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koreader/frontend/ui/wikipedia.lua
poire-z 4bb3999cbc RenderImage: factorize all image rendering and scaling code
New module RenderImage (alongside existing RenderText) to provides
image rendering and scaling facilities.
Uses MuPDF, but tries first giflib on GIF.
Allows for getting all the frames from an animated GIF.
2018-04-22 17:00:29 +02:00

1277 lines
56 KiB
Lua

local JSON = require("json")
local RenderImage = require("ui/renderimage")
local Screen = require("device").screen
local ffiutil = require("ffi/util")
local logger = require("logger")
local util = require("util")
local _ = require("gettext")
local T = ffiutil.template
--[[
-- Query wikipedia using Wikimedia Web API.
-- https://en.wikipedia.org/w/api.php?format=jsonfm&action=query&generator=search&gsrnamespace=0&gsrsearch=ereader&gsrlimit=10&prop=extracts&exintro&explaintext&exlimit=max
-- https://en.wikipedia.org/w/api.php?action=query&prop=extracts&format=jsonfm&explaintext=&redirects=&titles=E-reader
--
-- To get parsed HTML :
-- https://en.wikipedia.org/w/api.php?action=parse&page=E-book
-- https://en.wikipedia.org/w/api.php?action=parse&page=E-book&prop=text|sections|displaytitle|revid&disablelimitreport=&disableeditsection
-- https://www.mediawiki.org/wiki/API:Parsing_wikitext#parse
--]]
local Wikipedia = {
wiki_server = "https://%s.wikipedia.org",
wiki_path = "/w/api.php",
default_lang = "en",
-- See https://www.mediawiki.org/wiki/API:Main_page for details.
-- Search query, returns introductory texts (+ main thumbnail image)
wiki_search_params = {
action = "query",
generator = "search",
gsrnamespace = "0",
-- gsrsearch = nil, -- text to lookup, will be added below
gsrlimit = 20, -- max nb of results to get
exlimit = "max",
prop = "extracts|info|pageimages", -- 'extracts' to get text, 'info' to get full page length
format = "json",
explaintext = "",
exintro = "",
-- We have to use 'exintro=' to get extracts for ALL results
-- (otherwise, we get the full text for only the first result, and
-- no text at all for the others
},
-- Full article, parsed to output text (+ main thumbnail image)
wiki_full_params = {
action = "query",
prop = "extracts|pageimages",
format = "json",
-- exintro = nil, -- get more than only the intro
explaintext = "",
redirects = "",
-- title = nil, -- text to lookup, will be added below
},
-- Full article, parsed to output HTML, for Save as EPUB
wiki_phtml_params = {
action = "parse",
format = "json",
-- we only need the following informations
prop = "text|sections|displaytitle|revid",
-- page = nil, -- text to lookup, will be added below
-- disabletoc = "", -- if we want to remove toc IN html
disablelimitreport = "",
disableeditsection = "",
},
-- Full article, parsed to output HTML, for images extraction
-- (used with full article as text, if "show more images" enabled)
wiki_images_params = { -- same as previous one, with just text html
action = "parse",
format = "json",
-- we only need the following informations
prop = "text",
-- page = nil, -- text to lookup, will be added below
redirects = "",
disabletoc = "", -- remove toc in html
disablelimitreport = "",
disableeditsection = "",
},
-- There is an alternative for obtaining page's images:
-- prop=imageinfo&action=query&iiprop=url|dimensions|mime|extmetadata&generator=images&pageids=49448&iiurlwidth=100&iiextmetadatafilter=ImageDescription
-- but it gives all images (including wikipedia icons) in any order, without
-- any score or information that would help considering if they matter or not
--
-- Allow for disabling prettifying full page text
wiki_prettify = G_reader_settings:nilOrTrue("wikipedia_prettify"),
-- Can be set so HTTP requests will be done under Trapper and
-- be interruptible
trap_widget = nil,
-- For actions done with Trapper:dismissable methods, we may throw
-- and error() with this code. We make the value of this error
-- accessible here so that caller can know it's a user dismiss.
dismissed_error_code = "Interrupted by user",
}
function Wikipedia:getWikiServer(lang)
return string.format(self.wiki_server, lang or self.default_lang)
end
-- Codes that getUrlContent may get from requester.request()
local TIMEOUT_CODE = "timeout" -- from socket.lua
local MAXTIME_CODE = "maxtime reached" -- from sink_table_with_maxtime
-- Sink that stores into a table, aborting if maxtime has elapsed
local function sink_table_with_maxtime(t, maxtime)
-- Start counting as soon as this sink is created
local start_secs, start_usecs = ffiutil.gettime()
local starttime = start_secs + start_usecs/1000000
t = t or {}
local f = function(chunk, err)
local secs, usecs = ffiutil.gettime()
if secs + usecs/1000000 - starttime > maxtime then
return nil, MAXTIME_CODE
end
if chunk then table.insert(t, chunk) end
return 1
end
return f, t
end
-- Get URL content
local function getUrlContent(url, timeout, maxtime)
local socket = require('socket')
local ltn12 = require('ltn12')
local http = require('socket.http')
local https = require('ssl.https')
local requester
if url:sub(1,7) == "http://" then
requester = http
elseif url:sub(1,8) == "https://" then
requester = https
else
return false, "Unsupported protocol"
end
if not timeout then timeout = 10 end
-- timeout needs to be set to 'http', even if we use 'https'
http.TIMEOUT, https.TIMEOUT = timeout, timeout
local request = {}
local sink = {}
request['url'] = url
request['method'] = 'GET'
-- 'timeout' delay works on socket, and is triggered when
-- that time has passed trying to connect, or after connection
-- when no data has been read for this time.
-- On a slow connection, it may not be triggered (as we could read
-- 1 byte every 1 second, not triggering any timeout).
-- 'maxtime' can be provided to overcome that, and we start counting
-- as soon as the first content byte is received (but it is checked
-- for only when data is received).
-- Setting 'maxtime' and 'timeout' gives more chance to abort the request when
-- it takes too much time (in the worst case: in timeout+maxtime seconds).
