improvement: tags replace keywords. Better data model, less

limitations. Each image can be associated to as many tag as needed. Tags can
contain non ASCII characters. Oriented navigation with tags by association.


git-svn-id: http://piwigo.org/svn/trunk@1119 68402e56-0260-453c-a942-63ccdbb3a9ee

1 files changed, 218 insertions, 0 deletions

diff --git a/include/functions_tag.inc.php b/include/functions_tag.inc.php
new file mode 100644
index 000000000..5dd4884f4
--- /dev/null
+++ b/include/functions_tag.inc.php
@@ -0,0 +1,218 @@
+<?php
+// +-----------------------------------------------------------------------+
+// | PhpWebGallery - a PHP based picture gallery                           |
+// | Copyright (C) 2002-2003 Pierrick LE GALL - pierrick@phpwebgallery.net |
+// | Copyright (C) 2003-2006 PhpWebGallery Team - http://phpwebgallery.net |
+// +-----------------------------------------------------------------------+
+// | branch        : BSF (Best So Far)
+// | file          : $RCSfile$
+// | last update   : $Date: 2006-03-16 23:58:16 +0100 (jeu, 16 mar 2006) $
+// | last modifier : $Author: rub $
+// | revision      : $Revision: 1085 $
+// | revision      : $Revision: 1085 $
+// +-----------------------------------------------------------------------+
+// | This program is free software; you can redistribute it and/or modify  |
+// | it under the terms of the GNU General Public License as published by  |
+// | the Free Software Foundation                                          |
+// |                                                                       |
+// | This program 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      |
+// | General Public License for more details.                              |
+// |                                                                       |
+// | You should have received a copy of the GNU General Public License     |
+// | along with this program; if not, write to the Free Software           |
+// | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, |
+// | USA.                                                                  |
+// +-----------------------------------------------------------------------+
+
+
+/**
+ * Tags available. Each return tag is represented as an array with its id,
+ * its name, its weight (count), its url name. Tags are not sorted.
+ *
+ * The returned list can be a subset of all existing tags due to
+ * permissions, only if a list of forbidden categories is provided
+ *
+ * @param array forbidden categories
+ * @return array
+ */
+function get_available_tags($forbidden_categories = null)
+{
+  // we can find top fatter tags among reachable images
+  $tags_query = '
+SELECT tag_id, name, url_name, count(*) counter
+  FROM '.IMAGE_TAG_TABLE.'
+    INNER JOIN '.TAGS_TABLE.' ON tag_id = id';
+
+  if (!is_null($forbidden_categories))
+  {
+    // first we need all reachable image ids
+    $images_query = '
+SELECT DISTINCT image_id
+  FROM '.IMAGE_CATEGORY_TABLE.'
+  WHERE category_id NOT IN ('.implode(',', $forbidden_categories).')
+;';
+    $image_ids = array_from_query($images_query, 'image_id');
+
+    $tags_query.= '
+  WHERE image_id IN ('.
+      wordwrap(
+        implode(', ', $image_ids),
+        80,
+        "\n"
+        ).')';
+  }
+  
+  $tags_query.= '
+  GROUP BY tag_id
+;';
+
+  $result = pwg_query($tags_query);
+  
+  $tags = array();
+
+  while ($row = mysql_fetch_array($result))
+  {
+    array_push($tags, $row);
+  }
+
+  return $tags;
+}
+
+/**
+ * All tags, even tags associated to no image.
+ *
+ * @return array
+ */
+function get_all_tags()
+{
+  $query = '
+SELECT id AS tag_id, name, url_name
+  FROM '.TAGS_TABLE.'
+  ORDER BY name
+;';
+  $result = pwg_query($query);
+  
+  $tags = array();
+
+  while ($row = mysql_fetch_array($result))
+  {
+    array_push($tags, $row);
+  }
+
+  return $tags;
+}
+
+/**
+ * Giving a set of tags with a counter for each one, calculate the display
+ * level of each tag.
+ *
+ * The level of each tag depends on the average count of tags. This
+ * calcylation method avoid having very different levels for tags having
+ * nearly the same count when set are small.
+ *
+ * @param array tags
+ * @return array
+ */
+function add_level_to_tags($tags)
+{
+  global $conf;
+
+  if (count($tags) == 0)
+  {
+    return $tags;
+  }
+  
+  $total_count = 0;
+
+  foreach ($tags as $tag)
+  {
+    $total_count+= $tag['counter'];
+  }
+
+  // average count of available tags will determine the level of each tag
+  $tag_average_count = $total_count / count($tags);
+
+  // tag levels threshold calculation: a tag with an average rate must have
+  // the middle level.
+  for ($i = 1; $i < $conf['tags_levels']; $i++)
+  {
+    $threshold_of_level[$i] =
+      2 * $i * $tag_average_count / $conf['tags_levels'];
+  }
+
+  // display sorted tags
+  foreach (array_keys($tags) as $k)
+  {
+    $tags[$k]['level'] = 1;
+    
+    // based on threshold, determine current tag level
+    for ($i = $conf['tags_levels'] - 1; $i >= 1; $i--)
+    {
+      if ($tags[$k]['counter'] > $threshold_of_level[$i])
+      {
+        $tags[$k]['level'] = $i + 1;
+        break;
+      }
+    }
+  }
+
+  return $tags;
+}
+
+/**
+ * return the list of image ids corresponding to given tags. AND & OR mode
+ * supported.
+ *
+ * @param array tag ids
+ * @param string mode
+ * @return array
+ */
+function get_image_ids_for_tags($tag_ids, $mode = 'AND')
+{
+  switch ($mode)
+  {
+    case 'AND':
+    {
+      // strategy is to list images associated to each tag
+      $tag_images = array();
+      
+      foreach ($tag_ids as $tag_id)
+      {
+        $query = '
+SELECT image_id
+  FROM '.IMAGE_TAG_TABLE.'
+  WHERE tag_id = '.$tag_id.'
+;';
+        $tag_images[$tag_id] = array_from_query($query, 'image_id');
+      }
+
+      // then we calculate the intersection, the images that are associated to
+      // every tags
+      $items = array_shift($tag_images);
+      foreach ($tag_images as $images)
+      {
+        $items = array_intersect($items, $images);
+      }
+
+      return array_unique($items);
+      break;
+    }
+    case 'OR':
+    {
+      $query = '
+SELECT DISTINCT image_id
+  FROM '.IMAGE_TAG_TABLE.'
+  WHERE tag_id IN ('.implode(',', $tag_ids).')
+;';
+      return array_from_query($query, 'image_id');
+      break;
+    }
+    default:
+    {
+      die('get_image_ids_for_tags: unknown mode, only AND & OR are supported');
+    }
+  }
+}
+?>
\ No newline at end of file