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Diffstat (limited to 'src/luaotfload-colors.lua')
| -rw-r--r-- | src/luaotfload-colors.lua | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/src/luaotfload-colors.lua b/src/luaotfload-colors.lua new file mode 100644 index 0000000..d999df6 --- /dev/null +++ b/src/luaotfload-colors.lua @@ -0,0 +1,312 @@ +if not modules then modules = { } end modules ['luaotfload-colors'] = { + version = "2.5", + comment = "companion to luaotfload-main.lua (font color)", + author = "Khaled Hosny, Elie Roux, Philipp Gesang", + copyright = "Luaotfload Development Team", + license = "GNU GPL v2.0" +} + +--[[doc-- + +buggy coloring with the pre_output_filter when expansion is enabled + · tfmdata for different expansion values is split over different objects + · in ``initializeexpansion()``, chr.expansion_factor is set, and only + those characters that have it are affected + · in constructors.scale: chr.expansion_factor = ve*1000 if commented out + makes the bug vanish + +explanation: http://tug.org/pipermail/luatex/2013-May/004305.html + +--doc]]-- + + +local color_callback = config.luaotfload.color_callback +if not color_callback then + --- maybe this would be better as a method: "early" | "late" + color_callback = "pre_linebreak_filter" +-- color_callback = "pre_output_filter" --- old behavior, breaks expansion +end + + +local newnode = node.new +local nodetype = node.id +local traverse_nodes = node.traverse +local insert_node_before = node.insert_before +local insert_node_after = node.insert_after + +local stringformat = string.format +local stringgsub = string.gsub +local stringfind = string.find +local stringsub = string.sub + +local otffeatures = fonts.constructors.newfeatures("otf") +local identifiers = fonts.hashes.identifiers +local registerotffeature = otffeatures.register + +local add_color_callback --[[ this used to be a global‽ ]] + +--[[doc-- +This converts a single octet into a decimal with three digits of +precision. The optional second argument limits precision to a single +digit. +--doc]]-- + +--- string -> bool? -> string +local hex_to_dec = function (hex,one) --- one isn’t actually used anywhere ... + if one then + return stringformat("%.1g", tonumber(hex, 16)/255) + else + return stringformat("%.3g", tonumber(hex, 16)/255) + end +end + +--[[doc-- +Color string validator / parser. +--doc]]-- + +local lpeg = require"lpeg" +local lpegmatch = lpeg.match +local C, Cg, Ct, P, R, S = lpeg.C, lpeg.Cg, lpeg.Ct, lpeg.P, lpeg.R, lpeg.S + +local digit16 = R("09", "af", "AF") +local octet = C(digit16 * digit16) + +local p_rgb = octet * octet * octet +local p_rgba = p_rgb * octet +local valid_digits = C(p_rgba + p_rgb) -- matches eight or six hex digits + +local p_Crgb = Cg(octet/hex_to_dec, "red") --- for captures + * Cg(octet/hex_to_dec, "green") + * Cg(octet/hex_to_dec, "blue") +local p_Crgba = p_Crgb * Cg(octet/hex_to_dec, "alpha") +local extract_color = Ct(p_Crgba + p_Crgb) + +--- string -> (string | nil) +local sanitize_color_expression = function (digits) + digits = tostring(digits) + local sanitized = lpegmatch(valid_digits, digits) + if not sanitized then + luaotfload.warning( + "%q is not a valid rgb[a] color expression", digits) + return nil + end + return sanitized +end + +--[[doc-- +``setcolor`` modifies tfmdata.properties.color in place +--doc]]-- + +--- fontobj -> string -> unit +--- +--- (where “string” is a rgb value as three octet +--- hexadecimal, with an optional fourth transparency +--- value) +--- +local setcolor = function (tfmdata, value) + local sanitized = sanitize_color_expression(value) + local properties = tfmdata.properties + + if sanitized then + properties.color = sanitized + add_color_callback() + end +end + +registerotffeature { + name = "color", + description = "color", + initializers = { + base = setcolor, + node = setcolor, + } +} + + +--- something is carried around in ``res`` +--- for later use by color_handler() --- but what? + +local res = nil + +--- float -> unit +local function pageresources(alpha) + res = res or {} + res[alpha] = true +end + +--- we store results of below color handler as tuples of +--- push/pop strings +local color_cache = { } --- (string, (string * string)) hash_t + +--- string -> (string * string) +local hex_to_rgba = function (digits) + if not digits then + return + end + + --- this is called like a thousand times, so some + --- memoizing is in order. + local cached = color_cache[digits] + if not cached then + local push, pop + local rgb = lpegmatch(extract_color, digits) + if rgb.alpha then + pageresources(rgb.alpha) + push = stringformat( + "/TransGs%g gs %s %s %s rg", + rgb.alpha, + rgb.red, + rgb.green, + rgb.blue) + pop = "0 g /TransGs1 gs" + else + push = stringformat( + "%s %s %s rg", + rgb.red, + rgb.green, + rgb.blue) + pop = "0 g" + end + color_cache[digits] = { push, pop } + return push, pop + end + + return cached[1], cached[2] +end + +--- Luatex internal types + +local glyph_t = nodetype("glyph") +local hlist_t = nodetype("hlist") +local vlist_t = nodetype("vlist") +local whatsit_t = nodetype("whatsit") +local page_insert_t = nodetype("page_insert") +local sub_box_t = nodetype("sub_box") + +--- node -> nil | -1 | color‽ +local lookup_next_color +lookup_next_color = function (head) --- paragraph material + for n in traverse_nodes(head) do + local n_id = n.id + + if n_id == glyph_t then + local n_font + if identifiers[n_font] + and identifiers[n_font].properties + and identifiers[n_font].properties.color + then + return identifiers[n.font].properties.color + else + return -1 + end + + elseif n_id == vlist_t or n_id == hlist_t or n_id == sub_box_t then + local r = lookup_next_color(n.list) + if r then + return r + end + + elseif n_id == whatsit_t or n_id == page_insert_t then + return -1 + end + end + return nil +end + +--[[doc-- +While the second argument and second returned value are apparently +always nil when the function is called, they temporarily take string +values during the node list traversal. +--doc]]-- + +local cnt = 0 +--- node -> string -> int -> (node * string) +local node_colorize +node_colorize = function (head, current_color, next_color) + for n in traverse_nodes(head) do + local n_id = n.id + local nextnode = n.next + + if n_id == hlist_t or n_id == vlist_t or n_id == sub_box_t then + local next_color_in = lookup_next_color(nextnode) or next_color + n.list, current_color = node_colorize(n.list, current_color, next_color_in) + + elseif n_id == glyph_t then + cnt = cnt + 1 + local tfmdata = identifiers[n.font] + + --- colorization is restricted to those fonts + --- that received the “color” property upon + --- loading (see ``setcolor()`` above) + if tfmdata and tfmdata.properties and tfmdata.properties.color then + local font_color = tfmdata.properties.color +-- luaotfload.info( +-- "n: %d; %s; %d %s, %s", +-- cnt, utf.char(n.char), n.font, "<TRUE>", font_color) + if font_color ~= current_color then + local pushcolor = hex_to_rgba(font_color) + local push = newnode(whatsit_t, 8) + push.mode = 1 + push.data = pushcolor + head = insert_node_before(head, n, push) + current_color = font_color + end + local next_color_in = lookup_next_color (nextnode) or next_color + if next_color_in ~= font_color then + local _, popcolor = hex_to_rgba(font_color) + local pop = newnode(whatsit_t, 8) + pop.mode = 1 + pop.data = popcolor + head = insert_node_after(head, n, pop) + current_color = nil + end + +-- else +-- luaotfload.info( +-- "n: %d; %s; %d %s", +-- cnt, utf.char(n.char), n.font, "<FALSE>") + end + end + end + return head, current_color +end + +--- node -> node +local color_handler = function (head) + local new_head = node_colorize(head, nil, nil) + -- now append our page resources + if res then + res["1"] = true + local tpr, t = tex.pdfpageresources, "" + for k in pairs(res) do + local str = stringformat("/TransGs%s<</ca %s/CA %s>>", k, k, k) + if not stringfind(tpr,str) then + t = t .. str + end + end + if t ~= "" then + if not stringfind(tpr,"/ExtGState<<.*>>") then + tpr = tpr.."/ExtGState<<>>" + end + tpr = stringgsub(tpr,"/ExtGState<<","%1"..t) + tex.pdfpageresources = tpr + end + res = nil -- reset res + end + return new_head +end + +local color_callback_activated = 0 + +--- unit -> unit +add_color_callback = function ( ) + if color_callback_activated == 0 then + luatexbase.add_to_callback(color_callback, + color_handler, + "luaotfload.color_handler") + color_callback_activated = 1 + end +end + +-- vim:tw=71:sw=4:ts=4:expandtab + |