-- But time taken by DNS lookup cannot easily be accounted for, so
-- a request may (when dns lookup takes time) exceed timeout and maxtime...
if maxtime then
request['sink'] = sink_table_with_maxtime(sink, maxtime)
else
request['sink'] = ltn12.sink.table(sink)
end
local code, headers, status = socket.skip(1, requester.request(request))
local content = table.concat(sink) -- empty or content accumulated till now
-- logger.dbg("code:", code)
-- logger.dbg("headers:", headers)
-- logger.dbg("status:", status)
-- logger.dbg("#content:", #content)
if code == TIMEOUT_CODE or code == MAXTIME_CODE then
logger.warn("request interrupted:", code)
return false, code
end
if headers == nil then
logger.warn("No HTTP headers:", code, status)
return false, "Network or remote server unavailable"
end
if not code or string.sub(code, 1, 1) ~= "2" then -- all 200..299 HTTP codes are OK
logger.warn("HTTP status not okay:", code, status)
return false, "Remote server error or unavailable"
end
if headers and headers["content-length"] then
-- Check we really got the announced content size
local content_length = tonumber(headers["content-length"])
if #content ~= content_length then
return false, "Incomplete content received"
end
end
return true, content
end
function Wikipedia:setTrapWidget(trap_widget)
self.trap_widget = trap_widget
end
function Wikipedia:resetTrapWidget()
self.trap_widget = nil
end
-- Possible values for page_type parameter to loadPage()
local WIKIPEDIA_INTRO = 1
local WIKIPEDIA_FULL = 2
local WIKIPEDIA_PHTML = 3
local WIKIPEDIA_IMAGES = 4
--[[
-- return decoded JSON table from Wikipedia
--]]
function Wikipedia:loadPage(text, lang, page_type, plain)
local url = require('socket.url')
local query = ""
local parsed = url.parse(self:getWikiServer(lang))
parsed.path = self.wiki_path
if page_type == WIKIPEDIA_INTRO then -- search query
self.wiki_search_params.explaintext = plain and "" or nil
for k,v in pairs(self.wiki_search_params) do
query = string.format("%s%s=%s&", query, k, v)
end
parsed.query = query .. "gsrsearch=" .. url.escape(text)
elseif page_type == WIKIPEDIA_FULL then -- full page content
self.wiki_full_params.explaintext = plain and "" or nil
for k,v in pairs(self.wiki_full_params) do
query = string.format("%s%s=%s&", query, k, v)
end
parsed.query = query .. "titles=" .. url.escape(text)
elseif page_type == WIKIPEDIA_PHTML then -- parsed html page content
for k,v in pairs(self.wiki_phtml_params) do
query = string.format("%s%s=%s&", query, k, v)
end
parsed.query = query .. "page=" .. url.escape(text)
elseif page_type == WIKIPEDIA_IMAGES then -- images found in page html
for k,v in pairs(self.wiki_images_params) do
query = string.format("%s%s=%s&", query, k, v)
end
parsed.query = query .. "page=" .. url.escape(text)
else
return
end
local built_url = url.build(parsed)
local completed, success, content
if self.trap_widget then -- if previously set with Wikipedia:setTrapWidget()
local Trapper = require("ui/trapper")
local timeout, maxtime = 30, 60
-- We use dismissableRunInSubprocess with complex return values:
completed, success, content = Trapper:dismissableRunInSubprocess(function()
return getUrlContent(built_url, timeout, maxtime)
end, self.trap_widget)
if not completed then
error(self.dismissed_error_code) -- "Interrupted by user"
end
else
local timeout, maxtime = 10, 60
success, content = getUrlContent(built_url, timeout, maxtime)
end
if not success then
error(content)
end
if content ~= "" and string.sub(content, 1,1) == "{" then
local ok, result = pcall(JSON.decode, content)
if ok and result then
logger.dbg("wiki result json:", result)
return result
else
logger.warn("wiki result json decoding error:", result)
error("Failed decoding JSON")
end
else
logger.warn("wiki response is not json:", content)
error("Response is not JSON")
end
end
-- search wikipedia and get intros for results
function Wikipedia:searchAndGetIntros(text, lang)
local result = self:loadPage(text, lang, WIKIPEDIA_INTRO, true)
if result then
local query = result.query
if query then
local show_image = G_reader_settings:nilOrTrue("wikipedia_show_image")
-- Scale wikipedia normalized (we hope) thumbnail by 2 (adjusted
-- to screen size/dpi) for intros (and x8 more for highres image)
local image_size_factor = Screen:scaleBySize(200)/100.0
if show_image then
for pageid, page in pairs(query.pages) do
self:addImages(page, lang, false, image_size_factor, 8)
end
end
return query.pages
end
end
end
-- get full content of a wiki page
function Wikipedia:getFullPage(wiki_title, lang)
local result = self:loadPage(wiki_title, lang, WIKIPEDIA_FULL, true)
if result then
local query = result.query
if query then
local show_image = G_reader_settings:nilOrTrue("wikipedia_show_image")
local show_more_images = G_reader_settings:nilOrTrue("wikipedia_show_more_images")
-- Scale wikipedia normalized (we hope) thumbnails by 4 (adjusted
-- to screen size/dpi) for full page (and this *4 for highres image)
local image_size_factor = Screen:scaleBySize(400)/100.0
if self.wiki_prettify or show_image then
for pageid, page in pairs(query.pages) do
if self.wiki_prettify and page.extract then
-- Prettification of the plain text full page
page.extract = self:prettifyText(page.extract)
end
if show_image then
self:addImages(page, lang, show_more_images, image_size_factor, 4)
end
end
end
return query.pages
end
end
end
-- get parsed html content and other infos of a wiki page
function Wikipedia:getFullPageHtml(wiki_title, lang)
local result = self:loadPage(wiki_title, lang, WIKIPEDIA_PHTML, true)
if result and result.parse then
return result.parse
end
if result.error and result.error.info then
error(result.error.info)
end
end
-- get images extracted from parsed html
function Wikipedia:getFullPageImages(wiki_title, lang)
local images = {} -- will be returned, each in a format similar to page.thumbnail
local result = self:loadPage(wiki_title, lang, WIKIPEDIA_IMAGES, true)
if result and result.parse and result.parse.text and result.parse.text["*"] then
local html = result.parse.text["*"] -- html content
local url = require('socket.url')
local wiki_base_url = self:getWikiServer(lang)
local thumbs = {} -- bits of HTML containing an image
-- We first try to catch images in <div class=thumbinner>, which should exclude
-- wikipedia icons, flags... These seem to all end with a double </div>.
for thtml in html:gmatch([[<div class="thumbinner".-</div>%s*</div>]]) do
table.insert(thumbs, thtml)
end
-- We then also try to catch images in galleries (which often are less
-- interesting than those in thumbinner) as a 2nd set.
