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= {project-name}: A native EPUB3 converter for AsciiDoc Dan Allen[@mojavelinux]; Sarah White[@graphitefriction] // Settings: :experimental: :idprefix: :idseparator: - :imagesdir: data/samples/images ifdef::env-github,env-browser[] :toc: preamble :toclevels: 1 endif::[] ifdef::env-github[] :status: :!toc-title: :caution-caption: 🔥 :important-caption: ❗️ :note-caption: 📎 :tip-caption: 💡 :warning-caption: ⚠️ endif::[] ifndef::env-github[] :icons: font endif::[] // Aliases: :project-name: Asciidoctor EPUB3 :project-handle: asciidoctor-epub3 // URIs: :uri-project:{project-handle} :uri-gem: :uri-repo: {uri-project} :uri-issues: {uri-repo}/issues :uri-ci: {uri-repo}/actions?query=branch%3Amaster :uri-discuss: :uri-rvm: :uri-asciidoctor: :uri-idpf: :uri-epub: :uri-epubcheck: :uri-kindlegen: :uri-kf8: :uri-send-to-kindle: :uri-metadata-elem: :uri-dc: :uri-github-guides: :uri-github-guides-fork: :uri-asciidoctor-i18n: :uri-epubreadingsystem: :uri-android-sdk:

ifdef::status[] image:[Latest Release,link={uri-gem}] image:{uri-repo}/workflows/CI/badge.svg?branch=master[GitHub Actions,link={uri-ci}] endif::[]

{project-name} is a set of Asciidoctor extensions for converting AsciiDoc documents directly to the EPUB3 and KF8/MOBI e-book formats.

== Introduction

{project-name} is not merely a converter from AsciiDoc to EPUB3 and KF8/MOBI. Rather, it's a tool for creating highly aesthetic, professional, easy-to-read e-books. Let's face it, many of the technical e-books out there--especially those produced from software documentation--are hideous. {project-name} is on a mission to disrupt the status quo.

ifdef::env-github[] .An excerpt from an e-book produced by {project-name} shown in Day, Night and Sepia mode. image::screenshots/text.png[] endif::[]

=== Project Mission

The {project-name} project aims to produce EPUB3 documents that meet the following objectives:

[itemized,subject-stop=.] Fully Semantic:: Produce deeply semantic XHTML5 documents, including use of the recommended epub:type attribute. Exceptional Readability:: Readers should be drawn into the text so that they read and absorb it. Maximize the readability of the text using carefully crafted styles that are focused on:

  • Custom, readable fonts with strong UTF-8 character support
  • Sufficient line spacing and margins
  • Modular font size scale
  • Subtle, pleasing colors with good contrast
  • A responsive design that scales well from small to large screens
  • Widowed and orphaned content avoided where possible Complete and Accurate Metadata:: Fully populate the EPUB3 package metadata using information in the AsciiDoc source document. Consistent Rendering:: Render consistently across a broad range of EPUB3 (and select EPUB2+) e-readers and respond to any size screen. Polish, Polish, and More Polish:: Add polish to the final product such as font-based icons and callout numbers.

We believe that the e-books produced by {project-name} are the very best output you can expect to find in digital publishing today. Of course, there's always room for improvement, so we'll continue to work with you to achieve and maintain this goal.

=== Notable Features

  • Direct AsciiDoc to EPUB3 conversion
  • Direct AsciiDoc to KF8/MOBI conversion
  • Highly-aesthetic and readable styles with optimized text legibility
  • Respects font settings (if supported by the e-reader) without altering headings, code or icons
  • EPUB3 metadata, manifest and spine (assembled by Gepub)
  • Document metadata (title, authors, subject, keywords, etc.)
  • Internal cross reference links
  • Syntax highlighting with Rouge, CodeRay or Pygments
  • Unicode callout numbers
  • Page breaks avoided in block content (so much as it's supported by the e-reader)
  • Orphan section titles avoided (so much as it's supported by the e-reader)
  • Table border settings honored
  • Support for SVG images in the content
  • Stem blocks via AsciiMath

=== Project Status

CAUTION: {project-name} is currently alpha software. Use accordingly. Although the bulk of AsciiDoc content is converted, there's still work needed to fill in gaps where conversion is incomplete or unstyled.

