ReaderUI: Saner FM/RD lifecycle

* Ensure that going from one to the other tears down the former and
    its plugins before instantiating the latter and its plugins.

UIManager: Unify Event sending & broadcasting
  * Make the two behave the same way (walk the widget stack from top to
    bottom), and properly handle the window stack shrinking shrinking
    *and* growing.
    Previously, broadcasting happened bottom-to-top and didn't really
    handle the list shrinking/growing, while sending only handled the list
    shrinking by a single element, and hopefully that element being the one
    the event was just sent to.

These two items combined allowed us to optimize suboptimal
refresh behavior with Menu and other Menu classes when
opening/closing a document.
e.g., the "opening document" Notification is now properly regional,
and the "open last doc" option no longer flashes like a crazy person
anymore.

Plugins: Allow optimizing Menu refresh with custom menus, too.

Requires moving Menu's close_callback *after* onMenuSelect, which, eh,
probably makes sense, and is probably harmless in the grand scheme of
things.

frontend/apps/cloudstorage/dropbox.lua

@@ -21,7 +21,7 @@ function DropBox:showFiles(url, password)
     return DropBoxApi:showFiles(url, password)
 end
 
-function DropBox:downloadFile(item, password, path, close)
+function DropBox:downloadFile(item, password, path, callback_close)
     local code_response = DropBoxApi:downloadFile(item.url, password, path)
     if code_response == 200 then
         local __, filename = util.splitFilePathName(path)
@@ -34,7 +34,13 @@ function DropBox:downloadFile(item, password, path, close)
                 text = T(_("File saved to:\n%1\nWould you like to read the downloaded book now?"),
                     BD.filepath(path)),
                 ok_callback = function()
-                    close()
+                    local Event = require("ui/event")
+                    UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
+                    if callback_close then
+                        callback_close()
+                    end
+
                     ReaderUI:showReader(path)
                 end
             })

frontend/apps/cloudstorage/ftp.lua

@@ -20,7 +20,7 @@ function Ftp:run(address, user, pass, path)
     return FtpApi:listFolder(url, path)
 end
 
-function Ftp:downloadFile(item, address, user, pass, path, close)
+function Ftp:downloadFile(item, address, user, pass, path, callback_close)
     local url = FtpApi:generateUrl(address, util.urlEncode(user), util.urlEncode(pass)) .. item.url
     logger.dbg("downloadFile url", url)
     path = util.fixUtf8(path, "_")
@@ -43,7 +43,13 @@ function Ftp:downloadFile(item, address, user, pass, path, close)
                 text = T(_("File saved to:\n%1\nWould you like to read the downloaded book now?"),
                     BD.filepath(path)),
                 ok_callback = function()
-                    close()
+                    local Event = require("ui/event")
+                    UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
+                    if callback_close then
+                        callback_close()
+                    end
+
                     ReaderUI:showReader(path)
                 end
             })

frontend/apps/cloudstorage/webdav.lua

@@ -17,7 +17,7 @@ function WebDav:run(address, user, pass, path)
     return WebDavApi:listFolder(address, user, pass, path)
 end
 
-function WebDav:downloadFile(item, address, username, password, local_path, close)
+function WebDav:downloadFile(item, address, username, password, local_path, callback_close)
     local code_response = WebDavApi:downloadFile(address .. WebDavApi:urlEncode( item.url ), username, password, local_path)
     if code_response == 200 then
         local __, filename = util.splitFilePathName(local_path)
@@ -30,7 +30,13 @@ function WebDav:downloadFile(item, address, username, password, local_path, clos
                 text = T(_("File saved to:\n%1\nWould you like to read the downloaded book now?"),
                     BD.filepath(local_path)),
                 ok_callback = function()
-                    close()
+                    local Event = require("ui/event")
+                    UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
+                    if callback_close then
+                        callback_close()
+                    end
+
                     ReaderUI:showReader(local_path)
                 end
             })

frontend/apps/filemanager/filemanager.lua

@@ -222,7 +222,6 @@ function FileManager:setupLayout()
     end
 
     function file_chooser:onFileSelect(file)  -- luacheck: ignore
-        FileManager.instance:onClose()
         ReaderUI:showReader(file)
         return true
     end
@@ -507,6 +506,7 @@ function FileManager:setupLayout()
     end
 end
 
