mlib-pdf.lua / last modification: 2020-01-30 14:16
if not modules then modules = { } end modules ['mlib-pdf'] = {
    version   = 1.001,
    comment   = "companion to mlib-ctx.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files",
}

local gsub = string.gsub
local concat, insert, remove = table.concat, table.insert, table.remove
local abs, sqrt, round = math.abs, math.sqrt, math.round
local setmetatable, rawset, tostring, tonumber, type = setmetatable, rawset, tostring, tonumber, type
local P, S, C, Ct, Cc, Cg, Cf, Carg = lpeg.P, lpeg.S, lpeg.C, lpeg.Ct, lpeg.Cc, lpeg.Cg, lpeg.Cf, lpeg.Carg
local lpegmatch = lpeg.match
local formatters = string.formatters

local report_metapost = logs.reporter("metapost")

local trace_variables = false  trackers.register("metapost.variables",function(v) trace_variables = v end)

local mplib           = mplib
local context         = context

local allocate        = utilities.storage.allocate

local copy_node       = node.copy
local write_node      = node.write

local pen_info        = mplib.pen_info
local object_fields   = mplib.fields

local save_table      = false
local force_stroke    = false

metapost              = metapost or { }
local metapost        = metapost

metapost.flushers     = metapost.flushers or { }
local pdfflusher      = { }
metapost.flushers.pdf = pdfflusher

metapost.n            = 0

local experiment      = true -- uses context(node) that already does delayed nodes
local savedliterals   = nil  -- needs checking
local mpsliteral      = nodes.pool.originliteral

local f_f  = formatters["%.6N"]
local f_m  = formatters["%.6N %.6N m"]
local f_c  = formatters["%.6N %.6N %.6N %.6N %.6N %.6N c"]
local f_l  = formatters["%.6N %.6N l"]
local f_cm = formatters["%.6N %.6N %.6N %.6N %.6N %.6N cm"]
local f_M  = formatters["%.6N M"]
local f_j  = formatters["%i j"]
local f_J  = formatters["%i J"]
local f_d  = formatters["[%s] %.6N d"]
local f_w  = formatters["%.6N w"]

directives.register("metapost.savetable",function(v)
    if type(v) == "string" then
        save_table = file.addsuffix(v,"mpl")
    elseif v then
        save_table = file.addsuffix(environment.jobname .. "-graphic","mpl")
    else
        save_table = false
    end
end)

trackers.register("metapost.forcestroke",function(v)
    force_stroke = v
end)

-- Because in MKiV we always have two passes, we save the objects. When an extra
-- mp run is done (due to for instance texts identifier in the parse pass), we
-- get a new result table and the stored objects are forgotten. Otherwise they
-- are reused.

local function getobjects(result,figure,index)
    return figure:objects()
end

function metapost.convert(specification,result)
    local flusher  = specification.flusher
    local askedfig = specification.askedfig
    if save_table then
        table.save(save_table,metapost.totable(result,1)) -- direct
    end
    metapost.flush(specification,result)
    return true -- done
end

function metapost.flushliteral(d)
    if savedliterals then
        write_node(mpsliteral(savedliterals[d]))
    else
        report_metapost("problem flushing literal %a",d)
    end
end

function metapost.flushreset() -- will become obsolete and internal
    savedliterals = nil
end

function pdfflusher.comment(message)
    if message then
        message = formatters["%% mps graphic %s: %s"](metapost.n,message)
        if experiment then
            context(mpsliteral(message))
        elseif savedliterals then
            local last = #savedliterals + 1
            savedliterals[last] = message
            context.MPLIBtoPDF(last)
        else
            savedliterals = { message }
            context.MPLIBtoPDF(1)
        end
    end
end

function pdfflusher.startfigure(n,llx,lly,urx,ury,message)
    savedliterals = nil
    metapost.n = metapost.n + 1
    context.startMPLIBtoPDF(f_f(llx),f_f(lly),f_f(urx),f_f(ury))
    if message then pdfflusher.comment(message) end
end