NOTE: {project-name} only produces variable layout (i.e., reflowable) EPUB3 documents since this layout is best suited for the types of documents typically written in AsciiDoc. We may explore the use of fixed layout documents in the future if the need arises.

ifdef::env-github[] === Planned Features and Work In Progress

See link:WORKLOG.adoc[]. endif::[]

== Converter Workflow

{project-name} takes an aggregate AsciiDoc document and any assets it references as input and produces an EPUB3 publication archive (often described as a “website in a box”).

{project-name} can also produce KF8/MOBI files, the format required for viewing on Amazon Kindle. The conversion to KF8/MOBI is performed by generating a slightly modified EPUB3 publication, then passing it through the {uri-kindlegen}[KindleGen] application. The EPUB3 publication, which can be thought of as the “digital master”, is altered to adhere to certain Amazon Kindle requirements.

== Structuring your Manuscript

An EPUB3 archive is composed of multiple files. The content of each “chapter” is typically stored in a dedicated XHTML file. Therefore, the {project-name} converter “chunks” the AsciiDoc source document into multiple XHTML files to add to the EPUB3 archive. Like other converters, Asciidoctor EPUB3 handles this chunking task by automatically slicing up the XHTML output at predetermined heading levels.

When doctype attribute is set to book, each top-level section will become a separate ebook "chapter" file. This includes preface, bibliography, appendix, etc. This behavior can be configured via epub-chapter-level document attribute.

Otherwise, whole document is converted to a single ebook chapter.

You may specify custom chapter filenames by assigning IDs to sections:


[#custom-chapter-id] = Chapter

Here's an example showing the structure of a book:


= Book Title Author Name :doctype: book :imagesdir: images //...and so on

== Chapter One

Some interesting text here.

== Chapter Two

Even more exciting stuff.

In older Asciidoctor EPUB3 versions, there were strict rules on document organization: 'spine' master document with chapter includes. This is no longer the case. If you followed old rules, chances are your document will work with newer Asciidoctor EPUB3 either as-is or after minor adjustments.

== Prerequisites

All that's needed to use {project-name} is Ruby 2.3 or newer and a few Ruby gems (including at least Asciidoctor 1.5.6), which we'll explain how to install in the next section.

To check if you have Ruby available, use the ruby command to query the installed version:

$ ruby --version

== Getting Started

You can get {project-name} by <<Install the Published Gem,installing the published gem>>. ifndef::env-site[You can also <<Development,run the code from source>> if you want to use the development version or participate in development.]

=== Install the Published Gem

{project-name} is published as a pre-release on You can install the published gem using the following command:

$ NOKOGIRI_USE_SYSTEM_LIBRARIES=1 gem install asciidoctor-epub3 --pre

This optional environment variable tells the gem installer to link against the C libraries on the system, if available, instead of compiling the libraries from scratch. This speeds up the installation of Nokogiri considerably.

If you want to syntax highlight source listings, you'll also want to install Rouge, CodeRay or Pygments. Choose one (or more) of the following:

.Rouge $ gem install rouge

.CodeRay $ gem install coderay

.Pygments $ gem install pygments.rb

You then activate syntax highlighting for a given document by adding the source-highlighter attribute to the document header (Rouge shown):


:source-highlighter: rouge

NOTE: If a style is not specified, the black and white theme (i.e., bw) is used. This default is used so that the syntax highlighting is legible regardless of which reading mode the reader selects (white, black, sepia, etc). To override this default, you must set <highlighter>-style document header attribute to a valid highlighter style name (e.g., :rouge-style: pastie).

Assuming all the required gems install properly, verify you can run the asciidoctor-epub3 script:

$ asciidoctor-epub3 -v

If you see the version of {project-name} printed, you're ready to use {project-name}. Let's get an AsciiDoc document ready to convert to EPUB3.

=== EPUB-related AsciiDoc Attributes

The metadata in the generated EPUB3 file is populated from attributes in the AsciiDoc document. The names of the attributes and the metadata elements to which they map are documented in this section.

The term [term]package metadata in Table 1 is in reference to the {uri-metadata-elem}[ element] in the EPUB3 package document (e.g., [file]package.opf). The dc namespace prefix is in reference to the {uri-dc}[Dublin Core Metadata Element Set].

