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   1  <?php
   2  // $Id: content.inc,v 1.12.2.13 2010/08/19 20:35:03 merlinofchaos Exp $
   3  
   4  /**
   5   * @file
   6   * Contains the tools to handle pluggable content that can be used by other
   7   * applications such as Panels or Dashboard.
   8   *
   9   * See the context-content.html file in advanced help for documentation
  10   * of this tool.
  11   */
  12  
  13  /**
  14   * Implementation of hook_ctools_plugin_*.
  15   *
  16   * Give information to CTools about the content types plugin.
  17   */
  18  function ctools_ctools_plugin_content_types() {
  19    return array(
  20      'cache' => FALSE,
  21      'process' => 'ctools_content_process',
  22    );
  23  }
  24  
  25  /**
  26   * Provide defaults for a content type.
  27   *
  28   * Currently we check for automatically named callbacks to make life a little
  29   * easier on the developer.
  30   */
  31  function ctools_content_process(&$plugin, $info) {
  32    $function_base = $plugin['module'] . '_' . $plugin['name'] . '_content_type_';
  33  
  34    if (empty($plugin['render callback']) && function_exists($function_base . 'render')) {
  35      $plugin['render callback'] = $function_base . 'render';
  36    }
  37  
  38    if (empty($plugin['admin title'])) {
  39      if (function_exists($function_base . 'admin_title')) {
  40        $plugin['admin title'] = $function_base . 'admin_title';
  41      }
  42      else {
  43        $plugin['admin title'] = $plugin['title'];
  44      }
  45    }
  46  
  47    if (empty($plugin['admin info']) && function_exists($function_base . 'admin_info')) {
  48      $plugin['admin info'] = $function_base . 'admin_info';
  49    }
  50  
  51    if (!isset($plugin['edit form']) && function_exists($function_base . 'edit_form')) {
  52      $plugin['edit form'] = $function_base . 'edit_form';
  53    }
  54  
  55    if (!isset($plugin['add form']) && function_exists($function_base . 'add_form')) {
  56      $plugin['add form'] = $function_base . 'add_form';
  57    }
  58  
  59    if (!isset($plugin['add form']) && function_exists($function_base . 'edit_form')) {
  60      $plugin['add form'] = $function_base . 'edit_form';
  61    }
  62  
  63    // Another ease of use check:
  64    if (!isset($plugin['content types'])) {
  65      // If a subtype plugin exists, try to use it. Otherwise assume single.
  66      if (function_exists($function_base . 'content_types')) {
  67        $plugin['content types'] = $function_base . 'content_types';
  68      }
  69      else {
  70        $type = array(
  71          'title' => $plugin['title'],
  72          'description' => $plugin['description'],
  73          'icon' => $plugin['icon'],
  74          'category' => $plugin['category'],
  75        );
  76  
  77        if (isset($plugin['required context'])) {
  78          $type['required context'] = $plugin['required context'];
  79        }
  80        if (isset($plugin['top level'])) {
  81          $type['top level'] = $plugin['top level'];
  82        }
  83        $plugin['content types'] = array($plugin['name'] => $type);
  84        if (!isset($plugin['single'])) {
  85          $plugin['single'] = TRUE;
  86        }
  87      }
  88    }
  89  }
  90  
  91  /**
  92   * Fetch metadata on a specific content_type plugin.
  93   *
  94   * @param $content type
  95   *   Name of a panel content type.
  96   *
  97   * @return
  98   *   An array with information about the requested panel content type.
  99   */
 100  function ctools_get_content_type($content_type) {
 101    ctools_include('context');
 102    ctools_include('plugins');
 103    return ctools_get_plugins('ctools', 'content_types', $content_type);
 104  }
 105  
 106  /**
 107   * Fetch metadata for all content_type plugins.
 108   *
 109   * @return
 110   *   An array of arrays with information about all available panel content types.
 111   */
 112  function ctools_get_content_types() {
 113    ctools_include('context');
 114    ctools_include('plugins');
 115    return ctools_get_plugins('ctools', 'content_types');
 116  }
 117  
 118  /**
 119   * Get all of the individual subtypes provided by a given content type. This
 120   * would be all of the blocks for the block type, or all of the views for
 121   * the view type.
 122   *
 123   * @param $type
 124   *   The content type to load.
 125   *
 126   * @return
 127   *   An array of all subtypes available.
