summaryrefslogtreecommitdiff
path: root/src/luaotfload-colors.lua
blob: 12b490e75918b1b5e2d9f172a08140bcbc34a6c6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
if not modules then modules = { } end modules ['luaotfload-colors'] = {
    version   = "2.7",
    comment   = "companion to luaotfload-main.lua (font color)",
    author    = "Khaled Hosny, Elie Roux, Philipp Gesang, Dohyun Kim, David Carlisle",
    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 logreport             = luaotfload and luaotfload.log.report or print

local nodedirect            = node.direct
local newnode               = nodedirect.new
local insert_node_before    = nodedirect.insert_before
local insert_node_after     = nodedirect.insert_after
local todirect              = nodedirect.todirect
local tonode                = nodedirect.tonode
local setfield              = nodedirect.setfield
local getid                 = nodedirect.getid
local getfont               = nodedirect.getfont
local getlist               = nodedirect.getlist
local getsubtype            = nodedirect.getsubtype
local getnext               = nodedirect.getnext
local nodetail              = nodedirect.tail
local getattribute          = nodedirect.has_attribute
local setattribute          = nodedirect.set_attribute

local stringformat          = string.format
local identifiers           = fonts.hashes.identifiers

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 opaque         = S("fF") * S("fF")
local octet          = C(digit16 * digit16)

local p_rgb          = octet * octet * octet
local p_rgba         = p_rgb * (octet - opaque)
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
        logreport("both", 0, "color",
                  "%q is not a valid rgb[a] color expression",
                  digits)
        return nil
    end
    return sanitized
end

--- 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 nodetype          = node.id
local glyph_t           = nodetype("glyph")
local hlist_t           = nodetype("hlist")
local vlist_t           = nodetype("vlist")
local whatsit_t         = nodetype("whatsit")
local disc_t            = nodetype("disc")
local pdfliteral_t      = node.subtype("pdf_literal")
local colorstack_t      = node.subtype("pdf_colorstack")
local mlist_to_hlist    = node.mlist_to_hlist

local color_callback
local color_attr        = luatexbase.new_attribute("luaotfload_color_attribute")

-- (node * node * string * bool * (bool | nil)) -> (node * node * (string | nil))
local color_whatsit
color_whatsit = function (head, curr, color, push, tail)
    local pushdata  = hex_to_rgba(color)
    local colornode = newnode(whatsit_t, colorstack_t)
    setfield(colornode, "stack", 0)
    setfield(colornode, "command", push and 1 or 2) -- 1: push, 2: pop
    setfield(colornode, "data", push and pushdata or nil)
    if tail then
        head, curr = insert_node_after (head, curr, colornode)
    else
        head = insert_node_before(head, curr, colornode)
    end
    if not push and color:len() > 6 then
        local colornode = newnode(whatsit_t, pdfliteral_t)
        setfield(colornode, "mode", 2)
        setfield(colornode, "data", "/TransGs1 gs")
        if tail then
            head, curr = insert_node_after (head, curr, colornode)
        else
            head = insert_node_before(head, curr, colornode)
        end
    end
    color = push and color or nil
    return head, curr, color
end

-- number -> string | nil
local get_font_color = function (font_id)
    local tfmdata    = identifiers[font_id]
    local font_color = tfmdata and tfmdata.properties and tfmdata.properties.color
    return font_color
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]]--

--- (node * (string | nil)) -> (node * (string | nil))
local node_colorize
node_colorize = function (head, toplevel, current_color)
    local n = head
    while n do
        local n_id = getid(n)

        if n_id == hlist_t or n_id == vlist_t then
            local n_list = getlist(n)
            if getattribute(n_list, color_attr) then
                if current_color then
                    head, n, current_color = color_whatsit(head, n, current_color, false)
                end
            else
                n_list, current_color = node_colorize(n_list, false, current_color)
                if current_color and getsubtype(n) == 1 then -- created by linebreak
                    n_list, _, current_color = color_whatsit(n_list, nodetail(n_list), current_color, false, true)
                end
                setfield(n, "head", n_list)
            end

        elseif n_id == glyph_t then
            --- colorization is restricted to those fonts
            --- that received the “color” property upon
            --- loading (see ``setcolor()`` above)
            local font_color = get_font_color(getfont(n))
            if font_color ~= current_color then
                if current_color then
                    head, n, current_color = color_whatsit(head, n, current_color, false)
                end
                if font_color then
                    head, n, current_color = color_whatsit(head, n, font_color, true)
                end
            end

