QTabBar: Set style-sheet style as the proxy for the base style

The geometry of the scroll-left (SE_TabBarScrollLeftButton) and scroll- right (SE_TabBarScrollRightButton) buttons can be styled either through the base style or the style-sheet style, but not both, like position set by the base style and width of the button set through style-sheet. This patch fixes this issue by temporarily setting QStyleSheetStyle as the proxy of the base style. This solution has been adapted from the patch: f414c49. Amends 9a3bdbf. Fixes: QTBUG-139588 Pick-to: 6.10 6.8 Change-Id: If86e4ace3efd64f46def0ae338cbb547dcc33412 Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

Author: Santhosh Kumar

src/widgets/styles/qstylesheetstyle.cpp

@@ -6301,8 +6301,10 @@ QRect QStyleSheetStyle::subElementRect(SubElement se, const QStyleOption *opt, c
 
  case SE_TabBarScrollLeftButton:
  case SE_TabBarScrollRightButton:
- if (hasStyleRule(w, PseudoElement_TabBarScroller))
- return ParentStyle::subElementRect(se, opt, w);
+ if (hasStyleRule(w, PseudoElement_TabBarScroller)) {
+ QStyleSheetProxySaver proxySaver(this);
+ return baseStyle()->subElementRect(se, opt, w);
+ }
  break;
 
  case SE_TabBarTearIndicator: {

tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp

@@ -27,6 +27,7 @@
 #include <QtWidgets/QToolTip>
 #include <QtWidgets/QTreeView>
 #include <QtWidgets/QVBoxLayout>
+#include <QtWidgets/QProxyStyle>
 
 #include <QtGui/QPainter>
 #include <QtGui/QScreen>
@@ -94,6 +95,7 @@ private slots:
  void task206238_twice();
  void transparent();
  void proxyStyle();
+ void useProxyandStyleSheetStyleInTabBar();
  void dialogButtonBox();
  void emptyStyleSheet();
  void toolTip_data();
@@ -1593,6 +1595,51 @@ void tst_QStyleSheetStyle::proxyStyle()
  delete newProxy;
 }
 
+void tst_QStyleSheetStyle::useProxyandStyleSheetStyleInTabBar()
+{
+#ifdef Q_OS_MACOS
+ // Since macOS style doesn't support tabbar scroll buttons, skip this case
+ QSKIP("TabBar doesn't support scroll button in macOS");
+#endif
+
+ class CustomProxy : public QProxyStyle
+ {
+ public:
+ QRect subElementRect(SubElement subElement,
+ const QStyleOption *option,
+ const QWidget *widget) const override {
+ auto r = QProxyStyle::subElementRect(subElement, option, widget);
+ if (subElement == SE_TabBarScrollLeftButton)
+ r.moveLeft(0);
+ return r;
+ }
+ };
+
+ qApp->setStyleSheet("QTabBar::scroller { width: 50px; }");
+
+ QTabBar tabBar;
+ tabBar.setMaximumWidth(150);
+ tabBar.setStyle(new CustomProxy);
+ int totalWidth = 0;
+ for (int tabIndex = 0; tabIndex < 10; ++tabIndex) {
+ tabBar.addTab("Tab " + QString::number(tabIndex));
+ totalWidth += tabBar.tabRect(tabIndex).width();
+ }
+ if (totalWidth < 200)
+ tabBar.resize(totalWidth / 2, 30);
+ tabBar.show();
+ QVERIFY(QTest::qWaitForWindowActive(&tabBar));
+
+ QToolButton *scrollLeftButton = qobject_cast<QToolButton *>(tabBar.children().at(0));
+ QVERIFY(scrollLeftButton);
+ QCOMPARE(scrollLeftButton->pos(), QPoint(0, 0));
+ QCOMPARE(scrollLeftButton->width(), 25);
+
+ QToolButton *scrollRightButton = qobject_cast<QToolButton *>(tabBar.children().at(1));
+ QVERIFY(scrollRightButton);
+ QCOMPARE(scrollRightButton->width(), 25);
+}
+
 void tst_QStyleSheetStyle::dialogButtonBox()
 {
  QDialogButtonBox box;