabBar->addTab(title);
 #ifndef QT_NO_TOOLTIP
-            tabBar->setTabToolTip(tab_idx, title);
+            tabBar->setTabToolTip(tabPos, title);
 #endif
+            tabBar->setTabData(tabPos, id);
         }
-
-        ++tab_idx;
     }
 
-    while (tab_idx < tabBar->count()) {
-        tabBar->removeTab(tab_idx);
-    }
+    for (int i = seenTabs.size() - 1; i >= 0; --i)
+        if (!seenTabs.at(i))
+            tabBar->removeTab(i);
 
     tabBar->blockSignals(blocked);
 
diff --git a/tests/auto/widgets/widgets/qmainwindow/tst_qmainwindow.cpp b/tests/auto/widgets/widgets/qmainwindow/tst_qmainwindow.cpp
index e5a9b57..132310e 100644
--- a/tests/auto/widgets/widgets/qmainwindow/tst_qmainwindow.cpp
+++ b/tests/auto/widgets/widgets/qmainwindow/tst_qmainwindow.cpp
@@ -152,6 +152,7 @@ private slots:
     void toggleUnifiedTitleAndToolBarOnMac();
 #endif
     void QTBUG21378_animationFinished();
+    void QTBUG35148_rearrangeTabbedDockWidgets();
 };
 
 // Testing get/set functions
@@ -1875,5 +1876,30 @@ void tst_QMainWindow::QTBUG21378_animationFinished()
     delete mwClickTimer;
     QVERIFY(true);
 }
+
+void tst_QMainWindow::QTBUG35148_rearrangeTabbedDockWidgets()
+{
+     QMainWindow w;
+     w.resize(800, 600);
+     const QString title1 = QStringLiteral("DockWidget1");
+     const QString title2 = QStringLiteral("DockWidget2");
+     QDockWidget *dw1 = new QDockWidget(title1, &w);
+     QDockWidget *dw2 = new QDockWidget(title2, &w);
+     w.addDockWidget(Qt::LeftDockWidgetArea, dw1);
+     w.addDockWidget(Qt::LeftDockWidgetArea, dw2);
+     w.tabifyDockWidget(dw1, dw2);
+     const QList<QTabBar *> tabList = w.findChildren<QTabBar *>();
+     QVERIFY(!tabList.isEmpty());
+     QTabBar *tabBar = tabList.front();
+     QCOMPARE(tabBar->tabText(0), title1);
+     QCOMPARE(tabBar->currentIndex(), 1); // Index is that of QDockWidget added last.
+     tabBar->moveTab(0, 1); // Flip tabs: DockWidget2 is now at tab 0.
+     QCOMPARE(tabBar->tabText(0), title2);
+     QCOMPARE(tabBar->currentIndex(), 0);
+     tabBar->setCurrentIndex(1); // Switch, causing relayout of tabbar.
+     tabBar->setCurrentIndex(0);
+     QCOMPARE(tabBar->tabText(0), title2); // Ensure order is still preserved
+}
+
 QTEST_MAIN(tst_QMainWindow)
 #include "tst_qmainwindow.moc"
-- 
1.8.3.msysgit.0