stylesheet.cls.php

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<?php
/**
 * DOMPDF - PHP5 HTML to PDF renderer
 *
 * File: $RCSfile: stylesheet.cls.php,v $
 * Created on: 2004-06-01
 *
 * Copyright (c) 2004 - Benj Carson <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library in the file LICENSE.LGPL; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 * 02111-1307 USA
 *
 * Alternatively, you may distribute this software under the terms of the
 * PHP License, version 3.0 or later.  A copy of this license should have
 * been distributed with this file in the file LICENSE.PHP .  If this is not
 * the case, you can obtain a copy at http://www.php.net/license/3_0.txt.
 *
 * The latest version of DOMPDF might be available at:
 * http://www.digitaljunkies.ca/dompdf
 *
 * @link http://www.digitaljunkies.ca/dompdf
 * @copyright 2004 Benj Carson
 * @author Benj Carson <[e-mail]>
 * @package dompdf
 * @version 0.5.1
 */

/* $Id: stylesheet.cls.php,v 1.2 2006/07/21 10:46:20 mschering Exp $ */

/**
 * The location of the default built-in CSS file.
 * {@link Stylesheet::DEFAULT_STYLESHEET}
 */
define('__DEFAULT_STYLESHEET', DOMPDF_LIB_DIR . DIRECTORY_SEPARATOR . "res" . DIRECTORY_SEPARATOR . "html.css");

/**
 * The master stylesheet class
 *
 * The Stylesheet class is responsible for parsing stylesheets and style
 * tags/attributes.  It also acts as a registry of the individual Style
 * objects generated by the current set of loaded CSS files and style
 * elements.
 *
 * @see Style
 * @package dompdf
 */
class Stylesheet {
  
  

  /**
   * the location of the default built-in CSS file.
   * 
   */
  const DEFAULT_STYLESHEET = __DEFAULT_STYLESHEET; // Hack: can't
                                                   // concatenate stuff in
                                                   // const declarations,
                                                   // but I can do this?
  // protected members

  /**
   *  array of currently defined styles
   *  @var array
   */
  private $_styles;

  /**
   * base protocol of the document being parsed
   *
   * Used to handle relative urls.
   *
   * @var string 
   */
  private $_protocol;

  /**
   * base hostname of the document being parsed
   *
   * Used to handle relative urls.
   * @var string
   */
  private $_base_host;

  /**
   * base path of the document being parsed
   *
   * Used to handle relative urls.
   * @var string
   */
  private $_base_path;

  
  /**
   * the style defined by @page rules 
   *
   * @var Style
   */
  private $_page_style;


  /**
   * list of loaded files, used to prevent recursion
   *
   * @var array
   */
  private $_loaded_files;
  
  /**
   * accepted CSS media types 
   */
  static $ACCEPTED_MEDIA_TYPES = array("all", "static", "visual",
                                       "bitmap", "paged", "print");
  
  /**
   * The class constructor.
   *
   * The base protocol, host & path are initialized to those of
   * the current script.
   */
  function __construct() {
    $this->_styles = array();
    $this->_loaded_files = array();
    list($this->_protocol, $this->_base_host, $this->_base_path) = explode_url($_SERVER["SCRIPT_FILENAME"]);
    $this->_page_style = null;
  }

  /**
   * Set the base protocol
   *
   * @param string $proto
   */
  function set_protocol($proto) { $this->_protocol = $proto; }

  /**
   * Set the base host
   *
   * @param string $host
   */
  function set_host($host) { $this->_base_host = $host; }

  /**
   * Set the base path
   *
   * @param string $path
   */
  function set_base_path($path) { $this->_base_path = $path; }


  /**
   * Return the base protocol for this stylesheet
   *
   * @return string
   */
  function get_protocol() { return $this->_protocol; }

  /**
   * Return the base host for this stylesheet
   *
   * @return string
   */
  function get_host() { return $this->_base_host; }

  /**
   * Return the base path for this stylesheet
   *
   * @return string
   */
  function get_base_path() { return $this->_base_path; }
  
  /**
   * add a new Style object to the stylesheet
   *
   * add_style() adds a new Style object to the current stylesheet, or
   * merges a new Style with an existing one.
   *
   * @param string $key   the Style's selector
   * @param Style $style  the Style to be added
   */
  function add_style($key, Style $style) {
    if (!is_string($key))
      throw new DOMPDF_Exception("CSS rule must be keyed by a string.");

    if ( isset($this->_styles[$key]) )
      $this->_styles[$key]->merge($style);
    else
      $this->_styles[$key] = clone $style;
  }


  /**
   * lookup a specifc Style object
   *
   * lookup() returns the Style specified by $key, or null if the Style is
   * not found.
   *
   * @param string $key   the selector of the requested Style
   * @return Style
   */
  function lookup($key) {
    if ( !isset($this->_styles[$key]) )
      return null;
    
    return $this->_styles[$key];
  }

  /**
   * create a new Style object associated with this stylesheet
   *
   * @param Style $parent The style of this style's parent in the DOM tree
   * @return Style
   */
  function create_style($parent = null) {
    return new Style($this, $parent);
  }
  

  /**
   * load and parse a CSS string
   *
   * @param string $css
   */
  function load_css(&$css) { $this->_parse_css($css); }


  /**
   * load and parse a CSS file
   *
   * @param string $file
   */
  function load_css_file($file) {
    global $_dompdf_warnings;
    
