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Editing Module:TextFit

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given width and height, using real per-glyph advance widths rather than a
given width and height, using real per-glyph advance widths rather than a
character count.
character count.
Everything is measured at bold weight. Retail Demo's bold advances run about 4%
wider than its regular ones, so measuring regular text against the bold table
can only make the estimate slightly conservative -- text comes out a hair small
rather than overflowing -- and it removes the need to track font weight through
the markup at all. Both callers render their text bold in any case.


Widths are in em: each font's raw advances divided by its own unitsPerEm, so
Widths are in em: each font's raw advances divided by its own unitsPerEm, so
the tables are directly comparable despite the differing internal grids.
the tables are directly comparable despite the differing internal grids.
Extracted with fonttools from:
Extracted with fonttools from:
   Retail Demo bold [[:File:Retaildemo-bold.woff2]] unitsPerEm 1000
  Retail Demo regular  [[:File:Retaildemo-regular.woff2]]  unitsPerEm 1000
   Open Sans         [[:File:Open_Sans.woff2]]       unitsPerEm 2048
   Retail Demo bold     [[:File:Retaildemo-bold.woff2]]     unitsPerEm 1000
   Open Sans           [[:File:Open_Sans.woff2]]           unitsPerEm 2048


Note the level-2 long brackets on this comment: a plain --[[ ]] comment would
Note the level-2 long brackets on this comment: a plain --[[ ]] comment would
Line 24: Line 19:
local ustring = mw.ustring
local ustring = mw.ustring


-- Retail Demo, bold weight. Invisible characters are spelled with
-- Retail Demo, normal weight
-- ustring.char so they cannot be mistaken for a plain space when edited.
local RD_REGULAR = {
local WIDTHS = {
[" "]=0.240, [","]=0.221, ["."]=0.221, ["0"]=0.645, ["1"]=0.268, ["2"]=0.549, ["3"]=0.557, ["4"]=0.601,
["5"]=0.538, ["6"]=0.583, ["7"]=0.487, ["8"]=0.555, ["9"]=0.580, A=0.624, B=0.585, C=0.641,
D=0.696, E=0.554, F=0.525, G=0.695, H=0.703, I=0.237, J=0.268, K=0.626,
L=0.494, M=0.927, N=0.700, O=0.730, P=0.558, Q=0.734, R=0.614, S=0.527,
T=0.550, U=0.679, V=0.624, W=0.939, X=0.665, Y=0.603, Z=0.647, a=0.553,
b=0.587, c=0.530, d=0.588, e=0.551, f=0.394, g=0.544, h=0.600, i=0.238,
j=0.235, k=0.552, l=0.238, m=0.923, n=0.600, o=0.603, p=0.583, q=0.587,
r=0.369, s=0.477, t=0.413, u=0.600, v=0.509, w=0.810, x=0.540, y=0.513,
z=0.554,
[" "]=0.240, -- U+00A0 no-break space
}
 
-- Retail Demo, bold weight
local RD_BOLD = {
[" "]=0.240, [","]=0.281, ["."]=0.281, ["0"]=0.662, ["1"]=0.312, ["2"]=0.560, ["3"]=0.566, ["4"]=0.612,
[" "]=0.240, [","]=0.281, ["."]=0.281, ["0"]=0.662, ["1"]=0.312, ["2"]=0.560, ["3"]=0.566, ["4"]=0.612,
["5"]=0.562, ["6"]=0.601, ["7"]=0.520, ["8"]=0.583, ["9"]=0.598, A=0.677, B=0.590, C=0.621,
["5"]=0.562, ["6"]=0.601, ["7"]=0.520, ["8"]=0.583, ["9"]=0.598, A=0.677, B=0.590, C=0.621,
Line 36: Line 44:
r=0.392, s=0.496, t=0.404, u=0.602, v=0.549, w=0.776, x=0.571, y=0.550,
r=0.392, s=0.496, t=0.404, u=0.602, v=0.549, w=0.776, x=0.571, y=0.550,
z=0.561,
z=0.561,
[ustring.char(0xA0)]=0.240, -- no-break space
[" "]=0.240, -- U+00A0 no-break space
}
}
-- No bold Open Sans is loaded, so browsers synthesise it. Estimated from
-- Retail Demo's measured bold/regular ratio of 1.037.
local SYNTH_BOLD = 1.04


