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local function parse_charstring(cs, subrs, result)
result = result or {{false}}
local lastresult = result[#result]
local i = 1
while i~=#cs+1 do
local cmd = cs:byte(i)
if cmd == 255 then
lastresult[#lastresult+1] = string.unpack(">i4", cs:sub(i+1, i+4))
i = i+4
elseif cmd >= 251 then
lastresult[#lastresult+1] = -((cmd-251)*256)-string.byte(cs, i+1)-108
i = i+1
elseif cmd >= 247 then
lastresult[#lastresult+1] = (cmd-247)*256+string.byte(cs, i+1)+108
i = i+1
elseif cmd >= 32 then
lastresult[#lastresult+1] = cmd-139
elseif cmd == 9 then -- closepath, implicit in Type2
elseif cmd == 10 then
local subr = subrs[lastresult[#lastresult]]
lastresult[#lastresult] = nil
parse_charstring(subr, subrs, result)
lastresult = result[#result]
elseif cmd == 11 then
break -- We do not keep subroutines, so drop returns and continue with the outer commands
elseif cmd == 12 then
i = i+1
cmd = cs:byte(i)
if cmd == 12 then -- div, we might have huge parameters, so execute directly
lastresult[#lastresult-1] = lastresult[#lastresult-1]/lastresult[#lastresult]
lastresult[#lastresult] = nil
elseif cmd == 16 then -- othersubr...
cmd = lastresult[#lastresult]
lastresult[#lastresult] = nil
local numargs = lastresult[#lastresult]
lastresult[#lastresult] = nil
if cmd == 3 then -- Hint replacement. This is easy, we support hint replacement, so we
-- keep the original subr number
assert(numargs == 1)
elseif cmd == 1 then -- Flex initialization
elseif cmd == 2 then -- Flex parameter
if result[#result-1].flex then
result[#result] = nil -- TODO: Warn if there were additional values in lastresult.
lastresult = result[#result] -- We keep collecting arguments
end
lastresult.flex = true
elseif cmd == 0 then -- Flex
local flexinit = result[#result-1]
lastresult[2] = lastresult[2] + flexinit[2]
lastresult[3] = lastresult[3] + flexinit[3]
lastresult.flex = nil
result[#result-1] = lastresult
result[#result] = nil
lastresult[#lastresult] = nil
lastresult[#lastresult] = nil
lastresult[1] = -36
lastresult = {false}
result[#result+1] = lastresult
lastresult[#lastresult+1] = "setcurrentpointmark"
elseif cmd == 12 or cmd == 13 then
local pending = {}
local results = #lastresult
for i = 1,numargs do
pending[i] = lastresult[results-numargs+i]
lastresult[results-numargs+i] = nil
end
if lastresult.pendingargs then
for i = 1,#lastresult.pendingargs do
pending[numargs+i] = lastresult.pendingargs[i]
end
end
if cmd == 12 then
lastresult.pendingargs = pending
else
lastresult.pendingargs = nil
local n = pending[1]
local i = 2
local groups = {}
for group = 1, n do
local current = {20}
local last = 0
while pending[i+1] > 0 do
last = last + pending[i]
current[#current+1] = {1, last, pending[i+1]}
last = last + pending[i+1]
i = i+2
end
last = last + pending[i]
current[#current+1] = {1, last + pending[i+1], -pending[i+1]}
groups[group] = current
i = i+2
end
n = pending[i]
i = i+1
for group = 1, n do
local current = groups[group] or {20}
local last = 0
while pending[i+1] > 0 do
last = last + pending[i]
current[#current+1] = {3, last, pending[i+1]}
last = last + pending[i+1]
i = i+2
end
last = last + pending[i]
current[#current+1] = {3, last + pending[i+1], -pending[i+1]}
groups[group] = current
i = i+2
end
assert(i == #pending+1)
table.move(groups, 1, #groups, #result, result) -- This overwrites lastresult
result[#result+1] = lastresult -- And restore lastresult
end
else
error[[UNSUPPORTED Othersubr]]
end
elseif cmd == 17 then -- pop... Ignore them, they should already be handled by othersubr.
-- Compatibility with unknown othersubrs is futile, because
-- we can't interpret PostScript
elseif cmd == 33 then -- setcurrentpoint... If we expected this, it is already handled.
-- Otherwise fail, according to the spec it should
-- only be used with othersubrs.
assert(lastresult[#lastresult] == "setcurrentpointmark")
lastresult[#lastresult] = nil
else
lastresult[1] = -cmd-1
lastresult = {false}
result[#result+1] = lastresult
end
else
lastresult[1] = cmd
lastresult = {false}
result[#result+1] = lastresult
end
i = i+1
end
return result
end
local function adjust_charstring(cs) -- Here we get a not yet optimized but parsed Type1 charstring and
-- do some adjustments to make them more "Type2-like".
cs[#cs] = nil -- parse_charstring adds a `{false}` for internal reasons. Just drop it here. FIXME: Check that #cs[#cs]==1, otherwise there were values left on the charstring stack
if cs[1][1] ~= 13 then
error[[Unsupported first Type1 operator]] -- probably cs[1][1] == sbw
-- If you find a font using this, I'm sorry for you.
end
local hoffset = cs[1][2]
if hoffset ~= 0 then
-- non-zero sidebearings :-(
for i, cmd in ipairs(cs) do
if cmd[1] == 21 or cmd[1] == 22 then
cmd[2] = cmd[2] + cs[1][2]
break
elseif cmd[1] == 4 then
cmd[3] = cmd[2]
cmd[2] = cs[1][2]
cmd[1] = 21
break
end
-- Here I rely on the fact that the first relative command is always [hvr]moveto.
