save/restore koptconfig to setting files

frontend/document/koptdocument.lua

@@ -38,6 +38,14 @@ function Configurable:loadSettings(settings, prefix)
 	--Debug("loaded config:", dump(Configurable))
 end
 
+function Configurable:saveSettings(settings, prefix)
+	for key,value in pairs(self) do
+		if type(value) == "number" then
+			settings:saveSetting(prefix..key, value)
+		end
+	end
+end
+
 -- Any document processed by K2pdfopt is called a koptdocument
 KoptDocument = Document:new{
 	_document = false,

frontend/ui/reader/readerconfig.lua

@@ -216,3 +216,12 @@ function ReaderConfig:onSetDimensions(dimen)
 	-- update gesture listenning range according to new screen orientation
 	self:init()
 end
+
+function ReaderConfig:onReadSettings(config)
+	DEBUG("read setting", config)
+	self.configurable:loadSettings(config, 'kopt_')
+end
+
+function ReaderConfig:onCloseDocument()
+	self.configurable:saveSettings(self.ui.doc_settings, 'kopt_')
+end