function pdfflusher.stopfigure(message)
    if message then pdfflusher.comment(message) end
    context.stopMPLIBtoPDF()
    context.MPLIBflushreset() -- maybe just at the beginning
end

function pdfflusher.flushfigure(pdfliterals) -- table
    if #pdfliterals > 0 then
        pdfliterals = concat(pdfliterals,"\n")
        if experiment then
            context(mpsliteral(pdfliterals))
        else
            if savedliterals then
                local last = #savedliterals + 1
                savedliterals[last] = pdfliterals
                context.MPLIBtoPDF(last)
            else
                savedliterals = { pdfliterals }
                context.MPLIBtoPDF(1)
            end
        end
    end
end

function pdfflusher.textfigure(font,size,text,width,height,depth) -- we could save the factor
    text = gsub(text,".","\\hbox{%1}") -- kerning happens in metapost (i have to check if this is true for mplib)
    context.MPtextext(font,size,text,0,-number.dimenfactors.bp*depth)
end

local bend_tolerance = 131/65536

local rx, sx, sy, ry, tx, ty, divider = 1, 0, 0, 1, 0, 0, 1

local function pen_characteristics(object)
    local t = pen_info(object)
    rx, ry, sx, sy, tx, ty = t.rx, t.ry, t.sx, t.sy, t.tx, t.ty
    divider = sx*sy - rx*ry
    return not (sx==1 and rx==0 and ry==0 and sy==1 and tx==0 and ty==0), t.width
end

local function mpconcat(px, py) -- no tx, ty here / we can move this one inline if needed
    return (sy*px-ry*py)/divider,(sx*py-rx*px)/divider
end

local function curved(ith,pth)
    local d = pth.left_x - ith.right_x
    if abs(ith.right_x - ith.x_coord - d) <= bend_tolerance and abs(pth.x_coord - pth.left_x - d) <= bend_tolerance then
        d = pth.left_y - ith.right_y
        if abs(ith.right_y - ith.y_coord - d) <= bend_tolerance and abs(pth.y_coord - pth.left_y - d) <= bend_tolerance then
            return false
        end
    end
    return true
end

local function flushnormalpath(path, t, open)
    local pth, ith, nt
    local length = #path
    if t then
        nt = #t
    else
        t = { }
        nt = 0
    end
    for i=1,length do
        nt = nt + 1
        pth = path[i]
        if not ith then
            t[nt] = f_m(pth.x_coord,pth.y_coord)
        elseif curved(ith,pth) then
            t[nt] = f_c(ith.right_x,ith.right_y,pth.left_x,pth.left_y,pth.x_coord,pth.y_coord)
        else
            t[nt] = f_l(pth.x_coord,pth.y_coord)
        end
        ith = pth
    end
    if not open then
        nt = nt + 1
        local one = path[1]
        if curved(pth,one) then
            t[nt] = f_c(pth.right_x,pth.right_y,one.left_x,one.left_y,one.x_coord,one.y_coord )
        else
            t[nt] = f_l(one.x_coord,one.y_coord)
        end
    elseif length == 1 then
        -- special case .. draw point
        local one = path[1]
        nt = nt + 1
        t[nt] = f_l(one.x_coord,one.y_coord)
    end
    return t
end

