README

pdf.tocgen
==========

                          in.pdf
                            |
                            |
     +----------------------+--------------------+
     |                      |                    |
     V                      V                    V
+----------+          +-----------+         +----------+
|          |  recipe  |           |   ToC   |          |
| pdfxmeta +--------->| pdftocgen +-------->| pdftocio +---> out.pdf
|          |          |           |         |          |
+----------+          +-----------+         +----------+

pdf.tocgen is a set of command-line tools for automatically
extracting and generating the table of contents (ToC) of a
PDF file. It uses the embedded font attributes and position
of headings to deduce the basic outline of a PDF file.

It works best for PDF files produces from a TeX document
using pdftex (and its friends pdflatex, pdfxetex, etc.), but
it's designed to work with any *software-generated* PDF
files (i.e. you shouldn't expect it to work with scanned
PDFs). Some examples include troff/groff, Adobe InDesign,
Microsoft Word, and probably more.

Please see the homepage [1] for a detailed introduction.

Installation
------------

pdf.tocgen is written in Python 3. It is known to work with
Python 3.7 to 3.11 on Linux, Windows, and macOS (On BSDs,
you probably need to build PyMuPDF yourself). Use

    $ pip install -U pdf.tocgen

to install the latest version systemwide. Alternatively, use
`pipx` or

    $ pip install -U --user pdf.tocgen

to install it for the current user. I would recommend the
latter approach to avoid messing up the package manager on
your system.

If you are using an Arch-based Linux distro, the package is
also available on AUR [8]. It can be installed using any AUR
helper, for example yay:

    $ yay -S pdf.tocgen

Workflow
--------

The design of pdf.tocgen is influenced by the Unix philosophy [2].
I intentionally separated pdf.tocgen to 3 separate programs.
They work together, but each of them is useful on their own.

1. pdfxmeta: extract the metadata (font attributes, positions)
             of headings to build a *recipe* file.
2. pdftocgen: generate a table of contents from the recipe.
3. pdftocio: import the table of contents to the PDF document.

You should read the example [3] on the homepage for a proper
introduction, but the basic workflow follows like this.

First, use pdfxmeta to search for the metadata of headings,
and generate *heading filters* using the automatic setting

    $ pdfxmeta -p page -a 1 in.pdf "Section" >> recipe.toml
    $ pdfxmeta -p page -a 2 in.pdf "Subsection" >> recipe.toml

Note that `page` needs to be replaced by the page number of
the search keyword.

The output `recipe.toml` file would contain several heading
filters, each of which specifies the attribute of a heading
at a particular level should have.

An example recipe file would look like this:

    [[heading]]
    level = 1
    greedy = true
    font.name = "Times-Bold"
    font.size = 19.92530059814453

    [[heading]]
    level = 2
    greedy = true
    font.name = "Times-Bold"
    font.size = 11.9552001953125

Then pass the recipe to `pdftocgen` to generate a table of
contents,

    $ pdftocgen in.pdf < recipe.toml
    "Preface" 5
        "Bottom-up Design" 5
        "Plan of the Book" 7
        "Examples" 9
        "Acknowledgements" 9
    "Contents" 11
    "The Extensible Language" 14
        "1.1 Design by Evolution" 14
        "1.2 Programming Bottom-Up" 16
        "1.3 Extensible Software" 18
        "1.4 Extending Lisp" 19
        "1.5 Why Lisp (or When)" 21
    "Functions" 22
        "2.1 Functions as Data" 22
        "2.2 Defining Functions" 23
        "2.3 Functional Arguments" 26
        "2.4 Functions as Properties" 28
        "2.5 Scope" 29
        "2.6 Closures" 30
        "2.7 Local Functions" 34
        "2.8 Tail-Recursion" 35
        "2.9 Compilation" 37
        "2.10 Functions from Lists" 40
    "Functional Programming" 41
        "3.1 Functional Design" 41
        "3.2 Imperative Outside-In" 46
        "3.3 Functional Interfaces" 48
        "3.4 Interactive Programming" 50
    [--snip--]

which can be directly imported to the PDF file using
`pdftocio`,

    $ pdftocgen in.pdf < recipe.toml | pdftocio -o out.pdf in.pdf

Or if you want to edit the table of contents before
importing it,

    $ pdftocgen in.pdf < recipe.toml > toc
    $ vim toc # edit
    $ pdftocio in.pdf < toc

Each of the three programs has some extra functionalities.
Use the -h option to see all the options you could pass in.

Development
-----------

If you want to modify the source code or contribute anything,
first install poetry [4], which is a dependency and package
manager for Python used by pdf.tocgen. Then run

    $ poetry install

in the root directory of this repository to set up
development dependencies.

If you want to test the development version of pdf.tocgen,
use the `poetry run` command:

    $ poetry run pdfxmeta in.pdf "pattern"

Alternatively, you could also use the

    $ poetry shell

command to open up a virtual environment and run the
development version directly:

    (pdf.tocgen) $ pdfxmeta in.pdf "pattern"

Before you send a patch or pull request, make sure the unit
test passes by running:

    $ make test

GUI front end
-------------

If you are a Emacs user, you could install Daniel Nicolai's
toc-mode [9] package as a GUI front end for pdf.tocgen,
though it offers many more functionalities, such as
extracting (printed) table of contents from a PDF file. Note
that it uses pdf.tocgen under the hood, so you still need to
install pdf.tocgen before using toc-mode as a front end for
pdf.tocgen.

License
-------

pdf.tocgen itself a is free software. The source code of
pdf.tocgen is licensed under the GNU GPLv3 license. However,
the recipes in the `recipes` directory is separately
licensed under the CC BY-NC-SA 4.0 License [7] to prevent
any commercial usage, and thus not included in the
distribution.

pdf.tocgen is based on PyMuPDF [5], licensed under the GNU
GPLv3 license, which is again based on MuPDF [6], licensed
under the GNU AGPLv3 license. A copy of the AGPLv3 license
is included in the repository.

If you want to make any derivatives based on this project,
please follow the terms of the GNU GPLv3 license.


[1]: https://krasjet.com/voice/pdf.tocgen/
[2]: https://en.wikipedia.org/wiki/Unix_philosophy
[3]: https://krasjet.com/voice/pdf.tocgen/#a-worked-example
[4]: https://python-poetry.org/
[5]: https://github.com/pymupdf/PyMuPDF
[6]: https://mupdf.com/docs/index.html
[7]: https://creativecommons.org/licenses/by-nc-sa/4.0/
[8]: https://aur.archlinux.org/packages/pdf.tocgen/
[9]: https://github.com/dalanicolai/toc-mode