+-- NOTE: The only thing that will *ever* instantiate a new FileManager object is our very own showFiles below!
 function FileManager:init()
     self:setupLayout()
 
@@ -781,6 +781,21 @@ function FileManager:onClose()
     return true
 end
 
+function FileManager:onShowingReader()
+    -- Allows us to optimize out a few useless refreshes in various CloseWidgets handlers...
+    self.tearing_down = true
+    -- Clear the dither flag to prevent it from infecting the queue and re-inserting a full-screen refresh...
+    self.dithered = nil
+
+    self:onClose()
+end
+
+-- Same as above, except we don't close it yet. Useful for plugins that need to close custom Menus before calling showReader.
+function FileManager:onSetupShowReader()
+    self.tearing_down = true
+    self.dithered = nil
+end
+
 function FileManager:onRefresh()
     self.file_chooser:refreshPath()
     return true
@@ -826,9 +841,7 @@ function FileManager:openRandomFile(dir)
             text = T(_("Do you want to open %1?"), BD.filename(BaseUtil.basename(random_file))),
             choice1_text = _("Open"),
             choice1_callback = function()
-                FileManager.instance:onClose()
                 ReaderUI:showReader(random_file)
-
             end,
             -- @translators Another file. This is a button on the open random file dialog. It presents a file with the choices Open/Another.
             choice2_text = _("Another"),
@@ -1152,6 +1165,10 @@ function FileManager:showFiles(path, focused_file)
         end
     }
     UIManager:show(file_manager)
+
+    -- NOTE: This is a bit clunky. This ought to be private and accessed via a getCurrentInstance method, àla ReaderUI.
+    --       But, it points to the *current* FM instance, and is nil'ed on exit.
+    --       As such, code outside of FileManager can just check/use FileManager.instance (which they do. extensively).
     self.instance = file_manager
 end
 

frontend/apps/filemanager/filemanagercollection.lua

@@ -166,12 +166,7 @@ function FileManagerCollection:onShowColl(collection)
 
     self:updateItemTable()
     self.coll_menu.close_callback = function()
-        -- Close it at next tick so it stays displayed
+        UIManager:close(self.coll_menu)
-        -- while a book is opening (avoids a transient
-        -- display of the underlying File Browser)
-        UIManager:nextTick(function()
-            UIManager:close(self.coll_menu)
-        end)
     end
     UIManager:show(self.coll_menu)
     return true

frontend/apps/filemanager/filemanagerfilesearcher.lua

@@ -42,10 +42,24 @@ function FileSearcher:readDir()
                 -- Don't traverse hidden folders if we're not showing them
                 if attributes.mode == "directory" and f ~= "." and f ~= ".." and (G_reader_settings:isTrue("show_hidden") or not util.stringStartsWith(f, ".")) then
                     table.insert(new_dirs, fullpath)
-                    table.insert(self.files, {name = f, text = f.."/", attr = attributes, callback = function() FileManager:showFiles(fullpath) end})
+                    table.insert(self.files, {
+                        name = f,
+                        text = f.."/",
+                        attr = attributes,
+                        callback = function()
+                            FileManager:showFiles(fullpath)
+                        end,
+                    })
                 -- Always ignore macOS resource forks, too.
                 elseif attributes.mode == "file" and not util.stringStartsWith(f, "._") and (show_unsupported or DocumentRegistry:hasProvider(fullpath)) then
-                    table.insert(self.files, {name = f, text = f, attr = attributes, callback = function() ReaderUI:showReader(fullpath) end})
+                    table.insert(self.files, {
+                        name = f,
+                        text = f,
+                        attr = attributes,
+                        callback = function()
+                            ReaderUI:showReader(fullpath)
+                        end,
+                    })
                 end
             end
         end

frontend/apps/filemanager/filemanagerhistory.lua

@@ -155,12 +155,7 @@ function FileManagerHistory:onShowHist()
 
     self:updateItemTable()
     self.hist_menu.close_callback = function()
-        -- Close it at next tick so it stays displayed
+        UIManager:close(self.hist_menu)
-        -- while a book is opening (avoids a transient
-        -- display of the underlying File Browser)
-        UIManager:nextTick(function()
-            UIManager:close(self.hist_menu)
-        end)
     end
     UIManager:show(self.hist_menu)
     return true

frontend/apps/filemanager/filemanagermenu.lua

@@ -122,13 +122,17 @@ function FileManagerMenu:onOpenLastDoc()
         })
         return
     end
-    local ReaderUI = require("apps/reader/readerui")
-    ReaderUI:showReader(last_file)
 