local function flushconcatpath(path, t, open)
    local pth, ith, nt
    local length = #path
    if t then
        nt = #t
    else
        t = { }
        nt = 0
    end
    nt = nt + 1
    t[nt] = f_cm(sx,rx,ry,sy,tx,ty)
    for i=1,length do
        nt = nt + 1
        pth = path[i]
        if not ith then
            t[nt] = f_m(mpconcat(pth.x_coord,pth.y_coord))
        elseif curved(ith,pth) then
            local a, b = mpconcat(ith.right_x,ith.right_y)
            local c, d = mpconcat(pth.left_x,pth.left_y)
            t[nt] = f_c(a,b,c,d,mpconcat(pth.x_coord,pth.y_coord))
        else
           t[nt] = f_l(mpconcat(pth.x_coord, pth.y_coord))
        end
        ith = pth
    end
    if not open then
        nt = nt + 1
        local one = path[1]
        if curved(pth,one) then
            local a, b = mpconcat(pth.right_x,pth.right_y)
            local c, d = mpconcat(one.left_x,one.left_y)
            t[nt] = f_c(a,b,c,d,mpconcat(one.x_coord, one.y_coord))
        else
            t[nt] = f_l(mpconcat(one.x_coord,one.y_coord))
        end
    elseif length == 1 then
        -- special case .. draw point
        nt = nt + 1
        local one = path[1]
        t[nt] = f_l(mpconcat(one.x_coord,one.y_coord))
    end
    return t
end

local function toboundingbox(path)
    local size = #path
    if size == 4 then
        local pth = path[1]
        local x = pth.x_coord
        local y = pth.y_coord
        local llx, lly, urx, ury = x, y, x, y
        for i=2,size do
            pth = path[i]
            x   = pth.x_coord
            y   = pth.y_coord
            if x < llx then
                llx = x
            elseif x > urx then
                urx = x
            end
            if y < lly then
                lly = y
            elseif y > ury then
                ury = y
            end
        end
        return { llx, lly, urx, ury }
    else
        return { 0, 0, 0, 0 }
    end
end

metapost.flushnormalpath = flushnormalpath

-- The flusher is pdf based, if another backend is used, we need to overload the
-- flusher; this is beta code, the organization will change (already upgraded in
-- sync with mplib)
--
-- We can avoid the before table but I like symmetry. There is of course a small
-- performance penalty, but so is passing extra arguments (result, flusher, after)
-- and returning stuff.
--
-- This variable stuff will change in lmtx.

local ignore   = function() end

local space    = P(" ")
local equal    = P("=")
local key      = C((1-equal)^1) * equal
local newline  = S("\n\r")^1
local number   = (((1-space-newline)^1) / tonumber) * (space^0)

local p_number  = number
local p_string  = C((1-newline)^0)
local p_boolean = P("false") * Cc(false) + P("true") * Cc(true)
local p_set     = Ct(number^1)
local p_path    = Ct(Ct(number * number^-5)^1)

local variable =
    P("1:")            * p_number
  + P("2:")            * p_string
  + P("3:")            * p_boolean
  + S("4568") * P(":") * p_set
  + P("7:")            * p_path

local pattern_tab = Cf ( Carg(1) * (Cg(variable * newline^0)^0), rawset)

local variable =
    P("1:")            * p_number
  + P("2:")            * p_string
  + P("3:")            * p_boolean
  + S("4568") * P(":") * number^1
  + P("7:")            * (number * number^-5)^1

local pattern_lst = (variable * newline^0)^0

metapost.variables  = { } -- currently across instances
metapost.properties = { } -- to be stacked

function metapost.untagvariable(str,variables) -- will be redone
    if variables == false then
        return lpegmatch(pattern_lst,str)
    else
        return lpegmatch(pattern_tab,str,1,variables or { })
    end
end

-- function metapost.processspecial(str)
--     lpegmatch(pattern_key,object.prescript,1,variables)
-- end

function metapost.processspecial(str)
    local code = loadstring(str)
    if code then
        if trace_variables then
            report_metapost("executing special code: %s",str)
        end
        code()
    else
        report_metapost("invalid special code: %s",str)
    end
end

local stack = { }

local function pushproperties(figure)
    local boundingbox = figure:boundingbox()
    local properties = {
        llx    = boundingbox[1],
        lly    = boundingbox[2],
        urx    = boundingbox[3],
        ury    = boundingbox[4],
        slot   = figure:charcode(),
        width  = figure:width(),
        height = figure:height(),
        depth  = figure:depth(),
        italic = figure:italcorr(),
        number = figure:charcode() or 0,
    }
    insert(stack,properties)
    metapost.properties = properties
    return properties
end

