Font menu: open on page with currently selected font

Generic feature added to TouchMenu: an optional callback
'open_on_menu_item_id_func()' set on an items table can
tell which menu item should be shown when opening a menu.
TouchMenu: allows jumping to first or last page with
long-press on the chevrons.

frontend/apps/reader/modules/readerfont.lua

@@ -96,9 +96,13 @@ function ReaderFont:init()
             end,
             checked_func = function()
                 return v == self.font_face
-            end
+            end,
+            menu_item_id = v,
         })
     end
+    self.face_table.open_on_menu_item_id_func = function()
+        return self.font_face
+    end
     self.ui.menu:registerToMainMenu(self)
 end
 
@@ -332,7 +336,9 @@ function ReaderFont:addToMainMenu(menu_items)
     self.face_table.max_per_page = 5
     -- insert table to main reader menu
     menu_items.change_font = {
-        text = self.font_menu_title,
+        text_func = function()
+            return T(_("Font: %1"), BD.wrap(self.font_face))
+        end,
         sub_item_table = self.face_table,
     }
 end

frontend/ui/widget/touchmenu.lua

@@ -499,12 +499,14 @@ function TouchMenu:init()
     self.page_info_left_chev = Button:new{
         icon = chevron_left,
         callback = function() self:onPrevPage() end,
+        hold_callback = function() self:onFirstPage() end,
         bordersize = 0,
         show_parent = self.show_parent,
     }
     self.page_info_right_chev = Button:new{
         icon = chevron_right,
         callback = function() self:onNextPage() end,
+        hold_callback = function() self:onLastPage() end,
         bordersize = 0,
         show_parent = self.show_parent,
     }
@@ -787,6 +789,18 @@ function TouchMenu:onPrevPage()
     return true
 end
 
+function TouchMenu:onFirstPage()
+    self.page = 1
+    self:updateItems()
+    return true
+end
+
+function TouchMenu:onLastPage()
+    self.page = self.page_num
+    self:updateItems()
+    return true
+end
+
 function TouchMenu:onSwipe(arg, ges_ev)
     local direction = BD.flipDirectionIfMirroredUILayout(ges_ev.direction)
     if direction == "west" then
@@ -838,6 +852,16 @@ function TouchMenu:onMenuSelect(item)
             table.insert(self.item_table_stack, self.item_table)
             self.item_table = sub_item_table
             self.page = 1
+            if self.item_table.open_on_menu_item_id_func then
+                self:_recalculatePageLayout() -- we need an accurate self.perpage
+                local open_id = self.item_table.open_on_menu_item_id_func()
+                for i = 1, #self.item_table do
+                    if self.item_table[i].menu_item_id == open_id then
+                        self.page = math.floor( (i - 1) / self.perpage ) + 1
+                        break
+                    end
+                end
+            end
             self:updateItems()
         end
     end