How to generate a centered and captioned TikZ figure in a .docx file that has been converted from .tex with pandoc?

Question

Recently, I have been having some issues with TikZ in LaTeX. I want to convert my PhD dissertation, written in LaTeX, to .docx using pandoc. I am able to use lua filters to have pandoc convert TikZ images, thanks to help here.

However, a small problems remains. In the .docx file, the TikZ images are not centered. Nor are my captions included: it seems like pandoc simply ignores \begin{figure} whereafter I have included these commands.

Question

How to give a caption to and how to center TikZ figures in a .docx file converted with pandoc?

I am probably looking right over the solution, but as I am inexperienced with programming I do not know how to fix this.

Here is my .tex file:

\documentclass[a4paper,12pt]{book}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{tikz}
\begin{document}
\begin{figure}
\centering
\begin{tikzpicture}

         \draw circle(5cm);

\end{tikzpicture}


\caption{Admire my circle!}
\end{figure}
\end{document}

Here is my .lua file, taken from here, which functions as a filter:

local function file_exists(name)
  local f = io.open(name, 'r')
  if f ~= nil then io.close(f); return true
  else return false end
end
--- Create a standalone LaTeX document which contains only the TikZ picture.
--- Convert to png via Imagemagick.
local function tikz2image(src, outfile)
  local tmp = os.tmpname()
  local tmpdir = string.match(tmp, "^(.*[\/])") or "."
  -- local tmpdir = "."
  local f = io.open(tmp .. ".tex", 'w')
  f:write("\documentclass{standalone}\n")
  -- include all packages needed to compile your images
  f:write("\usepackage{tikz}\n\usepackage{stanli}\n\usetikzlibrary{arrows.meta,positioning}\n")
  f:write("\begin{document}\n")
  f:write(src)
  f:write("\n\end{document}\n")
  f:close()
  os.execute("pdflatex -output-directory " .. tmpdir  .. " " .. tmp)
  -- os.execute("convert " .. tmp .. ".pdf " .. "-colorspace RGB " .. outfile)
  os.execute("pdftoppm -png " .. tmp .. ".pdf " .. "> " .. outfile)
  os.remove(tmp .. ".tex")
  os.remove(tmp .. ".pdf")
  os.remove(tmp .. ".log")
  os.remove(tmp .. ".aux")
end
function RawBlock(el)
  -- Don't alter element if it's not a tikzpicture environment
  if not el.text:match'^\begin{tikzpicture}' then
    return nil
    -- Alternatively, parse the contained LaTeX now:
    -- return pandoc.read(el.text, 'latex').blocks
  end

  local fname = pandoc.sha1(el.text) .. ".png"
  if not file_exists(fname) then
    tikz2image(el.text, fname)
  end
  return pandoc.Para({pandoc.Image({}, fname)})
end

Here is the command I enter in the terminal:

pandoc -s --from latex+raw_tex --lua-filter=tikz.lua test.tex -o test.docx

Answer 1

I have done something similar, starting from the example at pandoc.org/lua-filters.html#building-images-with-tikz.

The main thing is that the filter looks for a raw LaTeX block that starts with '\begin{tikzpicture}', and your blocks start with '\begin{figure}'. You can replace the former with the latter.

I then modified the 'tikz_doc_template' for my use.

Here is the filter that I use: gitlab.com/twsh/pandoc-lua-filters/-/blob/master/tikz-qtree.lua

--[[ Turn figure environments into SVG images
Links are relative
Only one tikzpicture per block
If there is a \caption{...}, set the title text to ...;
pandoc will turn this into a <figcaption> for HTML.
It is assumed that the caption finishes at a line break ]]
local system = require 'pandoc.system'
local tikz_doc_template =
[[
\documentclass{standalone}
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{tikz-qtree}
\usepackage{amsmath}
\begin{document}
%s
\end{document}
]]
local function tikz2image(src, outfile)
    system.with_temporary_directory(
        'tikz2image',
        function(tmpdir)
            system.with_working_directory(
                tmpdir,
                function()
                    local f = io.open('tikz.tex', 'w')
                    f:write(tikz_doc_template:format(src))
                    f:close()
                    os.execute('pdflatex tikz.tex')
                    os.execute('pdf2svg tikz.pdf ' .. outfile)
                end
            )
        end
    )
end
local function file_exists(name)
    local f = io.open(name, 'r')
    if f ~= nil then
        io.close(f)
        return true
    else
        return false
    end
end
function RawBlock(el)
    tikz = el.text:match('\begin{tikzpicture}(.+)\end{tikzpicture}')
    if tikz then
        local fname = pandoc.sha1(tikz) .. '.' .. 'svg'
        local fpath = system.get_working_directory() .. '/' .. fname
        if not file_exists(fpath) then
            tikz2image(tikz, fpath)
        end
        local caption = el.text:match('\caption{(.+)}\n')
        if caption then
            local caption_text = pandoc.utils.stringify(pandoc.read(caption, 'latex').blocks)
            return pandoc.Para({pandoc.Image({pandoc.Str(caption_text)}, fname, 'fig:')})
        else
            return pandoc.Para({pandoc.Image({}, fname, 'fig:')})
        end
    else
        return el
    end
end

Answer 2

As a serial lurker, I don't have the reputation to comment. Sorry about that.

Image Magick seems to have updated their command from "Convert" to just "Magick" in version 7 and above (https://imagemagick.org/script/command-line-tools.php). Making that edit caused this too work for me with the Image Magick route.