class PDF::Reader::FontDescriptor

Font descriptors are outlined in Section 9.8, PDF 32000-1:2008, pp 281-288

Attributes

ascent[R]

: Numeric

avg_width[R]

: Numeric

cap_height[R]

: Numeric

descent[R]

: Numeric

font_bounding_box[R]

: Array

font_family[R]

: String?

font_flags[R]

: Integer

font_name[R]

: String

font_stretch[R]

: Symbol

font_weight[R]

: Numeric

italic_angle[R]

: Numeric?

leading[R]

: Numeric

max_width[R]

: Numeric

missing_width[R]

: Numeric

stem_v[R]

: Numeric?

x_height[R]

: Numeric?

Public Class Methods

new(ohash, fd_hash) click to toggle source

: (PDF::Reader::ObjectHash, Hash[untyped, untyped]) -> void

# File lib/pdf/reader/font_descriptor.rb, line 61
def initialize(ohash, fd_hash)
  # TODO change these to typed derefs
  @ascent                = ohash.deref_number(fd_hash[:Ascent])    || 0 #: Numeric
  @descent               = ohash.deref_number(fd_hash[:Descent])   || 0 #: Numeric
  @missing_width         = ohash.deref_number(fd_hash[:MissingWidth]) || 0 #: Numeric
  @font_bounding_box     = ohash.deref_array_of_numbers(
    fd_hash[:FontBBox]
  ) || [0,0,0,0] #: Array[Numeric]
  @avg_width             = ohash.deref_number(fd_hash[:AvgWidth])  || 0 #: Numeric
  @cap_height            = ohash.deref_number(fd_hash[:CapHeight]) || 0 #: Numeric
  @font_flags            = ohash.deref_integer(fd_hash[:Flags])     || 0 #: Integer
  @italic_angle          = ohash.deref_number(fd_hash[:ItalicAngle]) #: Numeric?
  @font_name             = ohash.deref_name(fd_hash[:FontName]).to_s #: String
  @leading               = ohash.deref_number(fd_hash[:Leading])   || 0 #: Numeric
  @max_width             = ohash.deref_number(fd_hash[:MaxWidth])  || 0 #: Numeric
  @stem_v                = ohash.deref_number(fd_hash[:StemV]) #: Numeric?
  @x_height              = ohash.deref_number(fd_hash[:XHeight]) #: Numeric?
  @font_stretch          = ohash.deref_name(fd_hash[:FontStretch]) || :Normal #: Symbol
  @font_weight           = ohash.deref_number(fd_hash[:FontWeight])  || 400 #: Numeric
  @font_family           = ohash.deref_string(fd_hash[:FontFamily]) #: String?

  # A FontDescriptor may have an embedded font program in FontFile
  # (Type 1 Font Program), FontFile2 (TrueType font program), or
  # FontFile3 (Other font program as defined by Subtype entry)
  # Subtype entries:
  # 1) Type1C:        Type 1 Font Program in Compact Font Format
  # 2) CIDFontType0C: Type 0 Font Program in Compact Font Format
  # 3) OpenType:      OpenType Font Program
  # see Section 9.9, PDF 32000-1:2008, pp 288-292
  @font_program_stream = ohash.deref_stream(fd_hash[:FontFile2]) #: PDF::Reader::Stream?
  #TODO handle FontFile and FontFile3
  @ttf_program_stream = nil #: TTFunk::File?

  @is_ttf = @font_program_stream ? true : false #: bool
  @glyph_to_pdf_sf = nil #: Numeric?
end

Public Instance Methods

glyph_to_pdf_scale_factor() click to toggle source
PDF states that a glyph is 1000 units wide, true type doesn't enforce
any behavior, but uses units/em to define how wide the 'M' is (the widest letter)

: () -> Numeric

# File lib/pdf/reader/font_descriptor.rb, line 118
def glyph_to_pdf_scale_factor
  if @is_ttf
    @glyph_to_pdf_sf ||= (1.0 / ttf_program_stream.header.units_per_em) * 1000.0
  else
    @glyph_to_pdf_sf ||= 1.0
  end
  @glyph_to_pdf_sf
end
glyph_width(char_code) click to toggle source

: (Integer) -> Numeric

# File lib/pdf/reader/font_descriptor.rb, line 99
def glyph_width(char_code)
  if @is_ttf
    if ttf_program_stream.cmap.unicode.length > 0
      glyph_id = ttf_program_stream.cmap.unicode.first[char_code]
    else
      glyph_id = char_code
    end
    char_metric = ttf_program_stream.horizontal_metrics.metrics[glyph_id]
    if char_metric
      char_metric.advance_width
    else
      0
    end
  end
end

Private Instance Methods

ttf_program_stream() click to toggle source

: () -> TTFunk::File

# File lib/pdf/reader/font_descriptor.rb, line 130
def ttf_program_stream
  raise MalformedPDFError, "No font_program_stream" unless @font_program_stream

  @ttf_program_stream ||= TTFunk::File.new(@font_program_stream.unfiltered_data)
end