[fontloader] sync Context as of 2016-04-07

1 files changed, 480 insertions, 0 deletions

diff --git a/src/fontloader/misc/fontloader-font-ttf.lua b/src/fontloader/misc/fontloader-font-ttf.lua
new file mode 100644
index 0000000..6df3392
--- /dev/null
+++ b/src/fontloader/misc/fontloader-font-ttf.lua
@@ -0,0 +1,480 @@
+if not modules then modules = { } end modules ['font-ttf'] = {
+    version   = 1.001,
+    comment   = "companion to font-ini.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+local next, type, unpack = next, type, unpack
+local bittest = bit32.btest
+local sqrt = math.sqrt
+
+local report      = logs.reporter("otf reader","ttf")
+
+local readers      = fonts.handlers.otf.readers
+local streamreader = readers.streamreader
+
+local setposition  = streamreader.setposition
+local getposition  = streamreader.getposition
+local skipbytes    = streamreader.skip
+local readbyte     = streamreader.readcardinal1  --  8-bit unsigned integer
+local readushort   = streamreader.readcardinal2  -- 16-bit unsigned integer
+local readulong    = streamreader.readcardinal4  -- 24-bit unsigned integer
+local readchar     = streamreader.readinteger1   --  8-bit   signed integer
+local readshort    = streamreader.readinteger2   -- 16-bit   signed integer
+local read2dot14   = streamreader.read2dot14     -- 16-bit signed fixed number with the low 14 bits of fraction (2.14) (F2DOT14)
+
+local function mergecomposites(glyphs,shapes)
+
+    local function merge(index,shape,components)
+        local contours    = { }
+        local nofcontours = 0
+        for i=1,#components do
+            local component   = components[i]
+            local subindex    = component.index
+            local subshape    = shapes[subindex]
+            local subcontours = subshape.contours
+            if not subcontours then
+                local subcomponents = subshape.components
+                if subcomponents then
+                    subcontours = merge(subindex,subshape,subcomponents)
+                end
+            end
+            if subcontours then
+                local matrix  = component.matrix
+                local xscale  = matrix[1]
+                local xrotate = matrix[2]
+                local yrotate = matrix[3]
+                local yscale  = matrix[4]
+                local xoffset = matrix[5]
+                local yoffset = matrix[6]
+                for i=1,#subcontours do
+                    local points = subcontours[i]
+                    local result = { }
+                    for i=1,#points do
+                        local p = points[i]
+                        local x = p[1]
+                        local y = p[2]
+                        result[i] = {
+                            xscale * x + xrotate * y + xoffset,
+                            yscale * y + yrotate * x + yoffset,
+                            p[3]
+                        }
+                    end
+                    nofcontours = nofcontours + 1
+                    contours[nofcontours] = result
+                end
+            else
+                report("missing contours composite %s, component %s of %s, glyph %s",index,i,#components,subindex)
+            end
+        end
+        shape.contours   = contours
+        shape.components = nil
+        return contours
+    end
+
+    for index=1,#glyphs do
+        local shape      = shapes[index]
+        local components = shape.components
+        if components then
+            merge(index,shape,components)
+        end
+    end
+
+end
+
+local function readnothing(f,nofcontours)
+    return {
+        type = "nothing",
+    }
+end
+
+-- begin of converter
+
+-- make paths: the ff code is quite complex but it looks like we need to deal
+-- with all kind of on curve border cases
+
+local function curveto(m_x,m_y,l_x,l_y,r_x,r_y) -- todo: inline this
+    return {
+        l_x + 2/3 *(m_x-l_x), l_y + 2/3 *(m_y-l_y),
+        r_x + 2/3 *(m_x-r_x), r_y + 2/3 *(m_y-r_y),
+        r_x, r_y, "c" -- "curveto"
+    }
+end
+
+-- We could omit the operator which saves some 10%:
+--
+-- #2=lineto  #4=quadratic  #6=cubic #3=moveto (with "m")
+--
+-- For the moment we keep the original outlines but that default might change
+-- in the future. In any case, a backend should support both.
+--
+-- The code is a bit messy. I looked at the ff code but it's messy too. It has
+-- to do with the fact that we need to look at points on the curve and control
+-- points in between. This also means that we start at point 2 and have to look at
+-- point 1 when we're at the end. We still use a ps like storage with the operator
+-- last in an entry. It's typical code that evolves stepwise till a point of no
+-- comprehension.
