path: root/tex/context/base/mkxl/font-imp-math.lmt

if not modules then modules = { } end modules ['font-imp-math'] = {
    version   = 1.001,
    comment   = "companion to font-ini.mkiv and hand-ini.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local next, type, tonumber = next, type, tonumber

local fonts              = fonts
local helpers            = fonts.helpers
local registerotffeature = fonts.handlers.otf.features.register

local setmetatableindex  = table.setmetatableindex
local sortedhash         = table.sortedhash
local copytable          = table.copy

local texconditionals    = tex.conditionals

-- tfmdata.properties.mathnolimitsmode = tonumber(value) or 0

local splitter  = lpeg.splitat(",",tonumber)
local lpegmatch = lpeg.match

local function initialize(tfmdata,value)
    local mathparameters = tfmdata.mathparameters
    if mathparameters then
        local sup, sub
        if type(value) == "string" then
            sup, sub = lpegmatch(splitter,value) -- settings_to_array
            if not sup then
                sub, sup = 0, 0
            elseif not sub then
                sub, sup = sup, 0
            end
        elseif type(value) == "number" then
            sup, sub = 0, value
        end
        if sup then
            mathparameters.NoLimitSupFactor = sup
        end
        if sub then
            mathparameters.NoLimitSubFactor = sub
        end
    end
end

registerotffeature {
    name         = "mathnolimitsmode",
    description  = "influence nolimits placement",
    initializers = {
        base = initialize,
        node = initialize,
    }
}


-- this will become a mode in the engine

local function initialize(tfmdata,value)
    tfmdata.properties.nostackmath = value and true
end

registerotffeature {
    name        = "nostackmath",
    description = "disable math stacking mechanism",
    initializers = {
        base = initialize,
        node = initialize,
    }
}

-- A quick and dirty and low level implementation but okay for testing:

function fonts.helpers.mathscriptslots(tfmdata,textcode)
    local rawdata           = tfmdata.shared.rawdata
    local rawresources      = rawdata and rawdata.resources
    local rawfeatures       = rawresources and rawresources.features
    local basesubstitutions = rawfeatures and rawfeatures.gsub
    local sequences         = basesubstitutions and tfmdata.resources.sequences
    if sequences then
        local characters = tfmdata.characters
        if characters[textcode] then
            for s=1,#sequences do
                local sequence  = sequences[s]
                local sfeatures = sequence.features
                if sfeatures and sfeatures.ssty then
                    local steps = sequence.steps
                    for i=1,#steps do
                        local coverage = steps[i].coverage
                        if coverage then
                            local okay = coverage[textcode]
                            if okay then
                                -- can be single or table
                                return okay
                            end
                        end
                    end
                end
            end
        end
    end
end

local function manipulate(tfmdata,value)
 -- if texconditionals["c_font_compact"] then
    if value then -- so basically always
        local rawdata           = tfmdata.shared.rawdata
        local rawresources      = rawdata and rawdata.resources
        local rawfeatures       = rawresources and rawresources.features
        local basesubstitutions = rawfeatures and rawfeatures.gsub
        local sequences         = basesubstitutions and tfmdata.resources.sequences
        if sequences then
            local characters = tfmdata.characters
            for s=1,#sequences do
                local sequence  = sequences[s]
                local sfeatures = sequence.features
                if sfeatures and sfeatures.ssty then
                    local steps = sequence.steps
                    for i=1,#steps do
                        local coverage = steps[i].coverage
                        if coverage then
                            for textcode, v in next, coverage do
                                local textdata = characters[textcode]
                                if textdata then
                                    local scriptcode, scriptscriptcode
                                    local sstykind = type(v)
                                    if sstykind == "table" then
                                        scriptcode       = v[1]
                                        scriptscriptcode = v[2]
                                    elseif sstykind == "number" then
                                        scriptcode       = v
                                        scriptscriptcode = v
                                    else
                                        -- weird
                                    end
                                    if scriptcode then
                                        local scriptdata       = characters[scriptcode]
                                        local scriptscriptdata = characters[scriptscriptcode]
                                        if scriptdata and scriptdata ~= textdata then
                                            textdata.smaller = scriptcode
                                            if scriptscriptdata and scriptdata ~= scriptscriptdata then
                                                scriptdata.smaller = scriptscriptcode
                                            end
                                        end
                                    end
                                end
                            end
                        end
                    end
                end
            end
        end
    end
end

local function initialize(tfmdata,value)
    -- Here it really gets enabled as the scales are used.
    if texconditionals["c_font_compact"] then
        local rawdata       = tfmdata.shared.rawdata
        local rawresources  = rawdata and rawdata.resources
        local mathconstants = rawresources.mathconstants
        if mathconstants then
            local parameters = tfmdata.parameters
            local properties = tfmdata.properties
            parameters.textscale         = 1000
            parameters.scriptscale       = mathconstants.ScriptPercentScaleDown * 10
            parameters.scriptscriptscale = mathconstants.ScriptScriptPercentScaleDown * 10
            properties.compactmath       = true
        end
    end
end