.AsciiDoc attributes that control the EPUB3 metadata (i.e., package.opf) [cols="1m,3"] |=== |Name |Description

|uuid |Populates the required unique identifier (<dc:identifier>) in the package metadata. An id will be generated automatically from the doctitle if not specified. The recommended practice is to identify the document by means of a string or number conforming to a formal identification system.

|lang |Populates the content language / locale (<dc:language>) in the package metadata.

|scripts |Controls the font subsets that are selected based on the specified scripts (e.g., alphabets). (values: latin, latin-ext, latin-cyrillic or multilingual)

|revdate |Populates the publication date (<dc:date>) in the package metadata. The date should be specified in a parsable format, such as 2014-01-01.

|doctitle |Populates the title (<dc:title>) in the package metadata. The title is added to the metadata in plain text format.

|author |Populates the contributors (<dc:contributor>) in the package metadata. The authors in each chapter document are aggregated together with the authors in the master file.

|username |Used to resolve an avatar for the author that is displayed in the header of a chapter when the doctype is set to a value other than book. The avatar image should be located at the path {imagesdir}/avatars/{username}.jpg, where \{username} is the value of this attribute.

|producer |Populates the publisher (<dc:publisher>) in the package metadata.

|creator |Populates the creator (<dc:creator>) in the package metadata. If the creator is not specified, Asciidoctor is set as the creator with the role "mfr" (an abbreviation for manufacturer).

|description |Populates the description (<dc:description>) in the package metadata.

|keywords |Populates the subjects (i.e., <dc:subject>) in the package metadata. The keywords should be represented as comma-separated values (CSV).

|front-cover-image |Populates the front cover image and the image on the cover page (EPUB3 only) in the package metadata. The image is also added to the e-book archive. The value may be specified as a path or inline image macro. Using the inline image macro is preferred as it allows the height and width to be specified.

|copyright |Populates the rights statement (<dc:rights>) in the package metadata.

|source |Populates the source reference (<dc:source>) in the package metadata. The recommended practice is to identify the referenced resource by means of a string or number conforming to a formal identification system.

|epub-properties |An optional override of the properties attribute for this document's item in the manifest. Only applies to a chapter document.

|epub-chapter-level |Specify the section level at which to split the EPUB into separate "chapter" files. This attribute only affects documents with :doctype: book. The default is to split into chapters at level-1 sections. This attribute only affects the internal composition of the EPUB, not the way chapters and sections are displayed to users. Some readers may be slow if the chapter files are too large, so for large documents with few level-1 headings, one might want to use a chapter level of 2 or 3.

|series-name, series-volume, series-id |Populates the series statements (belongs-to-collection) in the package metadata. Volume is a number, ID probably a UUID that is constant for all volumes in the series.

|epub3-frontmatterdir |The path to a directory that contains frontmatter files. The file names must match front-matter*.html and will be included in alphabetic order. The files are expected to be valid EPUB HTML files. If only one front matter page is required, the default 'front-matter.html' file can be used instead.

|epub3-stylesdir |The path to a directory that contains alternate epub3.css and epub3-css3-only.css files to customize the look and feel.

|doctype |Used to control the inclusion of special content in the generated HTML. If set to a value other than book, the byline information (author and avatar) is included below the chapter header and a typographic end mark is added at the end of the last paragraph. Suggested values include: book (default), article.

|toc |Adds table of contents at the beginning of the book. Depth is controlled by :toclevels: attribute.

|outlinelevels |Sets the depth of table of contents metadata. If not set, defaults to :toclevels: |===

When using the EPUB3 converter, the ebook-format attribute resolves to the name of the e-book format being generated (epub3 or kf8) and the corresponding attribute ebook-format-<name> is defined, where <name> is epub3 or kf8. You can use these attributes in a preprocessor directive if you only want to show certain content to readers using a particular device. For instance, if you want to display a message to readers on Kindle, you can use:


\ifdef::ebook-format-kf8[Hello Kindle reader!]

With that out of the way, it's time to convert the AsciiDoc document directly to EPUB3.

== Performing the Conversion

You can convert AsciiDoc documents to EPUB3 and KF8/MOBI from the commandline using the asciidoctor-epub3 script provided with the {project-name} project.

