TouchMenu: add support for checkmark_callback

Allows having a toggable checkmark on menu items
leading to a sub-menu.

frontend/ui/widget/touchmenu.lua

@@ -95,6 +95,8 @@ function TouchMenuItem:init()
         checked = true,
     }
 
+    self.checkmark_tap_width = checked_widget:getSize().w + 2*Size.padding.default
+
     -- text_max_width should be the TouchMenuItem width minus the below
     -- FrameContainer default paddings minus the checked widget width
     local text_max_width = self.dimen.w - 2*Size.padding.default - checked_widget:getSize().w
@@ -168,11 +170,20 @@ function TouchMenuItem:onTapSelect(arg, ges)
     end
     if enabled == false then return end
 
+    local tap_on_checkmark = false
+    if ges and ges.pos and ges.pos.x then
+        local tap_x = BD.mirroredUILayout() and self.dimen.w - ges.pos.x - 1
+                                             or ges.pos.x
+        if tap_x <= self.checkmark_tap_width then
+            tap_on_checkmark = true
+        end
+    end
+
     -- If the menu hasn't actually been drawn yet, don't do anything (as it's confusing, and the coordinates may be wrong).
     if not self.item_frame.dimen then return end
 
     if G_reader_settings:isFalse("flash_ui") then
-        self.menu:onMenuSelect(self.item)
+        self.menu:onMenuSelect(self.item, tap_on_checkmark)
     else
         -- c.f., ui/widget/iconbutton for the canonical documentation about the flash_ui code flow
 
@@ -200,7 +211,7 @@ function TouchMenuItem:onTapSelect(arg, ges)
 
         -- Callback
         --
-        self.menu:onMenuSelect(self.item)
+        self.menu:onMenuSelect(self.item, tap_on_checkmark)
 
         UIManager:forceRePaint()
     end
@@ -830,10 +841,15 @@ function TouchMenu:onSwipe(arg, ges_ev)
     end
 end
 
-function TouchMenu:onMenuSelect(item)
+function TouchMenu:onMenuSelect(item, tap_on_checkmark)
     if self.touch_menu_callback then
         self.touch_menu_callback()
     end
+    if tap_on_checkmark and item.checkmark_callback then
+        item.checkmark_callback()
+        self:updateItems()
+        return true
+    end
     if item.tap_input or type(item.tap_input_func) == "function" then
         if not item.keep_menu_open then
             self:closeMenu()