    // Prevent circular references
    if ( isset($this->_loaded_files[$file]) )
      return;

    $this->_loaded_files[$file] = true;
    $parsed_url = explode_url($file);

    list($this->_protocol, $this->_base_host, $this->_base_path, $filename) = $parsed_url;
    
    if ( !DOMPDF_ENABLE_REMOTE &&
         ($this->_protocol != "" && $this->_protocol != "file://") ) {
      record_warnings(E_USER_WARNING, "Remote CSS file '$file' requested, but DOMPDF_ENABLE_REMOTE is false.", __FILE__, __LINE__);
      return; 
    }
    
    // Fix submitted by Nick Oostveen for aliased directory support:
    if ( $this->_protocol == "" )
      $file = $this->_base_path . $filename;
    else
      $file = build_url($this->_protocol, $this->_base_host, $this->_base_path, $filename);
    
    set_error_handler("record_warnings");
    $css = file_get_contents($file);
    restore_error_handler();

    if ( $css == "" ) {
      record_warnings(E_USER_WARNING, "Unable to load css file $file", __FILE__, __LINE__);;
      return;
    }
    
    $this->_parse_css($css);

  }

  /**
   * @link http://www.w3.org/TR/CSS21/cascade.html#specificity}
   *
   * @param string $selector
   * @return int
   */
  private function _specificity($selector) {
    // http://www.w3.org/TR/CSS21/cascade.html#specificity

    $a = ($selector === "!style attribute") ? 1 : 0;
    
    $b = min(mb_substr_count($selector, "#"), 255);

    $c = min(mb_substr_count($selector, ".") +
             mb_substr_count($selector, ">") +
             mb_substr_count($selector, "+"), 255);
    
    $d = min(mb_substr_count($selector, " "), 255);

    return ($a << 24) | ($b << 16) | ($c << 8) | ($d);
  }


  /**
   * converts a CSS selector to an XPath query.
   *
   * @param string $selector
   * @return string
   */
  private function _css_selector_to_xpath($selector) {

    // Collapse white space and strip whitespace around delimiters
//     $search = array("/\\s+/", "/\\s+([.>#+:])\\s+/");
//     $replace = array(" ", "\\1");
//     $selector = preg_replace($search, $replace, trim($selector));
    
    // Initial query (non-absolute)
    $query = "//";
    
    // Parse the selector     
    //$s = preg_split("/([ :>.#+])/", $selector, -1, PREG_SPLIT_DELIM_CAPTURE);

    $delimiters = array(" ", ">", ".", "#", "+", ":", "[");

    // Add an implicit space at the beginning of the selector if there is no
    // delimiter there already.
    if ( !in_array($selector{0}, $delimiters) )
      $selector = " $selector";

    $tok = "";
    $len = mb_strlen($selector);
    $i = 0;
                   
    while ( $i < $len ) {

      $s = $selector{$i};
      $i++;

      // Eat characters up to the next delimiter
      $tok = "";

      while ($i < $len) {
        if ( in_array($selector{$i}, $delimiters) )
          break;
        $tok .= $selector{$i++};
      }

      switch ($s) {
        
      case " ":
      case ">":
        // All elements matching the next token that are direct children of
        // the current token
        $expr = $s == " " ? "descendant" : "child";

        if ( mb_substr($query, -1, 1) != "/" )
          $query .= "/";

        if ( !$tok )
          $tok = "*";
        
        $query .= "$expr::$tok";
        $tok = "";
        break;

      case ".":
      case "#":
        // All elements matching the current token with a class/id equal to
        // the _next_ token.

        $attr = $s == "." ? "class" : "id";

        // empty class/id == *
        if ( mb_substr($query, -1, 1) == "/" )
          $query .= "*";

        // Match multiple classes: $tok contains the current selected
        // class.  Search for class attributes with class="$tok",
        // class=".* $tok .*" and class=".* $tok"
        
        // This doesn't work because libxml only supports XPath 1.0...
        //$query .= "[matches(@$attr,\"^${tok}\$|^${tok}[ ]+|[ ]+${tok}\$|[ ]+${tok}[ ]+\")]";
        
        // Query improvement by Michael Sheakoski <[e-mail]>:
        $query .= "[contains(concat(' ', @$attr, ' '), concat(' ', '$tok', ' '))]";
        $tok = "";
        break;

      case "+":
        // All sibling elements that folow the current token
        if ( mb_substr($query, -1, 1) != "/" )
          $query .= "/";

        $query .= "following-sibling::$tok";
        $tok = "";
        break;

      case ":":
        // Pseudo-classes
        switch ($tok) {

        case "first-child":
          break;

        case "link":
          $query .= "[@href]";
          $tok = "";
          break;

        case "first-line":
          break;

        case "first-letter":
          break;

        case "before":
          break;

        case "after":
          break;
        
        }
        
        break;
        
      case "[":
        // Attribute selectors.  All with an attribute matching the following token(s)
        $attr_delimiters = array("=", "]", "~", "|");
        $tok_len = mb_strlen($tok);
        $j = 0;
        
        $attr = "";
        $op = "";
        $value = "";
        
        while ( $j < $tok_len ) {
          if ( in_array($tok{$j}, $attr_delimiters) )
            break;
          $attr .= $tok{$j++};
        }