local function popproperties()
    metapost.properties = remove(stack)
end

local function nocomment() end

metapost.comment = nocomment

function metapost.flush(specification,result)
    if result then
        local flusher   = specification.flusher
        local askedfig  = specification.askedfig
        local incontext = specification.incontext
        local figures   = result.fig
        if figures then
            flusher = flusher or pdfflusher
            local resetplugins       = metapost.resetplugins       or ignore -- before figure
            local processplugins     = metapost.processplugins     or ignore -- each object
            local synchronizeplugins = metapost.synchronizeplugins or ignore
            local pluginactions      = metapost.pluginactions      or ignore -- before / after
            local startfigure        = flusher.startfigure
            local stopfigure         = flusher.stopfigure
            local flushfigure        = flusher.flushfigure
            local textfigure         = flusher.textfigure
            local processspecial     = flusher.processspecial or metapost.processspecial
            metapost.comment         = flusher.comment or nocomment
            for index=1,#figures do
                local figure     = figures[index]
                local properties = pushproperties(figure)
                if askedfig == "direct" or askedfig == "all" or askedfig == properties.number then
                    local objects    = getobjects(result,figure,index)
                    local result     = { }
                    local miterlimit = -1
                    local linecap    = -1
                    local linejoin   = -1
                    local dashed     = false
                    local linewidth  = false
                    local llx        = properties.llx
                    local lly        = properties.lly
                    local urx        = properties.urx
                    local ury        = properties.ury
                    if urx < llx then
                        -- invalid
                        startfigure(properties.number,0,0,0,0,"invalid",figure)
                        stopfigure()
                    else