-    -- only close menu if we were called from the menu
+    -- Only close menu if we were called from the menu
     if self.menu_container then
+        -- Mimic's FileManager's onShowingReader refresh optimizations
+        self.ui.tearing_down = true
+        self.ui.dithered = nil
         self:onCloseFileManagerMenu()
     end
+
+    local ReaderUI = require("apps/reader/readerui")
+    ReaderUI:showReader(last_file)
 end
 
 function FileManagerMenu:setUpdateItemTable()
@@ -784,7 +788,7 @@ function FileManagerMenu:onShowMenu(tab_index)
         }
     end
 
-    main_menu.close_callback = function ()
+    main_menu.close_callback = function()
         self:onCloseFileManagerMenu()
     end
 

frontend/apps/reader/modules/readerfont.lua

@@ -188,7 +188,7 @@ function ReaderFont:onShowFontMenu()
         dimen = Screen:getSize(),
         main_menu,
     }
-    main_menu.close_callback = function ()
+    main_menu.close_callback = function()
         UIManager:close(menu_container)
     end
     -- show menu

frontend/apps/reader/modules/readermenu.lua

@@ -376,7 +376,7 @@ function ReaderMenu:onShowMenu(tab_index)
         }
     end
 
-    main_menu.close_callback = function ()
+    main_menu.close_callback = function()
         self.ui:handleEvent(Event:new("CloseReaderMenu"))
     end
 

frontend/apps/reader/readerui.lua

@@ -480,6 +480,21 @@ function ReaderUI:showFileManager(file)
     end
 end
 
+function ReaderUI:onShowingReader()
+    -- Allows us to optimize out a few useless refreshes in various CloseWidgets handlers...
+    self.tearing_down = true
+    self.dithered = nil
+
+    self:onClose()
+end
+
+-- Same as above, except we don't close it yet. Useful for plugins that need to close custom Menus before calling showReader.
+function ReaderUI:onSetupShowReader()
+    self.tearing_down = true
+    self.dithered = nil
+end
+
+--- @note: Will sanely close existing FileManager/ReaderUI instance for you!
 function ReaderUI:showReader(file, provider)
     logger.dbg("show reader ui")
 
@@ -497,6 +512,10 @@ function ReaderUI:showReader(file, provider)
         self:showFileManager(file)
         return
     end
+
+    -- We can now signal the existing ReaderUI/FileManager instances that it's time to go bye-bye...
+    UIManager:broadcastEvent(Event:new("ShowingReader"))
+
     -- prevent crash due to incompatible bookmarks
     --- @todo Split bookmarks from metadata and do per-engine in conversion.
     provider = provider or DocumentRegistry:getProvider(file)
@@ -550,7 +569,7 @@ end
 local _running_instance = nil
 function ReaderUI:doShowReader(file, provider)
     logger.info("opening file", file)
-    -- keep only one instance running
+    -- Keep only one instance running
     if _running_instance then
         _running_instance:onClose()
     end
@@ -591,12 +610,17 @@ function ReaderUI:doShowReader(file, provider)
     end
     Device:notifyBookState(title, document)
 