for thtml in html:gmatch([[<li class="gallerybox".-<div class="thumb".-</div>%s*</div>%s*<div class="gallerytext">.-</div>%s*</div>]]) do
table.insert(thumbs, thtml)
end
-- We may miss some interesting images in the page's top right table, but
-- there's no easy way to distinguish them from icons/flags in this table...
for _, thtml in ipairs(thumbs) do
-- We get <a href="/wiki/File:real_file_name.jpg (or /wiki/Fichier:real_file_name.jpg
-- depending on Wikipedia lang)
local filename = thtml:match([[<a href="/wiki/[^:]*:([^"]*)" class="image"]])
if filename then
filename = url.unescape(filename)
end
logger.dbg("found image with filename:", filename)
-- logger.dbg(thtml)
local timg, tremain = thtml:match([[(<img .->)(.*)]])
if timg and tremain then
-- (Should we discard those without caption ?)
local caption = tremain and util.htmlToPlainText(tremain)
if caption == "" then caption = nil end
logger.dbg(" caption:", caption)
-- logger.dbg(timg)
local src = timg:match([[src="([^"]*)"]])
if src and src ~= "" then
if src:sub(1,2) == "//" then
src = "https:" .. src
elseif src:sub(1,1) == "/" then -- non absolute url
src = wiki_base_url .. src
end
local width = tonumber(timg:match([[width="([^"]*)"]]))
local height = tonumber(timg:match([[height="([^"]*)"]]))
-- Ignore img without width and height, which should exlude
-- javascript maps and other unsupported stuff
if width and height then
-- Images in the html we got seem to be x4.5 the size of
-- the thumbnail we get with searchAndGetIntros() or
-- getFullPage(). Normalize them to the size of the thumbnail,
-- so we can resize them all later with the same rules.
width = math.ceil(width/4.5)
height = math.ceil(height/4.5)
-- No need to adjust width in src url here, as it will be
-- done in addImages() anyway
-- src = src:gsub("(.*/)%d+(px-[^/]*)", "%1"..width.."%2")
logger.dbg(" size:", width, "x", height, "url:", src)
table.insert(images, {
source = src,
width = width,
height = height,
filename = filename,
caption = caption,
})
end
end
end
end
end
return images
end
-- Function wrapped and plugged to image objects returned by :addImages()
local function image_load_bb_func(image, highres)
local source, trap_widget
if not highres then
-- We use an invisible widget that will resend the dismiss event,
-- so that image loading in TextBoxWdiget is unobtrusive and
-- interruptible
trap_widget = false
source = image.source
else
-- We need to let the user know image loading is happening,
-- with a discreet TrapWidget
trap_widget = _("Loading high-res image… (tap to cancel)")
source = image.hi_source
end
-- Image may be big or take some time to be resized on wikipedia servers.
-- As we use dismissableRunInSubprocess and can interrupt this loading,
-- we can use quite high timeouts
local timeout, maxtime = 60, 120
logger.dbg("fetching", source)
local Trapper = require("ui/trapper")
-- We use dismissableRunInSubprocess with simple string return value to
-- avoid dump()/load() a long string of image bytes
local completed, data = Trapper:dismissableRunInSubprocess(function()
local success, data = getUrlContent(source, timeout, maxtime)
-- With simple string value, we're not able to return the failure
-- reason, so log it here
if not success then
logger.warn("failed fetching image from", source, ":", data)
end
return success and data or nil
end, trap_widget, true) -- task_returns_simple_string=true
local success = data and true or false -- guess success from data
if not completed then
logger.dbg("image fetching interrupted by user")
return true -- let caller know it was interrupted
end
if not success then
-- log it again (on Android, log from sub-process seem to not work)
logger.warn("failed fetching image from", source)
return
end
logger.dbg(" fetched", #data)
local bb
if not highres then
-- For low-res, we should ensure the image we got from wikipedia is
-- the right size, so it does not overflow our reserved area
-- (TextBoxWidget may have adjusted image.width and height)
-- We don't get animated GIF multiple frames to keep TextBoxWidget
-- simple: they will be available when viewed in highres
bb = RenderImage:renderImageData(data, #data, false, image.width, image.height)
else
-- We provide want_frames=true for highres images, so ImageViewer
-- can display animated GIF
-- No need for width and height for high-res
bb = RenderImage:renderImageData(data, #data, true)
end
if not bb then
logger.warn("failed building image from", source)
return
end
if not highres then
image.bb = bb
else
image.hi_bb = bb
end
end
function Wikipedia:addImages(page, lang, more_images, image_size_factor, hi_image_size_factor)
-- List of images, table with keys as expected by TextBoxWidget
page.images = {}
-- List of wikipedia images data structures (page.thumbnail and images
-- extracted from html) made to have the same keys for common processing
local wimages = {}
-- We got what Wikipedia scored as the most interesting image for this
-- page in page.thumbnail, and its filename in page.pageimage, ie:
-- "thumbnail": {
-- "source": "https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Reading_on_the_bus_train_or_transit.jpg/37px-Reading_on_the_bus_train_or_transit.jpg",
-- "width": 37,
-- "height": 50
-- },
-- "pageimage": "Reading_on_the_bus_train_or_transit.jpg"
--
local first_image_filename = nil
if page.thumbnail and page.thumbnail.source then
page.thumbnail.filename = page.pageimage
first_image_filename = page.pageimage
table.insert(wimages, page.thumbnail)
end
-- To get more images, we need to make a second request to wikipedia
if more_images then
local ok, images_or_err = pcall(Wikipedia.getFullPageImages, Wikipedia, page.title, lang)
if not ok then
logger.warn("error getting more images", images_or_err)
else
for _, wimage in ipairs(images_or_err) do
if first_image_filename and wimage.filename == first_image_filename then
-- We got the same image as the thumbnail one, but it may have
-- a caption: replace thumbnail one with this one
table.remove(wimages, 1)
table.insert(wimages, 1, wimage)
else
table.insert(wimages, wimage)
end
end
end
end
-- All our wimages now have the keys: source, width, height, filename, caption
for _, wimage in ipairs(wimages) do
-- We trust wikipedia, and our x4.5 factor in :getFullPageImages(), for adequate
-- and homogeneous images' sizes. We'll just scale them according to the
-- provided 'image_size_factor' (which should account for screen size/DPI)
local width = wimage.width or 100 -- in case we don't get any width or height
local height = wimage.height or 100
-- Give a little boost in size to thin images
if width < height / 2 or height < width / 2 then
width = width * 1.3
height = height * 1.3
end
width = math.ceil(width * image_size_factor)
height = math.ceil(height * image_size_factor)
-- All wikipedia image urls like .../wikipedia/commons/A/BC/<filename>
-- or .../wikipedia/commons/thumb/A/BC/<filename>/<width>px-<filename>
-- can be transformed to another url with a requested new_width with the form:
-- /wikipedia/commons/thumb/A/BC/<filename>/<new_width>px-<filename>
-- (Additionally, the image format can be changed by appending .png,
-- .jpg or .gif to it)
-- The resize is so done on Wikipedia servers from the source image for
-- the best quality.
