ReadTimer: Don't blindly repaint the footer in update_status_bars

Send a dedicated event that will let ReaderFooter check if we actually have anything relevant to display, and will do the usual "should I repaint/refresh" checks ;).

Fix #12323
Regression since #12002

frontend/apps/reader/modules/readerfooter.lua

@@ -486,7 +486,7 @@ ReaderFooter.default_settings = {
 function ReaderFooter:init()
     self.settings = G_reader_settings:readSetting("footer", self.default_settings)
 
-    self.additional_footer_content = {} -- place, where additional header content can be inserted.
+    self.additional_footer_content = {} -- array, where additional header content can be inserted.
 
     -- Remove items not supported by the current device
     if not Device:hasFastWifiStatusQuery() then
@@ -2468,6 +2468,13 @@ function ReaderFooter:onBookMetadataChanged(prop_updated)
     end
 end
 
+function ReaderFooter:onRefreshAdditionalContent()
+    if #self.additional_footer_content > 0 then
+        -- Can be sent an any time, so we need to be careful about the repaint/refresh
+        self:maybeUpdateFooter()
+    end
+end
+
 function ReaderFooter:onCloseWidget()
     self:free()
 end

plugins/readtimer.koplugin/main.lua

@@ -98,7 +98,7 @@ function ReadTimer:update_status_bars(seconds)
         UIManager:broadcastEvent(Event:new("UpdateHeader"))
     end
     if self.show_value_in_footer then
-        UIManager:broadcastEvent(Event:new("UpdateFooter", true))
+        UIManager:broadcastEvent(Event:new("RefreshAdditionalContent"))
     end
     -- if seconds schedule 1ms later
     if seconds and seconds >= 0 then