treenode_class.php

《PHP和MySQL Web开发》(第三版) Source

<?php
// functions for loading, contructing and 
// displaying the tree are in this file 

class treenode
{ 
  // each node in the tree has member variables containing 
  // all the data for a post except the body of the message
  public $m_postid;
  public $m_title;
  public $m_poster;
  public $m_posted;
  public $m_children;
  public $m_childlist;
  public $m_depth;

  public function __construct($postid, $title, $poster, $posted, $children, 
                    $expand, $depth, $expanded, $sublist)
  { 
    // the constructor sets up the member variables, but more 
    // importantly recursively creates lower parts of the tree
    $this->m_postid = $postid;
    $this->m_title = $title;
    $this->m_poster = $poster;
    $this->m_posted = $posted;
    $this->m_children =$children;
    $this->m_childlist = array();
    $this->m_depth = $depth;

    // we only care what is below this node if it 
    // has children and is marked to be expanded
    // sublists are always expanded
    if(($sublist||$expand) && $children)
    {
      $conn = db_connect();

      $query = "select * from header where parent = $postid order by posted";
      $result = $conn->query($query);

      for ($count=0; $row = @$result->fetch_assoc(); $count++)
      {
        if($sublist||$expanded[ $row['postid'] ] == true)
          $expand = true;
        else
          $expand = false;
        $this->m_childlist[$count]= new treenode($row['postid'],$row['title'],
                                      $row['poster'],$row['posted'],
                                      $row['children'], $expand,
                                      $depth+1, $expanded, $sublist);
      }
    }
  }  


  function display($row, $sublist = false)
  {
    // as this is an object, it is responsible for displaying itself

    // $row tells us what row of the display we are up to 
    // so we know what color it should be

    // $sublist tells us whether we are on the main page
    // or the message page.  Message pages should have 
    // $sublist = true.  
    // On a sublist, all messages are expanded and there are
    // no "+" or "-" symbols.

    // if this is the empty root node skip displaying
    if($this->m_depth>-1)  
    {
      //color alternate rows
      echo '<tr><td bgcolor = ';
      if ($row%2) 
        echo "'#cccccc'>";
      else
        echo "'#ffffff'>";

      // indent replies to the depth of nesting
      for($i = 0; $i<$this->m_depth; $i++)
      {
        echo "<img src = 'images/spacer.gif' height = 22
                          width = 22 alt = '' valign = 'bottom' />";
      }
  
      // display + or - or a spacer 
      if ( !$sublist && $this->m_children && sizeof($this->m_childlist))
      // we're on the main page, have some children, and they're expanded 
      {
        // we are expanded - offer button to collapse
        echo "<a href = 'index.php?collapse=".
                         $this->m_postid."#$this->m_postid'
             ><img src = 'images/minus.gif' valign = 'bottom' 
             height = 22 width = 22 alt = 'Collapse Thread' border = 0 /></a>";
      }
      else if(!$sublist && $this->m_children)
      {
        // we are collapsed - offer button to expand
        echo "<a href = 'index.php?expand=".
             $this->m_postid."#$this->m_postid'><img src = 'images/plus.gif'  
             height = 22 width = 22 alt = 'Expand Thread' border = 0></a>";
      }
      else
      {
        // we have no children, or are in a sublist, do not give button
        echo "<img src = 'images/spacer.gif' height = 22 width = 22 
                   alt = '' valign = 'bottom' />";
      }


      echo " <a name = $this->m_postid ><a href = 
             'view_post.php?postid=$this->m_postid'>$this->m_title - 
              $this->m_poster - ".reformat_date($this->m_posted).'</a>';
      echo '</td></tr>';

      // increment row counter to alternate colors
      $row++;
    }
    // call display on each of this node's children
    // note a node will only have children in its list if expanded
    $num_children = sizeof($this->m_childlist);
    for($i = 0; $i<$num_children; $i++)
    {
      $row = $this->m_childlist[$i]->display($row, $sublist);
    }
    return $row;
  }

};



?>