mirror of https://github.com/koreader/koreader
started with a document abstraction
for now, only an implementation for PDFs exist. to be separated out... and we need implementations for the other supported enginespull/2/merge
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--[[
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This is a registry for document providers
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]]--
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DocumentRegistry = {
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providers = { }
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}
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function DocumentRegistry:addProvider(extension, mimetype, provider)
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table.insert(self.providers, { extension = extension, mimetype = mimetype, provider = provider })
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end
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function DocumentRegistry:getProvider(file)
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-- TODO: some implementation based on mime types?
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local extension = string.lower(string.match(file, ".+%.([^.]+)"))
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for _, provider in ipairs(self.providers) do
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if extension == provider.extension then
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return provider.provider:new{file = file}
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end
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end
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end
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--[[
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This is an abstract interface to a document
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]]--
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Document = {
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-- file name
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file = nil,
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info = {
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-- whether the document is pageable
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has_pages = false,
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-- whether words can be provided
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has_words = false,
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-- whether hyperlinks can be provided
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has_hyperlinks = false,
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-- whether (native to format) annotations can be provided
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has_annotations = false,
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-- whether pages can be rotated
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is_rotatable = false,
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number_of_pages = 0,
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-- if not pageable, length of the document in pixels
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length = 0,
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-- other metadata
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title = "",
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author = "",
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date = ""
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},
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-- flag to show whether the document was opened successfully
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is_open = false,
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error_message = nil,
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-- flag to show that the document needs to be unlocked by a password
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is_locked = false,
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}
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function Document:new(o)
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local o = o or {}
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setmetatable(o, self)
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self.__index = self
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if o.init then o:init() end
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return o
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end
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-- this might be overridden by a document implementation
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function Document:unlock(password)
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-- return true instead when the password provided unlocked the document
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return false
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end
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-- this might be overridden by a document implementation
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function Document:close()
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end
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-- this might be overridden by a document implementation
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function Document:getNativePageDimensions(pageno)
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return Geom:new{w=0, h=0}
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end
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-- calculates page dimensions
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function Document:getPageDimensions(pageno, zoom, rotation)
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local native_dimen = Geom:copy(self:getNativePageDimensions(pageno))
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if rotation == 90 or rotation == 270 then
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-- switch orientation
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native_dimen.w, native_dimen.h = native_dimen.h, native_dimen.w
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end
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native_dimen:scaleBy(zoom)
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debug("dimen for pageno", pageno, "zoom", zoom, "rotation", rotation, "is", native_dimen)
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return native_dimen
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end
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require "cache"
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require "geometry"
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PdfDocument = Document:new{
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_document = false,
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-- muPDF manages its own additional cache
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mupdf_cache_size = 5 * 1024 * 1024,
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dc_null = DrawContext.new()
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}
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function PdfDocument:init()
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local ok
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ok, self._document = pcall(pdf.openDocument, self.file, self.mupdf_cache_size)
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if not ok then
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self.error_message = self.doc -- will contain error message
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return
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end
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self.is_open = true
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self.info.has_pages = true
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if self._document:needsPassword() then
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self.is_locked = true
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else
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self:_readMetadata()
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end
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end
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function PdfDocument:unlock(password)
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if not self._document:authenticatePassword(password) then
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self._document:close()
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return false, "wrong password"
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end
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self.is_locked = false
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return self:_readMetadata()
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end
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function PdfDocument:_readMetadata()
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self.info.number_of_pages = self._document:getPages()
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return true
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end
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function PdfDocument:close()
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if self.is_open then
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self.is_open = false
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self._document:close()
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end
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end
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function PdfDocument:getNativePageDimensions(pageno)
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local hash = "pgdim|"..self.file.."|"..pageno
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local cached = Cache:check(hash)
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if cached then
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return cached[1]
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end
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local page = self._document:openPage(pageno)
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local page_size_w, page_size_h = page:getSize(self.dc_null)
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local page_size = Geom:new{ w = page_size_w, h = page_size_h }
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Cache:insert(hash, CacheItem:new{ page_size })
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page:close()
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return page_size
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end
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function PdfDocument:getUsedBBox(pageno)
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local hash = "pgubbox|"..self.file.."|"..pageno
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local cached = Cache:check(hash)
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if cached then
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return cached.data
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end
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local page = self._document:openPage(pageno)
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local used = {}
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used.x, used.y, used.w, used.h = page:getUsedBBox()
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Cache:insert(hash, CacheItem:new{ used })
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page:close()
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return used
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end
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function PdfDocument:getPageText(pageno)
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-- is this worth caching? not done yet.
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local page = self._document:openPage(pageno)
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local text = page:getPageText()
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page:close()
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return text
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end
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function PdfDocument:renderPage(pageno, rect, zoom, rotation)
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local hash = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation
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local page_size = self:getPageDimensions(pageno, zoom, rotation)
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-- this will be the size we actually render
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local size = page_size
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-- we prefer to render the full page, if it fits into cache
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if not Cache:willAccept(size.w * size.h / 2) then
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-- whole page won't fit into cache
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debug("rendering only part of the page")
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-- TODO: figure out how to better segment the page
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if not rect then
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debug("aborting, since we do not have a specification for that part")
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-- required part not given, so abort
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return
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end
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-- only render required part
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hash = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..tostring(rect)
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size = rect
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end
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-- prepare cache item with contained blitbuffer
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local tile = CacheItem:new{
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size = size.w * size.h / 2 + 64, -- estimation
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excerpt = size,
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pageno = pageno,
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bb = Blitbuffer.new(size.w, size.h)
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}
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-- create a draw context
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local dc = DrawContext.new()
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dc:setRotate(rotation)
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-- correction of rotation
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if rotation == 90 then
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dc:setOffset(page_size.w, 0)
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elseif rotation == 180 then
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dc:setOffset(page_size.w, page_size.h)
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elseif rotation == 270 then
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dc:setOffset(0, page_size.h)
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end
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dc:setZoom(zoom)
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-- render
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local page = self._document:openPage(pageno)
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page:draw(dc, tile.bb, size.x, size.y)
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page:close()
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Cache:insert(hash, tile)
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return tile
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end
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-- a hint for the cache engine to paint a full page to the cache
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-- TODO: this should trigger a background operation
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function PdfDocument:hintPage(pageno, zoom, rotation)
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self:renderPage(pageno, nil, zoom, rotation)
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end
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function PdfDocument:drawPage(target, x, y, rect, pageno, zoom, rotation)
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local hash_full_page = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation
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local hash_excerpt = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..tostring(rect)
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local tile = Cache:check(hash_full_page)
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if not tile then
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tile = Cache:check(hash_excerpt)
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if not tile then
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debug("rendering")
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tile = self:renderPage(pageno, rect, zoom, rotation)
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end
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end
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debug("now painting", tile)
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target:blitFrom(tile.bb, x, y, rect.x - tile.excerpt.x, rect.y - tile.excerpt.y, rect.w, rect.h)
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end
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DocumentRegistry:addProvider("pdf", "application/pdf", PdfDocument)
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