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@phi-gamma phi-gamma/beegradients.lua
Last active Sep 28, 2016

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bee gradients for TeX documents: http://tex.stackexchange.com/q/131883/14066
packagedata = packagedata or { }
packagedata.beegradients = { }
local beegradients = packagedata.beegradients
local processorid = "beegradients" --- name of callback
local err, warn, info
if luatexbase then
err, warn, info = luatexbase.provides_module {
name = "beegradients",
version = 42,
date = "2013-09-07 17:03:42+0200",
descriptions = "http://tex.stackexchange.com/q/131883/14066",
author = "Philipp Gesang",
copyright = "Philipp Gesang",
license = "BSD 2 clause",
}
end
local lpeg = require "lpeg"
local C, Cf, Cg, Ct = lpeg.C, lpeg.Cf, lpeg.Cg, lpeg.Ct
local P, R, S = lpeg.P, lpeg.R, lpeg.S
local lpegmatch = lpeg.match
local unpack = unpack or table.unpack
local stringformat = string.format
local stringis_empty = string.is_empty
local tableswapped = table.swapped
local nodes = nodes
local nodecodes = nodes.nodecodes or tableswapped (node.types ())
local hlist_t = nodecodes.hlist
local vlist_t = nodecodes.vlist
local glyph_t = nodecodes.glyph
local disc_t = nodecodes.disc
local whatsit_t = nodecodes.whatsit
local pdf_literal_t = 8
local traversenodes = node.traverse
local traversenodetype = node.traverse_id
local countnodes = node.count
local newnode = node.new
local copynode = node.copy
local insertnodebefore = node.insert_before
local insertnodeafter = node.insert_after
require "lualibs" --- requires extended set including util-prs.lua
local settingstoarray = utilities and utilities.parsers.settings_to_array
if not settingstoarray then --- old Lualibs
local comma = P","
local spacechar = S" \f\n\r\t\v"
local separator = comma * spacechar^0
local item = C((1 - comma - spacechar)^1)
local p_settings = spacechar^0
* item
* (separator * item)^0
* (separator + spacechar^0)
settingstoarray = function (settings)
return lpegmatch (Ct (p_settings), settings)
end
end
local practically_zero = 0.003921568627451
local practically_one = 0.99607843137255
local parse_gradient do
local tonumber16 = function (n) return tonumber (n, 16) end
local digit = R"09"
local hexdigit = R("09", "af", "AF")
local dash = P"-"
local colon = P":"
local asterisk = P"*"
--- values:
--- hexcolor -> 0xf00ba7 (triplet of hex octets, r->g->b)
--- deccolor -> 123*44*111 (triplet of decimal octets: r->g->b)
--- speccolor -> r:210*g:32*b:145 (prefixed octets, any order)
local hexcolor = Ct (P"0x" * Cg (hexdigit * hexdigit / tonumber16, "r")
* Cg (hexdigit * hexdigit / tonumber16, "g")
* Cg (hexdigit * hexdigit / tonumber16, "b"))
local decexp = digit * digit^-1 * digit^-1
local deccolor = Ct (Cg (decexp / tonumber, "r") * asterisk
* Cg (decexp / tonumber, "g") * asterisk
* Cg (decexp / tonumber, "b"))
local specexp = C(S"rgb") * colon * (C(decexp) / tonumber)
local speccolor = Cf (Ct ""
* Cg (specexp) * asterisk
* Cg (specexp) * asterisk
* Cg (specexp),
rawset)
local colexp = hexcolor + deccolor + speccolor
local zero = { 0, 0, 0 } --- fallback
--- string -> float * float * float
parse_color = function (raw)
local color = lpegmatch (colexp, raw)
local r = color.r / 255
local g = color.g / 255
local b = color.b / 255
if r < practically_zero then r = 0 end
if r > practically_one then r = 1 end
if g < practically_zero then g = 0 end
if g > practically_one then g = 1 end
if b < practically_zero then b = 0 end
if b > practically_one then b = 1 end
return { r, g, b }
end
end
local gradients = { } --- (float * float * float) list
--- string -> unit
local definegradients = function (groupid, raw)
local group = gradients [groupid]
if group then
warn (stringformat ("Gradient group %q already defined, redefining.",
groupid))
else
group = { }
end
local definitions = settingstoarray (raw)
if #definitions < 1 then
