Module: HtmlToPlainText

Included in:
Premailer
Defined in:
lib/premailer/html_to_plain_text.rb

Overview

Support functions for Premailer

Instance Method Summary collapse

Instance Method Details

#convert_to_text(html, line_length = 65, from_charset = 'UTF-8') ⇒ Object

Returns the text in UTF-8 format with all HTML tags removed

TODO:

- add support for DL, OL



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# File 'lib/premailer/html_to_plain_text.rb', line 11

def convert_to_text(html, line_length = 65, from_charset = 'UTF-8')
  r = Text::Reform.new(:trim => true, 
                       :squeeze => false, 
                       :break => Text::Reform.break_wrap)

  txt = html
  
  # decode HTML entities
  he = HTMLEntities.new
  txt = he.decode(txt)

  # handle headings (H1-H6)
  txt.gsub!(/(<\/h[1-6]>)/i, "\n\\1") # move closing tags to new lines
  txt.gsub!(/[\s]*<h([1-6]+)[^>]*>[\s]*(.*)[\s]*<\/h[1-6]+>/i) do |s|
    hlevel = $1.to_i

    htext = $2      
    htext.gsub!(/<br[\s]*\/?>/i, "\n") # handle <br>s
    htext.gsub!(/<\/?[^>]*>/i, '') # strip tags

    # determine maximum line length
    hlength = 0
    htext.each { |l| llength = l.strip.length; hlength = llength if llength > hlength }
    hlength = line_length if hlength > line_length

    case hlevel
      when 1   # H1, asterisks above and below
        htext = ('*' * hlength) + "\n" + htext + "\n" + ('*' * hlength)
      when 2   # H1, dashes above and below
        htext = ('-' * hlength) + "\n" + htext + "\n" + ('-' * hlength)
      else     # H3-H6, dashes below
        htext = htext + "\n" + ('-' * hlength)
    end
    
    "\n\n" + htext + "\n\n"
  end

  # links
  txt.gsub!(/<a.*href=\"([^\"]*)\"[^>]*>(.*)<\/a>/i) do |s|
    $2.strip + ' ( ' + $1.strip + ' )'
  end

  # lists -- TODO: should handle ordered lists
  txt.gsub!(/[\s]*(<li[^>]*>)[\s]*/i, '* ')
  # list not followed by a newline
  txt.gsub!(/<\/li>[\s]*(?![\n])/i, "\n")
  
  # paragraphs and line breaks
  txt.gsub!(/<\/p>/i, "\n\n")
  txt.gsub!(/<br[\/ ]*>/i, "\n")
  
  # strip remaining tags
  txt.gsub!(/<\/?[^>]*>/, '')

  # wrap text
  txt = r.format(('[' * line_length), txt)
  
  # remove linefeeds (\r\n and \r -> \n)
  txt.gsub!(/\r\n?/, "\n")
  
  # strip extra spaces
  txt.gsub!(/\302\240+/, " ") # non-breaking spaces -> spaces
  txt.gsub!(/\n[ \t]+/, "\n") # space at start of lines
  txt.gsub!(/[ \t]+\n/, "\n") # space at end of lines

  # no more than two consecutive newlines
  txt.gsub!(/[\n]{3,}/, "\n\n")

  txt.strip
end