fix #2110 by adding disable double tap option in screen options

frontend/apps/reader/readerui.lua

@@ -284,6 +284,7 @@ function ReaderUI:init()
             view = self.view,
             ui = self
         })
+        self.disable_double_tap = G_reader_settings:readSetting("disable_double_tap") ~= false
     end
     -- fulltext search
     self:registerModule("search", ReaderSearch:new{

frontend/ui/elements/common_settings_menu_table.lua

@@ -39,6 +39,7 @@ table.insert(common_settings, {
     sub_item_table = {
         require("ui/elements/screen_dpi_menu_table"),
         require("ui/elements/screen_eink_opt_menu_table"),
+        require("ui/elements/screen_disable_double_tap_table"),
         require("ui/elements/refresh_menu_table"),
     },
 })

frontend/ui/elements/screen_disable_double_tap_table.lua

@@ -0,0 +1,17 @@
+local InfoMessage = require("ui/widget/infomessage")
+local UIManager = require("ui/uimanager")
+local _ = require("gettext")
+
+return {
+    text = _("Disable double tap"),
+    checked_func = function()
+        return G_reader_settings:readSetting("disable_double_tap") ~= false
+    end,
+    callback = function()
+        disabled = G_reader_settings:readSetting("disable_double_tap") ~= false
+        G_reader_settings:saveSetting("disable_double_tap", not disabled)
+        UIManager:show(InfoMessage:new{
+            text = _("This will take effect on next restart."),
+        })
+    end,
+}

frontend/ui/uimanager.lua

@@ -168,7 +168,9 @@ function UIManager:show(widget, refreshtype, refreshregion, x, y)
     -- tell the widget that it is shown now
     widget:handleEvent(Event:new("Show"))
     -- check if this widget disables double tap gesture
-    if widget.disable_double_tap then
+    if widget.disable_double_tap == false then
+        Input.disable_double_tap = false
+    else
         Input.disable_double_tap = true
     end
 end
@@ -184,6 +186,8 @@ function UIManager:close(widget, refreshtype, refreshregion)
     local dirty = false
     -- first send close event to widget
     widget:handleEvent(Event:new("CloseWidget"))
+    -- make it enabled by default and check any widget that disable it
+    Input.disable_double_tap = false
     -- then remove all reference to that widget on stack and update
     for i = #self._window_stack, 1, -1 do
         if self._window_stack[i].widget == widget then