-    UIManager:show(reader)
+    -- This is mostly for the few callers that bypass the coroutine shenanigans and call doShowReader directly,
-    _running_instance = reader
+    -- instead of showReader...
+    -- Otherwise, showReader will have taken care of that *before* instantiating a new RD,
+    -- in order to ensure a sane ordering of plugins teardown -> instantiation.
     local FileManager = require("apps/filemanager/filemanager")
     if FileManager.instance then
         FileManager.instance:onClose()
     end
+
+    UIManager:show(reader)
+    _running_instance = reader
 end
 
 function ReaderUI:_getRunningInstance()
@@ -756,6 +780,11 @@ end
 function ReaderUI:reloadDocument(after_close_callback)
     local file = self.document.file
     local provider = getmetatable(self.document).__index
+
+    -- Mimic onShowingReader's refresh optimizations
+    self.tearing_down = true
+    self.dithered = nil
+
     self:handleEvent(Event:new("CloseReaderMenu"))
     self:handleEvent(Event:new("CloseConfigMenu"))
     self.highlight:onClose() -- close highlight dialog if any
@@ -764,15 +793,22 @@ function ReaderUI:reloadDocument(after_close_callback)
         -- allow caller to do stuff between close an re-open
         after_close_callback(file, provider)
     end
+
     self:showReader(file, provider)
 end
 
 function ReaderUI:switchDocument(new_file)
     if not new_file then return end
+
+    -- Mimic onShowingReader's refresh optimizations
+    self.tearing_down = true
+    self.dithered = nil
+
     self:handleEvent(Event:new("CloseReaderMenu"))
     self:handleEvent(Event:new("CloseConfigMenu"))
     self.highlight:onClose() -- close highlight dialog if any
     self:onClose(false)
+
     self:showReader(new_file)
 end
 

frontend/readhistory.lua

@@ -14,6 +14,11 @@ local ReadHistory = {
     last_read_time = 0,
 }
 
+local function selectCallback(path)
+    local ReaderUI = require("apps/reader/readerui")
+    ReaderUI:showReader(path)
+end
+
 local function buildEntry(input_time, input_file)
     local file_path = realpath(input_file) or input_file -- keep orig file path of deleted files
     local file_exists = lfs.attributes(file_path, "mode") == "file"
@@ -43,8 +48,7 @@ local function buildEntry(input_time, input_file)
             return lfs.attributes(file_path, "mode") == "file"
         end,
         callback = function()
-            local ReaderUI = require("apps/reader/readerui")
+            selectCallback(input_file)
-            ReaderUI:showReader(input_file)
         end
     }
 end
@@ -245,8 +249,7 @@ function ReadHistory:updateItemByPath(old_path, new_path)
             self.hist[i].text = new_path:gsub(".*/", "")
             self:_flush()
             self.hist[i].callback = function()
-                local ReaderUI = require("apps/reader/readerui")
+                selectCallback(new_path)
-                ReaderUI:showReader(new_path)
             end
             break
         end

frontend/ui/uimanager.lua

@@ -1076,7 +1076,10 @@ function UIManager:discardEvents(set_or_seconds)
 end
 
 --[[--
-Transmits an @{ui.event.Event|Event} to active widgets.
+Transmits an @{ui.event.Event|Event} to active widgets, top to bottom.
+Stops at the first handler that returns `true`.
+Note that most complex widgets are based on @{ui.widget.container.WidgetContainer|WidgetContainer},
+which itself will take care of propagating an event to its members.
 
 @param event an @{ui.event.Event|Event} object
 ]]
@@ -1113,26 +1116,34 @@ function UIManager:sendEvent(event)
         end
     end
 