=== Convert AsciiDoc to EPUB3

Converting an AsciiDoc document to EPUB3 is as simple as passing your document to the asciidoctor-epub3 command. This command should be available on your PATH if you installed the asciidoctor-epub3 gem. Otherwise, you can find the command in the [path]bin folder of the project. We also recommend specifying an output directory using the -D option flag.

$ asciidoctor-epub3 -D output data/samples/sample-book.adoc

When the script completes, you'll see the file [file]sample-book.epub appear in the [path]output directory. Open that file with an EPUB reader (aka e-reader) to view the result.

Below are several screenshots of this sample book as it appears on an Android phone.

.An example of a chapter title and abstract shown side-by-side in Day and Night mode image::screenshots/chapter-title.png[]

.An example of a section title followed by paragraph text separated by a literal block image::screenshots/section-title-paragraph.png[]

.An example of a figure and an admonition image::screenshots/figure-admonition.png[]

.An example of a sidebar image::screenshots/sidebar.png[]

.An example of a table image::screenshots/table.png[]

NOTE: The asciidoctor-epub3 command is a temporary solution for invoking the {project-name} converter. We plan to remove this script once we have completed proper integration with the asciidoctor command.

TIP: As another example, point asciidoctor-epub3 at the {uri-github-guides-fork}[GitHub Guides] that we've ported to AsciiDoc, then compare the output to the real {uri-github-guides}[GitHub Guides].

=== Validate the EPUB3 Archive

Next, let's validate the EPUB3 archive to ensure it built correctly.

.EPUB3 with validation $ asciidoctor-epub3 -D output -a ebook-validate data/samples/sample-book.adoc

.Validation success [.output] .... Validating using EPUB version 3.0.1 rules. No errors or warnings detected. Messages: 0 fatal / 0 errors / 0 warnings / 0 info EPUBCheck completed ....

If the EPUB3 archive contains any errors, they will be output in your terminal.

.EPUB Standard & Validator

The electronic publication (EPUB) standard is developed by the {uri-idpf}[International Digital Publishing Forum (IDPF)]. {uri-epub}[EPUB 3.1], released in January 2017, is the latest version of this standard.

An EPUB3 archive contains:

  • a package document (metadata, file manifest, spine)
  • a navigation document (table of contents)
  • one or more content documents
  • assets (images, fonts, stylesheets, etc.)

The IDPF also supports {uri-epubcheck}[EPUBCheck]. EPUBCheck parses and validates the file against the EPUB schema.

If you want to browse the contents of the EPUB3 file that is generated, or preview the XHTML files in a regular web browser, add the -a ebook-extract flag to the asciidoctor-epub3 command. The EPUB3 file will be extracted to a directory adjacent to the generated file, but without the file extension.

$ asciidoctor-epub3 -D output -a ebook-extract data/samples/sample-book.adoc

In this example, the contents of the EPUB3 will be extracted to the [path]output/sample-book directory.

=== Convert AsciiDoc to KF8/MOBI

Creating a KF8/MOBI archive directly from an AsciiDoc document is done with the same generation script (asciidoctor-epub3). You just need to specify the format (-a ebook-format) as kf8.

$ asciidoctor-epub3 -D output -a ebook-format=kf8 data/samples/sample-book.adoc

When the script completes, you'll see the file [file] as well as [file]sample-book-kf8.epub (the precursor) appear in the [path]output directory.

KindleGen does mandatory validation so you don't need to run the validate command after converting to KF8/MOBI.

.What is KF8?

Kindle Format 8 (KF8) is Amazon's next generation file format offering a wide range of new features and enhancements--including HTML5 and CSS3 support--that publishers can use to create a broad range of books. The format is close enough to EPUB3 that it's safe to think of it simply as an EPUB3 implementation under most circumstances. You can read more about the format on the {uri-kf8}[Kindle Format 8 page].

Amazon continues to use the .mobi file extension for KF8 archives, despite the fact that they've switched from the Mobipocket format to the EPUB3-like KF8 format. That's why we refer to the format in this project as KF8/MOBI.

=== Tuning Listing Captions

Unlike the built-in converters, the EPUB3 converter is configured to add a signifier (e.g., Listing) at the start the caption for all listing and source blocks that have a title. This behavior is triggered because the listing-caption attribute is set by default.

