mirror of https://github.com/koreader/koreader
Reader: rationalize "Back" key/action handling (#6840)
Have ReaderBack be the sole handler of onBack. Add 4 mutually exclusive options for the Back key, to avoid ReaderLink and ReaderBack location stacks from interfering (ReaderBack's stack being always a superset of ReaderLink's stack). So, remove "Enable back history", which is replaced by Back option "Go to previous read page". Fix a few possible crashes and inconsistencies (when zoom, scroll or reflow have changed) with ReaderPaging and ReaderView when restoring previous page/view.reviewable/pr6878/r1
poire-z
4 years ago
committed by
GitHub
parent
74c1813a82
commit
8403154d4d
@ -1,89 +1,193 @@
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local ConfirmBox = require("ui/widget/confirmbox")
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local Device = require("device")
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local Event = require("ui/event")
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local EventListener = require("ui/widget/eventlistener")
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local Notification = require("ui/widget/notification")
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local UIManager = require("ui/uimanager")
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local logger = require("logger")
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local util = require("util")
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local _ = require("gettext")
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-- This module handles the "Back" key (and the "Back" gesture action).
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-- When global setting "back_in_reader" == "previous_read_page", it
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-- additionally handles a location stack for each visited page or
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-- page view change (when scrolling in a same page)
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local ReaderBack = EventListener:new{
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location_stack = {},
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-- a limit not intended to be a practical limit but just a failsafe
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max_stack = 5000,
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-- allow for disabling back history, and having Back key
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-- quit immediately (useful for some developers)
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disabled = G_reader_settings:isFalse("enable_back_history"),
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}
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function ReaderBack:init()
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if Device:hasKeys() then
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self.ui.key_events.Back = { {"Back"}, doc = "Reader back" }
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end
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-- Regular function wrapping our method, to avoid re-creating
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-- an anonymous function at each page turn
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self._addPreviousLocationToStackCallback = function()
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self:_addPreviousLocationToStack()
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end
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end
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function ReaderBack:_getCurrentLocation()
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local current_location
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if self.ui.document.info.has_pages then
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current_location = self.ui.paging:getBookLocation()
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local current_location = self.ui.paging:getBookLocation()
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if current_location then
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-- We need a copy, as we're getting references to
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-- objects ReaderPaging/ReaderView may still modify
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local res = {}
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for i=1, #current_location do
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res[i] = util.tableDeepCopy(current_location[i])
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end
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return res
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end
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else
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current_location = {
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return {
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xpointer = self.ui.rolling:getBookLocation(),
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}
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end
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return current_location
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end
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local ignore_location
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function ReaderBack:_areLocationsSimilar(location1, location2)
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if self.ui.document.info.has_pages then
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-- locations are arrays of k/v tables
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if #location1 ~= #location2 then
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return false
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end
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for i=1, #location1 do
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if not util.tableEquals(location1[i], location2[i]) then
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return false
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end
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end
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return true
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else
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return location1.xpointer == location2.xpointer
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end
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end
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function ReaderBack:addCurrentLocationToStack()
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local location_stack = self.location_stack
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function ReaderBack:_addPreviousLocationToStack()
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local new_location = self:_getCurrentLocation()
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if util.tableEquals(ignore_location, new_location) then return end
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table.insert(location_stack, new_location)
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if #location_stack > self.max_stack then
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table.remove(location_stack, 1)
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if self.cur_location and new_location then
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if self:_areLocationsSimilar(self.cur_location, new_location) then
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-- Unchanged, don't add it yet
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return
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end
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table.insert(self.location_stack, self.cur_location)
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if #self.location_stack > self.max_stack then
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table.remove(self.location_stack, 1)
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end
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end
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end
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-- Scroll mode crengine
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function ReaderBack:onPosUpdate()
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if self.disabled then return end
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self:addCurrentLocationToStack()
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end
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-- Paged media
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function ReaderBack:onPageUpdate()
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if self.disabled then return end
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self:addCurrentLocationToStack()
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if new_location then
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self.cur_location = new_location
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end
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end
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-- Called when loading new document
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function ReaderBack:onReadSettings(config)
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self.location_stack = {}
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self.cur_location = nil
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end
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function ReaderBack:onBack()
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local location_stack = self.location_stack
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function ReaderBack:_onViewPossiblyUpdated()
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if G_reader_settings:readSetting("back_in_reader") == "previous_read_page" then
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-- As multiple modules will have their :onPageUpdate()/... called,
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-- and some of them will set up the new page with it, we need to
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-- delay our handling after all of them are called (otherwise,
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-- depending on the order of the calls, we may be have the location
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-- of either the previous page or the current one).
