wtspingif.lua

#!/usr/bin/env texlua

--
-- This is file 'wtspingif.lua'.
--
-- Copyright 2020 Takuto ASAKURA (wtsnjp)
--   GitHub:   https://github.com/wtsnjp
--   Twitter:  @wtsnjp
--
-- This package is distributed under the MIT License.
--

-- program information
prog_name = 'wtspingif'
version = '0.1'
release_date = '2020-12-31'
author = 'Takuto ASAKURA (wtsnjp)'

-- option flags (default)
option_density = 72
option_delay = 1
verbosity_level = 0

-- exit codes
exit_ok = 0
exit_error = 1
exit_usage = 2

----------------------------------------

-- library
local lfs = require 'lfs'
local pdfe = require 'pdfe'

-- global functions
function log(label, msg, ...)
  io.stderr:write(prog_name .. ' ' .. label .. ': ' .. msg:format(...) .. '\n')
end

function err_print(err_type, msg, ...)
  if (verbosity_level > 0) or (err_type == 'error')
      or (verbosity_level > -1 and err_type == 'warning') then
    log(err_type, msg, ...)
  end
end

function dbg_print(dbg_type, msg, ...)
  if debug[dbg_type] then
    log('debug-' .. dbg_type, msg, ...)
  end
end

----------------------------------------

do
  local function execute(cmd)
    err_print('info', 'Running command: ' .. cmd)
    local status = os.execute(cmd)
    if status > 0 then
      llmk.util.err_print('error',
        'Fail running %s (exit code: %d)', cmd, status)
      os.exit(exit_error)
    end
  end

  function convert(pdf_file)
    local basename = pdf_file:sub(1, -5)
    local function png_name(i)
      return string.format('__wtsg%s_%03d.png', basename, i)
    end

    -- estimate number of frames
    local doc = pdfe.open(pdf_file)
    local nof_frames = pdfe.getnofpages(doc)
    pdfe.close(doc)

    -- generating filenames
    local png_files = {}
    for i = 0, nof_frames - 1 do
      table.insert(png_files, png_name(i))
    end
    local png_args = table.concat(png_files, ' ')

    -- convert PDF -> PNG images
    for i = 0, nof_frames - 1 do
      execute(string.format(
        'magick %s[%d] -background white -alpha remove -density %d %s',
        pdf_file, i, option_density, png_name(i)))
    end

    -- convert PNG images -> animated GIF
    execute(string.format(
      'magick -delay %d %s %s.gif', option_delay, png_args, basename))

    -- remove PNG images
    for _, fn in pairs(png_files) do
      os.remove(fn)
    end
  end
end

----------------------------------------

do
  -- help texts
  local usage_text = [[
Usage: wtspingif [OPTION]... PDF_FILE
]]

  local version_text = [[
%s %s
]]

  -- show uasage / help
  local function show_usage(out)
    out:write(usage_text)
  end

  -- execution functions
  local function read_options()
    if #arg == 0 then
      show_usage(io.stderr)
      os.exit(exit_usage)
    end

    local curr_arg
    local action = false

    -- modified Alternative Get Opt
    -- cf. http://lua-users.org/wiki/AlternativeGetOpt
    local function getopt(arg, options)
      local tmp
      local tab = {}
      local saved_arg = { table.unpack(arg) }
      for k, v in ipairs(saved_arg) do
        if string.sub(v, 1, 2) == "--" then
          table.remove(arg, 1)
          local x = string.find(v, "=", 1, true)
          if x then
            table.insert(tab, { string.sub(v, 3, x-1), string.sub(v, x+1) })
          else
            table.insert(tab, { string.sub(v, 3), true })
          end
        elseif string.sub(v, 1, 1) == "-" then
          table.remove(arg, 1)
          local y = 2
          local l = string.len(v)
          local jopt
          while (y <= l) do
            jopt = string.sub(v, y, y)
            if string.find(options, jopt, 1, true) then
              if y < l then
                tmp = string.sub(v, y+1)
                y = l
              else
                table.remove(arg, 1)
                tmp = saved_arg[k + 1]
              end
              if string.match(tmp, '^%-') then
                table.insert(tab, { jopt, false })
              else
                table.insert(tab, { jopt, tmp })
              end
            else
              table.insert(tab, { jopt, true })
            end
            y = y + 1
          end
        end
      end
      return tab
    end

    opts = getopt(arg, 'db')
    for _, tp in ipairs(opts) do
      k, v = tp[1], tp[2]
      if #k == 1 then
        curr_arg = '-' .. k
      else
        curr_arg = '--' .. k
      end

      -- action
      if (curr_arg == '-h') or (curr_arg == '--help') then
        action = 'help'
      elseif (curr_arg == '-V') or (curr_arg == '--version') then
        action = 'version'
      elseif (curr_arg == '-v') or (curr_arg == '--verbose') then
        verbosity_level = 1
      elseif (curr_arg == '-d') or (curr_arg == '--density') then
        option_density = tonumber(v)
      elseif (curr_arg == '-b') or (curr_arg == '--boost') then
        option_delay = tonumber(v)
      else
        err_print('error', 'unknown option: ' .. curr_arg)
        err_print('error', error_msg)
        os.exit(exit_error)
      end
    end

    return action
  end

  local function do_action()
    if action == 'help' then
      show_usage(io.stdout)
    elseif action == 'version' then
      io.stdout:write(version_text:format(
        prog_name, version, release_date, author))
    end
  end

  function main()
    action = read_options()

    if action then
      do_action()
      os.exit(exit_ok)
    end

    convert(arg[1])
    os.exit(exit_ok)
  end
end

----------------------------------------

main()

-- EOF

Example: process the following with llmk:

% +++
% latex = "pdflatex"
% sequence = ["latex", "wtspingif"]
% extra_clean_files = ["%B.synctex.gz"]
% clobber_files = ["%B.gif", "%B.pdf"]
%
% [programs.wtspingif]
% command = "wtspingif"
% opts = ["-d 144", "-b 5"]
% args = ["%B.pdf"]
% +++
\documentclass{article}
\usepackage[paperwidth=15cm, paperheight=15cm, margin=0cm]{geometry}
\usepackage[svgnames]{xcolor}
\usepackage{scsnowman}
\usepackage{tcfaspin}

\makeatletter
\chardef\faAllTicks=32
\chardef\faStopTicks=0

\long\def\beginframe#1\endframe{%
  #1\clearpage
  \edef\x{\noexpand\chardef\noexpand\faStopTicks
    =\number\numexpr\faStopTicks+1\relax}\x\relax
  \ifnum\faStopTicks<\faAllTicks\beginframe #1\endframe\fi}
\makeatother

\pagestyle{empty}

\begin{document}

\centering

\beginframe
\mbox{}\vfill
\faSpin{\scsnowman[scale=40,
  muffler=Red,hat=Green,buttons=RoyalBlue,
  arms=Brown,snow=SkyBlue]}%
\vfill
\endframe

\end{document}