CSS::Inliner(3p)

NAME
CSS::Inliner - Library for converting CSS <style> blocks to inline styles.

SYNOPSIS
use CSS::Inliner;

my $inliner = new CSS::Inliner();

$inliner->read_file({ filename => 'myfile.html' });

print $inliner->inlinify();

DESCRIPTION
Library for converting CSS style blocks into inline styles in an HTML document. Specifically this is intended for the ease of generating HTML emails. This is useful as certain email clients don't support top level <style> declarations despite it being 2017.

NOTE: The development of the this module is currently suspended as the sponsoring entity, MailerMailer LLC, has been sold to j2 Global.

METHODS

  new
Instantiates the Inliner object. Sets up class variables that are used during file parsing/processing. Possible options are:

html_tree - (optional) Pass in a fresh unparsed instance of HTML::Treebuilder

NOTE: Any passed references to HTML::TreeBuilder will be substantially altered by passing it in here...

strip_attrs - (optional) Remove all "id" and "class" attributes during inlining

leave_style - (optional) Leave style/link tags alone within <head> during inlining

relaxed - (optional) Relaxed HTML parsing which will attempt to interpret non-HTML4 documents.

encode_entities - (optional) Encode generated inline-styles (in case they contain HTML meta characters)

ignore_style_type_attr - (optional) Ignore the deprecated type attribute of "style" tag

NOTE: This argument is not compatible with passing an html_tree.

agent - (optional) Pass in a string containing a preferred user-agent, overrides the internal default provided by the module for handling remote documents

  fetch_file
Fetches a remote HTML file that supposedly contains both HTML and a style declaration, properly tags the data with the proper charset as provided by the remote webserver (if any). Subsequently calls the read method automatically.

This method expands all relative urls, as well as fully expands the stylesheet reference within the document.

This method requires you to pass in a params hash that contains a url argument for the requested document. For example:

$self->fetch_file({ url => 'http://www.example.com' });

Note that you can specify a user-agent to override the default user-agent of 'Mozilla/4.0' within the constructor. Doing so may avoid certain issues with agent filtering related to quirky webserver configs.

Input Parameters:
 url - the desired url for a remote asset presumably containing both html and css
 charset - (optional) programmer specified charset for the pass url

  read_file
Opens and reads an HTML file that supposedly contains both HTML and a style declaration, properly tags the data with the proper charset if specified. It subsequently calls the read() method automatically.

This method requires you to pass in a params hash that contains a filename argument. For example:

$self->read_file({ filename => 'myfile.html' });

Additionally you can specify the character encoding within the file, for example:

$self->read_file({ filename => 'myfile.html', charset => 'utf8' });

Input Parameters:
 filename - name of local file presumably containing both html and css
 charset - (optional) programmer specified charset of the passed file

  read
Reads passed html data and parses it. The intermediate data is stored in class variables.

The <style> block is ripped out of the html here, and stored separately. Class/ID/Names used in the markup are left alone.

This method requires you to pass in a params hash that contains scalar html data. For example:

$self->read({ html => $html });

NOTE: You are required to pass a properly encoded perl reference to the html data. This method does *not* do the dirty work of encoding the html as utf8 - do that before calling this method.

Input Parameters:
 html - scalar presumably containing both html and css
 charset - (optional) scalar representing the original charset of the passed html

  detect_charset
Detect the charset of the passed content.

The algorithm present here is roughly based off of the HTML5 W3C working group document, which lays out a recommendation for determining the character set of a received document, which can be seen here under the "determining the character encoding" section: http://www.w3.org/TR/html5/syntax.html

NOTE: In the event that no charset can be identified the library will handle the content as a mix of UTF-8/CP-1252/8859-1/ASCII by attempting to use the Encoding::FixLatin module, as this combination is relatively common in the wild. Finally, if Encoding::FixLatin is unavailable the content will be treated as ASCII.

Input Parameters:
 content - scalar presumably containing both html and css
 charset - (optional) programmer specified charset for the passed content
 ctcharset - (optional) content-type specified charset for content retrieved via a url

  decode_characters
Implement the character decoding algorithm for HTML as outlined by the various working groups

Basically apply best practices for determining the applied character encoding and properly decode it

It is expected that this method will be called before any calls to read()

Input Parameters:
 content - scalar presumably containing both html and css
 charset - known charset for the passed content

  inlinify
Processes the html data that was entered through either 'read' or 'read_file', returns a scalar that contains a composite chunk of html that has inline styles instead of a top level <style> declaration.

  query
Given a particular selector return back the applicable styles

  specificity
Given a particular selector return back the associated selectivity

  content_warnings
Return back any warnings thrown while inlining a given block of content.

Note: content warnings are initialized at inlining time, not at read time. In order to receive back content feedback you must perform inlinify first

AUTHOR
 Kevin Kamel <kamelkev@underprint.com>

CONTRIBUTORS
 Dave Gray <cpan@doesntsuck.com>
 Vivek Khera <vivek@khera.org>
 Michael Peters <wonko@cpan.org>
 Chelsea Rio <chelseario@gmail.com>

LICENSE
This module is Copyright 2017 Khera Communications, Inc. It is licensed under the same terms as Perl itself.