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UIManager:nextTick(self._addPreviousLocationToStackCallback)
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end
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self.back_resist = nil
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end
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if self.disabled then
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self.ui:handleEvent(Event:new("Close"))
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elseif #location_stack > 1 then
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local saved_location = table.remove(location_stack)
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-- Hook to events that do/may change page/view (more than one of these events
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-- may be sent on a single page turn/scroll, _addPreviousLocationToStack()
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-- will ignore those for the same book location):
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-- Called after initial page is set up
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ReaderBack.onReaderReady = ReaderBack._onViewPossiblyUpdated
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-- New page on paged media or crengine in page mode
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ReaderBack.onPageUpdate = ReaderBack._onViewPossiblyUpdated
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-- New page on crengine in scroll mode
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ReaderBack.onPosUpdate = ReaderBack._onViewPossiblyUpdated
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-- View updated (possibly on the same page) on paged media
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ReaderBack.onViewRecalculate = ReaderBack._onViewPossiblyUpdated
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-- View updated (possibly on the same page) on paged media (needed in Reflow mode)
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ReaderBack.onPagePositionUpdated = ReaderBack._onViewPossiblyUpdated
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if saved_location then
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ignore_location = self:_getCurrentLocation()
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logger.dbg("[ReaderBack] restoring:", saved_location)
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self.ui:handleEvent(Event:new('RestoreBookLocation', saved_location))
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function ReaderBack:onBack()
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local back_in_reader = G_reader_settings:readSetting("back_in_reader") or "previous_location"
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local back_to_exit = G_reader_settings:readSetting("back_to_exit") or "prompt"
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if back_in_reader == "previous_read_page" then
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if #self.location_stack > 0 then
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local saved_location = table.remove(self.location_stack)
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if saved_location then
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-- Reset self.cur_location, which will be updated with the restored
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-- saved_location, which will then not be added to the stack
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self.cur_location = nil
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logger.dbg("[ReaderBack] restoring:", saved_location)
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self.ui:handleEvent(Event:new('RestoreBookLocation', saved_location))
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-- Ensure we always have self.cur_location updated, as in some
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-- cases (same page), no event that we handle might be sent.
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UIManager:nextTick(self._addPreviousLocationToStackCallback)
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return true
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end
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elseif not self.back_resist or back_to_exit == "disable" then
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-- Show a one time notification when location stack is empty.
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-- On next "Back" only, proceed with the default behaviour (unless
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-- it's disabled, in which case we always show this notification)
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self.back_resist = true
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UIManager:show(Notification:new{
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text = _("Location history is empty."),
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timeout = 2,
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})
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return true
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else
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self.back_resist = nil
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end
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else
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logger.dbg("[ReaderBack] no location history, closing")
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elseif back_in_reader == "previous_location" then
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-- ReaderLink maintains its own location_stack of less frequent jumps
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-- (links or TOC entries followed, skim document...)
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if back_to_exit == "disable" then
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-- Let ReaderLink always show its notification if empty
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self.ui.link:onGoBackLink(true) -- show_notification_if_empty=true
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return true
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end
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if self.back_resist then
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-- Notification "Location history is empty" previously shown by ReaderLink
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self.back_resist = nil
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elseif self.ui.link:onGoBackLink(true) then -- show_notification_if_empty=true
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return true -- some location restored
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else
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-- ReaderLink has shown its notification that location stack is empty.
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-- On next "Back" only, proceed with the default behaviour
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self.back_resist = true
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return true
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end
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elseif back_in_reader == "filebrowser" then
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self.ui:handleEvent(Event:new("Home"))
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-- Filebrowser will handle next "Back" and ensure back_to_exit
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return true
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end
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-- location stack empty, or back_in_reader == "default"
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if back_to_exit == "always" then
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self.ui:handleEvent(Event:new("Close"))
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elseif back_to_exit == "disable" then
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return true
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elseif back_to_exit == "prompt" then
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UIManager:show(ConfirmBox:new{
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text = _("Exit KOReader?"),
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ok_text = _("Exit"),
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ok_callback = function()
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self.ui:handleEvent(Event:new("Close"))
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end
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})
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end
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return true
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end
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return ReaderBack
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