+
+local function contours2outlines(glyphs,shapes)
+    local quadratic = true
+ -- local quadratic = false
+    for index=1,#glyphs do
+        local glyph    = glyphs[index]
+        local shape    = shapes[index]
+        local contours = shape.contours
+        if contours then
+            local nofcontours = #contours
+            local segments    = { }
+            local nofsegments = 0
+            glyph.segments    = segments
+            if nofcontours > 0 then
+                for i=1,nofcontours do
+                    local contour    = contours[i]
+                    local nofcontour = #contour
+                    if nofcontour > 0 then
+                        local first_pt = contour[1]
+                        local first_on = first_pt[3]
+                        -- todo no new tables but reuse lineto and quadratic
+                        if nofcontour == 1 then
+                            -- this can influence the boundingbox
+                            first_pt[3] = "m" -- "moveto"
+                            nofsegments = nofsegments + 1
+                            segments[nofsegments] = first_pt
+                        else -- maybe also treat n == 2 special
+                            local first_on     = first_pt[3]
+                            local last_pt      = contour[nofcontour]
+                            local last_on      = last_pt[3]
+                            local start        = 1
+                            local control_pt   = false
+                            if first_on then
+                                start = 2
+                            else
+                                if last_on then
+                                    first_pt = last_pt
+                                else
+                                    first_pt = { (first_pt[1]+last_pt[1])/2, (first_pt[2]+last_pt[2])/2, false }
+                                end
+                                control_pt = first_pt
+                            end
+                            nofsegments = nofsegments + 1
+                            segments[nofsegments] = { first_pt[1], first_pt[2], "m" } -- "moveto"
+                            local previous_pt = first_pt
+                            for i=start,nofcontour do
+                                local current_pt  = contour[i]
+                                local current_on  = current_pt[3]
+                                local previous_on = previous_pt[3]
+                                if previous_on then
+                                    if current_on then
+                                        -- both normal points
+                                        nofsegments = nofsegments + 1
+                                        segments[nofsegments] = { current_pt[1], current_pt[2], "l" } -- "lineto"
+                                    else
+                                        control_pt = current_pt
+                                    end
+                                elseif current_on then
+                                    local ps = segments[nofsegments]
+                                    nofsegments = nofsegments + 1
+                                    if quadratic then
+                                        segments[nofsegments] = { control_pt[1], control_pt[2], current_pt[1], current_pt[2], "q" } -- "quadraticto"
+                                    else
+                                        local p = segments[nofsegments-1]  local n = #p
+                                        segments[nofsegments] = curveto(control_pt[1],control_pt[2],p[n-2],p[n-1],current_pt[1],current_pt[2])
+                                    end
+                                    control_pt = false
+                                else
+                                    nofsegments = nofsegments + 1
+                                    local halfway_x = (previous_pt[1]+current_pt[1])/2
+                                    local halfway_y = (previous_pt[2]+current_pt[2])/2
+                                    if quadratic then
+                                        segments[nofsegments] = { control_pt[1], control_pt[2], halfway_x, halfway_y, "q" } -- "quadraticto"
+                                    else
+                                        local p = segments[nofsegments-1]  local n = #p
+                                        segments[nofsegments] = curveto(control_pt[1],control_pt[2],p[n-2],p[n-1],halfway_x,halfway_y)
+                                    end
+                                    control_pt = current_pt
+                                end
+                                previous_pt = current_pt
+                            end
+                            if first_pt == last_pt then
+                                -- we're already done, probably a simple curve
+                            else
+                                nofsegments = nofsegments + 1
+                                if not control_pt then
+                                    segments[nofsegments] = { first_pt[1], first_pt[2], "l" } -- "lineto"
