QMacStyle: Add back icon logic in tab layout

This was accidentally removed when we revamped the document
mode tabs appearance.

In retrospect, we should also consider adding CE_TabBarTabIcon
so that we can set the relative position of the icon w.r.t.
the tab title.

Change-Id: Ic8c3a69c31837018bfdd60f8084120cae47e91f8
Task-number: QTBUG-61092
Task-number: QTBUG-61742
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 25 insertions, 3 deletions

diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index 906bc85fa6..fafe9c9e2c 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -1066,9 +1066,10 @@ void QMacStylePrivate::drawFocusRing(QPainter *p, const QRect &targetRect, int h
 }
 
 #ifndef QT_NO_TABBAR
-void QMacStylePrivate::tabLayout(const QStyleOptionTab *opt, const QWidget *widget, QRect *textRect) const
+void QMacStylePrivate::tabLayout(const QStyleOptionTab *opt, const QWidget *widget, QRect *textRect, QRect *iconRect) const
 {
     Q_ASSERT(textRect);
+    Q_ASSERT(iconRect);
     QRect tr = opt->rect;
     const bool verticalTabs = opt->shape == QTabBar::RoundedEast
                               || opt->shape == QTabBar::RoundedWest
@@ -1102,6 +1103,26 @@ void QMacStylePrivate::tabLayout(const QStyleOptionTab *opt, const QWidget *widg
             tr.setLeft(tr.left() + 4 + buttonSize);
     }
 
+    // icon
+    if (!opt->icon.isNull()) {
+        QSize iconSize = opt->iconSize;
+        if (!iconSize.isValid()) {
+            int iconExtent = proxyStyle->pixelMetric(QStyle::PM_SmallIconSize);
+            iconSize = QSize(iconExtent, iconExtent);
+        }
+        QSize tabIconSize = opt->icon.actualSize(iconSize,
+                        (opt->state & QStyle::State_Enabled) ? QIcon::Normal : QIcon::Disabled,
+                        (opt->state & QStyle::State_Selected) ? QIcon::On : QIcon::Off);
+        // High-dpi icons do not need adjustment; make sure tabIconSize is not larger than iconSize
+        tabIconSize = QSize(qMin(tabIconSize.width(), iconSize.width()), qMin(tabIconSize.height(), iconSize.height()));
+
+        *iconRect = QRect(tr.left(), tr.center().y() - tabIconSize.height() / 2,
+                    tabIconSize.width(), tabIconSize.height());
+        if (!verticalTabs)
+            *iconRect = proxyStyle->visualRect(opt->direction, opt->rect, *iconRect);
+        tr.setLeft(tr.left() + tabIconSize.width() + 4);
+    }
+
     if (!verticalTabs)
         tr = proxyStyle->visualRect(opt->direction, opt->rect, tr);
 
@@ -4967,7 +4988,8 @@ QRect QMacStyle::subElementRect(SubElement sr, const QStyleOption *opt,
         break;
     case SE_TabBarTabText:
         if (const QStyleOptionTab *tab = qstyleoption_cast<const QStyleOptionTab *>(opt)) {
-            d->tabLayout(tab, widget, &rect);
+            QRect dummyIconRect;
+            d->tabLayout(tab, widget, &rect, &dummyIconRect);
         }
         break;
     case SE_TabBarTabLeftButton:
diff --git a/src/widgets/styles/qmacstyle_mac_p_p.h b/src/widgets/styles/qmacstyle_mac_p_p.h
index 1201ae3955..2b388091a6 100644
--- a/src/widgets/styles/qmacstyle_mac_p_p.h
+++ b/src/widgets/styles/qmacstyle_mac_p_p.h
@@ -231,7 +231,7 @@ public:
     void drawFocusRing(QPainter *p, const QRect &targetRect, int hMargin, int vMargin, qreal radius = 0) const;
 
 #ifndef QT_NO_TABBAR
-    void tabLayout(const QStyleOptionTab *opt, const QWidget *widget, QRect *textRect) const;
+    void tabLayout(const QStyleOptionTab *opt, const QWidget *widget, QRect *textRect, QRect *iconRect) const;
 #endif
 
 public: