Beware: GLOBALS!

At the moment, the layout/conversion engine makes use of several global variables:

• $g_config array (in particular, $g_config['renderforms'], $g_config['renderlinks'], $g_config['renderimages'], $g_config['debugbox'], $g_config['mode'], $g_config['cssmedia'] and $g_config['draw_page_border'] elements for all output methods and $g_config['ps2pdf'] and $g_config['transparency_workaround'] for 'fastps' output method.
• $g_px_scale
• $g_pt_scale

Also, there's some global items script initializes itself:

• $g_box_uid
• $g_colors
• $__g_css_manager
• $__g_css_handler_set
• $g_encoding_aliases
• $g_frame_level
• $g_font_resolver
• $g_font_resolver_pdf
• $g_html_entities
• $g_image_cache
• $g_last_assigned_font_id
• $g_manager_encodings
• $g_media
• $g_predefined_media
• $g_stylesheet_title
• $g_tag_attrs
• $g_unicode_glyphs
• $g_utf8_converters

Conversion pipeline

class PipelineFactory {
  function create_default_pipeline();
}

class Pipeline {
  var $fetchers;
  var $data_filters;
  var $parser;
  var $pre_tree_filters;
  var $layout_engine;
  var $post_tree_filters;
  var $output_driver;
  var $output_filter;
  var $destination;

  function Pipeline();

  function configure($options);
  function process($data_id, &$media);
  function process_batch($data_id_array, &$media);
  function error_message();

  function &get_dispatcher();
}

Description of interfaces and classes

get_data($data_id)

Fetches the URL and returns page content and supplementary information.

• $data_id – URI identifying the page location

get_base_url()

Returns URL to be used as the base url when resolving relative links

process($data)

Processes the FetchedData object and returns another FetchedData object with (probably) modified content

• $data – FetchedData object

process($data)

Processes the FetchedData object and returns the document tree (somewhat similar to DOM) object.

• $data – FetchedData object

process($data)

Make some modifications in document tree (in-place) before the layout engine have been run.

• $data – Document tree object

process($data)

Runs the layout process (document tree object is modified in-place).

• $data – Document tree object

process($data)

Apply some changes to document tree (in-place) after the layout engine have been run.

• $data – document tree object

Implementing your own fetcher class

Sometimes you may need to convert HTML code taken from database or from other non-standard sources. In this case you should implement Fetcher interface yourself, returning the string to be converted from the get_data method. Additional parameters (like database connection settings, template variables, etc) may be specified either as globals (not recommended, though), passed as a parameters to constructor of fetcher object or as $dataId parameter of get_data method.

Keep in mind that if you're including files from your HTML code (e.g. stylesheets or images), you should either return null from your fetcher for URL of these files, or handle them yourself. Unless you do it, these files will not be available.

class MyFetcherLocalFile extends Fetcher {
  var $_content;

  function MyFetcherLocalFile($file) {
    $this->_content = file_get_contents($file);
  }

  function get_data($dummy1) {
    return new FetchedDataURL($this->_content, array(), "");
  }

  function get_base_url() {
    return "";
  }
}

Class dependencies

• one or more objects implementing Fetcher interface;
• zero or more objects implementing DataFilter interface;
• one object implementing Parser interface;
• zero or more objects implementing PreTreeFilter interface;
• one object implementing LayoutEngine interface;
• zero or more objects implementing PostTreeFilter interface;
• one object implementing OutputDriver interface;
• one object implementing Destination interface;