            if current_color and color_callback == "pre_linebreak_filter" then
                local nn = getnext(n)
                while nn and getid(nn) == glyph_t do
                    local font_color = get_font_color(getfont(nn))
                    if font_color == current_color then
                        n = nn
                    else
                        break
                    end
                    nn = getnext(nn)
                end
                if getid(nn) == disc_t then
                    head, n, current_color = color_whatsit(head, nn, current_color, false, true)
                else
                    head, n, current_color = color_whatsit(head, n, current_color, false, true)
                end
            end

        elseif n_id == whatsit_t then
            if current_color then
                head, n, current_color = color_whatsit(head, n, current_color, false)
            end

        end

        n = getnext(n)
    end

    if toplevel and current_color then
        head, _, current_color = color_whatsit(head, nodetail(head), current_color, false, true)
    end

    setattribute(head, color_attr, 1)
    return head, current_color
end

local getpageres = pdf.getpageresources or function() return pdf.pageresources end
local setpageres = pdf.setpageresources or function(s) pdf.pageresources = s end
local catat11    = luatexbase.registernumber("catcodetable@atletter")
local gettoks, scantoks = tex.gettoks, tex.scantoks
local pgf = { bye = "pgfutil@everybye", extgs = "\\pgf@sys@addpdfresource@extgs@plain" }

--- node -> node
local color_handler = function (head)
    head = todirect(head)
    head = node_colorize(head, true)
    head = tonode(head)

    -- now append our page resources
    if res then
        res["1"]  = true
        if scantoks and pgf.bye and not pgf.loaded then
            pgf.loaded = token.create(pgf.bye).cmdname == "assign_toks"
            pgf.bye    = pgf.loaded and pgf.bye
        end
        local tpr = pgf.loaded and gettoks(pgf.bye) or getpageres() or ""

        local t   = ""
        for k in pairs(res) do
            local str = stringformat("/TransGs%s<</ca %s>>", k, k) -- don't touch stroking elements
            if not tpr:find(str) then
                t = t .. str
            end
        end
        if t ~= "" then
            if pgf.loaded then
                scantoks("global", pgf.bye, catat11, stringformat("%s{%s}%s", pgf.extgs, t, tpr))
            else
                local tpr, n = tpr:gsub("/ExtGState<<", "%1"..t)
                if n == 0 then
                    tpr = stringformat("%s/ExtGState<<%s>>", tpr, t)
                end
                setpageres(tpr)
            end
        end
        res = nil -- reset res
    end
    return head
end

local color_callback_name      = "luaotfload.color_handler"
local color_callback_activated = 0
local add_to_callback          = luatexbase.add_to_callback

--- unit -> bool
local mlist_to_hlist_initial = function ()
    local cdesc = luatexbase.callback_descriptions "mlist_to_hlist"
    return cdesc and cdesc[1] == color_callback_name
end

--- unit -> unit
add_color_callback = function ( )
    color_callback = config.luaotfload.run.color_callback
    if not color_callback then
        color_callback = "post_linebreak_filter"
    end

    if color_callback_activated == 0 then
        add_to_callback(color_callback,
                        color_handler,
                        color_callback_name)
        add_to_callback("hpack_filter",
                        function (head, groupcode)
                            if  groupcode == "hbox"          or
                                groupcode == "adjusted_hbox" or
                                groupcode == "align_set"     then
                                head = color_handler(head)
                            end
                            return head
                        end,
                        color_callback_name)
        add_to_callback("mlist_to_hlist",
                        function (head, display_type, need_penalties)
                            if mlist_to_hlist_initial () then
                                head = mlist_to_hlist(head, display_type, need_penalties)
                            end
                            if display_type == "text" then
                                return head
                            end
                            return color_handler(head)
                        end,
                        color_callback_name)
        color_callback_activated = 1
    end
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

return {
    init = function ()
        logreport = luaotfload.log.report
        if not fonts then
            logreport ("log", 0, "color",
                       "OTF mechanisms missing -- did you forget to \z
                       load a font loader?")
            return false
        end
        fonts.handlers.otf.features.register {
            name        = "color",
            description = "color",
            initializers = {
                base = setcolor,
                node = setcolor,
            }
        }
        return true
    end
}


-- vim:tw=71:sw=4:ts=4:expandtab