Create, cleanup, add and manage Table Of Contents (TOC) of pdf and djvu documents with Emacs
This package is also provided by the [[https://github.com/dalanicolai/toc-layer][toc-layer for Spacemacs]]
** Features:
For Spacemacs use the [[https://github.com/dalanicolai/toc-layer][toc-layer for Spacemacs]]. Installation instruction are found on that page.
For regular Emacs users, well... you probably know how to install packages.
** Requirements To use the pdf.tocgen functionality that software has to be installed (see [[https://krasjet.com/voice/pdf.tocgen/]]). For the other remaining functionality the package requires ~pdftotext~ (part of poppler-utils), ~pdfoutline~ (part of [[https://launchpad.net/ubuntu/bionic/+package/fntsample][fntsample]]) and ~djvused~ (part of [[http://djvu.sourceforge.net/][http://djvu.sourceforge.net/]]) command line utilities to be available. Extraction with OCR requires the ~tesseract~ command line utility to be available.
For 'software-generated' (i.e. PDF's not created from scans) PDF-files it is recommend to use =doc-toc-extract-with-pdf-tocgen=. To use this function you first have to provide the font properties for the different headline levels. For that select the word in a headline of a certain level and then type =M-x doc-toc-gen-set-level=. This function will ask which level you are setting, the highest level should be level 1. After you have set the various levels (1,2, etc.) then it is time to run =M-x doc-toc-extract-with-pdf-tocgen=. If a TOC is extracted succesfully, then in the pdftocgen-mode buffer simply press C-c C-c to add the contents to the PDF. The contents will be added to a copy of the original PDF with the filename output.pdf and this copy will be opened in a new buffer. If the pdf-tocgen option does not work well then continue with the steps below.
** toc-mode In each step below, check out available shortcuts using =C-h m=. Additionally you can find available functions by typing the M-x mode-name (e.g. =M-x doc-toc-cleanup=), or with two dashes in the mode name (e.g. =M-x doc-toc--cleanup=). Of course if you use packages like Ivy or Helm you just use the fuzzy search functionality.
Extraction and adding contents to a document is done in 4 steps:
In each step below, check out available shortcuts using =C-h m=. Additionally you can find available functions by typing the =M-x mode-name= (e.g. =M-x doc-toc-cleanup=), or with two dashes in the mode name (e.g. =M-x doc-toc--cleanup=). Of course if you use packages like Ivy or Helm you just use the fuzzy search functionality.
*** 1. Extraction For PDFs without TOC pages, with a very complicated TOC (i.e. that require much cleanup work) or with headlines well fitted for automatic extraction (you will have to decide for yourself by trying it), consider to use the [[https://krasjet.com/voice/pdf.tocgen/][pdf.tocgen]] functionality described below.
Otherwise, start with opening some pdf or djvu file in Emacs (pdf-tools and djvu package recommended). Find the pagenumbers for the TOC. Then type =M-x doc-toc-extract-pages=, or =M-x doc-toc-extract-pages-ocr= if doc has no text layer or the text layer is bad, and answer the subsequent prompts by entering the pagenumbers for the first and the last page each followed by =RET=. For PDF extraction with OCR, currently it is required to view all contents pages once before extraction (doc-toc uses the cached file data). For TOC's that are formatted as two columns per page, prepend the =doc-toc-extract-pages-ocr= command with two universal arguments. Then after you are asked for the start and finish pagenumbers, a third question asks you to set the tesseract psm code. For the double column layout it is best (as far as I know) to use psm code =1=. Also the languages used for tesseract OCR can be customized via the ~doc-toc-ocr-languages~ variable.
[[doc-toc-extract.gif]]
A buffer with the, somewhat cleaned up, extracted text will open in TOC-cleanup mode. Prefix command with the universal argument (=C-u=) to omit cleanup and get the raw text. If the extracted text is of too low quality you either can hack/extend the [[help:doc-toc-extract-pages-ocr][doc-toc-extract-pages-ocr]] definition, or alternatively you can try to extract the text with the [[https://pypi.org/project/document-contents-extractor/][python document-contents-extractor script]], which is more configurable (you are also welcome to hack on and improve that script). For this the [[https://tesseract-ocr.github.io/tessdoc/Command-Line-Usage.html][tesseract]] documentation might be useful.
If you merely want to extract text without further processing then you can use the command [[help:doc-toc-extract-only][doc-toc-extract-only]].
