Display Tab Buttons When Necessary

resources/css/style.css

@@ -216,7 +216,9 @@ QTabBar::tab:first {
 QTabBar::scroller {
     width: 0px;
     height: 0px;
-    border: none;
+
+    /* Last tab size is off by 1 if border not set. */
+    border: 1px solid transparent;
 }
 
 /* -----------------------------------------

src/mainwindow.cpp

@@ -31,6 +31,11 @@ MainWindow::MainWindow(QWidget *parent) :
     mp_ui->nextTabButton->setDefaultAction(app->getAction(KiwixApp::ScrollTabBarTowardEndAction));
     mp_ui->prevTabButton->setDefaultAction(app->getAction(KiwixApp::ScrollTabBarTowardStartAction));
 
+    connect(mp_ui->tabBar, &TabBar::sizeChanged, this, &MainWindow::updateTabButtons);
+    connect(mp_ui->tabBar, &QTabBar::currentChanged, this, &MainWindow::updateTabButtons);
+    connect(mp_ui->tabBar, &TabBar::tabRemovedSignal, this, &MainWindow::updateTabButtons);
+    connect(mp_ui->tabBar, &TabBar::tabInsertedSignal, this, &MainWindow::updateTabButtons);
+
     connect(mp_ui->nextTabButton, &QToolButton::triggered, mp_ui->tabBar, &TabBar::scrollTabBarTowardEnd);
     connect(mp_ui->prevTabButton, &QToolButton::triggered, mp_ui->tabBar, &TabBar::scrollTabBarTowardStart);
 
@@ -109,6 +114,30 @@ void MainWindow::showTabAndTop() {
     getTopWidget()->show();
 }
 
+void MainWindow::updateTabButtons()
+{
+    auto tabBar = getTabBar();
+    QRect tabBarRect = getTabBar()->rect();
+    QRect newButtonTabRect = tabBar->tabRect(tabBar->count() - 1);
+
+    /* Decision is made at half way of the new button tab for smoothness */
+    newButtonTabRect.setWidth(newButtonTabRect.width() / 2);
+    bool newTabVisible = tabBarRect.contains(newButtonTabRect);
+    if (mp_ui->newTabSideButton->isHidden())
+        mp_ui->newTabSideButton->setVisible(!newTabVisible);
+    else
+        mp_ui->newTabSideButton->setHidden(newTabVisible);
+
+    QRect firstTabRect = tabBar->tabRect(0);
+    QRect lastRealTabRect = tabBar->tabRect(tabBar->count() - 2);
+
+    bool firstVisible = tabBarRect.contains(firstTabRect);
+    bool lastVisible = tabBarRect.contains(lastRealTabRect);
+
+    firstVisible ? mp_ui->prevTabButton->hide() : mp_ui->prevTabButton->show();
+    lastVisible ? mp_ui->nextTabButton->hide() : mp_ui->nextTabButton->show();
+}
+
 bool MainWindow::eventFilter(QObject* /*object*/, QEvent* event)
 {
     if (event->type() == QEvent::MouseMove && isFullScreen())
@@ -136,6 +165,7 @@ void MainWindow::resizeEvent(QResizeEvent *event)
 {
     QMainWindow::resizeEvent(event);
     KiwixApp::instance()->getContentManager()->getView()->updateSizeHint();
+    updateTabButtons();
 }
 
 void MainWindow::readingListToggled(bool state)

src/mainwindow.h

@@ -37,6 +37,7 @@ private slots:
     void readingListToggled(bool state);
     void hideTabAndTop();
     void showTabAndTop();
+    void updateTabButtons();
 
 private:
     Ui::MainWindow *mp_ui;

src/tabbar.cpp

@@ -137,13 +137,13 @@ void TabBar::moveToPreviousTab()
 void TabBar::scrollTabBarTowardEnd()
 {
     const int index = currentIndex();
-    setCurrentIndex(index + 1);
+    setCurrentIndex(index == realTabCount() - 1 ? index : index + 1);
 }
 
 void TabBar::scrollTabBarTowardStart()
 {
     const int index = currentIndex();
-    setCurrentIndex(index - 1);
+    setCurrentIndex(index <= 0 ? index : index - 1);
 }
 
 void TabBar::setCloseTabButton(int index)
@@ -505,6 +505,24 @@ void TabBar::paintEvent(QPaintEvent *e)
     }
 }
 
+void TabBar::tabRemoved(int index)
+{
+    QTabBar::tabRemoved(index);
+    emit tabRemovedSignal(index);
+}
+
+void TabBar::tabInserted(int index)
+{
+    QTabBar::tabInserted(index);
+    emit tabInsertedSignal(index);
+}
+
+void TabBar::resizeEvent(QResizeEvent *event)
+{
+    QTabBar::resizeEvent(event);
+    emit sizeChanged();
+}
+
 void TabBar::onTabMoved(int from, int to)
 {
     // avoid infinitive recursion

src/tabbar.h

@@ -55,11 +55,17 @@ class TabBar : public QTabBar
 protected:
     void mousePressEvent(QMouseEvent *event);
     void paintEvent(QPaintEvent *);
+    void tabRemoved(int index) override;
+    void tabInserted(int index) override;
+    void resizeEvent(QResizeEvent *) override;
 
 signals:
     void webActionEnabledChanged(QWebEnginePage::WebAction action, bool enabled);
     void tabDisplayed(TabType tabType);
     void currentTitleChanged(const QString& title);
+    void tabRemovedSignal(int index);
+    void tabInsertedSignal(int index);
+    void sizeChanged();
 
 public slots:
     void closeTab(int index);