Class: Softcover::Builders::Epub

Inherits:
Softcover::Builder show all
Includes:
Output
Defined in:
lib/softcover/builders/epub.rb

Constant Summary

Constants included from Utils

Utils::UNITS

Instance Attribute Summary

Attributes inherited from Softcover::Builder

#built_files, #manifest

Instance Method Summary collapse

Methods included from Output

should_output?, silence!, silent?, #system, unsilence!

Methods inherited from Softcover::Builder

#clean!, #initialize

Methods included from Utils

#add_highlight_class!, #as_size, #book_txt_lines, #chapter_label, #commands, #current_book, #dependency_filename, #digest, #executable, #execute, #in_book_directory?, #language_labels, #linux?, #logged_in?, #master_content, #master_filename, #master_latex_header, #mkdir, #os_x?, #path, #raw_lines, #reset_current_book!, #rm, #silence, #source, #tmpify, #unpublish_slug, #write_master_latex_file, #write_pygments_file

Constructor Details

This class inherits a constructor from Softcover::Builder

Instance Method Details

#build!(options = {}) ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 6

def build!(options={})
  @preview = options[:preview]
  Softcover::Builders::Html.new.build!
  if manifest.markdown?
    self.manifest = Softcover::BookManifest.new(source: :polytex,
                                                origin: :markdown)
  end
  remove_html
  create_directories
  write_mimetype
  write_container_xml
  write_toc
  write_nav
  copy_image_files
  write_html(options)
  write_contents
  create_style_files
  make_epub(options)
  move_epub
end

#chapter_name(n) ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 396

def chapter_name(n)
  n == 0 ? language_labels["frontmatter"] : chapter_label(n)
end

#chapter_template(title, content) ⇒ Object

Returns the HTML template for a chapter.



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# File 'lib/softcover/builders/epub.rb', line 425

def chapter_template(title, content)
  %(<?xml version="1.0" encoding="utf-8"?>
  <!DOCTYPE html>

  <html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>#{title}</title>
    <link rel="stylesheet" href="styles/pygments.css" type="text/css" />
    <link rel="stylesheet" href="styles/softcover.css" type="text/css" />
    <link rel="stylesheet" href="styles/epub.css" type="text/css" />
    <link rel="stylesheet" href="styles/custom.css" type="text/css"/>
    <link rel="stylesheet" href="styles/custom_epub.css" type="text/css"/>
    <link rel="stylesheet" type="application/vnd.adobe-page-template+xml" href="styles/page-template.xpgt" />
  </head>

  <body>
    #{content}
  </body>
  </html>)
end

#chapters ⇒ Object

Returns the chapters to write (accounting for previews).



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# File 'lib/softcover/builders/epub.rb', line 65

def chapters
  preview? ? manifest.preview_chapters : manifest.chapters
end

#clean_book_id(filename) ⇒ Object

Removes the ‘#book’ CSS id. For some reason, EPUB books hate the #book ids in the stylesheet (i.e., such books fail to validate), so remove them.



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# File 'lib/softcover/builders/epub.rb', line 229

def clean_book_id(filename)
  File.read(filename).gsub(/#book/, '')
end

#container_xml ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 282

def container_xml
%(<?xml version="1.0"?>
<container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">
    <rootfiles>
  <rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/>
   </rootfiles>
</container>)
end

#content_opf ⇒ Object

Returns the content configuration file.



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# File 'lib/softcover/builders/epub.rb', line 292