                        -- we need to be indirect if we want the one-pass solution

                        local groupstack = { }

                        local function processfigure()
                            result[#result+1] = "q"
                            if objects then
    --                             resetplugins(result) -- we should move the colorinitializer here
                                local savedpath = nil
                                local savedhtap = nil
                                for o=1,#objects do
                                    local object = objects[o]
                                    local objecttype = object.type
                                    if objecttype == "text" then
                                        result[#result+1] = "q"
                                        local ot = object.transform -- 3,4,5,6,1,2
                                        result[#result+1] = f_cm(ot[3],ot[4],ot[5],ot[6],ot[1],ot[2])
                                        flushfigure(result) -- flush accumulated literals
                                        result = { }
                                        textfigure(object.font,object.dsize,object.text,object.width,object.height,object.depth)
                                        result[#result+1] = "Q"
                                    elseif objecttype == "special" then
                                        if processspecial then
                                            processspecial(object.prescript)
                                        end
                                    elseif objecttype == "start_clip" then
                                        local evenodd = not object.istext and object.postscript == "evenodd"
                                        result[#result+1] = "q"
                                        flushnormalpath(object.path,result,false)
                                        result[#result+1] = evenodd and "W* n" or "W n"
                                    elseif objecttype == "stop_clip" then
                                        result[#result+1] = "Q"
                                        miterlimit, linecap, linejoin, dashed = -1, -1, -1, "" -- was false
                                    elseif objecttype == "start_bounds" or objecttype == "stop_bounds" then
                                        -- skip
                                    elseif objecttype == "start_group" then
                                        if lpdf.flushgroup then
                                            local before, after = processplugins(object)
                                            if before then
                                                result[#result+1] = "q"
                                                result = pluginactions(before,result,flushfigure)
                                                insert(groupstack, {
                                                    after  = after,
                                                    result = result,
                                                    bbox   = toboundingbox(object.path),
                                                })
                                                result = { }
miterlimit, linecap, linejoin, dashed, linewidth = -1, -1, -1, "", false
                                            else
                                                insert(groupstack,false)
                                            end
                                        else
                                            insert(groupstack,false)
                                        end
                                    elseif objecttype == "stop_group" then
                                        local data = remove(groupstack)
                                        if data then
                                            local reference = lpdf.flushgroup(concat(result,"\r"),data.bbox)
                                            result = data.result
                                            result[#result+1] = reference
                                            result = pluginactions(data.after,result,flushfigure)
                                            result[#result+1] = "Q"
miterlimit, linecap, linejoin, dashed, linewidth = -1, -1, -1, "", false
                                        end
                                    else
                                        -- we use an indirect table as we want to overload
                                        -- entries but this is not possible in userdata
                                        --
                                        -- can be optimized if no path
                                        --
                                        local original = object
                                        local object   = { }
                                        setmetatable(object, {
                                            __index = original
                                        })
                                        local before,
                                              after      = processplugins(object)
                                        local evenodd    = false
                                        local collect    = false
                                        local both       = false
                                        local flush      = false
                                        local postscript = object.postscript
                                        if not object.istext then
                                            if postscript == "evenodd" then
                                                evenodd = true
                                            elseif postscript == "collect" then
                                                collect = true
                                            elseif postscript == "flush" then
                                                flush   = true
                                            elseif postscript == "both" then
                                                both = true
                                            elseif postscript == "eoboth" then
                                                evenodd = true
                                                both    = true
                                            end
                                        end
                                        --
                                        if flush and not savedpath then
                                            -- forget about it
                                        elseif collect then
                                            if not savedpath then
                                                savedpath = { object.path or false }
                                                savedhtap = { object.htap or false }
                                            else
                                                savedpath[#savedpath+1] = object.path or false
                                                savedhtap[#savedhtap+1] = object.htap or false
                                            end
                                        else
                                            local objecttype = object.type -- can have changed
                                            if before then
                                                result = pluginactions(before,result,flushfigure)
                                            end
                                            local ml = object.miterlimit
                                            if ml and ml ~= miterlimit then
                                                miterlimit = ml
                                                result[#result+1] = f_M(ml)
                                            end
                                            local lj = object.linejoin
                                            if lj and lj ~= linejoin then
                                                linejoin = lj
                                                result[#result+1] = f_j(lj)
                                            end
                                            local lc = object.linecap
                                            if lc and lc ~= linecap then
                                                linecap = lc
                                                result[#result+1] = f_J(lc)
                                            end
                                            if both then
                                                if dashed ~= false then -- was just dashed test
                                                   result[#result+1] = "[] 0 d"
                                                   dashed = false
                                                end
                                            else
                                                local dl = object.dash
                                                if dl then
                                                    local d = f_d(concat(dl.dashes or {}," "),dl.offset)
                                                    if d ~= dashed then
                                                        dashed = d
                                                        result[#result+1] = d
                                                    end
                                                elseif dashed ~= false then -- was just dashed test
                                                   result[#result+1] = "[] 0 d"
                                                   dashed = false
                                                end
                                            end
                                            local path        = object.path -- newpath
                                            local transformed = false
                                            local penwidth    = 1
                                            local open        = path and path[1].left_type and path[#path].right_type -- at this moment only "end_point"
                                            local pen         = object.pen
                                            if pen then
                                               if pen.type == "elliptical" then
                                                    transformed, penwidth = pen_characteristics(original) -- boolean, value
                                                    if penwidth ~= linewidth then
                                                        result[#result+1] = f_w(penwidth)
                                                        linewidth = penwidth
                                                    end
                                                    if objecttype == "fill" then
                                                        objecttype = "both"
                                                    end
                                               else -- calculated by mplib itself
                                                    objecttype = "fill"
                                               end
                                            end
                                            if transformed then
                                                result[#result+1] = "q"
                                            end
                                            if path then
                                                if savedpath then
                                                    for i=1,#savedpath do
                                                        local path = savedpath[i]
                                                        if transformed then
                                                            flushconcatpath(path,result,open)
                                                        else
                                                            flushnormalpath(path,result,open)
                                                        end
                                                    end
                                                    savedpath = nil
                                                end
                                                if flush then
                                                    -- ignore this path
                                                elseif transformed then
                                                    flushconcatpath(path,result,open)
                                                else
                                                    flushnormalpath(path,result,open)
                                                end
                                                if force_stroke then
                                                    result[#result+1] = open and "S" or "h S"
                                                elseif objecttype == "fill" then
                                                    result[#result+1] = evenodd and "h f*" or "h f" -- f* = eo
                                                elseif objecttype == "outline" then
                                                    if both then
                                                        result[#result+1] = evenodd and "h B*" or "h B" -- B* = eo
                                                    else
                                                        result[#result+1] = open and "S" or "h S"
                                                    end
                                                elseif objecttype == "both" then
                                                    result[#result+1] = evenodd and "h B*" or "h B" -- B* = eo -- b includes closepath
                                                end
                                            end
                                            if transformed then
                                                result[#result+1] = "Q"
                                            end
                                            local path = object.htap
                                            if path then
                                                if transformed then
                                                    result[#result+1] = "q"
                                                end
                                                if savedhtap then
                                                    for i=1,#savedhtap do
                                                        local path = savedhtap[i]
                                                        if transformed then
                                                            flushconcatpath(path,result,open)
                                                        else
                                                            flushnormalpath(path,result,open)
                                                        end
                                                    end
                                                    savedhtap = nil
                                                    evenodd   = true
                                                end
                                                if transformed then
                                                    flushconcatpath(path,result,open)
                                                else
                                                    flushnormalpath(path,result,open)
                                                end
                                                if force_stroke then
                                                    result[#result+1] = open and "S" or "h S"
                                                elseif objecttype == "fill" then
                                                    result[#result+1] = evenodd and "h f*" or "h f" -- f* = eo
                                                elseif objecttype == "outline" then
                                                    result[#result+1] = open and "S" or "h S"
                                                elseif objecttype == "both" then
                                                    result[#result+1] = evenodd and "h B*" or "h B" -- B* = eo -- b includes closepath
                                                end
                                                if transformed then
                                                    result[#result+1] = "Q"
                                                end
                                            end
                                            if after then
                                                result = pluginactions(after,result,flushfigure)
                                            end
                                        end
                                        if object.grouped then
                                            -- can be qQ'd so changes can end up in groups
                                            miterlimit, linecap, linejoin, dashed, linewidth = -1, -1, -1, "", false
                                        end
                                    end
                                end
                            end
                            result[#result+1] = "Q"
                            flushfigure(result)
                        end
                        startfigure(properties.number,llx,lly,urx,ury,"begin",figure)
                        if incontext then
                            context(function() processfigure() end)
                        else
                            processfigure()
                        end
                        stopfigure("end")

