Bidi: keep invert() generic, handle settings in ReaderView (#8876)

Follow up to 42dd5aad. Handle settings only in
ReaderView:shouldInvertBiDiLayoutMirroring().

frontend/apps/reader/modules/readertoc.lua

@@ -643,7 +643,7 @@ function ReaderToc:expandParentNode(index)
 end
 
 function ReaderToc:onShowToc()
-    if self.view.inverse_reading_order then
+    if self.view:shouldInvertBiDiLayoutMirroring() then
         BD.invert()
     end
 

frontend/apps/reader/modules/readerview.lua

@@ -831,6 +831,11 @@ function ReaderView:onReadSettings(config)
                                               or 8)
 end
 
+function ReaderView:shouldInvertBiDiLayoutMirroring()
+    -- A few widgets may temporarily invert UI layout mirroring when both these settings are true
+    return self.inverse_reading_order and G_reader_settings:isTrue("invert_ui_layout_mirroring")
+end
+
 function ReaderView:onPageUpdate(new_page_no)
     self.state.page = new_page_no
     self.state.drawn = false

frontend/ui/bidi.lua

@@ -130,7 +130,7 @@ end
 -- This fuction can be used by document widgets to temporarily match a widget
 -- to the document page turn direction instead of the UI layout direction.
 function Bidi.invert()
-    if G_reader_settings:isTrue("invert_ui_layout_mirroring") and not Bidi._inverted then
+    if not Bidi._inverted then
         Bidi._mirrored_ui_layout = not Bidi._mirrored_ui_layout
         Bidi._inverted = true
     end

frontend/ui/widget/bookmapwidget.lua

@@ -527,7 +527,7 @@ local BookMapWidget = InputContainer:new{
 }
 
 function BookMapWidget:init()
-    if self.ui.view.inverse_reading_order then
+    if self.ui.view:shouldInvertBiDiLayoutMirroring() then
         BD.invert()
     end
 

frontend/ui/widget/pagebrowserwidget.lua

@@ -39,7 +39,7 @@ local PageBrowserWidget = InputContainer:new{
 }
 
 function PageBrowserWidget:init()
-    if self.ui.view.inverse_reading_order then
+    if self.ui.view:shouldInvertBiDiLayoutMirroring() then
         BD.invert()
     end