ReaderFooter: Don't duplicate a 12h clock time format option (#6973)

* ReaderFooter:
	* Honor the global twelve_hour_clock setting, instead of
	  duplicating a local one.
	  (Re #6969)

* os.date is a thin wrapper around strftime, so we might be able to get
away with some not-quite-standard extensions...

These are *definitely* supported on Linux, but are *NOT* the glibc
extension (that'd be e.g., %-I), so, hopefully, they're somewhat
portable...

They are also supported on BSD/macOS.
They are *not* supported by the MS UCRT. That means MinGW-w64, too.
This *appears* to be supported on current Bionic (it might even support
said glibc format altering extensions).

* And of course, Windows is terrible, so, make this terribly ugly to not
break it there...

* Turns out BSD also supports the dash trim format extension, so, leave
the trimming to the libc, and handle the special-casing in a way that
doesn't create stupid locals.

* Random unrelated cleanup ^^.

(https://gitter.im/koreader/koreader?at=5fd24be492aa1c4ef5d11f31)

* Update the testsuite

(Because the default used to be 24h clock).

Changed the default to 24h clock ;p.

* Explain why we don't try to fix it in Lua

frontend/apps/reader/modules/readerfooter.lua

@@ -177,7 +177,7 @@ local footerTextGeneratorMap = {
     time = function(footer)
         local symbol_type = footer.settings.item_prefix or "icons"
         local prefix = symbol_prefix[symbol_type].time
-        local clock = util.secondsToHour(os.time(), footer.settings.time_format == "12")
+        local clock = util.secondsToHour(os.time(), G_reader_settings:isTrue("twelve_hour_clock"))
         if not prefix then
             return clock
         else
@@ -1287,43 +1287,6 @@ function ReaderFooter:addToMainMenu(menu_items)
                     },
                 },
             },
-            {
-                text = _("Time format"),
-                sub_item_table = {
-                    {
-                        text_func = function()
-                            local footer = {}
-                            footer.settings = {}
-                            footer.settings.time_format = "24"
-                            footer.settings.item_prefix = self.settings.item_prefix or "icons"
-                            return T(_("24-hour (%1)"),footerTextGeneratorMap.time(footer))
-                        end,
-                        checked_func = function()
-                            return self.settings.time_format == "24" or self.settings.time_format == nil
-                        end,
-                        callback = function()
-                            self.settings.time_format = "24"
-                            self:refreshFooter(true)
-                        end,
-                    },
-                    {
-                        text_func = function()
-                            local footer = {}
-                            footer.settings = {}
-                            footer.settings.time_format = "12"
-                            footer.settings.item_prefix = self.settings.item_prefix or "icons"
-                            return T(_("12-hour (%1)"),footerTextGeneratorMap.time(footer))
-                        end,
-                        checked_func = function()
-                            return self.settings.time_format == "12"
-                        end,
-                        callback = function()
-                            self.settings.time_format = "12"
-                            self:refreshFooter(true)
-                        end,
-                    },
-                }
-            },
             {
                 text = _("Duration format"),
                 sub_item_table = {

frontend/readhistory.lua

@@ -37,7 +37,7 @@ local function buildEntry(input_time, input_file)
                 -- we fallback to it no sidecar file)
                 last_read_ts = DocSettings:getLastSaveTime(file_path) or input_time
             end
-            return util.secondsToDate(last_read_ts, G_reader_settings:nilOrTrue("twelve_hour_clock"))
+            return util.secondsToDate(last_read_ts, G_reader_settings:isTrue("twelve_hour_clock"))
         end,
         callback = function()
             local ReaderUI = require("apps/reader/readerui")

frontend/ui/elements/common_settings_menu_table.lua

@@ -77,10 +77,10 @@ common_settings.time = {
         text = _("12-hour clock"),
         keep_menu_open = true,
         checked_func = function()
-            return G_reader_settings:nilOrTrue("twelve_hour_clock")
+            return G_reader_settings:isTrue("twelve_hour_clock")
         end,
         callback = function()
-            G_reader_settings:flipNilOrTrue("twelve_hour_clock")
+            G_reader_settings:flipNilOrFalse("twelve_hour_clock")
         end,
         }
     }

frontend/ui/widget/touchmenu.lua

@@ -640,7 +640,7 @@ function TouchMenu:updateItems()
     self.page_info_left_chev:enableDisable(self.page > 1)
     self.page_info_right_chev:enableDisable(self.page < self.page_num)
 
