From 6e9d24212db60743f13497f942713961d6601844 Mon Sep 17 00:00:00 2001
From: Oleg Yadrov <oleg.yadrov@qt.io>
Date: Fri, 16 Jun 2017 17:06:53 -0400
Subject: [PATCH] QTabBar: fix expanded tabs appearance

Fix regression introduced by 175f33ed8. 'expanding' property set to true
was ignored when QStyle::styleHint() returned Qt::AlignRight for
SH_TabBar_Alignment.

When we calculate tabs geometry, we put an empty tab at the front and
back and set its expansive attribute depending on tab alignment AND
'expanding' property.

Task-number: QTBUG-61480
Change-Id: I6a1827ae8a3f2c6bee5124c18c7f2b1c0a7862f3
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
---
 src/widgets/widgets/qtabbar.cpp | 18 +++++++++---------
 tests/manual/qtabbar/main.cpp   | 18 +++++++++++++++++-
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/widgets/widgets/qtabbar.cpp b/src/widgets/widgets/qtabbar.cpp
index b9020253a58..85bc9a4a09c 100644
--- a/src/widgets/widgets/qtabbar.cpp
+++ b/src/widgets/widgets/qtabbar.cpp
@@ -447,9 +447,10 @@ void QTabBarPrivate::layoutTabs()
     QVector<QLayoutStruct> tabChain(tabList.count() + 2);
 
     // We put an empty item at the front and back and set its expansive attribute
-    // depending on tabAlignment.
+    // depending on tabAlignment and expanding.
     tabChain[tabChainIndex].init();
-    tabChain[tabChainIndex].expansive = (tabAlignment != Qt::AlignLeft)
+    tabChain[tabChainIndex].expansive = (!expanding)
+                                        && (tabAlignment != Qt::AlignLeft)
                                         && (tabAlignment != Qt::AlignJustify);
     tabChain[tabChainIndex].empty = true;
     ++tabChainIndex;
@@ -514,13 +515,12 @@ void QTabBarPrivate::layoutTabs()
         maxExtent = maxWidth;
     }
 
-    if (!expanding) {
-        // Mirror our front item.
-        tabChain[tabChainIndex].init();
-        tabChain[tabChainIndex].expansive = (tabAlignment != Qt::AlignRight)
-                                            && (tabAlignment != Qt::AlignJustify);
-        tabChain[tabChainIndex].empty = true;
-    }
+    // Mirror our front item.
+    tabChain[tabChainIndex].init();
+    tabChain[tabChainIndex].expansive = (!expanding)
+                                        && (tabAlignment != Qt::AlignRight)
+                                        && (tabAlignment != Qt::AlignJustify);
+    tabChain[tabChainIndex].empty = true;
     Q_ASSERT(tabChainIndex == tabChain.count() - 1); // add an assert just to make sure.
 
     // Do the calculation
diff --git a/tests/manual/qtabbar/main.cpp b/tests/manual/qtabbar/main.cpp
index b1ef0df100a..5a1a558c10a 100644
--- a/tests/manual/qtabbar/main.cpp
+++ b/tests/manual/qtabbar/main.cpp
@@ -56,12 +56,28 @@
 #include <QLayout>
 #include <QDesktopWidget>
 #include <QTabWidget>
+#include <QProxyStyle>
+
+class MyProxyStyle : public QProxyStyle
+{
+public:
+    int styleHint(StyleHint hint, const QStyleOption *option = 0,
+                  const QWidget *widget = 0, QStyleHintReturn *returnData = 0) const
+    {
+        if (hint == QStyle::SH_TabBar_Alignment)
+            return Qt::AlignLeft;
+//            return Qt::AlignRight;
+//            return Qt::AlignCenter;
+        return QProxyStyle::styleHint(hint, option, widget, returnData);
+    }
+};
 
 const int TabCount = 5;
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
+    app.setStyle(new MyProxyStyle);
 
     QWidget widget;
     QStackedWidget stackedWidget;
@@ -69,7 +85,7 @@ int main(int argc, char *argv[])
     tabBar.setDocumentMode(true);
     tabBar.setTabsClosable(true);
     tabBar.setMovable(true);
-    tabBar.setExpanding(true);
+    tabBar.setExpanding(false);
 
     // top
     tabBar.setShape(QTabBar::RoundedNorth);