UI/Qt: Consistently place the tab close button across platforms

Before the recent Qt overhaul, we had no control over the position of
the tab close button (without drawing/maintaining it ourselves, which we
now do). Qt automatically placed the tab close button on the left side
of the tab bar on macOS, and as such, we had to go out of our way to
place the audio state button on the right side. See:
dd54780

We now consistently place the audio state button on the left and the tab
close button on the right. Qt still attempts to draw its own tab close
button on the left, so we also explicitly set that to null initially.

Author: trflynn89

UI/Qt/BrowserWindow.cpp

@@ -50,6 +50,9 @@
 
 namespace Ladybird {
 
+static constexpr auto AUDIO_STATE_BUTTON_POSITION = QTabBar::LeftSide;
+static constexpr auto TAB_CLOSE_BUTTON_POSITION = QTabBar::RightSide;
+
 static QString reopen_recently_closed_action_text(Optional<WebView::RecentlyClosedEntry const&> entry)
 {
     if (entry.has_value() && entry->was_window)
@@ -564,8 +567,7 @@ void BrowserWindow::initialize_tab(Tab* tab)
         return new_tab.view().handle();
     };
 
-    m_tabs_container->set_tab_icon(m_tabs_container->index_of(tab), tab->tab_icon());
-    create_close_button_for_tab(tab);
+    initialize_tab_buttons(tab);
 }
 
 void BrowserWindow::uninitialize_tab(Tab* tab)
@@ -741,38 +743,32 @@ void BrowserWindow::tab_favicon_changed(int index, QIcon const& icon)
     m_tabs_container->set_tab_icon(index, icon);
 }
 
-void BrowserWindow::create_close_button_for_tab(Tab* tab)
+void BrowserWindow::initialize_tab_buttons(Tab* tab)
 {
     auto index = m_tabs_container->index_of(tab);
     m_tabs_container->set_tab_icon(index, tab->tab_icon());
 
-    auto* button = new TabBarButton(create_chrome_icon(ChromeIcon::Close, palette()));
-    button->setToolTip("Close Tab");
-
-    auto position = audio_button_position_for_tab(index) == QTabBar::LeftSide ? QTabBar::RightSide : QTabBar::LeftSide;
+    auto* close_button = new TabBarButton(create_chrome_icon(ChromeIcon::Close, palette()));
+    close_button->setToolTip("Close Tab");
 
-    connect(button, &QPushButton::clicked, this, [this, tab]() {
+    connect(close_button, &QPushButton::clicked, this, [this, tab]() {
         auto index = m_tabs_container->index_of(tab);
         request_to_close_tab(index);
     });
 
-    m_tabs_container->tab_bar()->setTabButton(index, position, button);
+    m_tabs_container->tab_bar()->setTabButton(index, AUDIO_STATE_BUTTON_POSITION, nullptr);
+    m_tabs_container->tab_bar()->setTabButton(index, TAB_CLOSE_BUTTON_POSITION, close_button);
 }
 
 void BrowserWindow::update_tab_close_button_icons()
 {
-    auto update_button = [this](int index, QTabBar::ButtonPosition position) {
-        auto* button = m_tabs_container->tab_bar()->tabButton(index, position);
+    for (int index = 0; index < m_tabs_container->count(); ++index) {
+        auto* button = m_tabs_container->tab_bar()->tabButton(index, TAB_CLOSE_BUTTON_POSITION);
         if (!button || button->objectName() != "LadybirdTabButton")
             return;
 
         if (auto* tab_bar_button = qobject_cast<TabBarButton*>(button))
             tab_bar_button->setIcon(create_chrome_icon(ChromeIcon::Close, palette()));
-    };
-
-    for (int index = 0; index < m_tabs_container->count(); ++index) {
-        update_button(index, QTabBar::LeftSide);
-        update_button(index, QTabBar::RightSide);
     }
 }
 
@@ -853,36 +849,35 @@ bool BrowserWindow::start_window_move()
 void BrowserWindow::tab_audio_play_state_changed(int index, Web::HTML::AudioPlayState play_state)
 {
     auto* tab = m_tabs_container->tab(index);
-    auto position = audio_button_position_for_tab(index);
 
     switch (play_state) {
     case Web::HTML::AudioPlayState::Paused:
         if (tab->view().page_mute_state() == Web::HTML::MuteState::Unmuted)
-            m_tabs_container->tab_bar()->setTabButton(index, position, nullptr);
+            m_tabs_container->tab_bar()->setTabButton(index, AUDIO_STATE_BUTTON_POSITION, nullptr);
         break;
 
     case Web::HTML::AudioPlayState::Playing:
         auto* button = new TabBarButton(icon_for_page_mute_state(*tab));
         button->setToolTip(tool_tip_for_page_mute_state(*tab));
         button->setObjectName("LadybirdAudioState");
 
-        connect(button, &QPushButton::clicked, this, [this, tab, position]() {
+        connect(button, &QPushButton::clicked, this, [this, tab]() {
             tab->view().toggle_page_mute_state();
             auto index = tab_index(tab);
 
             switch (tab->view().audio_play_state()) {
             case Web::HTML::AudioPlayState::Paused:
-                m_tabs_container->tab_bar()->setTabButton(index, position, nullptr);
+                m_tabs_container->tab_bar()->setTabButton(index, AUDIO_STATE_BUTTON_POSITION, nullptr);
                 break;
             case Web::HTML::AudioPlayState::Playing:
-                auto* button = m_tabs_container->tab_bar()->tabButton(index, position);
+                auto* button = m_tabs_container->tab_bar()->tabButton(index, AUDIO_STATE_BUTTON_POSITION);
                 as<TabBarButton>(button)->setIcon(icon_for_page_mute_state(*tab));
                 button->setToolTip(tool_tip_for_page_mute_state(*tab));
                 break;
             }
         });
 
-        m_tabs_container->tab_bar()->setTabButton(index, position, button);
+        m_tabs_container->tab_bar()->setTabButton(index, AUDIO_STATE_BUTTON_POSITION, button);
         break;
     }
 }
@@ -911,16 +906,6 @@ QString BrowserWindow::tool_tip_for_page_mute_state(Tab& tab) const
     VERIFY_NOT_REACHED();
 }
 
-QTabBar::ButtonPosition BrowserWindow::audio_button_position_for_tab(int tab_index) const
-{
-    if (auto* button = m_tabs_container->tab_bar()->tabButton(tab_index, QTabBar::LeftSide)) {
-        if (button->objectName() != "LadybirdAudioState")
-            return QTabBar::RightSide;
-    }
-
-    return QTabBar::LeftSide;
-}
-
 void BrowserWindow::open_next_tab()
 {
     if (m_tabs_container->count() <= 1)

UI/Qt/BrowserWindow.h

@@ -164,7 +164,7 @@ public slots:
             callback(*m_tabs_container->tab(i));
     }
 
-    void create_close_button_for_tab(Tab*);
+    void initialize_tab_buttons(Tab*);
     void create_menu_bar_window_controls();
     void update_tab_close_button_icons();
     void update_menu_bar_style();
@@ -175,7 +175,6 @@ public slots:
 
     QIcon icon_for_page_mute_state(Tab&) const;
     QString tool_tip_for_page_mute_state(Tab&) const;
-    QTabBar::ButtonPosition audio_button_position_for_tab(int tab_index) const;
 
     QScreen* m_current_screen { nullptr };
     double m_device_pixel_ratio { 0 };