-- Open Sans, for the characters Retail Demo does not contain
-- Open Sans, for the characters Retail Demo does not contain
Line 50: Line 54:
["_"]=0.438, ["`"]=0.277, ["{"]=0.375, ["|"]=0.549, ["}"]=0.375, ["~"]=0.572, ["¡"]=0.264, ["¢"]=0.572,
["_"]=0.438, ["`"]=0.277, ["{"]=0.375, ["|"]=0.549, ["}"]=0.375, ["~"]=0.572, ["¡"]=0.264, ["¢"]=0.572,
["£"]=0.572, ["¤"]=0.572, ["¥"]=0.572, ["¦"]=0.549, ["§"]=0.514, ["¨"]=0.580, ["©"]=0.832, ["ª"]=0.353,
["£"]=0.572, ["¤"]=0.572, ["¥"]=0.572, ["¦"]=0.549, ["§"]=0.514, ["¨"]=0.580, ["©"]=0.832, ["ª"]=0.353,
["«"]=0.496, ["¬"]=0.572, [ustring.char(0xAD)]=0.322, -- soft hyphen
["«"]=0.496, ["¬"]=0.572, ["­"]=0.322, ["®"]=0.832, ["¯"]=0.500, ["°"]=0.428, ["±"]=0.572, ["²"]=0.348,
["®"]=0.832, ["¯"]=0.500, ["°"]=0.428, ["±"]=0.572, ["²"]=0.348,
["³"]=0.348, ["´"]=0.277, ["µ"]=0.618, ["¶"]=0.655, ["·"]=0.263, ["¸"]=0.222, ["¹"]=0.348, ["º"]=0.374,
["³"]=0.348, ["´"]=0.277, ["µ"]=0.618, ["¶"]=0.655, ["·"]=0.263, ["¸"]=0.222, ["¹"]=0.348, ["º"]=0.374,
["»"]=0.496, ["¼"]=0.740, ["½"]=0.768, ["¾"]=0.778, ["¿"]=0.432, ["À"]=0.632, ["Á"]=0.632, ["Â"]=0.632,
["»"]=0.496, ["¼"]=0.740, ["½"]=0.768, ["¾"]=0.778, ["¿"]=0.432, ["À"]=0.632, ["Á"]=0.632, ["Â"]=0.632,
Line 92: Line 95:
["‘"]=0.169, ["’"]=0.169, ["‚"]=0.245, ["‛"]=0.169, ["“"]=0.349, ["”"]=0.349, ["…"]=0.778, ["€"]=0.572,
["‘"]=0.169, ["’"]=0.169, ["‚"]=0.245, ["‛"]=0.169, ["“"]=0.349, ["”"]=0.349, ["…"]=0.778, ["€"]=0.572,
}
}
-- No bold Open Sans is loaded, so browsers synthesise it
-- Estimated from Retail Demo's measured bold/regular of 1.037.
local SYNTH_BOLD = 1.04


-- Characters in neither face (CJK, rare symbols).
-- Characters in neither face (CJK, rare symbols).
Line 97: Line 104:
local FALLBACK  = 0.55
local FALLBACK  = 0.55


local function charWidth(ch)
local VOID_TAGS = { br = true, img = true, hr = true, input = true,
local w = WIDTHS[ch]
                    meta = true, link = true, wbr = true }
local BOLD_TAGS = { b = true, strong = true }
 
local function charWidth(ch, bold)
local w = (bold and RD_BOLD or RD_REGULAR)[ch]
if w then return w end
if w then return w end


w = FALLBACK_WIDTHS[ch]
w = FALLBACK_WIDTHS[ch]
if w then return w * SYNTH_BOLD end
if w then
return bold and w * SYNTH_BOLD or w
end


local cp = ustring.codepoint(ch) or 0
local cp = ustring.codepoint(ch) or 0
Line 115: Line 128:
local function wordWidth(word)
local function wordWidth(word)
local total = 0
local total = 0
for ch in ustring.gmatch(word, ".") do
for _, part in ipairs(word) do
total = total + charWidth(ch)
for ch in ustring.gmatch(part.text, ".") do
total = total + charWidth(ch, part.bold)
end
end
end
return total
return total
end
-- Parser state. `lines` is the finished output; `line`, `word` and `part` are
-- the containers currently being filled. A part is a run of one weight inside
-- a word, so a word split across tags stays a single word.
local function newState()
return { lines = {}, line = {}, word = {}, part = nil }
end
local function endWord(st)
if st.part then
table.insert(st.word, st.part)
st.part = nil
end
if #st.word > 0 then
table.insert(st.line, st.word)
st.word = {}
end
end
local function endLine(st)
endWord(st)
table.insert(st.lines, st.line)
st.line = {}
end
local function pushChar(st, ch, bold)
if st.part == nil or st.part.bold ~= bold then
if st.part then table.insert(st.word, st.part) end
st.part = { text = ch, bold = bold }
else
st.part.text = st.part.text .. ch
end
end
-- True if any open tag on the stack set bold weight.
local function stackIsBold(stack)
for k = #stack, 1, -1 do
if stack[k] then return true end
end
return false
end
end