def content_opf
  title  = manifest.title
  author = manifest.author
  copyright = manifest.copyright
  uuid = manifest.uuid
  man_ch = chapters.map do |chapter|
             %(<item id="#{chapter.slug}" href="#{chapter.fragment_name}" media-type="application/xhtml+xml"/>)
           end
  toc_ch = chapters.map do |chapter|
             %(<itemref idref="#{chapter.slug}"/>)
           end
  image_files = Dir['epub/OEBPS/images/**/*'].select { |f| File.file?(f) }
  images = image_files.map do |image|
             ext = File.extname(image).sub('.', '')   # e.g., 'png'
             # Strip off the leading 'epub/OEBPS'.
             sep  = File::SEPARATOR
             href = image.split(sep)[2..-1].join(sep)
             # Define an id based on the filename.
             # Prefix with 'img-' in case the filname starts with an
             # invalid character such as a number.
             label = File.basename(image).gsub('.', '-')
             id = "img-#{label}"
             %(<item id="#{id}" href="#{href}" media-type="image/#{ext}"/>)
           end
%(<?xml version="1.0" encoding="UTF-8"?>
  <package unique-identifier="BookID" version="3.0" xmlns="http://www.idpf.org/2007/opf">
    <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/"
  xmlns:opf="http://www.idpf.org/2007/opf">
  <dc:title>#{title}</dc:title>
  <dc:language>en</dc:language>
  <dc:rights>Copyright (c) #{copyright} #{author}</dc:rights>
  <dc:creator>#{author}</dc:creator>
  <dc:publisher>Softcover</dc:publisher>
  <dc:identifier id="BookID">urn:uuid:#{uuid}</dc:identifier>
  <meta property="dcterms:modified">#{Time.now.strftime('%Y-%m-%dT%H:%M:%S')}Z</meta>
  <meta name="cover" content="img-cover-png"/>
    </metadata>
    <manifest>
  <item href="nav.html" id="nav" media-type="application/xhtml+xml" properties="nav"/>
  <item id="ncx" href="toc.ncx" media-type="application/x-dtbncx+xml"/>
  <item id="page-template.xpgt" href="styles/page-template.xpgt" media-type="application/vnd.adobe-page-template+xml"/>
  <item id="pygments.css" href="styles/pygments.css" media-type="text/css"/>
  <item id="softcover.css" href="styles/softcover.css" media-type="text/css"/>
  <item id="epub.css" href="styles/epub.css" media-type="text/css"/>
  <item id="custom.css" href="styles/custom.css" media-type="text/css"/>
  <item id="custom_epub.css" href="styles/custom_epub.css" media-type="text/css"/>
  <item id="cover" href="cover.html" media-type="application/xhtml+xml"/>
  #{man_ch.join("\n")}
  #{images.join("\n")}
    </manifest>
    <spine toc="ncx">
<itemref idref="cover" linear="no" />
#{toc_ch.join("\n")}
    </spine>
  </package>
)
end

#copy_image_files ⇒ Object

Copies the image files from the HTML version of the document. We remove PDF images, which are valid in PDF documents but not in EPUB.



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# File 'lib/softcover/builders/epub.rb', line 235

def copy_image_files
  FileUtils.cp_r(File.join('html', 'images'),
                 File.join('epub', 'OEBPS'))
  File.delete(*Dir['epub/OEBPS/images/**/*.pdf'])
end

#cover_page ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 350

def cover_page
%(<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Cover</title>
</head>
<body>
  <div id="cover">
     <img width="573" height="800" src="images/cover.png" alt="cover image" />
  </div>
</body>
</html>
)
end

#create_directories ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 38

def create_directories
  mkdir('epub')
  mkdir(path('epub/OEBPS'))
  mkdir(path('epub/OEBPS/styles'))
  mkdir(path('epub/META-INF'))
  mkdir('ebooks')
end

#create_style_files ⇒ Object 



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# File 'lib/softcover/builders/epub.rb', line 208

def create_style_files
  html_styles = File.join('html', 'stylesheets')
  epub_styles = File.join('epub', 'OEBPS', 'styles')

  FileUtils.cp(File.join(html_styles, 'pygments.css'), epub_styles)
  File.write(File.join(epub_styles, 'softcover.css'),
             clean_book_id(path("#{html_styles}/softcover.css")))

  # Copy over the EPUB-specific CSS.
  template_dir = File.join(File.dirname(__FILE__), '..', 'template')
  epub_css     = File.join(template_dir, epub_styles, 'epub.css')
  FileUtils.cp(epub_css, epub_styles)

  # Copy over custom CSS.
  File.write(File.join(epub_styles, 'custom.css'),
             clean_book_id(path("#{html_styles}/custom.css")))
end

#html_with_math(chapter, images_dir, texmath_dir, pngs, options = {}) ⇒ Object

Returns HTML for HTML source that includes math. As a side-effect, html_with_math creates PNGs corresponding to any math in the given source. The technique involves using PhantomJS to hit the HTML source for each page containing math to create SVGs for every math element. Since ereader support for SVGs is spotty, they are then converted to PNGs using Inkscape. The filenames are SHAs of their contents, which arranges both for unique filenames and for automatic disk caching.



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# File 'lib/softcover/builders/epub.rb', line 115

def html_with_math(chapter, images_dir, texmath_dir, pngs, options={})
  content = File.read(File.join("html", "#{chapter.slug}.html"))
  pagejs = "#{File.dirname(__FILE__)}/utils/page.js"
  url = "file://#{Dir.pwd}/html/#{chapter.slug}.html"
  cmd = "#{phantomjs} #{pagejs} #{url}"
  silence { silence_stream(STDERR) { system cmd } }
  # Sometimes in tests the phantomjs_source.html file is missing.
  # It shouldn't ever happen, but it does no harm to skip it.
  return nil unless File.exist?('phantomjs_source.html')
  raw_source = File.read('phantomjs_source.html')
  source = strip_attributes(Nokogiri::HTML(raw_source))
  rm 'phantomjs_source.html'
  # Remove the first body div, which is the hidden MathJax SVGs.
  if (mathjax_svgs = source.at_css('body div'))
    mathjax_svgs.remove
  else
    # There's not actually any math, so return nil.
    return nil
  end
  # Remove all the unneeded raw TeX displays.
  source.css('script').each(&:remove)
  # Remove all the MathJax preview spans.
  source.css('MathJax_Preview').each(&:remove)