 128   */
 129  function ctools_content_get_subtypes($type) {
 130    static $cache = array();
 131  
 132    $subtypes = array();
 133  
 134    if (is_array($type)) {
 135      $plugin = $type;
 136    }
 137    else {
 138      $plugin = ctools_get_content_type($type);
 139    }
 140  
 141    if (empty($plugin) || empty($plugin['name'])) {
 142      return;
 143    }
 144  
 145    if (isset($cache[$plugin['name']])) {
 146      return $cache[$plugin['name']];
 147    }
 148  
 149    if (isset($plugin['content types'])) {
 150      $function = $plugin['content types'];
 151      if (is_array($function)) {
 152        $subtypes = $function;
 153      }
 154      else if (function_exists($function)) {
 155        // Cast to array to prevent errors from non-array returns.
 156        $subtypes = (array) $function($plugin);
 157      }
 158    }
 159  
 160    // Walk through the subtypes and ensure minimal settings are
 161    // retained.
 162    foreach ($subtypes as $id => $subtype) {
 163      // Use exact name since this is a modify by reference.
 164      ctools_content_prepare_subtype($subtypes[$id], $plugin);
 165    }
 166  
 167    $cache[$plugin['name']] = $subtypes;
 168  
 169    return $subtypes;
 170  }
 171  
 172  /**
 173   * Given a content type and a subtype id, return the information about that
 174   * content subtype.
 175   *
 176   * @param $type
 177   *   The content type being fetched.
 178   * @param $subtype_id
 179   *   The id of the subtype being fetched.
 180   *
 181   * @return
 182   *   An array of information describing the content subtype.
 183   */
 184  function ctools_content_get_subtype($type, $subtype_id) {
 185    $subtype = array();
 186    if (is_array($type)) {
 187      $plugin = $type;
 188    }
 189    else {
 190      $plugin = ctools_get_content_type($type);
 191    }
 192  
 193    $function = ctools_plugin_get_function($plugin, 'content type');
 194    if ($function) {
 195      $subtype = $function($subtype_id, $plugin);
 196    }
 197    else {
 198      $subtypes = ctools_content_get_subtypes($type);
 199      if (isset($subtypes[$subtype_id])) {
 200        $subtype = $subtypes[$subtype_id];
 201      }
 202      // If there's only 1 and we somehow have the wrong subtype ID, do not
 203      // care. Return the proper subtype anyway.
 204      if (empty($subtype) && !empty($plugin['single'])) {
 205        $subtype = current($subtypes);
 206      }
 207    }
 208  
 209    if ($subtype) {
 210      ctools_content_prepare_subtype($subtype, $plugin);
 211    }
 212    return $subtype;
 213  }
 214  
 215  /**
 216   * Ensure minimal required settings on a content subtype exist.
 217   */
 218  function ctools_content_prepare_subtype(&$subtype, $plugin) {
 219    foreach (array('path', 'js', 'css') as $key) {
 220      if (!isset($subtype[$key]) && isset($plugin[$key])) {
 221        $subtype[$key] = $plugin[$key];
 222      }
 223    }
 224  }
 225  
 226  /**
 227   * Get the content from a given content type.
 228   *
 229   * @param $type
 230   *   The content type. May be the name or an already loaded content type plugin.
 231   * @param $subtype
 232   *   The name of the subtype being rendered.
 233   * @param $conf
 234   *   The configuration for the content type.
 235   * @param $keywords
 236   *   An array of replacement keywords that come from outside contexts.
 237   * @param $args
 238   *   The arguments provided to the owner of the content type. Some content may
 239   *   wish to configure itself based on the arguments the panel or dashboard
 240   *   received.
 241   * @param $context
 242   *   An array of context objects available for use.
 243   * @param $incoming_content
 244   *   Any incoming content, if this display is a wrapper.
 245   *
 246   * @return
 247   *   The content as rendered by the plugin. This content should be an array
 248   *   with the following possible keys:
 249   *   - title: The safe to render title of the content.
 250   *   - content: The safe to render HTML content.
 251   *   - links: An array of links associated with the content suitable for
 252   *     theme('links').
 253   *   - more: An optional 'more' link (destination only)
 254   *   - admin_links: Administrative links associated with the content, suitable
 255   *     for theme('links').
 256   *   - feeds: An array of feed icons or links associated with the content.
 257   *     Each member of the array is rendered HTML.
 258   *   - type: The content type.
