Class: Prawn::Font::Metrics::Adobe

Inherits:
Prawn::Font::Metrics show all
Defined in:
lib/prawn/font/metrics.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Prawn::Font::Metrics

[], data, #font_height, #string_height

Methods included from Wrapping

#naive_wrap

Constructor Details

#initialize(font_name) ⇒ Adobe

Returns a new instance of Adobe.



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# File 'lib/prawn/font/metrics.rb', line 40

def initialize(font_name)            
  @attributes     = {}   
  @glyph_widths   = {}
  @bounding_boxes = {}
  @kern_pairs     = {}
  
  file = font_name.sub(/\.afm$/,'') + '.afm'
  unless file[0..0] == "/"
     file = find_font(file)
  end    
                   
  parse_afm(file)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *args, &block) ⇒ Object

Hackish, but does the trick for now.



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# File 'lib/prawn/font/metrics.rb', line 132

def method_missing(method, *args, &block)
  name = method.to_s.delete("_")
  @attributes.include?(name) ? @attributes[name] : super
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Returns the value of attribute attributes.



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# File 'lib/prawn/font/metrics.rb', line 38

def attributes
  @attributes
end

Instance Method Details

#ascender ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 119

def ascender
  @attributes["ascender"].to_i
end

#bbox ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 54

def bbox
  fontbbox.split(/\s+/).map { |e| Integer(e) }
end

#convert_text(text, options = {}) ⇒ Object

perform any changes to the string that need to happen before it is rendered to the canvas

String must be encoded as WinAnsi



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# File 'lib/prawn/font/metrics.rb', line 162

def convert_text(text, options={})
  options[:kerning] ? kern(text) : text
end

#descender ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 123

def descender
  @attributes["descender"].to_i 
end

#has_kerning_data? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/font/metrics.rb', line 149

def has_kerning_data?
  true
end

#kern(string) ⇒ Object

converts a string into an array with spacing offsets bewteen characters that need to be kerned

String must be encoded as WinAnsi



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# File 'lib/prawn/font/metrics.rb', line 85

def kern(string) 
  kerned = string.unpack("C*").inject([]) do |a,r|
    if a.last.is_a? Array
      if k = latin_kern_pairs_table[[a.last.last, r]]
        a << k << [r]
      else
        a.last << r
      end
    else
      a << [r]
    end
    a
  end            
  
  kerned.map { |r| 
    i = r.is_a?(Array) ? r.pack("C*") : r 
    i.force_encoding("ISO-8859-1") if i.respond_to?(:force_encoding)
    i.is_a?(Numeric) ? -i : i
  }                        
end

#latin_glyphs_table ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 113

def latin_glyphs_table
  @glyphs_table ||= (0..255).map do |i|
    @glyph_widths[Encoding::WinAnsi::CHARACTERS[i]].to_i
  end 
end

#latin_kern_pairs_table ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 106

def latin_kern_pairs_table   
  @kern_pairs_table ||= @kern_pairs.inject({}) do |h,p|
    h[p[0].map { |n| Encoding::WinAnsi::CHARACTERS.index(n) }] = p[1]
    h
  end
end

#line_gap ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 127

def line_gap    
  Float(bbox[3] - bbox[1]) - (ascender - descender)
end

#metrics_path ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 137

def metrics_path
  if m = ENV['METRICS']
    @metrics_path ||= m.split(':')
  else 
    @metrics_path ||= [
      ".", "/usr/lib/afm",
      "/usr/local/lib/afm",
      "/usr/openwin/lib/fonts/afm/", 
       Prawn::BASEDIR+'/data/fonts/'] 
  end
end

#string_width(string, font_size, options = {}) ⇒ Object

calculates the width of the supplied string.

String must be encoded as WinAnsi



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# File 'lib/prawn/font/metrics.rb', line 62

def string_width(string, font_size, options = {}) 
  scale = font_size / 1000.0
  
  if options[:kerning]
    kern(string).inject(0) do |s,r|   
      if r.is_a? String
        s + string_width(r, font_size, :kerning => false)
      else 
        s - (r * scale)
      end
    end
  else
    string.unpack("C*").inject(0) do |s,r|
      s + latin_glyphs_table[r]
    end * scale
  end
end

#type0? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/font/metrics.rb', line 153

def type0?
  false
end