  # Suck out all the SVGs
  svgs   = source.css('div#book svg')
  frames = source.css('span.MathJax_SVG')
  svgs.zip(frames).each do |svg, frame|
    # Save the SVG file.
    svg['viewBox'] = svg['viewbox']
    svg.remove_attribute('viewbox')
    first_child = frame.children.first
    first_child.replace(svg) unless svg == first_child
    output = svg.to_xhtml
    svg_filename = File.join(texmath_dir, "#{digest(output)}.svg")
    File.write(svg_filename, output)
    # Convert to PNG.
    png_filename = svg_filename.sub('.svg', '.png')
    pngs << png_filename
    unless File.exist?(png_filename)
      unless options[:silent] || options[:quiet]
        puts "Creating #{png_filename}"
      end
      svg_height = svg['style'].scan(/height: (.*?);/).flatten.first
      scale_factor = 8   # This scale factor turns out to look good.
      h = scale_factor * svg_height.to_f
      cmd = "#{inkscape} -f #{svg_filename} -e #{png_filename} -h #{h}pt"
      if options[:silent]
        silence { silence_stream(STDERR) { system cmd } }
      else
        silence_stream(STDERR) { system cmd }
      end
    end
    rm svg_filename
    png = Nokogiri::XML::Node.new('img', source)
    png['src'] = File.join('images', 'texmath',
                           File.basename(png_filename))
    png['alt'] = png_filename.sub('.png', '')
    svg.replace(png)
  end
  source.at_css('div#book').children.to_xhtml
end

#inkscape ⇒ Object

Returns the Inkscape executable (if available).



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# File 'lib/softcover/builders/epub.rb', line 184

def inkscape
  @inkscape ||= executable(dependency_filename(:inkscape))
end

#make_epub(options = {}) ⇒ Object

Make the EPUB, which is basically just a zipped HTML file.



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# File 'lib/softcover/builders/epub.rb', line 242

def make_epub(options={})
  filename = manifest.filename
  zip_filename = filename + '.zip'
  base_file = "zip -X0    #{zip_filename} mimetype"
  zip = "zip -rDXg9"
  meta_info = "#{zip} #{zip_filename} META-INF -x \*.DS_Store -x mimetype"
  main_info = "#{zip} #{zip_filename} OEBPS    -x \*.DS_Store \*.gitkeep"
  rename = "mv #{zip_filename} #{filename}.epub"
  commands = [base_file, meta_info, main_info, rename]
  command = commands.join(' && ')
  Dir.chdir('epub') do
    if Softcover.test? || options[:quiet] || options[:silent]
      silence { system(command) }
    else
      system(command)
    end
  end
end

#math?(string) ⇒ Boolean

Returns true if a string appears to have LaTeX math. We detect math via opening math commands: (, [, and beginequation This gives a false positive when math is included in verbatim environments and nowhere else, but it does little harm (requiring only an unnecessary call to page.js).

Returns:

  • (Boolean) 


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# File 'lib/softcover/builders/epub.rb', line 204

def math?(string)
  !!string.match(/(?:\\\(|\\\[|\\begin{equation})/)
end

#move_epub ⇒ Object

Move the completed EPUB book to the ‘ebooks` directory. Note that we handle the case of a preview book as well.



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# File 'lib/softcover/builders/epub.rb', line 263

def move_epub
  origin = manifest.filename
  target = preview? ? origin + '-preview' : origin
  FileUtils.mv(File.join('epub',   "#{origin}.epub"),
               File.join('ebooks', "#{target}.epub"))
end

#nav_html ⇒ Object

Returns the nav HTML content.



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# File 'lib/softcover/builders/epub.rb', line 401

def nav_html
  title = manifest.title
  nav_list = manifest.chapters.map do |chapter|
               %(<li><a href="#{chapter.fragment_name}">#{chapter.title}</a></li>)
             end
%(<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
    <head>
  <meta charset="UTF-8" />
  <title>#{title}</title>
    </head>
    <body>
  <nav epub:type="toc">
      <h1>#{title}</h1>
      <ol>
        #{nav_list.join("\n")}
      </ol>
  </nav>
    </body>
</html>
)
end

#phantomjs ⇒ Object

Returns the PhantomJS executable (if available).



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# File 'lib/softcover/builders/epub.rb', line 179

def phantomjs
  @phantomjs ||= executable(dependency_filename(:phantomjs))
end

#preview? ⇒ Boolean

Returns true if generating a book preview.