If you don't want the signifier to be included at the beginning of the caption on listing and source blocks, simply unset the listing-caption when invoking Asciidoctor EPUB3.

$ asciidoctor-epub3 -a listing-caption! book.adoc

Now the behavior will match that of the built-in converters. For more information about this attribute and other related attributes, see {uri-asciidoctor-i18n}[internationalization and numbering].

=== Command Arguments

-h, --help :: Show the usage message

-D, --destination-dir :: Writes files to specified directory (defaults to the current directory)

-a ebook-epubcheck-path=:: Specifies path to EPUBCheck executable to use with -a ebook-validate. This attribute takes precedence over EPUBCHECK environment variable.

-a ebook-extract :: Extracts the EPUB3 to a folder in the destination directory after the file is generated

-a ebook-format= :: Specifies the ebook format to generate (epub3 or kf8, default: epub3)

-a ebook-kindlegen-path=:: Specifies path to KindleGen executable to use when producing KF8/Mobi. This attribute takes precedence over KINDLEGEN environment variable.

-a ebook-validate :: Runs {uri-epubcheck}[EPUBCheck] to validate output file against the EPUB3 specification

-a ebook-compress=<0|1|2|none|standard|huffdic> :: Controls the compression type used by kindlegen (0=none [default if unset], 1=standard [default if empty], 2=huffdic)

-v, --version :: Display the program version

=== Environment variables

EPUBCHECK:: Specifies path to EPUBCheck executable to use with -a ebook-validate. Effect of this variable can be overriden with -a ebook-epubcheck-path attribute.

KINDLEGEN:: Specifies path to KindleGen executable to use when producing KF8/Mobi. Effect of this variable can be overriden with -a ebook-kindlegen-path attribute.

=== EPUB3 Archive Structure

Here's a sample manifest of files found in an EPUB3 document produced by {project-name}.

.... META-INF/ container.xml EPUB/ fonts/ awesome/ fa-solid-900.ttf font-icons.ttf mplus-1mn-latin-bold.ttf mplus-1mn-latin-light.ttf mplus-1mn-latin-medium.ttf mplus-1mn-latin-regular.ttf mplus-1p-latin-bold.ttf mplus-1p-latin-light.ttf mplus-1p-latin-regular.ttf noto-serif-bold-italic.ttf noto-serif-bold.ttf noto-serif-italic.ttf noto-serif-regular.ttf images/ avatars/ default.png figure-01.png figure-02.png styles/ epub3-css3-only.css epub3.css chapter-01.xhtml chapter-02.xhtml ... cover.xhtml nav.xhtml package.opf toc.ncx mimetype ....

== Working with Images

Images referenced in your AsciiDoc document must be stored in the images catalog. The images catalog is defined by the imagesdir attribute. If set, the value of this attribute is resolved relative to the document and must be at or below (i.e., within) the directory of that document. (In other words, it cannot point to a location outside the document directory). If this attribute is not set, the images catalog defaults to the directory of the document. {project-name} will discover all local image references and insert those images into the EPUB3 archive at the same relative path.

=== Default Images

The sample book contains placeholder image for an author avatar.

// TODO explain the avatar and book cover images

=== Adding the Cover Image

Ereaders have different image resolution and file size limits regarding a book's cover. Kindle covers tend to be 1050x1600 (16:9 resolution). To ensure your cover displays correctly, you'll want to review the documentation or publisher guidelines for the e-reading platform you're targeting.

WARNING: We've found that if the book cover is more than 1600px on any side, Aldiko will not render it and may even crash.

Feel free to use the SVG of the sample cover in the [path]data/images folder as a template for creating your own cover. Once your image is ready, you can set the cover image by defining the front-cover-image attribute in the header of the master document.


:front-cover-image: image:cover.png[Front Cover,1050,1600]

The image is resolved relative to the directory specified in the imagesdir attribute, which defaults to the directory of the3 document. The image can be in any format, though we recommend using PNG, JPG, or SVG as they are the most portable formats.

IMPORTANT: You should always specify the dimensions of the cover image. This ensures the viewer will preserve the aspect ratio if it needs to be scaled to fit the screen. If you don't specify a width and height, then the dimensions are assumed to be 1050x1600.

