add language setting menu item

frontend/apps/filemanager/filemanagermenu.lua

@@ -8,6 +8,7 @@ local Device = require("ui/device")
 local GestureRange = require("ui/gesturerange")
 local Geom = require("ui/geometry")
 local Screen = require("ui/screen")
+local Language = require("ui/language")
 local _ = require("gettext")
 
 local FileManagerMenu = InputContainer:extend{
@@ -85,6 +86,7 @@ function FileManagerMenu:setUpdateItemTable()
 			})
 		end
 	})
+	table.insert(self.tab_item_table.main, Language:getLangMenuTable())
 end
 
 function FileManagerMenu:onShowMenu()

frontend/ui/language.lua

@@ -0,0 +1,53 @@
+-- high level wrapper module for gettext
+
+local UIManager = require("ui/uimanager")
+local InfoMessage = require("ui/widget/infomessage")
+local _ = require("gettext")
+
+Language = {}
+
+function Language:changeLanguage(lang_po)
+	_.changeLang(lang_po)
+	G_reader_settings:saveSetting("language_po", lang_po)
+	UIManager:show(InfoMessage:new{
+		text = _("Please restart reader for new language setting to take effect."),
+		timeout = 3,
+	})
+end
+
+function Language:genLanguageSubItem(lang, lang_po)
+	return {
+		text = lang,
+		callback = function()
+			self:changeLanguage(lang_po)
+		end
+	}
+end
+
+function Language:getLangMenuTable()
+	-- cache menu table
+	if not self.LangMenuTable then
+		self.LangMenuTable = {
+			text = _("Language"),
+			-- NOTE: language with no translation are commented out for now
+			sub_item_table = {
+				self:genLanguageSubItem("English", ""),
+				self:genLanguageSubItem("čeština", "cs_CZ"),
+				self:genLanguageSubItem("Deutsch", "de"),
+				self:genLanguageSubItem("français", "fr"),
+				--self:genLanguageSubItem("magyar", "hu"),
+				self:genLanguageSubItem("Italiano", "it_IT"),
+				self:genLanguageSubItem("język polski", "pl"),
+				self:genLanguageSubItem("Português do Brasil", "pt_BR"),
+				self:genLanguageSubItem("Русский язык", "ru"),
+				--self:genLanguageSubItem("svenska", "sv"),
+				self:genLanguageSubItem("Türkçe", "tr"),
+				--self:genLanguageSubItem("Tiếng Việt", "vi"),
+				self:genLanguageSubItem("简体中文", "zh_CN"),
+			}
+		}
+	end
+	return self.LangMenuTable
+end
+
+return Language

frontend/ui/reader/readermenu.lua

@@ -9,6 +9,7 @@ local Event = require("ui/event")
 local Screen = require("ui/screen")
 local Menu = require("ui/widget/menu")
 local InfoMessage = require("ui/widget/infomessage")
+local Language = require("ui/language")
 local _ = require("gettext")
 
 local ReaderMenu = InputContainer:new{
@@ -66,6 +67,7 @@ function ReaderMenu:setUpdateItemTable()
 	for _, widget in pairs(self.registered_widgets) do
 		widget:addToMainMenu(self.tab_item_table)
 	end
+
 	table.insert(self.tab_item_table.main, {
 		text = _("Help"),
 		callback = function()
@@ -82,6 +84,7 @@ function ReaderMenu:setUpdateItemTable()
 			})
 		end
 	})
+	table.insert(self.tab_item_table.main, Language:getLangMenuTable())
 end
 
 function ReaderMenu:onShowReaderMenu()

reader.lua

@@ -154,13 +154,20 @@ if Device:hasNoKeyboard() then
 	Menu.is_enable_shortcut = false
 end
 
--- set up reader's setting: font
+-- read some global reader setting here:
 G_reader_settings = DocSettings:open(".reader")
-fontmap = G_reader_settings:readSetting("fontmap")
+-- font
+local fontmap = G_reader_settings:readSetting("fontmap")
 if fontmap ~= nil then
 	Font.fontmap = fontmap
 end
+-- last file
 local last_file = G_reader_settings:readSetting("lastfile")
+-- language
+local lang_po = G_reader_settings:readSetting("language_po")
+if lang_po then
+	_.changeLang(lang_po)
+end
 
 
 --@TODO we can read version here, refer to commit in master tree:   (houqp)