*** 2. TOC-Cleanup In this mode you can further cleanup the contents to create a list where each line has the structure:
TITLE (SOME) PAGENUMBER
There can be any number of spaces between TITLE and PAGE. The correct pagenumbers can be edited in the next step. A document outline supports different levels and levels are automatically assigned in order of increasing number of preceding spaces, i.e. the lines with the least amount of preceding spaces are assigned level 0 etc., and lines with equal number of spaces get assigned the same levels.
Contents 1 Chapter 1 2 Section 1 3 Section 1.1 4 Chapter 2 5
There are some handy functions to assist in the cleanup. =C-c C-j= jumps automatically to the next line not ending with a number and joins it with the next line. If the indentation structure of the different lines does not correspond with the levels, then the levels can be set automatically from the number of seperators in the indices with =M-x doc-toc-cleanup-set-level-by-index=. The default seperator is a ~.~ but a different seperator can be entered by preceding the function invocation with the universal argument (=C-u=). Some documents contain a structure like
1 Chapter 1 1 Section 1 2
Here the indentation can be set with =M-x replace-regexp= ~^[^0-9]~ -> ~\&~ (where there is a space character before the ~\&~).
Type =C-c C-c= when finished
*** 3. TOC-tabular (adjust pagenumbers) This mode provides the functionality for easy adjustment of pagenmumbers. The buffer can be navigated with the arrow =up/down= keys. The =left= and =right= arrow keys will shift =down/up= all the page numbers from the current line and below (combine with =SHIFT= for setting individual pagenumbers).
The =TAB= key jumps to the pagenumber of the current line, while =C-right/C-left= will shift all remaining page numbers up/down while jumping/scrolling to the line its page in the document window. Because the numbering of scanned books often breaks at sections of a certain level, =C-j= will let jo jump quickly to the next entry of a certain level (e.g. you can quickly check if the page numbers of all level 0 sections correspond to the page numbers in the document). The =S-up/S-down= in the tablist window will just scroll page up/down in the document window and, =C-up/C-down= will scroll smoothly in that window.
If you discover some small error in some field, then you put the cursor on that field and press =r= to correct the text in that field.
Type =C-c C-c= when done.
*** 4. TOC-mode (add outline to document) The text of this buffer should have the right structure for adding the contents to (for pdf's a copy of) the original document. Final adjustments can be done but should not be necessary. Type =C-c C-c= for adding the contents to the document.
By default, the TOC is simply added to the original file. (ONLY FOR PDF's, if the (customizable) variable [[help:doc-toc-replace-original-file][doc-toc-replace-original-file]] is ~nil~, then the TOC is added to a copy of the original pdf file with the path as defined by the variable ~doc-toc-destination-file-name~. Either a relative path to the original file directory or an absolute path can be given.)
Sometimes the =pdfoutline/djvused= application is not able to add the TOC to the document. In that case you can either debug the problem by copying the used terminal command from the =messages= buffer and run it manually in the document's folder iside the terminal, or you can delete the outline source buffer and run =doc-toc--tablist-to-handyoutliner= from the tablist buffer to get an outline source file that can be used with [[http://handyoutlinerfo.sourceforge.net/][HandyOutliner]] (unfortunately the handyoutliner command does not take arguments, but if you customize the [[help:doc-toc-handyoutliner-path][doc-toc-handyoutliner-path]] and [[help:doc-toc-file-browser-command][doc-toc-file-browser-command]] variables, then Emacs will try to open HandyOutliner and the file browser so that you can drag the file ~contents.txt~ directly into HandyOutliner).
all-modes (i.e. all steps) | Key Binding | Description | |-------------+----------------------| | ~C-c C-c~ | dispatch (next step) | doc-toc-cleanup-mode | ~C-c C-j~ | doc-toc-join-next-unnumbered-lines | | =C-c C-s= | doc-toc--roman-to-arabic | doc-toc-mode (tablist) | ~TAB~ | preview/jump-to-page | | ~right/left~ | doc-toc-in/decrease-remaining | | ~C-right/C-left~ | doc-toc-in/decrease-remaining and view page | | ~S-right/S-left~ | in/decrease pagenumber current entry | | ~C-down/C-up~ | scroll document other window (only when other buffer shows document) | | ~S-down/S-up~ | full page scroll document other window ( idem ) | | =C-j= | doc-toc--jump-to-next-entry-by-level | | =r= | doc-toc--replace-input |
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