pdfkit/lib/font.coffee
2011-07-11 10:52:49 -04:00

140 lines
4.3 KiB
CoffeeScript

###
PDFFont - embeds fonts in PDF documents
By Devon Govett
###
TTFFont = require './font/ttf'
AFMFont = require './font/afm'
zlib = require 'zlib'
class PDFFont
constructor: (@document, @filename, @family, @id) ->
if @filename in @_standardFonts
@embedStandard()
else if /\.(ttf|ttc)$/i.test @filename
@ttf = TTFFont.open @filename, @family
@embedTTF()
else if /\.dfont$/i.test @filename
@ttf = TTFFont.fromDFont @filename, @family
@embedTTF()
else
throw new Error 'Not a supported font format or standard PDF font.'
embedTTF: ->
@scaleFactor = 1000.0 / @ttf.head.unitsPerEm
@bbox = (Math.round e * @scaleFactor for e in @ttf.bbox)
@basename = @ttf.name.postscriptName
@stemV = 0 # not sure how to compute this for true-type fonts...
if @ttf.post.exists
raw = @ttf.post.italic_angle
hi = raw >> 16
low = raw & 0xFF
hi = -((hi ^ 0xFFFF) + 1) if hi & 0x8000 isnt 0
@italicAngle = +"#{hi}.#{low}"
else
@italicAngle = 0
@ascender = Math.round @ttf.ascender * @scaleFactor
@decender = Math.round @ttf.decender * @scaleFactor
@lineGap = Math.round @ttf.lineGap * @scaleFactor
@capHeight = (@ttf.os2.exists and @ttf.os2.capHeight) or @ascender
@xHeight = (@ttf.os2.exists and @ttf.os2.xHeight) or 0
@familyClass = (@ttf.os2.exists and @ttf.os2.familyClass or 0) >> 8
@isSerif = @familyClass in [1,2,3,4,5,7]
@isScript = @familyClass is 10
@flags = 0
@flags |= 1 << 0 if @ttf.post.isFixedPitch
@flags |= 1 << 1 if @isSerif
@flags |= 1 << 3 if @isScript
@flags |= 1 << 6 if @italicAngle isnt 0
@flags |= 1 << 5 # assume the font is nonsymbolic...
@cmap = @ttf.cmap.unicode
throw new Error 'No unicode cmap for font' if not @cmap
@hmtx = @ttf.hmtx
@charWidths = (Math.round @hmtx.widths[gid] * @scaleFactor for i, gid of @cmap.codeMap when i >= 32)
data = @ttf.rawData
compressedData = zlib.deflate(data)
@fontfile = @document.ref
Length: compressedData.length
Length1: data.length
Filter: 'FlateDecode'
@fontfile.add compressedData
@descriptor = @document.ref
Type: 'FontDescriptor'
FontName: @basename
FontFile2: @fontfile
FontBBox: @bbox
Flags: @flags
StemV: @stemV
ItalicAngle: @italicAngle
Ascent: @ascender
Descent: @decender
CapHeight: @capHeight
XHeight: @xHeight
@ref = @document.ref
Type: 'Font'
BaseFont: @basename
Subtype: 'TrueType'
FontDescriptor: @descriptor
FirstChar: 32
LastChar: 255
Widths: @document.ref @charWidths
Encoding: 'MacRomanEncoding'
embedStandard: ->
@isAFM = true
font = AFMFont.open __dirname + "/font/data/#{@filename}.afm"
{@ascender,@decender,@bbox,@lineGap,@charWidths} = font
@ref = @document.ref
Type: 'Font'
BaseFont: @filename
Subtype: 'Type1'
_standardFonts: [
"Courier"
"Courier-Bold"
"Courier-Oblique"
"Courier-BoldOblique"
"Helvetica"
"Helvetica-Bold"
"Helvetica-Oblique"
"Helvetica-BoldOblique"
"Times-Roman"
"Times-Bold"
"Times-Italic"
"Times-BoldItalic"
"Symbol"
"ZapfDingbats"
]
widthOfString: (string, size) ->
string = '' + string
width = 0
for i in [0...string.length]
charCode = string.charCodeAt(i) - if @isAFM then 0 else 32
width += @charWidths[charCode] or 0
scale = size / 1000
return width * scale
lineHeight: (size, includeGap = false) ->
gap = if includeGap then @lineGap else 0
(@ascender + gap - @decender) / 1000 * size
module.exports = PDFFont