Line 131: Line 187:
end
end


-- Reduce expanded wikitext/HTML to the text a reader actually sees: a list of
-- Apply one HTML tag: push or pop the weight stack, or end the line on <br>.
-- lines, each a list of words.
local function applyTag(st, stack, tag)
-- Tags are deleted rather than replaced, so a word broken across a tag boundary
local closing, name = tag:match("^%s*(/?)%s*(%a+)")
-- stays one word. Splitting on ASCII whitespace only leaves NBSP joining its
if not name then return end
-- neighbours, which is how the browser wraps.
name = name:lower()
function p.parse(src)
 
if name == "br" then
endLine(st)
elseif VOID_TAGS[name] then -- no effect on weight
elseif closing == "/" then
table.remove(stack)
elseif not tag:match("/%s*$") then
local lower = tag:lower()
table.insert(stack, BOLD_TAGS[name] == true
or lower:match("font%-weight%s*:%s*bold") ~= nil
or lower:match("font%-weight%s*:%s*[6-9]00") ~= nil)
end
end
 
-- Reduce expanded wikitext/HTML to the text a reader actually sees, keeping
-- track of which runs are bold. Returns a list of lines; each line is a list
-- of words; each word is a list of {text=, bold=} parts.
-- Words break only on real whitespace: NBSP and tag boundaries do not split
-- them, matching how the browser wraps.
-- `baseBold` measures every run as bold, for callers whose text is entirely
-- bold by CSS rather than by markup.
function p.parse(src, baseBold)
src = stripMarkup(src)
src = stripMarkup(src)
src = src:gsub("<%s*[bB][rR]%s*/?%s*>", "\n")
src = src:gsub("<[^<>]*>", "")
-- Decode after the tags are gone, so an escaped &lt; cannot look like one.
src = mw.text.decode(src, true)


local lines = {}
local st = newState()
for line in (src .. "\n"):gmatch("([^\n]*)\n") do
local stack = {}
local words = {}
local i, n = 1, #src
for word in line:gmatch("%S+") do
 
words[#words + 1] = word
while i <= n do
if src:sub(i, i) == "<" then
local j = src:find(">", i, true)
if not j then break end
applyTag(st, stack, src:sub(i + 1, j - 1))
i = j + 1
else
local k = src:find("<", i, true) or (n + 1)
local chunk = mw.text.decode(src:sub(i, k - 1), true)
local bold = baseBold == true or stackIsBold(stack)
for ch in ustring.gmatch(chunk, ".") do
if ch == "\n" then
endLine(st)
elseif ch == " " or ch == "\t" or ch == "\r" then
endWord(st)
else
pushChar(st, ch, bold)  -- NBSP falls here: joins, never breaks
end
end
i = k
end
end
lines[#lines + 1] = words
end
end
return lines
 
endLine(st)
return st.lines
end
end


-- Greedy wrap with the usable width normalised to 1, so `r` is the font size
-- Greedy wrap with the usable width normalised to 1, so `r` is the font size
-- expressed as a fraction of that width. Takes lines of word WIDTHS, already
-- expressed as a fraction of that width. Returns the number of rendered lines.
-- measured by fit(). Returns the number of rendered lines.
local function lineCount(lines, r, bold)
local function lineCount(lines, r)
local space = charWidth(" ", bold == true) * r
local space = charWidth(" ") * r
local total = 0
local total = 0
for _, widths in ipairs(lines) do
for _, words in ipairs(lines) do
local cur = 0
local cur = 0
total = total + 1
total = total + 1
for _, ww in ipairs(widths) do
for _, word in ipairs(words) do
ww = ww * r
local ww = wordWidth(word) * r
if cur == 0 then
if cur == 0 then
cur = ww
cur = ww
Line 188: Line 280:
--  max, min    ceiling and floor, also as a percentage of the width
--  max, min    ceiling and floor, also as a percentage of the width
--  step        search granularity
--  step        search granularity
--  bold        measure every run at bold weight, for callers whose text is
--              entirely bold rather than marked up
function p.fit(text, opts)
function p.fit(text, opts)
local aspect = opts.aspect
local aspect = opts.aspect
Line 194: Line 288:
local minPct = opts.min or 1
local minPct = opts.min or 1
local step  = opts.step or 0.1
local step  = opts.step or 0.1
local bold  = opts.bold == true
local lines = p.parse(text, bold)


-- Measure every word once; the shrink loop below only scales the results.
local widest = 0
local lines, widest = {}, 0
for _, words in ipairs(lines) do
for _, words in ipairs(p.parse(text)) do
for _, word in ipairs(words) do
local widths = {}
local ww = wordWidth(word)
for i, word in ipairs(words) do
if ww > widest then widest = ww end
widths[i] = wordWidth(word)
if widths[i] > widest then widest = widths[i] end
end
end
lines[#lines + 1] = widths
end
end
if widest == 0 then return maxPct end
if widest == 0 then return maxPct end
Line 211: Line 305:


-- Then shrink until the wrapped block fits vertically
-- Then shrink until the wrapped block fits vertically
while pct > minPct and lineCount(lines, pct / 100) * lineH * (pct / 100) > aspect do
while pct > minPct and lineCount(lines, pct / 100, bold) * lineH * (pct / 100) > aspect do
pct = pct - step
pct = pct - step
end
end
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