[ComboTabBar] Draw TabBarBase also on parts that are not QTabBar

Draw TabBarBase on left/right corner widgets and left/right scroll
buttons.

src/lib/tools/combotabbar.cpp

@@ -617,8 +617,8 @@ bool ComboTabBar::eventFilter(QObject* obj, QEvent* ev)
         }
     }
 
+    // Handle wheel events exclusively in ComboTabBar
     if (ev->type() == QEvent::Wheel) {
-        // Handle wheel events exclusively in ComboTabBar
         wheelEvent(static_cast<QWheelEvent*>(ev));
         return true;
     }
@@ -626,6 +626,40 @@ bool ComboTabBar::eventFilter(QObject* obj, QEvent* ev)
     return QWidget::eventFilter(obj, ev);
 }
 
+void ComboTabBar::paintEvent(QPaintEvent* ev)
+{
+    QWidget::paintEvent(ev);
+
+    // Draw tabbar base even on parts of ComboTabBar that are not directly QTabBar
+    QPainter p(this);
+    QStyleOptionTabBarBaseV2 opt;
+    TabBarHelper::initStyleBaseOption(&opt, m_mainTabBar, size());
+
+    // Left container
+    opt.rect.setX(m_leftContainer->x());
+    opt.rect.setWidth(m_leftContainer->width());
+    style()->drawPrimitive(QStyle::PE_FrameTabBarBase, &opt, &p);
+
+    // Right container
+    opt.rect.setX(m_rightContainer->x());
+    opt.rect.setWidth(m_rightContainer->width());
+    style()->drawPrimitive(QStyle::PE_FrameTabBarBase, &opt, &p);
+
+    if (m_mainBarOverFlowed) {
+        const int scrollButtonWidth = m_mainTabBarWidget->scrollButtonsWidth();
+
+        // Left scroll button
+        opt.rect.setX(m_mainTabBarWidget->x());
+        opt.rect.setWidth(scrollButtonWidth);
+        style()->drawPrimitive(QStyle::PE_FrameTabBarBase, &opt, &p);
+
+        // Right scroll button
+        opt.rect.setX(m_mainTabBarWidget->x() + m_mainTabBarWidget->width() - scrollButtonWidth);
+        opt.rect.setWidth(scrollButtonWidth);
+        style()->drawPrimitive(QStyle::PE_FrameTabBarBase, &opt, &p);
+    }
+}
+
 int ComboTabBar::comboTabBarPixelMetric(ComboTabBar::SizeType sizeType) const
 {
     switch (sizeType) {
@@ -972,7 +1006,7 @@ bool TabBarHelper::event(QEvent* ev)
     return false;
 }
 
-// taken from qtabbar.cpp
+// Taken from qtabbar.cpp
 void TabBarHelper::initStyleBaseOption(QStyleOptionTabBarBaseV2* optTabBase, QTabBar* tabbar, QSize size)
 {
     QStyleOptionTab tabOverlap;
@@ -1006,7 +1040,7 @@ void TabBarHelper::initStyleBaseOption(QStyleOptionTabBarBaseV2* optTabBase, QTa
     }
 }
 
-// some codes were taken from qtabbar.cpp
+// Adapted from qtabbar.cpp
 void TabBarHelper::paintEvent(QPaintEvent* event)
 {
     if (m_bluredBackground) {
@@ -1015,7 +1049,7 @@ void TabBarHelper::paintEvent(QPaintEvent* event)
         p.fillRect(event->rect(), QColor(0, 0, 0, 0));
     }
 
-    // note: this code doesn't support vertical tabs
+    // Note: this code doesn't support vertical tabs
     if (m_dragInProgress) {
         QTabBar::paintEvent(event);
         return;
@@ -1090,6 +1124,7 @@ void TabBarHelper::paintEvent(QPaintEvent* event)
             p.drawControl(QStyle::CE_TabBarTab, tb);
 
             // Draw the tab without selected state
+
             tab.state = tab.state & ~QStyle::State_Selected;
         }
 
@@ -1373,6 +1408,12 @@ void TabBarScrollWidget::scrollByWheel(QWheelEvent* event)
     }
 }
 
+int TabBarScrollWidget::scrollButtonsWidth() const
+{
+    // Assumes both buttons have the same width
+    return m_leftScrollButton->width();
+}
+
 bool TabBarScrollWidget::usesScrollButtons() const
 {
     return m_usesScrollButtons;

src/lib/tools/combotabbar.h

@@ -164,6 +164,7 @@ protected:
     void enterEvent(QEvent* event);
     void leaveEvent(QEvent* event);
     bool eventFilter(QObject* obj, QEvent* ev);
+    void paintEvent(QPaintEvent* ev);
 
     virtual int comboTabBarPixelMetric(SizeType sizeType) const;
     virtual QSize tabSizeHint(int index, bool fast = false) const;
@@ -220,6 +221,8 @@ public:
     bool isDragInProgress() const;
     void enableBluredBackground(bool enable);
 
+    static void initStyleBaseOption(QStyleOptionTabBarBaseV2* optTabBase, QTabBar* tabbar, QSize size);
+
 public slots:
     void setCurrentIndex(int index);
 
@@ -227,7 +230,6 @@ private slots:
     void resetDragState();
 
 private:
-    void initStyleBaseOption(QStyleOptionTabBarBaseV2* optTabBase, QTabBar* tabbar, QSize size);
     bool event(QEvent* ev);
     void paintEvent(QPaintEvent* event);
     void mousePressEvent(QMouseEvent* event);
@@ -271,6 +273,7 @@ public:
 
     void scrollByWheel(QWheelEvent* event);
 
+    int scrollButtonsWidth() const;
     bool usesScrollButtons() const;
     void setUsesScrollButtons(bool useButtons);
 

src/lib/tools/tabstackedwidget.cpp

@@ -41,7 +41,6 @@ TabStackedWidget::TabStackedWidget(QWidget* parent)
     m_mainLayout->addWidget(m_stack);
     setLayout(m_mainLayout);
 
-    setTabBar(new ComboTabBar);
     connect(m_stack, SIGNAL(widgetRemoved(int)), this, SLOT(tabWasRemoved(int)));
 }