Add a new feature 'read from right to left'

A new feature 'read from right to left' is added, which is more fit for
Traditional Chinese and Japanese books. Once the feature is enabled:
1. The gesture region of TapForward and area will be flipped
horizonally;
2. The action for swiping to west and to east will be exchanged.

frontend/apps/reader/modules/readerpaging.lua

@@ -19,6 +19,7 @@ local ReaderPaging = InputContainer:new{
     show_overlap_enable = nil,
     overlap = Screen:scaleBySize(DOVERLAPPIXELS),
 
+    inverse_reading_order = false,
     page_flipping_mode = false,
     bookmark_flipping_mode = false,
     flip_steps = {0,1,2,5,10,20,50,100}
@@ -117,6 +118,7 @@ function ReaderPaging:initGesListener()
             }
         },
     }
+    self:updateReadOrder()
 end
 
 function ReaderPaging:onReadSettings(config)
@@ -128,6 +130,7 @@ function ReaderPaging:onReadSettings(config)
     end
     self.flipping_zoom_mode = config:readSetting("flipping_zoom_mode") or "page"
     self.flipping_scroll_mode = config:readSetting("flipping_scroll_mode") or false
+    self.inverse_reading_order = config:readSetting("inverse_reading_order") or false
 end
 
 function ReaderPaging:onSaveSettings()
@@ -138,6 +141,7 @@ function ReaderPaging:onSaveSettings()
     self.ui.doc_settings:saveSetting("show_overlap_enable", self.show_overlap_enable)
     self.ui.doc_settings:saveSetting("flipping_zoom_mode", self.flipping_zoom_mode)
     self.ui.doc_settings:saveSetting("flipping_scroll_mode", self.flipping_scroll_mode)
+    self.ui.doc_settings:saveSetting("inverse_reading_order", self.inverse_reading_order)
 end
 
 function ReaderPaging:getLastProgress()
@@ -178,6 +182,14 @@ function ReaderPaging:addToMainMenu(tab_item_table)
         end,
         sub_item_table = page_overlap_menu,
     })
+    table.insert(tab_item_table.typeset, {
+        text = _("Read from right to left"),
+        checked_func = function() return self.inverse_reading_order end,
+        callback = function()
+            self.inverse_reading_order = not self.inverse_reading_order
+            self:updateReadOrder()
+        end,
+    })
 end
 
 --[[
@@ -320,9 +332,17 @@ function ReaderPaging:onSwipe(arg, ges)
     elseif self.page_flipping_mode and self.original_page then
         self:_gotoPage(self.original_page)
     elseif ges.direction == "west" then
-        self:onPagingRel(1)
+        if self.inverse_reading_order then
+            self:onPagingRel(-1)
+        else
+            self:onPagingRel(1)
+        end
     elseif ges.direction == "east" then
-        self:onPagingRel(-1)
+        if self.inverse_reading_order then
+            self:onPagingRel(1)
+        else
+            self:onPagingRel(-1)
+        end
     else
         -- trigger full refresh
         UIManager:setDirty(nil, "full")
@@ -829,4 +849,54 @@ function ReaderPaging:onGotoPercentage(percentage)
     return true
 end
 
+function ReaderPaging:updateReadOrder()
+    if self.inverse_reading_order then
+        self.ges_events.TapForward = {
+            GestureRange:new{
+                ges = "tap",
+                range = Geom:new{
+                    x = Screen:getWidth()*(1-DTAP_ZONE_FORWARD.x-DTAP_ZONE_FORWARD.w),
+                    y = Screen:getHeight()*DTAP_ZONE_FORWARD.y,
+                    w = Screen:getWidth()*DTAP_ZONE_FORWARD.w,
+                    h = Screen:getHeight()*DTAP_ZONE_FORWARD.h,
+                },
+            }
+        },
+        self.ges_events.TapBackward = {
+            GestureRange:new{
+                ges = "tap",
+                range = Geom:new{
+                    x = Screen:getWidth()*(1-DTAP_ZONE_BACKWARD.x-DTAP_ZONE_BACKWARD.w),
+                    y = Screen:getHeight()*DTAP_ZONE_BACKWARD.y,
+                    w = Screen:getWidth()*DTAP_ZONE_BACKWARD.w,
+                    h = Screen:getHeight()*DTAP_ZONE_BACKWARD.h,
+                },
+            }
+        },
+    else
+                self.ges_events.TapForward = {
+            GestureRange:new{
+                ges = "tap",
+                range = Geom:new{
+                    x = Screen:getWidth()*DTAP_ZONE_FORWARD.x,
+                    y = Screen:getHeight()*DTAP_ZONE_FORWARD.y,
+                    w = Screen:getWidth()*DTAP_ZONE_FORWARD.w,
+                    h = Screen:getHeight()*DTAP_ZONE_FORWARD.h,
+                }
+            }
+        }
+        self.ges_events.TapBackward = {
+            GestureRange:new{
+                ges = "tap",
+                range = Geom:new{
+                    x = Screen:getWidth()*DTAP_ZONE_BACKWARD.x,
+                    y = Screen:getHeight()*DTAP_ZONE_BACKWARD.y,
+                    w = Screen:getWidth()*DTAP_ZONE_BACKWARD.w,
+                    h = Screen:getHeight()*DTAP_ZONE_BACKWARD.h,
+                }
+            }
+        }
+    end
+end
+
 return ReaderPaging

frontend/ui/data/koptoptions.lua

@@ -277,13 +277,6 @@ local KoptOptions = {
                     return enable_if_equals(configurable, "text_wrap", 1)
                 end,
             },
-            {
-               name = "inverse_reading_order",
-               name_text = S.INVERSE_READING_ORDER,
-               toggle = {S.ON, S.OFF},
-               values = {1, 0},
-               default_value = DKOPTREADER_CONFIG_INVERSE_READING_ORDER,
-            },
         }
     },
 }