-    -- if the event is not consumed, active widgets (from top to bottom) can access it.
+    -- If the event was not consumed (no handler returned true), active widgets (from top to bottom) can access it.
-    -- NOTE: _window_stack can shrink when widgets are closed (CloseWidget & Close events).
+    -- NOTE: _window_stack can shrink/grow when widgets are closed (CloseWidget & Close events) or opened.
+    --       Simply looping in reverse would only cover the list shrinking, and that only by a *single* element,
+    --       something we can't really guarantee, hence the more dogged iterator below,
+    --       which relies on a hash check of already processed widgets (LuaJIT actually hashes the table's GC reference),
+    --       rather than a simple loop counter, and will in fact iterate *at least* #items ^ 2 times.
+    --       Thankfully, that list should be very small, so the overhead should be minimal.
     local checked_widgets = {top_widget}
-    for i = #self._window_stack, 1, -1 do
+    local i = #self._window_stack
+    while i > 0 do
         local widget = self._window_stack[i]
         if checked_widgets[widget] == nil then
-            -- active widgets has precedence to handle this event
+            checked_widgets[widget] = true
+            -- Widget's active widgets have precedence to handle this event
             -- NOTE: While FileManager only has a single (screenshotter), ReaderUI has many active_widgets (each ReaderUI module gets added to the list).
             if widget.widget.active_widgets then
-                checked_widgets[widget] = true
                 for _, active_widget in ipairs(widget.widget.active_widgets) do
                     if active_widget:handleEvent(event) then return end
                 end
             end
             if widget.widget.is_always_active then
-                -- active widgets will handle this event
+                -- Widget itself is flagged always active, let it handle the event
                 -- NOTE: is_always_active widgets currently are widgets that want to show a VirtualKeyboard or listen to Dispatcher events
-                checked_widgets[widget] = true
                 if widget.widget:handleEvent(event) then return end
             end
+            i = #self._window_stack
+        else
+            i = i - 1
         end
     end
 end
@@ -1143,18 +1154,18 @@ Transmits an @{ui.event.Event|Event} to all registered widgets.
 @param event an @{ui.event.Event|Event} object
 ]]
 function UIManager:broadcastEvent(event)
-    -- the widget's event handler might close widgets in which case
+    -- Unlike sendEvent, we send the event to *all* (window-level) widgets (i.e., we don't stop, even if a handler returns true).
-    -- a simple iterator like ipairs would skip over some entries
+    -- NOTE: Same defensive approach to _window_stack changing from under our feet as above.
-    local i = 1
+    local checked_widgets = {}
-    while i <= #self._window_stack do
+    local i = #self._window_stack
-        local prev_widget = self._window_stack[i].widget
+    while i > 0 do
-        self._window_stack[i].widget:handleEvent(event)
+        local widget = self._window_stack[i]
-        local top_widget = self._window_stack[i]
+        if checked_widgets[widget] == nil then
-        if top_widget == nil then
+            checked_widgets[widget] = true
-            -- top widget closed itself
+            widget.widget:handleEvent(event)
-            break
+            i = #self._window_stack
-        elseif top_widget.widget == prev_widget then
+        else
-            i = i + 1
+            i = i - 1
         end
     end
 end

frontend/ui/widget/dictquicklookup.lua

@@ -392,6 +392,8 @@ function DictQuickLookup:init()
                                                     self:onHoldClose(true)
                                                     -- close current ReaderUI in 1 sec, and create a new one
                                                     UIManager:scheduleIn(1.0, function()
+                                                        UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
                                                         if self.ui then
                                                             -- close Highlight menu if any still shown
                                                             if self.ui.highlight and self.ui.highlight.highlight_dialog then
@@ -399,6 +401,7 @@ function DictQuickLookup:init()
                                                             end
                                                             self.ui:onClose()
                                                         end
+
                                                         self.ui:showReader(epub_path)
                                                     end)
                                                 end,

frontend/ui/widget/filechooser.lua

@@ -540,7 +540,6 @@ function FileChooser:showSetProviderButtons(file, filemanager_instance, reader_u
                         ok_callback = function()
                             DocumentRegistry:setProvider(file, provider, false)
 
-                            filemanager_instance:onClose()
                             reader_ui:showReader(file, provider)
                             UIManager:close(self.set_provider_dialog)
                         end,
@@ -554,14 +553,12 @@ function FileChooser:showSetProviderButtons(file, filemanager_instance, reader_u
                         ok_callback = function()
                             DocumentRegistry:setProvider(file, provider, true)
 