=== How to Organize Images by Chapter

You can set the imagesdir attribute per chapter (as long as the attribute is not overridden by the API). To do so, use an attribute entry to set the value of the imagesdir attribute on the line above the include directive for a chapter.


:imagesdir: chapter-one/images \include::chapter-one.adoc[]

:imagesdir: chapter-two/images \include::chapter-two.adoc[]

== About the Theme

EPUB3 and KF8/MOBI files are styled using CSS3. However, each e-reading platform honors a reduced set of CSS3 styles, and the styles they allow and how they implement them are rarely documented. All we've got to say is thank goodness for CSS hacks, media queries and years of CSS experience!

The theme provided with {project-name} has been crafted to display EPUB3 and KF8/MOBI files as consistently as possible across the most common EPUB3 platforms and to degrade gracefully in select EPUB2 platforms. The theme maintains readability regardless of the reading mode (i.e., day, night or sepia) or the display device's pixel density and screen resolution.

The theme's CSS files are located in the [path]data/style directory.

IMPORTANT: {project-name} only provides one theme, and, at this time, you can not replace it with a custom theme using the stylesheet attribute. However, you can use your own [path]epub3.css and [path]epub3-css3-only.css files by specifying the directory where they are located using the epub3-stylesdir attribute.

=== Fonts

{project-name} embeds a set of fonts and font icons. The theme's fonts are located in the [path]data/fonts directory.

The M+ Outline fonts are used for titles, headings, literal (monospace) text, and annotation numbers. The body text uses Noto Serif. Admonition icons and the end-of-chapter mark are from the Font Awesome icon font. Refer to the link:NOTICE.adoc[] file for further information about the fonts.

// TODO document command to generate the M+ 1p latin fonts

=== Device-specific Styles

For readers that support JavaScript, {project-name} adds a CSS class to the body element of each chapter that corresponds to the name of the reader as reported by the {uri-epubreadingsystem}[epubReadingSystem] JavaScript object. This enhancement allows you to use styles targeted specifically at that reader.

Below you can find the readers that are known to support this feature and the CSS class name that gets added to the body element.

,=== Reader,HTML Element,CSS Class Name

Gitden,body,gitden-reader Namo PubTreeViewer,body,namo-epub-library Readium,body,readium-js-viewer iBooks,body,ibooks Adobe RMSDK >= 11,body,rmsdk Google Books,div,gb-reader-container ,===

NOTE: Kobo does not support the epubReadingSystem JavaScript object, despite the fact that it does support JavaScript.

== Pushing to Android

While it's certainly possible to view the EPUB3 on your desktop/laptop, you'll probably want to test it where it's most likely going to be read--on a reading device such as a smartphone or a tablet. Assuming you have an Android device available, transferring the EPUB3 to the device is easy once you get a bit of setup out of the way.

You transfer files from your computer to an Android phone over a USB connection using a command from the Android SDK Tools called adb. Follow these steps to get it setup:

. Download the Android SDK Tools zip from the table labeled SDK Tools Only on the {uri-android-sdk}[Get the Android SDK] page . Extract the archive . Locate the path to the adb command (Hint: Look in the platform-tools folder) . Set the environment variable named ADB to the path of the adb command

$ export ADB=~/apps/android-sdk/platform-tools/adb

Now you can use the adb-push-ebook script provided by {project-name} to push the EPUB3 and KF8/MOBI files to your Android device.

.Publish both EPUB3 and KF8 files to Android device $ adb-push-ebook output/sample-book

IMPORTANT: Don't include the file extension since the script will check for both the .epub and .mobi files.

The adb-push-ebook script copies the files to the following locations on the device:

,=== File type,Destination on Android device

*.epub,/sdcard/ *.mobi,/sdcard/Android/data/ ,===

Amazon Kindle should immediately detect the new file and display it in your “On Device” library. You'll have to manually import the EPUB3 into your e-reader of choice.

== E-book Reader Recommendations and Quirks

EPUB3 e-readers will provide the best reading experience when viewing the book generated by {project-name}. Here's a list of some of the e-readers we know to have good EPUB3 support and the systems on which they run:

IMPORTANT: To get the full experience, ensure that the e-reader is configured to use the publisher's styles. Different e-readers word this setting in different ways. Look for the option screen that allows you to set the fonts and font colors and disable it. With publisher's styles active, you'll still be able to adjust the relative size of the fonts and margins and toggle between day, night and sepia mode.

