\documentclass{article}

\usepackage{fontspec}

\usepackage{tikz}

\usepackage{luacode}

\begin{luacode*}

local concat = table.concat

​

local function f_moveto(...)

    return string.format("\\pgfsyssoftpath@movetotoken{%fpt}{%fpt}", ...)

end

local function f_lineto(...)

    return string.format("\\pgfsyssoftpath@linetotoken{%fpt}{%fpt}", ...)

end

local function f_curveto(...)

    return string.format(

        "\\pgfsyssoftpath@curvetosupportatoken{%fpt}{%fpt}" ..

        "\\pgfsyssoftpath@curvetosupportbtoken{%fpt}{%fpt}" ..

        "\\pgfsyssoftpath@curvetotoken{%fpt}{%fpt}", ...)

end

local s_cycle = "\\pgfsyssoftpath@closepath"

-- from font-mps.lua

local function glyph_to_paths(d,xfactor,yfactor)

    local sequence = d.sequence

    local segments = d.segments

    local list     = { }

    local path     = { } -- recycled

    local size     = 0

    local xfactor  = xfactor or 1

    local yfactor  = yfactor or xfactor

    if sequence then

        local i = 1

        local n = #sequence

        while i < n do

            local operator = sequence[i]

            if operator == "m" then -- "moveto"

                if size > 0 then

                    size = size + 1

                    path[size] = s_cycle

                    list[#list+1] = concat(path,"",1,size)

                    size = 1

                else

                    size = size + 1

                end

                path[size] = f_moveto(xfactor*sequence[i+1],yfactor*sequence[i+2])

                i = i + 3

            elseif operator == "l" then -- "lineto"

                size = size + 1

                path[size] = f_lineto(xfactor*sequence[i+1],yfactor*sequence[i+2])

                i = i + 3

            elseif operator == "c" then -- "curveto"

                size = size + 1

                path[size] = f_curveto(xfactor*sequence[i+1],yfactor*sequence[i+2],xfactor*sequence[i+3],yfactor*sequence[i+4],xfactor*sequence[i+5],yfactor*sequence[i+6])

                i = i + 7

            elseif operator =="q" then -- "quadraticto"

                size = size + 1

                -- first is always a moveto

                local l_x = xfactor*sequence[i-2]

                local l_y = yfactor*sequence[i-1]

                local m_x = xfactor*sequence[i+1]

                local m_y = yfactor*sequence[i+2]

                local r_x = xfactor*sequence[i+3]

                local r_y = yfactor*sequence[i+4]

                path[size] = f_curveto (

                    l_x + 2/3 * (m_x-l_x),

                    l_y + 2/3 * (m_y-l_y),

                    r_x + 2/3 * (m_x-r_x),

                    r_y + 2/3 * (m_y-r_y),

                    r_x, r_y

                )

                i = i + 5

            else

                -- weird

                i = i + 1

            end

        end

    elseif segments then

        for i=1,#segments do

            local segment  = segments[i]

            local operator = segment[#segment]

            if operator == "m" then -- "moveto"

                if size > 0 then

                    size = size + 1

                    path[size] = s_cycle

                    list[#list+1] = concat(path,"",1,size)

                    size = 1

                else

                    size = size + 1

                end

                path[size] = f_moveto(xfactor*segment[1],yfactor*segment[2])

            elseif operator == "l" then -- "lineto"

                size = size + 1

                path[size] = f_lineto(xfactor*segment[1],yfactor*segment[2])

            elseif operator == "c" then -- "curveto"

                size = size + 1

                path[size] = f_curveto(xfactor*segment[1],yfactor*segment[2],xfactor*segment[3],yfactor*segment[4],xfactor*segment[5],yfactor*segment[6])

            elseif operator =="q" then -- "quadraticto"

                size = size + 1

                -- first is always a moveto

                local prev = segments[i-1]

                local l_x = xfactor*prev[#prev-2]

                local l_y = yfactor*prev[#prev-1]

                local m_x = xfactor*segment[1]

                local m_y = yfactor*segment[2]

                local r_x = xfactor*segment[3]

                local r_y = yfactor*segment[4]

                path[size] = f_curveto (

                    l_x + 2/3 * (m_x-l_x),

                    l_y + 2/3 * (m_y-l_y),

                    r_x + 2/3 * (m_x-r_x),

                    r_y + 2/3 * (m_y-r_y),

                    r_x, r_y

                )

            else

                -- weird

            end

        end

    else

        return

    end

    if size > 0 then

        size = size + 1

        path[size] = s_cycle

        list[#list+1] = concat(path,"",1,size)

    end

    return list

end

​

-- from meta-imp-outlines.mkiv

-- That's a simple reimplemetation of ConTeXt's \showshape macro

function outlinepaths(character)

    local fontid      = font.current()

    local shapedata   = fonts.hashes.shapes[fontid] -- by index

    local chardata    = fonts.hashes.characters[fontid] -- by unicode

    local shapeglyphs = shapedata.glyphs or { }

​

    character = utf.byte(character)

    local c = chardata[character]

    if c then

        if not c.index then

            return {}

        end

        local glyph = shapeglyphs[c.index]

        if glyph and (glyph.segments or glyph.sequence) then

            local units  = shapedata.units or 1000

            local factor = 100/units

            local paths  = glyph_to_paths(glyph,factor)

            return paths

        end

    end

end

\end{luacode*}

\begin{document}

​

\makeatletter

\directlua{

    for i, path in ipairs(outlinepaths("A")) do

        token.set_macro("path" .. string.char(string.byte("A") + i - 1), path)

    end

}

\makeatother

​

\begin{tikzpicture}

  \draw[use path=\pathA];

  \draw[use path=\pathB];

\end{tikzpicture}

​

\end{document}