Add checkbox for fallback

frontend/apps/filemanager/filemanagerbookinfo.lua

@@ -366,7 +366,7 @@ function BookInfo:getCoverImage(doc, file, force_orig)
     end
     if doc then
         cover_bb = doc:getCoverPageImage()
-        if not cover_bb and doc.loadDocument then -- try falling back to first page image
+        if not cover_bb and doc.loadDocument and G_reader_settings:readSetting("cover_fallback") then
             local img_pos = Geom:new{x = 50, y = 50}
             doc:gotoPage(0)
             doc._document:loadDocument(doc.file, false)

frontend/apps/filemanager/filemanagermenu.lua

@@ -167,6 +167,11 @@ function FileManagerMenu:setUpdateItemTable()
                 callback = function() FileChooser:toggleShowFilesMode("show_unsupported") end,
                 separator = true,
             },
+            {
+                text = _("Use cover fallback image"),
+                checked_func = function() return G_reader_settings:readSetting("cover_fallback") end,
+                callback = function() FileChooser:toggleCoverFallback() end,
+            },
             {
                 text = _("Classic mode settings"),
                 sub_item_table = {

frontend/ui/widget/filechooser.lua

@@ -24,6 +24,7 @@ local FileChooser = Menu:extend{
     show_finished    = G_reader_settings:readSetting("show_finished", true), -- books marked as finished
     show_hidden      = G_reader_settings:readSetting("show_hidden", false), -- folders/files starting with "."
     show_unsupported = G_reader_settings:readSetting("show_unsupported", false), -- set to true to ignore file_filter
+    cover_fallback = G_reader_settings:readSetting("cover_fallback", false), -- set to true to use first image as cover fallback
     file_filter = nil, -- function defined in the caller, returns true for files to be shown
     -- NOTE: Input is *always* a relative entry name
     exclude_dirs = { -- const
@@ -567,6 +568,12 @@ function FileChooser:toggleShowFilesMode(mode)
     self:refreshPath()
 end
 
+function FileChooser:toggleCoverFallback()
+    local newValue = not G_reader_settings:readSetting("cover_fallback")
+    G_reader_settings:saveSetting("cover_fallback", newValue)
+    self:refreshPath()
+end
+
 function FileChooser:onMenuSelect(item)
     -- parent directory of dir without permission get nil mode
     -- we need to change to parent path in this case