When the book is viewed in EPUB2 e-readers and Kindle apps/devices which have reached their end-of-life (EOL), the e-book relies on the strong semantics of the HTML and some fallback styles to render properly. EPUB2 e-readers, such as Aldiko, don't understand CSS3 styles and therefore miss out on some of subtleties in the formatting.

As mentioned in the <<About the Theme,theme section>>, the stylesheet attempts to provide as consistent a reading experience as possible in the common EPUB3 e-readers, despite the different CSS implementation rules and limitations unique to each e-book application. Most of these obstacles were addressed using media queries or explicit classes. Some we haven't conquered. Yet.

The <<kindle-quirks,Kindle quirks list>> shows you just a few of the constraints we encountered. To see all of the workarounds and why we chose certain style options, check out the code and comments in the [file]epub3.css and [file]epub3-css-only.css files.

// TODO add[Namo PubTreeViewer] (iOS, Android & Windows) and[Kobo] (iOS, Android, OSX & Windows)

[#kindle-quirks] .Kindle Quirks

  • overrules margins and line heights like a medieval tyrant
  • font-family can't be set on <body>
  • requires !important on text-decoration
  • position: relative isn't permitted
  • strips (or unwraps) <header> tags
  • @page isn't supported
  • page-break: avoid isn't supported
  • page-break-* cannot be applied using a compound or nested CSS selector; must be a simple ID or class
  • max-width isn't supported
  • widows are left in the cold
  • won't style footers without an explicit class
  • -webkit-hyphens: auto causes Kindle for Mac (and perhaps others) to crash
  • text-rendering: optimizeLegibility causes file to be rejected by KFP (and causes the text to disappear in some previewers)
  • Kindle Direct Publishing (KDP) strips out select font-related CSS rules (e.g., font-family) under certain conditions (for reasons that have proved nearly impossible to reverse engineer); the known workaround is to add a layer of indirection by using @import to hide the CSS files from the script

=== Kindle Direct Publishing

If you want to publish your book to the Amazon Kindle store, and have your styles and fonts preserved, you must use[Kindle Direct Publishing]. No other method of publishing to the Amazon Kindle store will leave your book intact.

This workflow also allows you to preview the book the way your readers will see it. So it's a good way to acceptance test your custom styles to discover which ones are honored and which ones are ignored.

==== Look Inside

The Amazon Kindle store offers a “Look Inside” feature for reader. This so-called feature aims to gives readers a glimpse at the contents of the book. Sadly, it does no such thing. Instead, it shows pages from the legacy MOBI document that kindlegen adds to your e-book file, not the higher fidelity KF8 document. This means the preview won't look at all like what the Kindle reader or application will actually show. Custom fonts, font-based icons, and most styles will be missing.

This situation is unfortunate for authors. What we recommend is to complain loudly to Amazon that they are hurting your sales by displaying a crippled version of your product. Tell them that under no circumstances should they show an altered version of your product. Another option is to contact Amazon to opt-out of this program.

=== Send to Kindle

WARNING: Don't use it!

{uri-send-to-kindle}[Send to Kindle] is a tempting choice for transferring MOBI files to a Kindle device. However, it's utterly broken. If you use this tool, don't be surprised if you see missing font-based icons, default fonts, and other font and style errors in your manuscript. It's known to strip out all the font files and break the encoding of the document.

We strongly recommend you transfer the file to your device using either a USB cable or a sync service such as Dropbox. Once transferred, Whispersync will detect the new file (usually looking in the Books folder) and add it to the “On Device” library.

It's important to note that “Send to Kindle” is not reflective of the experience readers will have when shopping in the Kindle store. If you use Kindle Direct Publishing (KDP) to publish your book, the integrity of your book will be preserved (to the degree that Amazon allows).

//// head-stop (default '.') stack-head role (run-in is default) signature role (sets hardbreaks option)

subject-stop (default ':') ////

//// == Device and Application Testing

{project-name} has been tested on the following devices and applications.

