Class: PDF::Reader::FontDescriptor

Inherits:
Object
  • Object
show all
Defined in:
lib/pdf/reader/font_descriptor.rb

Overview

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ohash, fd_hash) ⇒ FontDescriptor

Returns a new instance of FontDescriptor.

Signature:

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



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# 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

Instance Attribute Details

#ascent ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 31

def ascent
  @ascent
end

#avg_width ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 40

def avg_width
  @avg_width
end

#cap_height ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 28

def cap_height
  @cap_height
end

#descent ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 34

def descent
  @descent
end

#font_bounding_box ⇒ Object (readonly)

Signature:

  • Array[Numeric]



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# File 'lib/pdf/reader/font_descriptor.rb', line 25

def font_bounding_box
  @font_bounding_box
end

#font_family ⇒ Object (readonly)

Signature:

  • String?



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# File 'lib/pdf/reader/font_descriptor.rb', line 16

def font_family
  @font_family
end

#font_flags ⇒ Object (readonly)

Signature:

  • Integer



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# File 'lib/pdf/reader/font_descriptor.rb', line 58

def font_flags
  @font_flags
end

#font_name ⇒ Object (readonly)

Signature:

  • String



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# File 'lib/pdf/reader/font_descriptor.rb', line 13

def font_name
  @font_name
end

#font_stretch ⇒ Object (readonly)

Signature:

  • Symbol



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# File 'lib/pdf/reader/font_descriptor.rb', line 19

def font_stretch
  @font_stretch
end

#font_weight ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 22

def font_weight
  @font_weight
end

#italic_angle ⇒ Object (readonly)

Signature:

  • Numeric?



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# File 'lib/pdf/reader/font_descriptor.rb', line 49

def italic_angle
  @italic_angle
end

#leading ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 37

def leading
  @leading
end

#max_width ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 43

def max_width
  @max_width
end

#missing_width ⇒ Object (readonly)

Signature:

  • Numeric



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# File 'lib/pdf/reader/font_descriptor.rb', line 46

def missing_width
  @missing_width
end

#stem_v ⇒ Object (readonly)

Signature:

  • Numeric?



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# File 'lib/pdf/reader/font_descriptor.rb', line 52

def stem_v
  @stem_v
end

#x_height ⇒ Object (readonly)

Signature:

  • Numeric?



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# File 'lib/pdf/reader/font_descriptor.rb', line 55

def x_height
  @x_height
end

Instance Method Details

#glyph_to_pdf_scale_factor ⇒ Object

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)

Signature:

  • () -> Numeric



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# 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) ⇒ Object

Signature:

  • (Integer) -> Numeric



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# 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