add new tab button with basic css

add a new tab with a button inside at the start of the app. When this button
is pressed, it inserts a new tab just before this tab.
To avoid that this tab/button can be selected when a tab is closed, the
SelectionBehaviorOnRemove is set to select the left tab if it's the most
right before the tab/button and the right if not

resources/css/style.css

@@ -134,6 +134,14 @@ QTabBar::close-button {
     subcontrol-position: right;
 }
 
+QTabBar::tab:last {
+    border: none;
+}
+
+QTabBar::tab:last QToolButton {
+    font-size: 30px;
+    margin-bottom: 5px;
+}
 
 /* -----------------------------------------
     TabWidget

src/kiwixapp.cpp

@@ -88,6 +88,7 @@ KiwixApp::KiwixApp(int& argc, char *argv[])
     mp_mainWindow = new MainWindow;
     mp_tabWidget = mp_mainWindow->getTabBar();
     mp_tabWidget->setContentManagerView(m_manager.getView());
+    mp_tabWidget->setNewTabButton();
     mp_mainWindow->getSideContentManager()->setContentManager(&m_manager);
     setSideBar(CONTENTMANAGER_BAR);
     postInit();

src/tabbar.cpp

@@ -4,6 +4,7 @@
 #include <QAction>
 #include <QTimer>
 #include <QWebEnginePage>
+#include <QToolButton>
 
 #define QUITIFNULL(VIEW) if (nullptr==(VIEW)) { return; }
 #define QUITIFNOTCURRENT(VIEW) if((VIEW)!=currentWidget()) {return;}
@@ -83,6 +84,18 @@ void TabBar::setContentManagerView(ContentManagerView* view)
     setTabButton(0, RightSide, nullptr);
 }
 
+void TabBar::setNewTabButton()
+{
+    QToolButton *tb = new QToolButton();
+    tb->setDefaultAction(KiwixApp::instance()->getAction(KiwixApp::NewTabAction));
+    tb->setText("+");
+    addTab("");
+    setTabEnabled(1, false);
+    setTabButton(1, QTabBar::LeftSide, tb);
+    tabButton(1, QTabBar::RightSide)->deleteLater();
+    setTabButton(1, QTabBar::RightSide, 0);
+}
+
 WebView* TabBar::createNewTab(bool setCurrent)
 {
     WebView* webView = new WebView();
@@ -110,8 +123,9 @@ WebView* TabBar::createNewTab(bool setCurrent)
                 emit webActionEnabledChanged(QWebEnginePage::Forward, webView->isWebActionEnabled(QWebEnginePage::Forward));
             });
     // Ownership of webview is passed to the tabWidget
-    mp_stackedWidget->addWidget(webView);
-    auto index = addTab("");
+    auto index = count() - 1;
+    mp_stackedWidget->insertWidget(index, webView);
+    insertTab(index, "");
     if (setCurrent) {
         setCurrentIndex(index);
     }
@@ -184,6 +198,7 @@ void TabBar::closeTab(int index)
 {
     if (index == 0)
         return;
+    setSelectionBehaviorOnRemove(index);
     auto webview = widget(index);
     mp_stackedWidget->removeWidget(webview);
     webview->setParent(nullptr);
@@ -192,6 +207,16 @@ void TabBar::closeTab(int index)
     delete webview;
 }
 
+void TabBar::setSelectionBehaviorOnRemove(int index)
+{
+    if (index == count() - 2)
+    {
+        QTabBar::setSelectionBehaviorOnRemove(QTabBar::SelectLeftTab);
+    } else {
+        QTabBar::setSelectionBehaviorOnRemove(QTabBar::SelectRightTab);
+    }
+}
+
 void TabBar::onCurrentChanged(int index)
 {
     if (index == -1)

src/tabbar.h

@@ -17,6 +17,7 @@ public:
     void setStackedWidget(QStackedWidget* widget);
 
     void     setContentManagerView(ContentManagerView* view);
+    void     setNewTabButton();
     WebView* createNewTab(bool setCurrent);
     WebView* widget(int index) { return (index != 0) ? static_cast<WebView*>(mp_stackedWidget->widget(index)) : nullptr; }
     WebView* currentWidget() { auto current = mp_stackedWidget->currentWidget();
@@ -47,6 +48,8 @@ private:
     ContentManagerView* mp_contentManagerView;
     QStackedWidget*     mp_stackedWidget;
 
+    void setSelectionBehaviorOnRemove(int index);
+
 };
 
 #endif // TABWIDGET_H