warn (stringformat ("Need at least one definition in gradient group %q, skipping.",
groupid))
return nil
end
for i = 1, #definitions do
local definition = definitions [i]
if definition and not stringis_empty (definition) then
group [#group + 1] = parse_color (definition)
end
end
gradients [groupid] = group
end
beegradients.define = definegradients
local pdf_literal = newnode(whatsit_t, pdf_literal_t)
local get_colornode = function (r, g, b)
local push, pop = copynode (pdf_literal), copynode (pdf_literal)
local pushcolor = stringformat ("%.3g %.3g %.3g rg", r, g, b)
local popcolor = "0 g"
push.mode, push.data = 1, pushcolor
pop.mode, pop.data = 1, popcolor
return push, pop
end
--- more accurate, recursive glyph counter than node.count;
--- this includes, for instance, the lowered -Y´E¡ in \TeX
--- node_t -> int? -> int
local countglyphs countglyphs = function (hd, cnt)
cnt = cnt or 0
for n in traversenodes (hd) do
local nid = n.id
if nid == glyph_t or nid == disc_t then
cnt = cnt + 1
elseif nid == hlist_t or nid == vlist_t then
cnt = countglyphs (n.list, cnt)
end
end
return cnt
end
--- node_t -> float -> float -> float ->
-- -> float -> float -> float -> node_t
local colorize_glyphs colorize_glyphs = function (hd, done,
r, g, b,
rstep, gstep, bstep)
local cur = hd
while cur do
local id = cur.id
if id == glyph_t or id == disc_t then
local before, after = get_colornode (r, g, b)
local curprev, curnext = cur.prev, cur.next
before.next, cur.prev = cur, before
after.prev, cur.next = cur, after
if not curprev then --- first
hd = before
else
before.prev, curprev.next = curprev, before
end
if curnext then
after.next, curnext.prev = curnext, after
end -- else last node
done = done + 1
cur = curnext
if cur then
r = r + rstep
g = g + gstep
b = b + bstep
--- safeguard against rounding
if r < practically_zero then r = 0 end
if r > practically_one then r = 1 end
if g < practically_zero then g = 0 end
if g > practically_one then g = 1 end
if b < practically_zero then b = 0 end
if b > practically_one then b = 1 end
end
elseif id == hlist_t or id == vlist_t then
local list = cur.list
if list then
cur.list, done = colorize_glyphs (cur.list, done,
r, g, b,
rstep, gstep, bstep)
end
cur = cur.next
else
cur = cur.next
end
end
--print (stringformat ("final> %.3f %.3f %.3f -A× %d", r, g, b, done))
return hd, done
end
local lineprocessor = function (hd, from, to)
local list = hd.list
local nglyphs = countglyphs (list)
local nsteps = nglyphs - 1
local rstart, gstart, bstart = unpack (from)
local rstep = (to [1] - rstart) / nsteps
local gstep = (to [2] - gstart) / nsteps
local bstep = (to [3] - bstart) / nsteps
--print (stringformat ("from> %.3f %.3f %.3f", rstart, gstart, bstart))
--print (stringformat ("to> %.3f %.3f %.3f", to [1], to [2], to [3]))
--print (stringformat ("step> %.3f %.3f %.3f × %d", rstep, gstep, bstep, nglyphs))
--print (">>", nglyphs, countnodes (glyph_t, list), from, to)
local glyphs_done
hd.list, glyphs_done = colorize_glyphs (list, 0,
rstart, gstart, bstart,
rstep, gstep, bstep)
--print (">>", nglyphs, glyphs_done, from, to)
end
local currentgroup
local currentgradient = 1
local processor = function (hd)
local group = gradients [currentgroup]
local ngradients = #group
if not group then
warn (stringformat ("No such gradient group: %q, bailing out.",
currentgroup))
return hd
end
for line in traversenodetype (hlist_t, hd) do
local fromcolor = group [currentgradient]
currentgradient = currentgradient + 1
if currentgradient > ngradients then
currentgradient = 1
end
local tocolor = group [currentgradient]
lineprocessor (line, fromcolor, tocolor)
end
return hd
end
local active = false
local enable = function (groupid)
if not stringis_empty (groupid) then
if currentgroup ~= groupid then -- reset gradient pointer
currentgradient = 1
end
currentgroup = groupid
end
if currentgroup == nil then
warn "Cannot inject node processor: no gradient group defined."
