Bookshelf: Move group by context menu to button on search bar

More discoverable and does not modify the context menu which is under
user control.

src/calibre/gui2/init.py

@@ -247,6 +247,7 @@ class AlternateViewsButtons(LayoutButton):  # {{{
 
     buttons = set()
     ignore_toggles = False
+    needs_group_by = False
 
     def __init__(self, name: str, icon: str, label: str, view_name: str, gui: CentralContainer, shortcut=None, config_key=None):
         super().__init__(name, icon, label, gui, shortcut=shortcut)
@@ -298,6 +299,7 @@ class AlternateViewsButtons(LayoutButton):  # {{{
                 btn.update_state(False)
         self.gui.library_view.alternate_views.show_view(self.view_name if show else None)
         self.gui.sort_button.setVisible(show)
+        self.gui.group_by_button.setVisible(self.needs_group_by and show)
         AlternateViewsButtons.ignore_toggles = False
 # }}}
 
@@ -317,6 +319,7 @@ class GridViewButton(AlternateViewsButtons):  # {{{
 
 
 class BookshelfViewButton(AlternateViewsButtons):  # {{{
+    needs_group_by = True
     def __init__(self, gui):
         super().__init__(
             'bookshelf_view',

src/calibre/gui2/layout.py

@@ -239,6 +239,19 @@ class SearchBar(QFrame):  # {{{
         sb.setVisible(False)
         l.addWidget(sb)
 
+        parent.group_by_button = self.group_by_button = gb = QToolButton(self)
+        gb.setToolButtonStyle(Qt.ToolButtonStyle.ToolButtonTextBesideIcon)
+        gb.setToolTip(_('Change how the displayed books are grouped'))
+        gb.setCursor(Qt.CursorShape.PointingHandCursor)
+        gb.setPopupMode(QToolButton.ToolButtonPopupMode.InstantPopup)
+        gb.setAutoRaise(True)
+        gb.setText(_('Group by'))
+        gb.setIcon(QIcon.ic('bookshelf.png'))
+        gb.setMenu(QMenu(gb))
+        gb.menu().aboutToShow.connect(self.populate_group_by_menu)
+        gb.setVisible(False)
+        l.addWidget(gb)
+
         x = parent.search = SearchBox2(self, as_url=search_as_url)
         x.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Minimum)
         x.setObjectName('search')
@@ -292,6 +305,10 @@ class SearchBar(QFrame):  # {{{
         from calibre.gui2.ui import get_gui
         get_gui().iactions['Sort By'].update_menu(self.sort_button.menu())
 
+    def populate_group_by_menu(self):
+        from calibre.gui2.ui import get_gui
+        get_gui().bookshelf_view.populate_group_by_menu(self.group_by_button.menu())
+
     def do_fts(self):
         from calibre.gui2.ui import get_gui
         get_gui().iactions['Full Text Search'].show_fts()

src/calibre/gui2/library/bookshelf_view.py

@@ -1997,12 +1997,8 @@ class BookshelfView(MomentumScrollMixin, QAbstractScrollArea):
     def set_context_menu(self, menu: QMenu):
         self.context_menu = menu
 
-    def contextMenuEvent(self, ev: QContextMenuEvent):
-        # Create menu with grouping options
-        menu = QMenu(self)
-
-        # Add grouping submenu
-        grouping_menu = menu.addMenu(QIcon.ic('bookshelf.png'), _('Group by'))
+    def populate_group_by_menu(self, grouping_menu: QMenu) -> None:
+        grouping_menu.clear()
         fm = self.gui.current_db.new_api.field_metadata
 
         def add(field: str, name: str) -> None:
@@ -2020,14 +2016,11 @@ class BookshelfView(MomentumScrollMixin, QAbstractScrollArea):
             cf[k] = numeric_sort_key(fm[k])
         for k in sorted(cf, key=cf.get):
             add(k, fm[k]['name'])
-        # Add standard context menu items if available
-        if cm := self.context_menu:
-            menu.addSeparator()
-            for action in cm.actions():
-                menu.addAction(action)
 
-        menu.popup(ev.globalPos())
-        ev.accept()
+    def contextMenuEvent(self, ev: QContextMenuEvent):
+        if self.context_menu:
+            self.context_menu.popup(ev.globalPos())
+            ev.accept()
 
     def set_grouping_mode(self, mode: str):
         '''Set the grouping mode and refresh display.'''