+                                elseif quadratic then
+                                    segments[nofsegments] = { control_pt[1], control_pt[2], first_pt[1], first_pt[2], "q" } -- "quadraticto"
+                                else
+                                    local p = last_pt  local n = #p
+                                    segments[nofsegments] = curveto(control_pt[1],control_pt[2],p[n-2],p[n-1],first_pt[1],first_pt[2])
+                                end
+                            end
+                        end
+                    end
+                end
+            end
+        end
+    end
+end
+
+-- end of converter
+
+local function readglyph(f,nofcontours)
+    local points       = { }
+    local endpoints    = { }
+    local instructions = { }
+    local flags        = { }
+    for i=1,nofcontours do
+        endpoints[i] = readshort(f) + 1
+    end
+    local nofpoints       = endpoints[nofcontours]
+    local nofinstructions = readushort(f)
+--     f:seek("set",f:seek()+nofinstructions)
+    skipbytes(f,nofinstructions)
+    -- because flags can repeat we don't know the amount ... in fact this is
+    -- not that efficient (small files but more mem)
+    local i = 1
+    while i <= nofpoints do
+        local flag = readbyte(f)
+        flags[i] = flag
+        if bittest(flag,0x0008) then
+            for j=1,readbyte(f) do
+                i = i + 1
+                flags[i] = flag
+            end
+        end
+        i = i + 1
+    end
+    -- first come the x coordinates, and next the y coordinates and they
+    -- can be repeated
+    local x = 0
+    for i=1,nofpoints do
+        local flag  = flags[i]
+        local short = bittest(flag,0x0002)
+        local same  = bittest(flag,0x0010)
+        if short then
+            if same then
+                x = x + readbyte(f)
+            else
+                x = x - readbyte(f)
+            end
+        elseif same then
+            -- copy
+        else
+            x = x + readshort(f)
+        end
+        points[i] = { x, y, bittest(flag,0x0001) }
+    end
+    local y = 0
+    for i=1,nofpoints do
+        local flag  = flags[i]
+        local short = bittest(flag,0x0004)
+        local same  = bittest(flag,0x0020)
+        if short then
+            if same then
+                y = y + readbyte(f)
+            else
+                y = y - readbyte(f)
+            end
+        elseif same then
+         -- copy
+        else
+            y = y + readshort(f)
+        end
+        points[i][2] = y
+    end
+    -- we could integrate this if needed
+    local first = 1
+    for i=1,#endpoints do
+        local last = endpoints[i]
+        endpoints[i] = { unpack(points,first,last) }
+        first = last + 1
+    end
+    return {
+        type     = "glyph",
+     -- points   = points,
+        contours = endpoints,
+    }
+end
+
+local function readcomposite(f)
+    local components    = { }
+    local nofcomponents = 0
+    local instructions  = false
+    while true do
+        local flags      = readushort(f)
+        local index      = readushort(f)
+        ----- f_words    = bittest(flags,0x0001)
+        local f_xyarg    = bittest(flags,0x0002)
+        ----- f_round    = bittest(flags,0x0004+0x0002)
+        ----- f_scale    = bittest(flags,0x0008)
+        ----- f_reserved = bittest(flags,0x0010)
+        ----- f_more     = bittest(flags,0x0020)
+        ----- f_xyscale  = bittest(flags,0x0040)
+        ----- f_matrix   = bittest(flags,0x0080)
+        ----- f_instruct = bittest(flags,0x0100)
+        ----- f_usemine  = bittest(flags,0x0200)
+        ----- f_overlap  = bittest(flags,0x0400)
+        local f_offset   = bittest(flags,0x0800)
+        ----- f_uoffset  = bittest(flags,0x1000)
+        local xscale     = 1
+        local xrotate    = 0
+        local yrotate    = 0
+        local yscale     = 1
+        local xoffset    = 0
+        local yoffset    = 0
+        local base       = false
+        local reference  = false
+        if f_xyarg then
+            if bittest(flags,0x0001) then -- f_words
+                xoffset = readshort(f)
+                yoffset = readshort(f)
+            else
+                xoffset = readchar(f) -- signed byte, stupid name
+                yoffset = readchar(f) -- signed byte, stupid name
+            end
+        else
+            if bittest(flags,0x0001) then -- f_words
+                base      = readshort(f)
+                reference = readshort(f)
+            else
+                base      = readchar(f) -- signed byte, stupid name
+                reference = readchar(f) -- signed byte, stupid name
+            end
+        end
+        if bittest(flags,0x0008) then -- f_scale
+            xscale = read2dot14(f)
+            yscale = xscale
+            if f_xyarg and f_offset then
+                xoffset = xoffset * xscale
+                yoffset = yoffset * yscale
+            end
+        elseif bittest(flags,0x0040) then -- f_xyscale
+            xscale = read2dot14(f)