-                            filemanager_instance:onClose()
                             reader_ui:showReader(file, provider)
                             UIManager:close(self.set_provider_dialog)
                         end,
                     })
                 else
                     -- just once
-                    filemanager_instance:onClose()
                     reader_ui:showReader(file, provider)
                     UIManager:close(self.set_provider_dialog)
                 end

frontend/ui/widget/menu.lua

@@ -955,6 +955,12 @@ function Menu:init()
     end
 end
 
+function Menu:onShowingReader()
+    -- Clear the dither flag to prevent it from infecting the queue and re-inserting a full-screen refresh...
+    self.dithered = nil
+end
+Menu.onSetupShowReader = Menu.onShowingReader
+
 function Menu:onCloseWidget()
     --- @fixme
     -- we cannot refresh regionally using the dimen field
@@ -965,7 +971,14 @@ function Menu:onCloseWidget()
     -- the filemanager menu.
     -- NOTE: For the same reason, don't make it flash,
     --       because that'll trigger when we close the FM and open a book...
-    UIManager:setDirty(nil, "partial")
+
+    -- Don't do anything if we're in the process of tearing down FM or RD, or if we don't actually have a live instance of 'em...
+    local FileManager = require("apps/filemanager/filemanager")
+    local ReaderUI = require("apps/reader/readerui")
+    local reader_ui = ReaderUI:_getRunningInstance()
+    if (FileManager.instance and not FileManager.instance.tearing_down) or (reader_ui and not reader_ui.tearing_down) then
+        UIManager:setDirty(nil, "ui")
+    end
 end
 
 function Menu:updatePageInfo(select_number)
@@ -1192,10 +1205,10 @@ function Menu:onMenuSelect(item)
                 return true
             end
         end
+        self:onMenuChoice(item)
         if self.close_callback then
             self.close_callback()
         end
-        self:onMenuChoice(item)
     else
         -- save menu title for later resume
         self.item_table.title = self.title

frontend/ui/widget/touchmenu.lua

@@ -592,8 +592,15 @@ function TouchMenu:init()
 end
 
 function TouchMenu:onCloseWidget()
-    -- NOTE: We don't pass a region in order to ensure a full-screen flash to avoid ghosting
+    -- NOTE: We don't pass a region in order to ensure a full-screen flash to avoid ghosting,
-    UIManager:setDirty(nil, "flashui")
+    --       but we only need to do that if we actually have a FM or RD below us.
+    -- Don't do anything when we're switching between the two, or if we don't actually have a live instance of 'em...
+    local FileManager = require("apps/filemanager/filemanager")
+    local ReaderUI = require("apps/reader/readerui")
+    local reader_ui = ReaderUI:_getRunningInstance()
+    if (FileManager.instance and not FileManager.instance.tearing_down) or (reader_ui and not reader_ui.tearing_down) then
+        UIManager:setDirty(nil, "flashui")
+    end
 end
 
 function TouchMenu:_recalculatePageLayout()

plugins/autosuspend.koplugin/main.lua

@@ -110,8 +110,8 @@ function AutoSuspend:init()
     self.auto_suspend_timeout_seconds = G_reader_settings:readSetting("auto_suspend_timeout_seconds") or default_auto_suspend_timeout_seconds
 
     UIManager.event_hook:registerWidget("InputEvent", self)
-    -- We need an instance-specific function reference to schedule, because when going from FM to RD,
+    -- We need an instance-specific function reference to schedule, because in some rare cases,
-    -- we instantiate the RD instance *before* tearing down the old FM instance.
+    -- we may instantiate a new plugin instance *before* tearing down the old one.
     self.task = function(shutdown_only)
         self:_schedule(shutdown_only)
     end

plugins/calibre.koplugin/search.lua

@@ -283,9 +283,13 @@ function CalibreSearch:bookCatalog(t, option)
             entry.text = string.format("%s - %s", book.title, book.authors[1])
         end
         entry.callback = function()
+            local Event = require("ui/event")
+            UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
+            self.search_menu:onClose()
+
             local ReaderUI = require("apps/reader/readerui")
             ReaderUI:showReader(book.rootpath .. "/" .. book.lpath)
-            self.search_menu:onClose()
         end
         table.insert(catalog, entry)
     end

plugins/movetoarchive.koplugin/main.lua

@@ -97,6 +97,9 @@ function MoveToArchive:commonProcess(is_move_process, moved_done_text)
     self.settings:saveSetting("last_copied_from_dir", self.last_copied_from_dir)
     self.settings:flush()
 