                    end
                    if askedfig ~= "all" then
                        break
                    end
                end
                popproperties()
            end
            metapost.comment = nocomment
            resetplugins(result) -- we should move the colorinitializer here
        end
    end
end

-- tracing:

do

    local result = { }

    local flusher = {
        startfigure = function()
            result = { }
            context.startnointerference()
        end,
        flushfigure = function(literals)
            local n = #result
            for i=1,#literals do
                result[n+i] = literals[i]
            end
        end,
        stopfigure = function()
            context.stopnointerference()
        end
    }

    local specification = {
        flusher   = flusher,
     -- incontext = true,
    }

    function metapost.pdfliterals(result)
        metapost.flush(specification,result)
        return result
    end

end

function metapost.totable(result,askedfig)
    local askedfig = askedfig or 1
    local figure   = result and result.fig and result.fig[1]
    if figure then
        local results = { }
        local objects = getobjects(result,figure,askedfig)
        for o=1,#objects do
            local object = objects[o]
            local result = { }
            local fields = object_fields(object) -- hm, is this the whole list, if so, we can get it once
            for f=1,#fields do
                local field = fields[f]
                result[field] = object[field]
            end
            results[o] = result
        end
        local boundingbox = figure:boundingbox()
        return {
            boundingbox = {
                llx = boundingbox[1],
                lly = boundingbox[2],
                urx = boundingbox[3],
                ury = boundingbox[4],
            },
            objects = results
        }
    else
        return nil
    end
end