+            yscale = read2dot14(f)
+            if f_xyarg and f_offset then
+                xoffset = xoffset * xscale
+                yoffset = yoffset * yscale
+            end
+        elseif bittest(flags,0x0080) then -- f_matrix
+            xscale  = read2dot14(f)
+            xrotate = read2dot14(f)
+            yrotate = read2dot14(f)
+            yscale  = read2dot14(f)
+            if f_xyarg and f_offset then
+                xoffset = xoffset * sqrt(xscale ^2 + xrotate^2)
+                yoffset = yoffset * sqrt(yrotate^2 + yscale ^2)
+            end
+        end
+        nofcomponents = nofcomponents + 1
+        components[nofcomponents] = {
+            index      = index,
+            usemine    = bittest(flags,0x0200), -- f_usemine
+            round      = bittest(flags,0x0006), -- f_round,
+            base       = base,
+            reference  = reference,
+            matrix     = { xscale, xrotate, yrotate, yscale, xoffset, yoffset },
+        }
+        if bittest(flags,0x0100) then
+            instructions = true
+        end
+        if not bittest(flags,0x0020) then -- f_more
+            break
+        end
+    end
+    return {
+        type         = "composite",
+        components   = components,
+    }
+end
+
+-- function readers.cff(f,offset,glyphs,doshapes) -- false == no shapes (nil or true otherwise)
+
+-- The glyf table depends on the loca table. We have one entry to much
+-- in the locations table (the last one is a dummy) because we need to
+-- calculate the size of a glyph blob from the delta, although we not
+-- need it in our usage (yet). We can remove the locations table when
+-- we're done (todo: cleanup finalizer).
+
+function readers.loca(f,fontdata,specification)
+    if specification.glyphs then
+        local datatable = fontdata.tables.loca
+        if datatable then
+            -- locations are relative to the glypdata table (glyf)
+            local offset    = fontdata.tables.glyf.offset
+            local format    = fontdata.fontheader.indextolocformat
+            local locations = { }
+            setposition(f,datatable.offset)
+            if format == 1 then
+                local nofglyphs = datatable.length/4 - 1
+            -1
+                for i=0,nofglyphs do
+                    locations[i] = offset + readulong(f)
+                end
+                fontdata.nofglyphs = nofglyphs
+            else
+                local nofglyphs = datatable.length/2 - 1
+            -1
+                for i=0,nofglyphs do
+                    locations[i] = offset + readushort(f) * 2
+                end
+                fontdata.nofglyphs = nofglyphs
+            end
+            fontdata.locations = locations
+        end
+    end
+end
+
+function readers.glyf(f,fontdata,specification) -- part goes to cff module
+    if specification.glyphs then
+        local datatable = fontdata.tables.glyf
+        if datatable then
+            local locations = fontdata.locations
+            if locations then
+                local glyphs     = fontdata.glyphs
+                local nofglyphs  = fontdata.nofglyphs
+                local filesize   = fontdata.filesize
+                local nothing    = { 0, 0, 0, 0 }
+                local shapes     = { }
+                local loadshapes = specification.shapes
+                for index=0,nofglyphs do
+                    local location = locations[index]
+                    if location >= filesize then
+                        report("discarding %s glyphs due to glyph location bug",nofglyphs-index+1)
+                        fontdata.nofglyphs = index - 1
+                        fontdata.badfont   = true
+                        break
+                    elseif location > 0 then
+                        setposition(f,location)
+                        local nofcontours = readshort(f)
+                        glyphs[index].boundingbox = {
+                            readshort(f), -- xmin
+                            readshort(f), -- ymin
+                            readshort(f), -- xmax
+                            readshort(f), -- ymax
+                        }
+                        if not loadshapes then
+                            -- save space
+                        elseif nofcontours == 0 then
+                            shapes[index] = readnothing(f,nofcontours)
+                        elseif nofcontours > 0 then
+                            shapes[index] = readglyph(f,nofcontours)
+                        else
+                            shapes[index] = readcomposite(f,nofcontours)
+                        end
+                    else
+                        if loadshapes then
+                            shapes[index] = { }
+                        end
+                        glyphs[index].boundingbox = nothing
+                    end
+                end
+                if loadshapes then
+                    mergecomposites(glyphs,shapes)
+                    contours2outlines(glyphs,shapes)
+                end
+            end
+        end
+    end
+end