local source = wimage.source:gsub("(.*/)%d+(px-[^/]*)", "%1"..width.."%2")
-- We build values for a high resolution version of the image, to be displayed
-- with ImageViewer (x 4 by default)
local hi_width = width * (hi_image_size_factor or 4)
local hi_height = height * (hi_image_size_factor or 4)
local hi_source = wimage.source:gsub("(.*/)%d+(px-[^/]*)", "%1"..hi_width.."%2")
local title = wimage.filename
if title then
title = title:gsub("_", " ")
end
local image = {
-- As expected by TextBoxWidget (with additional source and
-- hi_source, that will be used by load_bb_func)
title = title,
caption = wimage.caption,
source = source,
width = width,
height = height,
bb = nil, -- will be loaded and build only if needed
hi_source = hi_source,
hi_width = hi_width,
hi_height = hi_height,
hi_bb = nil, -- will be loaded and build only if needed
}
-- If bb or hi_bb is nil, TextBoxWidget will call a method named "load_bb_func"
image.load_bb_func = function(highres)
return image_load_bb_func(image, highres)
end
table.insert(page.images, image)
end
end
-- UTF8 of unicode geometrical shapes we can use to replace
-- the "=== title ===" of wkipedia plaintext pages
-- These chosen ones are available in most fonts (prettier symbols
-- exist in unicode, but are available in a few fonts only) and
-- have a quite consistent size/weight in all fonts.
local th1_sym = "\xE2\x96\x88" -- full block (big black rectangle) (never met, only for web page title?)
local th2_sym = "\xE2\x96\x89" -- big black square
local th3_sym = "\xC2\xA0\xE2\x97\xA4" -- black upper left triangle (indented, nicer)
local th4_sym = "\xE2\x97\x86" -- black diamond
local th5_sym = "\xE2\x9C\xBF" -- black florette
local th6_sym = "\xE2\x9D\x96" -- black diamond minus white x
-- Others available in most fonts
-- local thX_sym = "\xE2\x9C\x9A" -- heavy greek cross
-- local thX_sym = "\xE2\x97\xA2" -- black lower right triangle
-- local thX_sym = "\xE2\x97\x89" -- fish eye
-- local thX_sym = "\xE2\x96\x97" -- quadrant lower right
-- For optional prettification of the plain text full page
function Wikipedia:prettifyText(text)
-- We use \a for an additional leading \n that we don't want shortened later
text = text:gsub("\n= ", "\n\a"..th1_sym.." ") -- 2 empty lines before
text = text:gsub("\n== ", "\n\a"..th2_sym.." ") -- 2 empty lines before
text = text:gsub("\n=== ", "\n"..th3_sym.." ")
text = text:gsub("\n==== ", "\n"..th4_sym.." ")
text = text:gsub("\n===== ", "\n"..th5_sym.." ")
text = text:gsub("\n====== ", "\n"..th6_sym.." ")
text = text:gsub("Modifier ==", " ==") -- fr wikipedia fix for some articles modified by clumsy editors
text = text:gsub("==$", "==\n") -- for a </hN> at end of text to be matched by next gsub
text = text:gsub(" ===?\n+", "\n\n") -- </h2> to </h3> : empty line after
text = text:gsub(" ====+\n+", "\n") -- </h4> to </hN> : single \n, no empty line
text = text:gsub("\n\n+\xE2\x80\x94", "\n\xE2\x80\x94") -- em dash, used for quote author, make it stick to prev text
text = text:gsub("\n +\n", "\n") -- trim lines full of only spaces (often seen in math formulas)
text = text:gsub("^\n*", "") -- trim new lines at start
text = text:gsub("\n*$", "") -- trim new lines at end
text = text:gsub("\n\n+", "\n\n") -- shorten multiple new lines
text = text:gsub("\a", "\n") -- re-add our wished \n
return text
end
-- UTF8 of unicode geometrical shapes we'll prepend to wikipedia section headers,
-- to help identifying hierarchy (othewise, the small font size differences helps).
-- Best if identical to the ones used above for prettifying full plain text page.
-- These chosen ones are available in most fonts (prettier symbols
-- exist in unicode, but are available in a few fonts only) and
-- have a quite consistent size/weight in all fonts.
local h1_sym = "\xE2\x96\x88" -- full block (big black rectangle) (never met, only for web page title?)
local h2_sym = "\xE2\x96\x89" -- big black square
local h3_sym = "\xE2\x97\xA4" -- black upper left triangle
local h4_sym = "\xE2\x97\x86" -- black diamond
local h5_sym = "\xE2\x9C\xBF" -- black florette
local h6_sym = "\xE2\x9D\x96" -- black diamond minus white x
-- Other available ones in most fonts
-- local hXsym = "\xE2\x9C\x9A" -- heavy greek cross
-- local hXsym = "\xE2\x97\xA2" -- black lower right triangle
-- local hXsym = "\xE2\x97\x89" -- fish eye
-- local hXsym = "\xE2\x96\x97" -- quadrant lower right
local ext_to_mimetype = {
png = "image/png",
jpg = "image/jpeg",
jpeg = "image/jpeg",
gif = "image/gif",
svg = "image/svg+xml",
html= "application/xhtml+xml",
xhtml= "application/xhtml+xml",
ncx = "application/x-dtbncx+xml",
js = "text/javascript",
css = "text/css",
otf = "application/opentype",
ttf = "application/truetype",
woff = "application/font-woff",
}
-- Create an epub file (with possibly images)
function Wikipedia:createEpub(epub_path, page, lang, with_images)
-- Use Trapper to display progress and ask questions through the UI.