return
end
if active == false then
info (stringformat ("Injecting node processor, active group %q.",
currentgroup))
luatexbase.add_to_callback ("post_linebreak_filter",
processor,
processorid)
active = true
end
end
local disable = function ()
if active == true then
info "Removing node processor."
luatexbase.remove_from_callback ("post_linebreak_filter",
processorid)
active = false
end
end
beegradients.enable = enable
beegradients.disable = disable
\RequireLuaModule {beegradients}
\def \pkgcmd #1{\directlua {packagedata.#1}}
%% defining a sequence of gradients; order matters
\def \definegradientgroup [#1][#2]{%% groupid, settings
\pkgcmd {beegradients.define ([[#1]], [[\detokenize {#2}]])}%
}
%% node processor handling
\chardef \oldatcatcode = \catcode `\@
\catcode `\@ = 11
\def \startbeegradients{%% groupid
\lltxb@ifnextchar[\startbeegradientsindeed
{\startbeegradientsindeed[]}%
}
\catcode `\@ = \oldatcatcode
\def \startbeegradientsindeed [#1]{%% groupid
\pkgcmd {beegradients.enable [[#1]]}%
}
\def \stopbeegradients {%
\endgraf %% post_linebreak_filter is paragraph-based
\pkgcmd {beegradients.disable ()}%
}
\documentclass {scrartcl}
\usepackage {fontspec} %% this loads luaotfload as well
\setmainfont {Antykwa Poltawskiego}
\input beegradients.tex
\definegradientgroup [red-green-blue][255*0*0, 0*255*0, 0*0*255]
\begin {document}
\startbeegradients [red-green-blue]
\input knuth
\stopbeegradients
\end {document}
\input luaotfload.sty
\input beegradients.tex
\font \mainfont = file:Iwona-Regular.otf at 10pt
\mainfont
\definegradientgroup [mygradients][
42*11*242, %% decimal notation, separated by “*”
83*242*55,
0xf00ba7, %% hex notation
0x1ec001,
g:23*b:42*r:133, %% rgb notation, also separated by “*”
b:53*g:184*r:10,
]
\definegradientgroup [blackwhite][0x000000, 0xFFFFFF]
\definegradientgroup [red-green-blue][255*0*0, 0*255*0, 0*0*255]
\definegradientgroup [red][255*0*0, 0*0*0]
\definegradientgroup [green][0*100*0, 0*255*0]
\definegradientgroup [blue][0*0*20, 0*0*210]
\input knuth
\startbeegradients [mygradients] \input knuth \stopbeegradients
\startbeegradients [blackwhite] \input knuth \stopbeegradients
\startbeegradients [red-green-blue] \input knuth \stopbeegradients
\input knuth
\startbeegradients \input knuth \stopbeegradients
\startbeegradients [red] \input knuth \stopbeegradients
\startbeegradients [green] \input knuth \stopbeegradients
\startbeegradients [blue] \input knuth \stopbeegradients
\bye
@davidcarlisle

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commented Aug 1, 2016

This needs a few updates for current luatex, I added some minimal patches here http://tex.stackexchange.com/a/321962/1090

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