-    local time_info_txt = util.secondsToHour(os.time(), G_reader_settings:nilOrTrue("twelve_hour_clock"))
+    local time_info_txt = util.secondsToHour(os.time(), G_reader_settings:isTrue("twelve_hour_clock"))
     local powerd = Device:getPowerDevice()
     local batt_lvl = powerd:getCapacity()
     local batt_symbol

frontend/up_reg.list

@@ -1,19 +0,0 @@
-./apps/reader/modules/readerfooter.lua:        UIManager.update_regions_func = function()
-./apps/reader/modules/readerhighlight.lua:        UIManager.update_regions_func = function()
-./ui/widget/button.lua:            UIManager.update_regions_func = function()
-./ui/widget/iconbutton.lua:        UIManager.update_regions_func = function()
-./ui/widget/dictquicklookup.lua:    UIManager.update_regions_func = function()
-./ui/widget/scrolltextwidget.lua:    UIManager.update_regions_func = function()
-./ui/widget/touchmenu.lua:        UIManager.update_regions_func = function()
-./ui/widget/touchmenu.lua:        UIManager.update_regions_func = function()
-./ui/widget/virtualkeyboard.lua:    UIManager.update_regions_func = function()
-./ui/widget/virtualkeyboard.lua:    UIManager.update_regions_func = function()
-./ui/widget/virtualkeyboard.lua:    UIManager.update_regions_func = nil
-./ui/widget/toggleswitch.lua:    UIManager.update_regions_func = function()
-./ui/widget/configdialog.lua:    UIManager.update_regions_func = function()
-./ui/widget/configdialog.lua:    UIManager.update_regions_func = function()
-./ui/uimanager.lua:    update_regions_func = nil,
-./ui/uimanager.lua:        if self.update_regions_func then
-./ui/uimanager.lua:            local update_regions = self.update_regions_func()
-./ui/uimanager.lua:            for _, update_region in ipairs(update_regions) do
-./ui/uimanager.lua:            self.update_regions_func = nil

frontend/util.lua

@@ -224,21 +224,40 @@ end
 ---- @int seconds number of seconds
 ---- @bool twelve_hour_clock
 ---- @treturn string hour string
-function util.secondsToHour(seconds, twelve_hour_clock)
-    local time
-    if twelve_hour_clock then
-        if os.date("%p", seconds) == "AM" then
-            -- @translators This is the time in the morning in the 12-hour clock (%I is the hour, %M the minute).
-            time = os.date(_("%I:%M AM"), seconds)
+--- @note: The MS CRT doesn't support either %l & %k, or the - format modifier (as they're not technically C99 or POSIX).
+---        They are otherwise supported on Linux, BSD & Bionic, so, just special-case Windows...
+---        We *could* arguably feed the os.date output to gsub("^0(%d)(.*)$", "%1%2"), but, while unlikely,
+---        it's conceivable that a translator would put something other that the hour at the front of the string ;).
+if jit.os == "Windows" then
+    function util.secondsToHour(seconds, twelve_hour_clock)
+        if twelve_hour_clock then
+            if os.date("%p", seconds) == "AM" then
+                -- @translators This is the time in the morning using a 12-hour clock (%I is the hour, %M the minute).
+                return os.date(_("%I:%M AM"), seconds)
+            else
+                -- @translators This is the time in the afternoon using a 12-hour clock (%I is the hour, %M the minute).
+                return os.date(_("%I:%M PM"), seconds)
+            end
         else
-            -- @translators This is the time in the afternoon in the 12-hour clock (%I is the hour, %M the minute).
-            time = os.date(_("%I:%M PM"), seconds)
+            -- @translators This is the time using a 24-hour clock (%H is the hour, %M the minute).
+            return os.date(_("%H:%M"), seconds)
+        end
+    end
+else
+    function util.secondsToHour(seconds, twelve_hour_clock)
+        if twelve_hour_clock then
+            if os.date("%p", seconds) == "AM" then
+                -- @translators This is the time in the morning using a 12-hour clock (%-I is the hour, %M the minute).
+                return os.date(_("%-I:%M AM"), seconds)
+            else
+                -- @translators This is the time in the afternoon using a 12-hour clock (%-I is the hour, %M the minute).
+                return os.date(_("%-I:%M PM"), seconds)
+            end
+        else
+            -- @translators This is the time using a 24-hour clock (%-H is the hour, %M the minute).
+            return os.date(_("%-H:%M"), seconds)
         end
-    else
-        -- @translators This is the time in the 24-hour clock (%H is the hour, %M the minute).
-        time = os.date(_("%H:%M"), seconds)
     end
-    return time
 end
 
 --- Converts timestamp to a date string