Returns:

  • (Boolean) 


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# File 'lib/softcover/builders/epub.rb', line 28

def preview?
  !!@preview
end

#remove_html ⇒ Object

Removes HTML. All the HTML is generated, so this clears out any unused files.



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# File 'lib/softcover/builders/epub.rb', line 34

def remove_html
  FileUtils.rm(Dir.glob(path('epub/OEBPS/*.html')))
end

#strip_attributes(doc) ⇒ Object

Strip attributes that are invalid in EPUB documents.



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# File 'lib/softcover/builders/epub.rb', line 189

def strip_attributes(doc)
  attrs = %w[data-tralics-id data-label data-number data-chapter
             role aria-readonly]
  doc.tap do
    attrs.each do |attr|
      doc.xpath("//@#{attr}").remove
    end
  end
end

#toc_ncx ⇒ Object

Returns the Table of Contents for the spine.



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# File 'lib/softcover/builders/epub.rb', line 367

def toc_ncx
  title = manifest.title
  chapter_nav = []
  offset = preview? ? manifest.preview_chapter_range.first : 0
  chapters.each_with_index do |chapter, i|
    n = i + offset
    chapter_nav << %(<navPoint id="#{chapter.slug}" playOrder="#{n+1}">)
    chapter_nav << %(    <navLabel><text>#{chapter_name(n)}</text></navLabel>)
    chapter_nav << %(    <content src="#{chapter.fragment_name}"/>)
    chapter_nav << %(</navPoint>)
  end
%(<?xml version="1.0" encoding="UTF-8"?>
<ncx xmlns="http://www.daisy.org/z3986/2005/ncx/" version="2005-1">
    <head>
  <meta name="dtb:uid" content="#{manifest.uuid}"/>
  <meta name="dtb:depth" content="2"/>
  <meta name="dtb:totalPageCount" content="0"/>
  <meta name="dtb:maxPageNumber" content="0"/>
    </head>
    <docTitle>
  <text>#{title}</text>
    </docTitle>
    <navMap>
#{chapter_nav.join("\n")}
    </navMap>
</ncx>
)
end

#write_container_xml ⇒ Object

Writes the container XML file. This is required by the EPUB standard.



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# File 'lib/softcover/builders/epub.rb', line 54

def write_container_xml
  File.write(path('epub/META-INF/container.xml'), container_xml)
end

#write_contents ⇒ Object

Writes the content.opf file. This is required by the EPUB standard.



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# File 'lib/softcover/builders/epub.rb', line 60

def write_contents
  File.write(path('epub/OEBPS/content.opf'), content_opf)
end

#write_html(options = {}) ⇒ Object

Writes the HTML for the EPUB. Included is a math detector that processes the page with MathJax (via page.js) so that math can be included in EPUB (and thence MOBI).



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# File 'lib/softcover/builders/epub.rb', line 72

def write_html(options={})
  images_dir  = File.join('epub', 'OEBPS', 'images')
  texmath_dir = File.join(images_dir, 'texmath')
  mkdir images_dir
  mkdir texmath_dir

  File.write(path('epub/OEBPS/cover.html'), cover_page)

  pngs = []
  chapters.each_with_index do |chapter, i|
    target_filename = path("epub/OEBPS/#{chapter.fragment_name}")
    File.open(target_filename, 'w') do |f|
      content = File.read(path("html/#{chapter.fragment_name}"))
      doc = strip_attributes(Nokogiri::HTML(content))
      inner_html = doc.at_css('body').children.to_xhtml
      if math?(inner_html)
        html = html_with_math(chapter, images_dir, texmath_dir, pngs,
                              options)
        html ||= inner_html # handle case of spurious math detection
      else
        html = inner_html
      end
      f.write(chapter_template("Chapter #{i}", html))
    end
  end
  # Clean up unused PNGs.
  png_files = Dir[path("#{texmath_dir}/*.png")]
  (png_files - pngs).each do |f|
    if File.exist?(f)
      puts "Removing unused PNG #{f}" unless options[:silent]
      FileUtils.rm(f)
    end
  end
end

#write_mimetype ⇒ Object

Writes the mimetype file. This is required by the EPUB standard.



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# File 'lib/softcover/builders/epub.rb', line 48

def write_mimetype
  File.write(path('epub/mimetype'), 'application/epub+zip')
end

#write_nav ⇒ Object

Writes the navigation file. This is required by the EPUB standard.



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# File 'lib/softcover/builders/epub.rb', line 278

def write_nav
  File.write('epub/OEBPS/nav.html', nav_html)
end

#write_toc ⇒ Object

Writes the Table of Contents. This is required by the EPUB standard.



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# File 'lib/softcover/builders/epub.rb', line 272

def write_toc
  File.write('epub/OEBPS/toc.ncx', toc_ncx)
end