.Computers |=== |Device |OS |Resolution |ppi |Browsers |Readium |Gitden |Kindle

|Asus |Fedora 17 |no x no | |Chrome x |Readium

Asus, Fedora 20, display resolution, Chrome x, Readium Ideapad Y460 |Fedora 20 |1366 x 768 (16:9) | PC, Windows X, |===

.Tablets |=== Asus Transformer, Android x, display resolution, Aldiko, Kindle, Readium, Readmill Nexus, |===

.Phones |=== HTC Sensation, Android x, display resolution, xxxx Nexus , |===


ifndef::env-site[] == Contributing

In the spirit of free software, everyone is encouraged to help improve this project.

To contribute code, simply fork the project on GitHub, hack away and send a pull request with your proposed changes.

Feel free to use the {uri-issues}[issue tracker] or {uri-discuss}[Asciidoctor mailing list] to provide feedback or suggestions in other ways.

== Development

To help develop {project-name}, or to simply test drive the development version, you need to get the source from GitHub. Follow the instructions below to learn how to clone the source and run it from your local copy.

=== Retrieve the Source Code

You can retrieve {project-name} in one of two ways:

. Clone the git repository . Download a zip archive of the repository

==== Option 1: Fetch Using git clone

If you want to clone the git repository, simply copy the {uri-repo}[GitHub repository URL] and pass it to the git clone command:

[subs=attributes+] $ git clone {uri-repo}

Next, change to the project directory:

[subs=attributes+] $ cd {project-handle}

==== Option 2: Download the Archive

If you want to download a zip archive, click on the btn:[icon:cloud-download[] Download Zip] button on the right-hand side of the repository page on GitHub. Once the download finishes, extract the archive, open a console and change to that directory.

TIP: Instead of working out of the {project-handle} directory, you can simply add the absolute path of the [path]bin directory to your PATH environment variable.

We'll leverage the project configuration to install the necessary dependencies.

=== Prepare RVM (optional step)

If you're using {uri-rvm}[RVM], we recommend creating a new gemset to work with {project-name}:

$ rvm use [email protected] --create

We like RVM because it keeps the dependencies required by various projects isolated.

=== Install the Dependencies

The dependencies needed to use {project-name} are defined in the [file]Gemfile at the root of the project. We can use Bundler to install the dependencies for us.

To check if you have Bundler available, use the bundle command to query the version installed:

$ bundle --version

If it's not installed, use the gem command to install it.

$ gem install bundler

Then use the bundle command to install the project dependencies:

$ bundle

NOTE: You need to call bundle from the project directory so that it can find the [file]Gemfile.

=== Build and Install the Gem

Now that the dependencies are installed, you can build and install the gem.

Use the Rake build tool to build and install the gem (into the current RVM gemset or into the system if not using RVM):

$ rake install:local

The build will report that it built the gem into the [path]pkg directory and that it installed the gem.

Once the development version of the gem is installed, you can run {project-name} by invoking the asciidoctor-epub3 script:

$ asciidoctor-epub3 -v

If you see the version of {project-name} printed to your console, you're ready to use {project-name}!

=== Shortcut: Run the Launch Script Directly

Assuming all the required gems install properly, you can run the asciidoctor-epub3 script directly out of the project folder using either:

$ bin/asciidoctor-epub3 -v


$ bundle exec bin/asciidoctor-epub3 -v

You're now ready to test drive the development version of {project-name}!

Jump back to <> to learn how to create an AsciiDoc document and convert it to EPUB3. endif::[]

== Authors

{project-name} was written by[Dan Allen] and[Sarah White] of OpenDevise on behalf of the Asciidoctor Project.

== Copyright

Copyright (C) 2014-2019 OpenDevise Inc. and the Asciidoctor Project. Free use of this software is granted under the terms of the MIT License.

For the full text of the license, see the link:LICENSE[] file. Refer to the link:NOTICE.adoc[] file for information about third-party Open Source software in use.

//// == Additional Points of Note

  • uppercase chapter titles to work around line-height limitation in Kindle (1.4 minimum)
  • using vw units crashes Aldiko
  • circled numbers from M+ 1mn for annotation numbers in listing blocks
  • avatars for authors
  • document command to generate the M+ 1p latin fonts
  • recommended e-readers (Readium, Gitden, Kindle, etc) ////

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