-- local specification = {
--     name         = "compactmath",
--     description  = "use one math font",
--     manipulators = {
--         base = manipulate,
--         node = manipulate,
--     },
--     initializers = {
--         base = initialize,
--         node = initialize,
--     }
-- }

registerotffeature {
    name         = "compactmath",
    description  = "use one math font",
    initializers = {
        base = function(...) manipulate(...) initialize(...) end,
        node = function(...) manipulate(...) initialize(...) end,
    }
}

-- The problem is that the traditional code path doesn't add an italic to the subscript,
-- simply because it assumes that the width has that already subtracted. So, we cannot
-- compensate in the following way. We're stuck with the fact that the texgyre fonts
-- assume a traditional tex engine.

-- local function manipulate(tfmdata,key,value)
--     if value == "correct" then
--         local chardata = characters.data
--         for unicode, data in next, tfmdata.characters do
--             local italic = data.italic
--             if italic then
--                 -- todo: only letters
--                 data.width = (data.width or 0) + italic
--                 local cd = chardata[unicode]
--                 if cd then
--                     local visual = cd.visual
--                     if visual == "it" or visual == "bi" then
--                         italic = -italic
--                     else
--                         italic = 0
--                     end
--                 else
--                     italic = 0
--                 end
--                 data.italic = italic
--             end
--         end
--     end
-- end

local function initialize(tfmdata,value)
    if type(value) == "string" then
        local rawdata       = tfmdata.shared.rawdata
        local rawresources  = rawdata and rawdata.resources
        local mathconstants = rawresources.mathconstants
        if mathconstants then
            local bitmap = tex.stringtocodesbitmap(value,tex.mathcontrolcodes)
         -- logs.report("mathfont","setting math control to %08X",bitmap)
            tfmdata.properties.mathcontrol = bitmap
        end
    end
end

registerotffeature {
    name         = "mathcontrol",
    description  = "control specific old/new math handling",
    initializers = {
        base = initialize,
        node = initialize,
    }
}

local function initialize(tfmdata,value)
    if value then
        local validlookups, lookuplist = fonts.handlers.otf.collectlookups(tfmdata.shared.rawdata,"flac","math","dflt")
        if validlookups then
            -- it's quite likely just one step
            local characters = tfmdata.characters
            local changed = tfmdata.changed
            for i=1,#lookuplist do
                local lookup   = lookuplist[i]
                local steps    = lookup.steps
                local nofsteps = lookup.nofsteps
                for i=1,nofsteps do
                    local coverage = steps[i].coverage
                    if coverage then
                        for k, v in next, coverage do
                            local c = characters[k]
                            local f = characters[v]
                            if c and f then
                                c.flataccent = v
                                if not f.unicode then
                                    f.unicode = c.unicode
                                end
                            end
                        end
                    end
                end
            end
        end
    end
end

registerotffeature {
    name         = "flattenaccents",
    description  = "mapping accents to flat ones",
    initializers = {
        base = initialize,
        node = initialize,
    }
}

-- todo: document our privates

-- This horrible hack is needed because when opentype math showed up and math was
-- added to unicode folks had forgotten about different script shapes so we not only
-- have a retrospective variant selector but inconsistent defaults. What a mess it
-- is. So the quick and dirty solution is:
--
-- add copies in private slots
-- use a pseudo feature to access those
-- and optionally afterwards replace the original slots

-- local coverage = { }
--
-- local function initialize(tfmdata,value)
--     if value then
--         if not next(coverage) then
--             for k, char in next, mathematics.alphabets.sr.tf.lcletters do
--                 coverage[char] = 0xFE800 + k
--             end
--             for k, char in next, mathematics.alphabets.sr.tf.ucletters do
--                 coverage[char] = 0xFE800 + k
--             end
--             fonts.handlers.otf.addfeature {
--                 name = "savemathscripts",
--                 type = "substitution",
--                 data = coverage,
--             }
--         end
--         local characters   = tfmdata.characters
--         local descriptions = tfmdata.descriptions
--         for char, private in next, coverage do
--             local data = characters[char]
--             if data and not characters[private] then
--                 -- otherwise we need a virtual
--                 characters  [private] = copytable(data)
--                 descriptions[private] = copytable(descriptions[char])
--             end
--         end
--     end
-- end
--
-- registerotffeature {
--     name         = "copymathscripts",
--     description  = "copy math script",
--     prepend      = 1,
--     initializers = {
--         base = initialize,
--         node = initialize,
--     }
-- }