+    local Event = require("ui/event")
+    UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
     self.ui:onClose()
     if is_move_process then
         FileManager:moveFile(document_full_path, self.archive_dir_path)
@@ -110,10 +113,10 @@ function MoveToArchive:commonProcess(is_move_process, moved_done_text)
     ReadCollection:updateItemByPath(document_full_path, dest_file)
     UIManager:show(ConfirmBox:new{
         text = moved_done_text,
-        ok_callback = function ()
+        ok_callback = function()
             ReaderUI:showReader(dest_file)
         end,
-        cancel_callback = function ()
+        cancel_callback = function()
             self:openFileBrowser(self.last_copied_from_dir)
         end,
     })

plugins/opds.koplugin/opdscatalog.lua

@@ -31,7 +31,11 @@ function OPDSCatalog:init()
                 ok_text = _("Read now"),
                 cancel_text = _("Read later"),
                 ok_callback = function()
+                    local Event = require("ui/event")
+                    UIManager:broadcastEvent(Event:new("SetupShowReader"))
+
                     self:onClose()
+
                     ReaderUI:showReader(downloaded_file)
                 end
             })

reader.lua

@@ -284,6 +284,7 @@ else
     if start_with == "last" and last_file then
         local ReaderUI = require("apps/reader/readerui")
         UIManager:nextTick(function()
+            -- Instantiate RD
             ReaderUI:showReader(last_file)
         end)
         exit_code = UIManager:run()
@@ -292,10 +293,11 @@ else
         local home_dir =
             G_reader_settings:readSetting("home_dir") or Device.home_dir or lfs.currentdir()
         UIManager:nextTick(function()
+            -- Instantiate FM
             FileManager:showFiles(home_dir)
         end)
-        -- Always open history on top of filemanager so closing history
+        -- Always open FM modules on top of filemanager, so closing 'em doesn't result in an exit
-        -- doesn't result in exit.
+        -- because of an empty widget stack, and so they can interact with the FM instance as expected.
         if start_with == "history" then
             local FileManagerHistory = require("apps/filemanager/filemanagerhistory")
             UIManager:nextTick(function()

spec/unit/uimanager_spec.lua

@@ -326,33 +326,76 @@ describe("UIManager spec", function()
         UIManager:broadcastEvent("foo")
         assert.is.same(#UIManager._window_stack, 0)
 
+        -- Remember that the stack is processed top to bottom!
+        -- Test making a hole in the middle of the stack.
         UIManager._window_stack = {
             {
                 widget = {
                     handleEvent = function()
-                        UIManager._window_stack[1] = nil
+                        assert.truthy(true)
-                        UIManager._window_stack[2] = nil
+                    end
-                        UIManager._window_stack[3] = nil
+                }
+            },
+            {
+                widget = {
+                    handleEvent = function()
+                        assert.falsy(true)
+                    end
+                }
+            },
+            {
+                widget = {
+                    handleEvent = function()
+                        assert.falsy(true)
+                    end
+                }
+            },
+            {
+                widget = {
+                    handleEvent = function()
+                        table.remove(UIManager._window_stack, #UIManager._window_stack - 2)
+                        table.remove(UIManager._window_stack, #UIManager._window_stack - 2)
+                        table.remove(UIManager._window_stack, #UIManager._window_stack - 1)
+                    end
+                }
+            },
+            {
+                widget = {
+                    handleEvent = function()
+                        assert.truthy(true)
                     end
                 }
             },
+        }
+        UIManager:broadcastEvent("foo")
+        assert.is.same(2, #UIManager._window_stack)
+
+        -- Test inserting a new widget in the stack
+        local new_widget = {
+            widget = {
+                handleEvent = function()
+                    assert.truthy(true)
+                end
+            }
+        }
+        UIManager._window_stack = {
             {
                 widget = {
                     handleEvent = function()
-                        assert.falsy(true);
+                        table.insert(UIManager._window_stack, new_widget)
                     end
                 }
             },
             {
                 widget = {
                     handleEvent = function()
-                        assert.falsy(true);
+                        assert.truthy(true)
                     end
                 }
             },
         }
         UIManager:broadcastEvent("foo")
-        assert.is.same(0, #UIManager._window_stack)
+        assert.is.same(3, #UIManager._window_stack)
     end)
 
     it("should handle stack change when closing widgets", function()