 259   *   - subtype: The content subtype. These two may be used together as
 260   *     module-delta for block style rendering.
 261   */
 262  function ctools_content_render($type, $subtype, $conf, $keywords = array(), $args = array(), $context = array(), $incoming_content = '') {
 263    if (is_array($type)) {
 264      $plugin = $type;
 265    }
 266    else {
 267      $plugin = ctools_get_content_type($type);
 268    }
 269  
 270    $subtype_info = ctools_content_get_subtype($plugin, $subtype);
 271  
 272    $function = ctools_plugin_get_function($subtype_info, 'render callback');
 273    if (!$function) {
 274      $function = ctools_plugin_get_function($plugin, 'render callback');
 275    }
 276  
 277    if ($function) {
 278      $pane_context = ctools_content_select_context($plugin, $subtype, $conf, $context);
 279      if ($pane_context === FALSE) {
 280        return;
 281      }
 282  
 283      $content = $function($subtype, $conf, $args, $pane_context, $incoming_content);
 284  
 285      // Set up some defaults and other massaging on the content before we hand
 286      // it back to the caller.
 287      if (!isset($content->type)) {
 288        $content->type = $plugin['name'];
 289      }
 290  
 291      if (!isset($content->subtype)) {
 292        $content->subtype = $subtype;
 293      }
 294  
 295      // Override the title if configured to
 296      if (!empty($conf['override_title'])) {
 297        // Give previous title as an available substitution here.
 298        $keywords['%title'] = empty($content->title) ? '' : $content->title;
 299        $content->original_title = $keywords['%title'];
 300        $content->title = $conf['override_title_text'];
 301      }
 302  
 303      if (!empty($content->title)) {
 304        // Perform substitutions
 305        if (!empty($keywords) || !empty($context)) {
 306          $content->title = ctools_context_keyword_substitute($content->title, $keywords, $context);
 307        }
 308  
 309        // Sterilize the title
 310        $content->title = filter_xss_admin($content->title);
 311  
 312        // If a link is specified, populate.
 313        if (!empty($content->title_link)) {
 314          if (!is_array($content->title_link)) {
 315            $url = array('href' => $content->title_link);
 316          }
 317          else {
 318            $url = $content->title_link;
 319          }
 320          // set defaults so we don't bring up notices
 321          $url += array('href' => '', 'attributes' => NULL, 'query' => NULL, 'fragment' => NULL, 'absolute' => NULL, 'html' => TRUE);
 322          $content->title = l($content->title, $url['href'], $url);
 323        }
 324      }
 325  
 326      return $content;
 327    }
 328  }
 329  
 330  /**
 331   * Determine if a content type can be edited or not.
 332   *
 333   * Some content types simply have their content and no options. This function
 334   * lets a UI determine if it should display an edit link or not.
 335   */
 336  function ctools_content_editable($type, $subtype, $conf) {
 337    if (empty($type['edit form']) && empty($subtype['edit form'])) {
 338      return FALSE;
 339    }
 340  
 341    if ($function = ctools_plugin_get_function($subtype, 'check editable')) {
 342      return $function($type, $subtype, $conf);
 343    }
 344  
 345    return TRUE;
 346  }
 347  
 348  /**
 349   * Get the administrative title from a given content type.
 350   *
 351   * @param $type
 352   *   The content type. May be the name or an already loaded content type object.
 353   * @param $subtype
 354   *   The subtype being rendered.
 355   * @param $conf
 356   *   The configuration for the content type.
 357   * @param $context
 358   *   An array of context objects available for use. These may be placeholders.
 359   */
 360  function ctools_content_admin_title($type, $subtype, $conf, $context = NULL) {
 361    if (is_array($type)) {
 362      $plugin = $type;
 363    }
 364    else if (is_string($type)) {
 365      $plugin = ctools_get_content_type($type);
 366    }
 367    else {
 368      return;
 369    }
 370  
 371    if ($function = ctools_plugin_get_function($plugin, 'admin title')) {
 372      $pane_context = ctools_content_select_context($plugin, $subtype, $conf, $context);
 373      if ($pane_context === FALSE) {
 374        if ($plugin['name'] == $subtype) {
 375          return t('@type will not display due to missing context', array('@type' => $plugin['name']));
 376        }
 377        return t('@type:@subtype will not display due to missing context', array('@type' => $plugin['name'], '@subtype' => $subtype));
 378      }
 379  
 380      return $function($subtype, $conf, $pane_context);
 381    }
 382    else if (isset($plugin['admin title'])) {
 383      return $plugin['admin title'];
 384    }
 385    else if (isset($plugin['title'])) {
 386      return $plugin['title'];
 387    }
 388  }
 389  
 390  /**
 391   * Get the proper icon path to use, falling back to default icons if no icon exists.