-- We need to have been Trapper.wrap()'ed for UI to be used, otherwise
-- Trapper:info() and Trapper:confirm() will just use logger.
local UI = require("ui/trapper")
UI:info(_("Retrieving Wikipedia article…"))
local ok, phtml = pcall(self.getFullPageHtml, self, page, lang)
if not ok then
UI:info(phtml) -- display error in InfoMessage
-- Sleep a bit to make that error seen
ffiutil.sleep(2)
UI:reset()
return false
end
-- We may need to build absolute urls for non-absolute links and images urls
local wiki_base_url = self:getWikiServer(lang)
-- Get infos from wikipedia result
-- (see example at https://en.wikipedia.org/w/api.php?action=parse&page=E-book&prop=text|sections|displaytitle|revid&disablelimitreport=&disableeditsection)
local cancelled = false
local html = phtml.text["*"] -- html content
local page_cleaned = page:gsub("_", " ") -- page title
local page_htmltitle = phtml.displaytitle -- page title with possible <sup> tags
-- We need to encode plain '&' in those so we can put them in XML/HTML
-- We wouldn't need to escape as many as util.htmlEntitiesToUtf8() does, but
-- we need to to not mess existing ones ('&nbsp;' may happen) with our '&'
-- encodes. (We don't escape < or > as these JSON strings may contain HTML tags)
page_cleaned = util.htmlEntitiesToUtf8(page_cleaned):gsub("&", "&#38;")
page_htmltitle = util.htmlEntitiesToUtf8(page_htmltitle):gsub("&", "&#38;")
local sections = phtml.sections -- Wikipedia provided TOC
local bookid = string.format("wikipedia_%s_%s_%s", lang, phtml.pageid, phtml.revid)
-- Not sure if this bookid may ever be used by indexing software/calibre, but if it is,
-- should it changes if content is updated (as now, including the wikipedia revisionId),
-- or should it stays the same even if revid changes (content of the same book updated).
-- We need to find images in HTML to tell how many when asking user if they should be included
local images = {}
local seen_images = {}
local imagenum = 1
local cover_imgid = nil -- best candidate for cover among our images
local processImg = function(img_tag)
local src = img_tag:match([[src="([^"]*)"]])
if src == nil or src == "" then
logger.info("no src found in ", img_tag)
return nil
end
if src:sub(1,2) == "//" then
src = "https:" .. src -- Wikipedia redirects from http to https, so use https
elseif src:sub(1,1) == "/" then -- non absolute url
src = wiki_base_url .. src
end
-- Some SVG urls don't have any extension, like:
-- "/api/rest_v1/media/math/render/svg/154a342afea5a9f13caf1a5bb6acd5c4e69733b6""
-- Furthermore, as of early 2018, it looks like most (all?) mathematical SVG
-- obtained from such urls use features not supported by crengine's nanosvg
-- renderer (so, they are displayed as a blank square).
-- But we can get a PNG version of it thanks to wikipedia APIs :
-- https://wikimedia.org/api/rest_v1/#!/Math/get_media_math_render_format_hash
-- We tweak the url now (and fix the mimetype below), before checking for
-- duplicates in seen_images.
-- Think about disabling that when nanosvg gets better!
if src:find("/math/render/svg/") then
src = src:gsub("/math/render/svg/", "/math/render/png/")
end
local cur_image
if seen_images[src] then -- already seen
cur_image = seen_images[src]
else
local src_ext = src
if src_ext:find("?") then -- "/w/extensions/wikihiero/img/hiero_D22.png?0b8f1"
src_ext = src_ext:match("(.-)%?") -- remove ?blah
end
local ext = src_ext:match(".*%.(%S%S%S?%S?%S?)$") -- extensions are only 2 to 5 chars
if ext == nil or ext == "" then
if src_ext:find("/math/render/png/") then -- tweaked above
ext = "png"
else
-- we won't know what mimetype to use, ignore it
logger.info("no file extension found in ", src)
return nil
end
end
ext = ext:lower()
local imgid = string.format("img%05d", imagenum)
local imgpath = string.format("images/%s.%s", imgid, ext)
local mimetype = ext_to_mimetype[ext] or ""
local width = tonumber(img_tag:match([[width="([^"]*)"]]))
local height = tonumber(img_tag:match([[height="([^"]*)"]]))
-- Get higher resolution (2x) image url
local src2x = nil
local srcset = img_tag:match([[srcset="([^"]*)"]])
if srcset then
srcset = " "..srcset.. ", " -- for next pattern to possibly match 1st or last item
src2x = srcset:match([[ (%S+) 2x, ]])
if src2x then
if src2x:sub(1,2) == "//" then
src2x = "https:" .. src2x
elseif src2x:sub(1,1) == "/" then -- non absolute url
src2x = wiki_base_url .. src2x
end
end
end
cur_image = {
imgid = imgid,
imgpath = imgpath,
src = src,
src2x = src2x,
mimetype = mimetype,
width = width,
height = height,
}
table.insert(images, cur_image)
seen_images[src] = cur_image
-- Use first image of reasonable size (not an icon) and portrait-like as cover-image
if not cover_imgid and width and width > 50 and height and height > 50 and height > width then
cover_imgid = imgid
end
imagenum = imagenum + 1
end
-- crengine will NOT use width and height attributes, but it will use
-- those found in a style attribute.
-- If we get src2x images, crengine will scale them down to the 1x image size
-- (less space wasted by images while reading), but the 2x quality will be
-- there when image is viewed full screen with ImageViewer widget.
local style_props = {}
if cur_image.width then
table.insert(style_props, string.format("width: %spx", cur_image.width))
end
if cur_image.height then
table.insert(style_props, string.format("height: %spx", cur_image.height))
end
local style = table.concat(style_props, "; ")
return string.format([[<img src="%s" style="%s" alt=""/>]], cur_image.imgpath, style)
end
html = html:gsub("(<%s*img [^>]*>)", processImg)
logger.dbg("Images found in html:", images)
-- See what to do with images
local include_images = false
local use_img_2x = false
if with_images then
-- If no UI (Trapper:wrap() not called), UI:confirm() will answer true
if #images > 0 then
include_images = UI:confirm(T(_("This article contains %1 images.\nWould you like to download and include them in the generated EPUB file?"), #images), _("Don't include"), _("Include"))
if include_images then
use_img_2x = UI:confirm(_("Would you like to use slightly higher quality images? This will result in a bigger file size."), _("Standard quality"), _("Higher quality"))
end
else
UI:info(_("This article does not contain any images."))
ffiutil.sleep(1) -- Let the user see that
end
end
if not include_images then
-- Remove img tags to avoid little blank squares of missing images
html = html:gsub("<%s*img [^>]*>", "")
-- We could remove the whole image container <div class="thumb"...> ,
-- but it's a lot of nested <div> and not easy to do.