-- This is based on "Use rmoveto for the first point in the path." in the T1 spec
-- for hsbw. I am not entirely sure if this is a strict requirement or if there could
-- be weird charstrings where this fails (esp. since [hv]moveto are also used in the example),
-- but I decided to take the risk.
-- hints are affected too. They do not use relative coordinates in T1, so we store the offset
-- and handle hints later
end
end
cs[1][2] = cs[1][3]
cs[1][3] = nil
cs[1][1] = nil
-- That's it for the width, now we need some hinting stuff. This would be easy, if hint replacement
-- wouldn't require hint masks in Type2. And because we really enjoy this BS, we get counter
-- hinting as an additional treat... Oh, if you actually use counter hinting: Please test this
-- and report back if it works, because this is pretty much untested.
local stems = {}
local stem3 = {20}
local cntrs = {}
-- First iterate over the charstring, recording all hints and collecting them in stems/stem3/cntrs
for i, cmd in ipairs(cs) do
if cmd[1] == 1 or cmd[1] == 3 then
stems[#stems + 1] = cmd
elseif cmd[1] == -2 or cmd[1] == -3 then
local c = cmd[1] == -2 and 3 or 1
stems[#stems + 1] = {c, cmd[2], cmd[3]}
stems[#stems + 1] = {c, cmd[4], cmd[5]}
stems[#stems + 1] = {c, cmd[6], cmd[7]}
table.move(stems, #stems-2, #stems, #stem3+1, stem3)
cs[i] = false
elseif cmd[1] == 20 then
cntrs[#cntrs+1] = cmd
table.move(cmd, 2, #cmd, #stems+1, stems)
end
end
table.sort(stems, function(first, second)
if first[1] ~= second[1] then return first[1] < second[1] end
if first[2] ~= second[2] then return first[2] < second[2] end
return first[3] < second[3]
end)
-- Now store the index of every stem in the idx member of the hint command
-- After that `j` stores the number of stems
local j,k = 1,1
if stems[1] then stems[1].idx = 1 end
for i = 2,#stems do
if stems[i][2] == stems[k][2] and stems[i][3] == stems[k][3] then
stems[i].idx = j
stems[i] = false
else
j, k = j+1, i
stems[i].idx = j
end
end
-- Now the indices are known, so the cntrmask can be written, if counters or stem3 occured.
-- This is done before writing the stem list to make the thable.insert parameters easier.
-- First translate stem3 into a counter group
if stem3[2] then
cntrs[#cntrs+1] = stem3
table.insert(cs, 2, stem3)
end
local bytes = {}
for i=1, #cntrs do
local cntr = cntrs[i]
for l = 1, math.floor((j + 7)/8) do
bytes[l] = 0
end
for l = 2, #cntr do
local idx = cntr[l].idx-1
bytes[math.floor(idx/8) + 1] = bytes[math.floor(idx/8) + 1] | (1<<(7-idx%8))
cntr[l] = nil
end
cntr[2] = string.char(table.unpack(bytes))
end
local current = 1
-- Then list the collected stems at the beginning of the charstring
if stems[current] and stems[current][1] == 1 then
local stem_tbl, last = {18}, 0
while stems[current] ~= nil and (not stems[current] or stems[current][1] == 1) do
if stems[current] then
stem_tbl[#stem_tbl + 1] = stems[current][2] - last
last = stems[current][2] + stems[current][3]
stem_tbl[#stem_tbl + 1] = stems[current][3]
end
current = current + 1
end
table.insert(cs, 2, stem_tbl)
end
if stems[current] and stems[current][1] == 3 then
local stem_tbl, last = {false}, -hoffset
while stems[current] ~= nil and (not stems[current] or stems[current][1] == 3) do
if stems[current] then
stem_tbl[#stem_tbl + 1] = stems[current][2] - last
last = stems[current][2] + stems[current][3]
stem_tbl[#stem_tbl + 1] = stems[current][3]
end
current = current + 1
end
table.insert(cs, stems[1][1] == 1 and 3 or 2, stem_tbl)
end
-- Finally, replace every run of hint commands, corresponding to a hint replacement, by a single hintmask
local i = 1
while cs[i] ~= nil do
if cs[i] and cs[i].idx then
for l = 1, math.floor((j + 7)/8) do
bytes[l] = 0
end
while (cs[i] or {}).idx do
local idx = cs[i].idx-1
bytes[math.floor(idx/8) + 1] = bytes[math.floor(idx/8) + 1] | (1<<(7-idx%8))
cs[i] = false
i = i+1
end
for l = 2, #stem3 do
local idx = stem3[l].idx-1
bytes[math.floor(idx/8) + 1] = bytes[math.floor(idx/8) + 1] | (1<<(7-idx%8))
end
i = i-1
cs[i] = {19, string.char(table.unpack(bytes))}
end
i = i+1
end
end
return function(cs, subrs)
local parsed = parse_charstring(cs, subrs)
adjust_charstring(parsed)
return parsed
end