 392   *
 393   * $subtype
 394   *   The loaded subtype info.
 395   */
 396  function ctools_content_admin_icon($subtype) {
 397    $icon = '';
 398  
 399    if (isset($subtype['icon'])) {
 400      $icon = $subtype['icon'];
 401      if (!file_exists($icon)) {
 402        $icon = $subtype['path'] . '/' . $icon;
 403      }
 404    }
 405  
 406    if (empty($icon) || !file_exists($icon)) {
 407      $icon = ctools_image_path('no-icon.png');
 408    }
 409  
 410    return $icon;
 411  }
 412  
 413  /**
 414   * Set up the default $conf for a new instance of a content type.
 415   */
 416  function ctools_content_get_defaults($plugin, $subtype) {
 417    if (isset($plugin['defaults'])) {
 418      $defaults = $plugin['defaults'];
 419    }
 420    else if (isset($subtype['defaults'])) {
 421      $defaults = $subtype['defaults'];
 422    }
 423    if (isset($defaults)) {
 424      if (is_string($defaults) && function_exists($defaults)) {
 425        if ($return = $defaults($pane)) {
 426          return $return;
 427        }
 428      }
 429      else if (is_array($defaults)) {
 430        return $defaults;
 431      }
 432    }
 433  
 434    return array();
 435  }
 436  
 437  /**
 438   * Get the administrative title from a given content type.
 439   *
 440   * @param $type
 441   *   The content type. May be the name or an already loaded content type object.
 442   * @param $subtype
 443   *   The subtype being rendered.
 444   * @param $conf
 445   *   The configuration for the content type.
 446   * @param $context
 447   *   An array of context objects available for use. These may be placeholders.
 448   */
 449  function ctools_content_admin_info($type, $subtype, $conf, $context = NULL) {
 450    if (is_array($type)) {
 451      $plugin = $type;
 452    }
 453    else {
 454      $plugin = ctools_get_content_type($type);
 455    }
 456  
 457    if ($function = ctools_plugin_get_function($plugin, 'admin info')) {
 458      $output = $function($subtype, $conf, $context);
 459    }
 460    if (empty($output) || !is_object($output)) {
 461      $output = new stdClass();
 462      $output->title = t('No info');
 463      $output->content =t ('No info available.');
 464    }
 465    return $output;
 466  }
 467  
 468  /**
 469   * Add the default FAPI elements to the content type configuration form
 470   */
 471  function ctools_content_configure_form_defaults(&$form, &$form_state) {
 472    $plugin = $form_state['plugin'];
 473    $subtype = $form_state['subtype'];
 474    $contexts = isset($form_state['contexts']) ? $form_state['contexts'] : NULL;
 475    $conf = $form_state['conf'];
 476  
 477    $add_submit = FALSE;
 478    if (!empty($subtype['required context']) && is_array($contexts)) {
 479      $form['context'] = ctools_context_selector($contexts, $subtype['required context'], isset($conf['context']) ? $conf['context'] : array());
 480      $add_submit = TRUE;
 481    }
 482  
 483    ctools_include('dependent');
 484  
 485    // Unless we're not allowed to override the title on this content type, add this
 486    // gadget to all panes.
 487    if (empty($plugin['no title override']) && empty($subtype['no title override'])) {
 488      $form['aligner_start'] = array(
 489        '#value' => '<div class="option-text-aligner">',
 490      );
 491      $form['override_title'] = array(
 492        '#type' => 'checkbox',
 493        '#default_value' => isset($conf['override_title']) ? $conf['override_title'] : '',
 494        '#title' => t('Override title'),
 495        '#id' => 'override-title-checkbox',
 496      );
 497      $form['override_title_text'] = array(
 498        '#type' => 'textfield',
 499        '#default_value' => isset($conf['override_title_text']) ? $conf['override_title_text'] : '',
 500        '#size' => 35,
 501        '#id' => 'override-title-textfield',
 502        '#process' => array('ctools_dependent_process'),
 503        '#dependency' => array('override-title-checkbox' => array(1)),
 504        '#dependency_type' => 'disable',
 505      );
 506      $form['aligner_stop'] = array(
 507        '#value' => '</div><div style="clear: both; padding: 0; margin: 0"></div>',
 508      );
 509      if (is_array($contexts)) {
 510        $form['override_title_markup'] = array(
 511          '#prefix' => '<div class="description">',
 512          '#suffix' => '</div>',
 513          '#value' => t('You may use %keywords from contexts, as well as %title to contain the original title.'),
 514        );
 515      }
 516      $add_submit = TRUE;
 517    }
 518  
 519    if ($add_submit) {
 520      // '#submit' is already set up due to the wizard.