-- So the user will see the image legends and know a bit about
-- the images he chose to not get.
end
UI:info(_("Building EPUB…"))
-- Open the zip file (with .tmp for now, as crengine may still
-- have a handle to the final epub_path, and we don't want to
-- delete a good one if we fail/cancel later)
local epub_path_tmp = epub_path .. ".tmp"
local ZipWriter = require("ffi/zipwriter")
local epub = ZipWriter:new{}
if not epub:open(epub_path_tmp) then
return false
end
-- We now create and add all the required epub files
-- ----------------------------------------------------------------
-- /mimetype : always "application/epub+zip"
epub:add("mimetype", "application/epub+zip")
-- ----------------------------------------------------------------
-- /META-INF/container.xml : always the same content
epub:add("META-INF/container.xml", [[
<?xml version="1.0"?>
<container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">
<rootfiles>
<rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/>
</rootfiles>
</container>]])
-- ----------------------------------------------------------------
-- OEBPS/content.opf : metadata + list of other files (paths relative to OEBPS/ directory)
-- Other possible items in this file that are of no interest to crengine :
-- In <manifest> :
-- <item id="cover" href="title.html" media-type="application/xhtml+xml"/>
-- <item id="cover-image" href="images/cover.png" media-type="image/png"/>
-- (crengine only uses <meta name="cover" content="cover-image" /> to get the cover image)
-- In <spine toc="ncx"> :
-- <itemref idref="cover" linear="no"/>
-- And a <guide> section :
-- <guide>
-- <reference href="title.html" type="cover" title="Cover"/>
-- <reference href="toc.html" type="toc" title="Table of Contents" href="toc.html" />
-- </guide>
local koreader_version = "KOReader"
if lfs.attributes("git-rev", "mode") == "file" then
koreader_version = "KOReader "..io.open("git-rev", "r"):read()
end
local content_opf_parts = {}
-- head
local meta_cover = "<!-- no cover image -->"
if include_images and cover_imgid then
meta_cover = string.format([[<meta name="cover" content="%s"/>]], cover_imgid)
end
table.insert(content_opf_parts, string.format([[
<?xml version='1.0' encoding='utf-8'?>
<package xmlns="http://www.idpf.org/2007/opf"
xmlns:dc="http://purl.org/dc/elements/1.1/"
unique-identifier="bookid" version="2.0">
<metadata>
<dc:title>%s</dc:title>
<dc:creator>Wikipedia %s</dc:creator>
<dc:identifier id="bookid">%s</dc:identifier>
<dc:language>%s</dc:language>
<dc:publisher>%s</dc:publisher>
%s
</metadata>
<manifest>
<item id="ncx" href="toc.ncx" media-type="application/x-dtbncx+xml"/>
<item id="content" href="content.html" media-type="application/xhtml+xml"/>
<item id="css" href="stylesheet.css" media-type="text/css"/>
]], page_cleaned, lang:upper(), bookid, lang, koreader_version, meta_cover))
-- images files
if include_images then
for inum, img in ipairs(images) do
table.insert(content_opf_parts, string.format([[ <item id="%s" href="%s" media-type="%s"/>%s]], img.imgid, img.imgpath, img.mimetype, "\n"))
end
end
-- tail
table.insert(content_opf_parts, [[
</manifest>
<spine toc="ncx">
<itemref idref="content"/>
</spine>
</package>
]])
epub:add("OEBPS/content.opf", table.concat(content_opf_parts))
-- ----------------------------------------------------------------
-- OEBPS/stylesheet.css
-- crengine will use its own data/epub.css, we just add/fix a few styles
-- to look more alike wikipedia web pages (that the user can ignore
-- with "Embedded Style" off)
epub:add("OEBPS/stylesheet.css", [[
/* make section headers looks left aligned and avoid some page breaks */
h1, h2 {
text-align: left;
}
h3, h4, h5, h6, h7 {
page-break-before: avoid;
page-break-after: avoid;
text-align: left;
}
/* avoid page breaks around our centered titles on first page */
h1.koreaderwikifrontpage, h5.koreaderwikifrontpage {
page-break-before: avoid;
page-break-inside: avoid;
page-break-after: avoid;
text-align: center;
margin-top: 0em;
}
p.koreaderwikifrontpage {
font-style: italic;
font-size: 90%;
margin-left: 2em;
margin-right: 2em;
margin-top: 1em;
margin-bottom: 1em;
}
hr.koreaderwikifrontpage {
margin-left: 20%;
margin-right: 20%;
margin-bottom: 1.2em;
}
/* So many links, make them look like normal text except for underline */
a {
display:inline;
text-decoration: underline;
color: black;
font-weight: normal;
}
/* No underline for links without their href that we removed */
a.newwikinonexistent {
text-decoration: none;
}
/* show a box around image thumbnails */
div.thumb {
border: dotted 1px black;
margin-top: 0.5em;
margin-bottom: 0.5em;
margin-left: 2.5em;
margin-right: 2.5em;
padding-top: ]].. (include_images and "0.5em" or "0.15em") .. [[;
padding-bottom: 0.2em;
padding-left: 0.5em;
padding-right: 0.5em;
text-align: center;
font-size: 90%;
}
/* don't waste left margin for notes and list of pages */
ul, ol {
margin-left: 0em;
}
/* avoid a line with a standalone bullet */
li.gallerybox {
display: inline;
}
/* helps crengine to not display them as block elements */
time, abbr, sup {
display: inline;
}
]])
-- ----------------------------------------------------------------
-- OEBPS/toc.ncx : table of content
local toc_ncx_parts = {}
local depth = 0
local cur_level = 0
local np_end = [[</navPoint>]]
local num = 1
-- Add our own first section for first page, with page name as title
table.insert(toc_ncx_parts, string.format([[<navPoint id="navpoint-%s" playOrder="%s"><navLabel><text>%s</text></navLabel><content src="content.html"/>]], num, num, page_cleaned))
table.insert(toc_ncx_parts, np_end)
-- Wikipedia sections items seem to be already sorted by index, so no need to sort
for isec, s in ipairs(sections) do
num = num + 1
-- Some chars in headings are converted to html entities in the
-- wikipedia-generated HTML. We need to do the same in TOC links
-- for the links to be valid.
