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koreader/frontend/document/document.lua

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