 521      $form['#submit'][] = 'ctools_content_configure_form_defaults_submit';
 522    }
 523    return $form;
 524  }
 525  
 526  /**
 527   * Submit handler to store context/title override info.
 528   */
 529  function ctools_content_configure_form_defaults_submit(&$form, &$form_state) {
 530    if (isset($form_state['values']['context'])) {
 531      $form_state['conf']['context'] = $form_state['values']['context'];
 532    }
 533    if (isset($form_state['values']['override_title'])) {
 534      $form_state['conf']['override_title'] = $form_state['values']['override_title'];
 535      $form_state['conf']['override_title_text'] = $form_state['values']['override_title_text'];
 536    }
 537  }
 538  
 539  /**
 540   * Get the config form.
 541   *
 542   * The $form_info and $form_state need to be preconfigured with data you'll need
 543   * such as whether or not you're using ajax, or the modal. $form_info will need
 544   * your next/submit callbacks so that you can cache your data appropriately.
 545   *
 546   * @return
 547   *   If this function returns false, no form exists.
 548   */
 549  function ctools_content_form($op, $form_info, &$form_state, $plugin, $subtype_name, $subtype, &$conf, $step = NULL) {
 550    $form_state += array(
 551      'plugin' => $plugin,
 552      'subtype' => $subtype,
 553      'subtype_name' => $subtype_name,
 554      'conf' => &$conf,
 555      'op' => $op,
 556    );
 557  
 558    $form_info += array(
 559      'id' => 'ctools_content_form',
 560      'show back' => TRUE,
 561    );
 562  
 563    // Turn the forms defined in the plugin into the format the wizard needs.
 564    if ($op == 'add') {
 565      if (!empty($subtype['add form'])) {
 566        _ctools_content_create_form_info($form_info, $subtype['add form'], $subtype, $subtype, $op);
 567      }
 568      else if (!empty($plugin['add form'])) {
 569        _ctools_content_create_form_info($form_info, $plugin['add form'], $plugin, $subtype, $op);
 570      }
 571    }
 572  
 573    if (empty($form_info['order'])) {
 574      // Use the edit form for the add form if add form was completely left off.
 575      if (!empty($subtype['edit form'])) {
 576        _ctools_content_create_form_info($form_info, $subtype['edit form'], $subtype, $subtype, $op);
 577      }
 578      else if (!empty($plugin['edit form'])) {
 579        _ctools_content_create_form_info($form_info, $plugin['edit form'], $plugin, $subtype, $op);
 580      }
 581    }
 582  
 583    if (empty($form_info['order'])) {
 584      return FALSE;
 585    }
 586  
 587    ctools_include('wizard');
 588    return ctools_wizard_multistep_form($form_info, $step, $form_state);
 589  
 590  }
 591  
 592  function _ctools_content_create_form_info(&$form_info, $info, $plugin, $subtype, $op) {
 593    if (is_string($info)) {
 594      if (empty($subtype['title'])) {
 595        $title = t('Configure');
 596      }
 597      else if ($op == 'add') {
 598        $title = t('Configure new !subtype_title', array('!subtype_title' => $subtype['title']));
 599      }
 600      else {
 601        $title = t('Configure !subtype_title', array('!subtype_title' => $subtype['title']));
 602      }
 603      $form_info['order'] = array('form' => $title);
 604      $form_info['forms'] = array(
 605        'form' => array(
 606          'title' => $title,
 607          'form id' => $info,
 608          'wrapper' => 'ctools_content_configure_form_defaults',
 609        ),
 610      );
 611    }
 612    else if (is_array($info)) {
 613      $form_info['order'] = array();
 614      $form_info['forms'] = array();
 615      $count = 0;
 616      $base = 'step';
 617      $wrapper = NULL;
 618      foreach ($info as $form_id => $title) {
 619        // @todo -- docs say %title can be used to sub for the admin title.