local s_anchor = s.anchor:gsub("&", "&amp;"):gsub('"', "&quot;"):gsub(">", "&gt;"):gsub("<", "&lt;")
local s_title = string.format("%s %s", s.number, s.line)
-- Titles may include <i> and other html tags: let's remove them as
-- our TOC can only display text
s_title = (s_title:gsub("(%b<>)", ""))
-- We need to do as for page_htmltitle above. But headings can contain
-- html entities for < and > that we need to put back as html entities
s_title = util.htmlEntitiesToUtf8(s_title):gsub("&", "&#38;"):gsub(">", "&gt;"):gsub("<", "&lt;")
local s_level = s.toclevel
if s_level > depth then
depth = s_level -- max depth required in toc.ncx
end
if s_level == cur_level then
table.insert(toc_ncx_parts, np_end) -- close same-level previous navPoint
elseif s_level < cur_level then
table.insert(toc_ncx_parts, np_end) -- close same-level previous navPoint
while s_level < cur_level do -- close all in-between navPoint
table.insert(toc_ncx_parts, np_end)
cur_level = cur_level - 1
end
elseif s_level > cur_level + 1 then
-- a jump from level N to level N+2 or more ... should not happen
-- per epub spec, but we don't know about wikipedia...
-- so we create missing intermediate navPoints with same anchor as current section
while s_level > cur_level + 1 do
table.insert(toc_ncx_parts, "\n"..(" "):rep(cur_level))
table.insert(toc_ncx_parts, string.format([[<navPoint id="navpoint-%s" playOrder="%s"><navLabel><text>-</text></navLabel><content src="content.html#%s"/>]], num, num, s_anchor))
cur_level = cur_level + 1
num = num + 1
end
-- elseif s_level == cur_level + 1 then
-- sublevel, nothing to close, nothing to add
end
cur_level = s_level
table.insert(toc_ncx_parts, "\n"..(" "):rep(cur_level)) -- indentation, in case a person looks at it
table.insert(toc_ncx_parts, string.format([[<navPoint id="navpoint-%s" playOrder="%s"><navLabel><text>%s</text></navLabel><content src="content.html#%s"/>]], num, num, s_title, s_anchor))
end
-- close nested <navPoint>
while cur_level > 0 do
table.insert(toc_ncx_parts, np_end)
cur_level = cur_level - 1
end
-- Prepend NCX head
table.insert(toc_ncx_parts, 1, string.format([[
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE ncx PUBLIC "-//NISO//DTD ncx 2005-1//EN" "http://www.daisy.org/z3986/2005/ncx-2005-1.dtd">
<ncx xmlns="http://www.daisy.org/z3986/2005/ncx/" version="2005-1">
<head>
<meta name="dtb:uid" content="%s"/>
<meta name="dtb:depth" content="%s"/>
<meta name="dtb:totalPageCount" content="0"/>
<meta name="dtb:maxPageNumber" content="0"/>
</head>
<docTitle>
<text>%s</text>
</docTitle>
<navMap>
]], bookid, depth, page_cleaned))
-- Append NCX tail
table.insert(toc_ncx_parts, [[
</navMap>
</ncx>
]])
epub:add("OEBPS/toc.ncx", table.concat(toc_ncx_parts))
-- ----------------------------------------------------------------
-- OEBPS/content.html
-- Some small fixes to Wikipedia HTML to make crengine and the user happier
-- Most images are in a link to the image info page, which is a useless
-- external link for us, so let's remove this link.
html = html:gsub("<a[^>]*>%s*(<%s*img [^>]*>)%s*</a>", "%1")
-- TODO: do something for <li class="gallerybox"...> so they are no more
-- a <li> (crengine displays them one above the other) and can be displayed
-- side by side
-- For some <div class="thumb tright"> , which include nested divs, although
-- perfectly balanced, crengine seems to miss some closing </div> and we
-- end up having our image bordered box including the remaining main wiki text.
-- It looks like this code is supposed to deal with class= containing multiple
-- class names :
-- https://github.com/koreader/crengine/commit/0930ec7230e720c148fd6f231d69558832b4d53a
-- and that it may stumble on some cases.
-- It's all perfectly fine if we make all these div with a single class name
-- html = html:gsub([[<div class="thumb [^"]*">]], [[<div class="thumb">]])
--
-- But we may as well make all class= have a single name to avoid other problems
-- (no real risk with that, as we don't define any style for wikipedia class names,
-- except div.thumb that always appears first).
html = html:gsub([[(<[^>]* class="[^ "]+)%s+[^"]*"]], [[%1"]])
-- crengine seems to consider unknown tag as 'block' elements, so we may
-- want to remove or replace those that should be considered 'inline' elements
html = html:gsub("</?time[^>]*>", "")
-- crengine does not support the <math> family of tags for displaying formulas,
-- which results in lots of space taken by individual character in the formula, each
-- on a single line...
-- Also, usally, these <math> tags are followed by a <img> tag pointing to a
-- SVG version of the formula, that we took care earlier to change the url to
-- point to a PNG version of the formula (which is still not perfect, as it does
-- not adjust to the current html font size, but it is at least readable).
-- So, remove the whole <math>...</math> content
html = html:gsub([[<math xmlns="http://www.w3.org/1998/Math/MathML".-</math>]], "")
-- Fix internal wikipedia links with full server url (including lang) so
-- ReaderLink can notice them and deal with them with a LookupWikipedia event.
-- We need to remove any "?somekey=somevalue" from url (a real "?" part of the
-- wiki_page word would be encoded as %3F, but ReaderLink would get it decoded and
-- would not be able to distinguish them).
-- Do that first (need to be done first) for full links to other language wikipedias
local cleanOtherLangWikiPageTitle = function(wiki_lang, wiki_page)
wiki_page = wiki_page:gsub("%?.*", "")
return string.format([[href="https://%s.wikipedia.org/wiki/%s"]], wiki_lang, wiki_page)
end
html = html:gsub([[href="https?://([^%.]+).wikipedia.org/wiki/([^"]*)"]], cleanOtherLangWikiPageTitle)
-- Now, do it for same wikipedia short urls
local cleanWikiPageTitle = function(wiki_page)
wiki_page = wiki_page:gsub("%?.*", "")
return string.format([[href="%s/wiki/%s"]], wiki_base_url, wiki_page)
end
html = html:gsub([[href="/wiki/([^"]*)"]], cleanWikiPageTitle)
-- Remove href from links to non existant wiki page so they are not clickable :
-- <a href="/w/index.php?title=PageTitle&amp;action=edit&amp;redlink=1" class="new" title="PageTitle">PageTitle____on</a>
-- (removal of the href="" will make them non clickable)
html = html:gsub([[<a[^>]* class="new"[^>]*>]], [[<a class="newwikinonexistent">]])
-- Fix some other protocol-less links to wikipedia (href="//fr.wikipedia.org/w/index.php..)
html = html:gsub([[href="//]], [[href="https://]])
-- crengine does not return link if multiple class names in <a> (<a class="external text" href="">)
-- it would be no problem as we can't follow them, but when the user tap
-- on it, the tap is propagated to other widgets and page change happen...
