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.



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# File 'lib/pdf/reader/font_descriptor.rb', line 17

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

  # 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])
  #TODO handle FontFile and FontFile3

  @is_ttf = true if @font_program_stream
end

Instance Attribute Details

#ascent ⇒ Object (readonly)

Returns the value of attribute ascent.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def ascent
  @ascent
end

#avg_width ⇒ Object (readonly)

Returns the value of attribute avg_width.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def avg_width
  @avg_width
end

#cap_height ⇒ Object (readonly)

Returns the value of attribute cap_height.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def cap_height
  @cap_height
end

#descent ⇒ Object (readonly)

Returns the value of attribute descent.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def descent
  @descent
end

#font_bounding_box ⇒ Object (readonly)

Returns the value of attribute font_bounding_box.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_bounding_box
  @font_bounding_box
end

#font_family ⇒ Object (readonly)

Returns the value of attribute font_family.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_family
  @font_family
end

#font_flags ⇒ Object (readonly)

Returns the value of attribute font_flags.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_flags
  @font_flags
end

#font_name ⇒ Object (readonly)

Returns the value of attribute font_name.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_name
  @font_name
end

#font_stretch ⇒ Object (readonly)

Returns the value of attribute font_stretch.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_stretch
  @font_stretch
end

#font_weight ⇒ Object (readonly)

Returns the value of attribute font_weight.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def font_weight
  @font_weight
end

#italic_angle ⇒ Object (readonly)

Returns the value of attribute italic_angle.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def italic_angle
  @italic_angle
end

#leading ⇒ Object (readonly)

Returns the value of attribute leading.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def leading
  @leading
end

#max_width ⇒ Object (readonly)

Returns the value of attribute max_width.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def max_width
  @max_width
end

#missing_width ⇒ Object (readonly)

Returns the value of attribute missing_width.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def missing_width
  @missing_width
end

#stem_v ⇒ Object (readonly)

Returns the value of attribute stem_v.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

def stem_v
  @stem_v
end

#x_height ⇒ Object (readonly)

Returns the value of attribute x_height.



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# File 'lib/pdf/reader/font_descriptor.rb', line 12

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)



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# File 'lib/pdf/reader/font_descriptor.rb', line 68

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 



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# File 'lib/pdf/reader/font_descriptor.rb', line 50

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