-- html = html:gsub([[<a rel="nofollow" class="external text"]], [[<a rel="nofollow" class="externaltext"]])
-- html = html:gsub([[<a class="external text"]], [[<a class="externaltext"]])
-- Solved by our multiple class names suppression above
-- Avoid link being clickable before <a> (if it starts a line) or after </a> (if it
-- ends a line or a block) by wrapping it with U+200B ZERO WIDTH SPACE which will
-- make the DOM tree walking code to find a link stop at it.
-- html = html:gsub("(<[aA])", "\xE2\x80\x8B%1")
-- html = html:gsub("(</[aA]>)", "%1\xE2\x80\x8B")
-- Fixed in crengine lvtinydom.
if self.wiki_prettify then
-- Prepend some symbols to section titles for a better visual feeling of hierarchy
html = html:gsub("<h1>", "<h1> "..h1_sym.." ")
html = html:gsub("<h2>", "<h2> "..h2_sym.." ")
html = html:gsub("<h3>", "<h3> "..h3_sym.." ")
html = html:gsub("<h4>", "<h4> "..h4_sym.." ")
html = html:gsub("<h5>", "<h5> "..h5_sym.." ")
html = html:gsub("<h6>", "<h6> "..h6_sym.." ")
end
-- Note: in all the gsub patterns above, we used lowercase for tags and attributes
-- because it's how they are in wikipedia HTML and it makes the pattern simple.
-- If one day this changes, they'll have to be replaced with href => [Hh][Rr][Ee][Ff] ...
-- We can finally build the final HTML with some header of our own
local saved_on = T(_("Saved on %1"), os.date("%b %d, %Y %H:%M:%S"))
local online_version_htmllink = string.format([[<a href="%s/wiki/%s">%s</a>]], wiki_base_url, page:gsub(" ", "_"), _("online version"))
local see_online_version = T(_("See %1 for up-to-date content"), online_version_htmllink)
epub:add("OEBPS/content.html", string.format([[
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>%s</title>
<link type="text/css" rel="stylesheet" href="stylesheet.css"/>
</head>
<body>
<h1 class="koreaderwikifrontpage">%s</h1>
<h5 class="koreaderwikifrontpage">Wikipedia %s</h5>
<p class="koreaderwikifrontpage">%s<br/>%s</p>
<hr class="koreaderwikifrontpage"/>
%s
</body>
</html>
]], page_cleaned, page_htmltitle, lang:upper(), saved_on, see_online_version, html))
-- Force a GC to free the memory we used till now (the second call may
-- help reclaim more memory).
collectgarbage()
collectgarbage()
-- ----------------------------------------------------------------
-- OEBPS/images/*
if include_images then
local nb_images = #images
for inum, img in ipairs(images) do
-- Process can be interrupted at this point between each image download
-- by tapping while the InfoMessage is displayed
-- We use the fast_refresh option from image #2 for a quicker download
local go_on = UI:info(T(_("Retrieving image %1 / %2 …"), inum, nb_images), inum >= 2)
if not go_on then
cancelled = true
break
end
local src = img.src
if use_img_2x and img.src2x then
src = img.src2x
end
logger.dbg("Getting img ", src)
local success, content = getUrlContent(src)
-- success, content = getUrlContent(src..".unexistant") -- to simulate failure
if success then
logger.dbg("success, size:", #content)
else
logger.info("failed fetching:", src)
end
if success then
-- Images do not need to be compressed, so spare some cpu cycles
local no_compression = true
if img.mimetype == "image/svg+xml" then -- except for SVG images (which are XML text)
no_compression = false
end
epub:add("OEBPS/"..img.imgpath, content, no_compression)
else
go_on = UI:confirm(T(_("Downloading image %1 failed. Continue anyway?"), inum), _("Stop"), _("Continue"))
if not go_on then
cancelled = true
break
end
end
end
end
-- Done with adding files
if cancelled then
if UI:confirm(_("Download did not complete.\nDo you want to create an EPUB with the already downloaded images?"), _("Don't create"), _("Create")) then
cancelled = false
end
end
if cancelled then
UI:info(_("Canceled. Cleaning up…"))
else
UI:info(_("Packing EPUB…"))
end
epub:close()
-- This was nearly a no-op, so sleep a bit to make that progress step seen
ffiutil.usleep(300000)
UI:reset() -- close last InfoMessage
if cancelled then
-- Build was cancelled, remove half created .epub
if lfs.attributes(epub_path_tmp, "mode") == "file" then
os.remove(epub_path_tmp)
end
return false
end
-- Finally move the .tmp to the final file
os.rename(epub_path_tmp, epub_path)
logger.info("successfully created:", epub_path)
-- Force a GC to free the memory we used (the second call may help
-- reclaim more memory).
collectgarbage()
collectgarbage()
return true
end
-- Wrap Wikipedia:createEpub() with UI progress info, provided
-- by Trapper module.
function Wikipedia:createEpubWithUI(epub_path, page, lang, result_callback)
-- To do any UI interaction while building the EPUB, we need
-- to use a coroutine, so that our code can be suspended while waiting
-- for user interaction, and resumed by UI widgets callbacks.
-- All this is hidden and done by Trapper with a simple API.
local Trapper = require("ui/trapper")
Trapper:wrap(function()
Trapper:setPausedText("Download paused")
-- If errors in Wikipedia:createEpub(), the coroutine (used by
-- Trapper) would just abort (no reader crash, no error logged).
-- So we use pcall to catch any errors, log it, and report
-- the failure via result_callback.
local ok, success = pcall(self.createEpub, self, epub_path, page, lang, true)
if ok and success then
result_callback(true)
else
Trapper:reset() -- close any last widget not cleaned if error
logger.warn("Wikipedia.createEpub pcall:", ok, success)
result_callback(false)
end
end)
end
return Wikipedia