 620        $step = $base . ++$count;
 621        if (empty($wrapper)) {
 622          $wrapper = $step;
 623        }
 624  
 625        if (is_array($title)) {
 626          if (!empty($title['default'])) {
 627            $wrapper = $step;
 628          }
 629          $title = $title['title'];
 630        }
 631  
 632        $form_info['order'][$step] = $title;
 633        $form_info['forms'][$step] = array(
 634          'title' => $title,
 635          'form id' => $form_id,
 636        );
 637      }
 638      if ($wrapper) {
 639        $form_info['forms'][$wrapper]['wrapper'] = 'ctools_content_configure_form_defaults';
 640      }
 641    }
 642  }
 643  
 644  /**
 645   * Get an array of all available content types that can be fed into the
 646   * display editor for the add content list.
 647   *
 648   * @param $context
 649   *   If a context is provided, content that requires that context can apepar.
 650   * @param $has_content
 651   *   Whether or not the display will have incoming content
 652   * @param $allowed_types
 653   *   An array of allowed content types (pane types) keyed by content_type . '-' . sub_type
 654   * @param $default_types
 655   *   A default allowed/denied status for content that isn't known about
 656   */
 657  function ctools_content_get_available_types($contexts = NULL, $has_content = FALSE, $allowed_types = NULL, $default_types = NULL) {
 658    $plugins = ctools_get_content_types();
 659    $available = array();
 660  
 661    foreach ($plugins as $id => $plugin) {
 662      foreach (ctools_content_get_subtypes($plugin) as $subtype_id => $subtype) {
 663        // exclude items that require content if we're saying we don't
 664        // provide it.
 665        if (!empty($subtype['requires content']) && !$has_content) {
 666          continue;
 667        }
 668  
 669        // Check to see if the content type can be used in this context.
 670        if (!empty($subtype['required context'])) {
 671          if (!ctools_context_match_requirements($contexts, $subtype['required context'])) {
 672            continue;
 673          }
 674        }
 675  
 676        // Check to see if the passed-in allowed types allows this content.
 677        if ($allowed_types) {
 678          $key = $id . '-' . $subtype_id;
 679          if (!isset($allowed_types[$key])) {
 680            $allowed_types[$key] = isset($default_types[$id]) ? $default_types[$id] : $default_types['other'];
 681          }
 682          if (!$allowed_types[$key]) {
 683            continue;
 684          }
 685        }
 686  
 687        // If we made it through all the tests, then we can use this content.
 688        $available[$id][$subtype_id] = $subtype;
 689      }
 690    }
 691    return $available;
 692  }
 693  
 694  /**
 695   * Get an array of all content types that can be fed into the
 696   * display editor for the add content list, regardless of
 697   * availability.
 698   *
 699   */
 700  function ctools_content_get_all_types() {
 701    $plugins = ctools_get_content_types();
 702    $available = array();
 703  
 704    foreach ($plugins as $id => $plugin) {
 705      foreach (ctools_content_get_subtypes($plugin) as $subtype_id => $subtype) {
 706        // If we made it through all the tests, then we can use this content.
 707        $available[$id][$subtype_id] = $subtype;
 708      }
 709    }
 710    return $available;
 711  }
 712  
 713  /**
 714   * Select the context to be used for a piece of content, based upon config.
 715   *
 716   * @param $plugin
 717   *   The content plugin
 718   * @param $subtype
 719   *   The subtype of the content.
 720   * @param $conf
 721   *   The configuration array that should contain the context.
 722   * @param $contexts
 723   *   A keyed array of available contexts.
 724   *
 725   * @return
 726   *   The matching contexts or NULL if none or necessary, or FALSE if
 727   *   requirements can't be met.
 728   */
 729  function ctools_content_select_context($plugin, $subtype, $conf, $contexts) {
 730    // Identify which of our possible contexts apply.
 731    if (empty($subtype)) {
 732      return;
 733    }
 734  
 735    $subtype_info = ctools_content_get_subtype($plugin, $subtype);
 736    if (empty($subtype_info)) {
 737      return;
 738    }
 739  
 740    if (!empty($subtype_info['all contexts']) || !empty($plugin['all contexts'])) {
 741      return $contexts;
 742    }
 743  
 744    // If the content requires a context, fetch it; if no context is returned,
 745    // do not display the pane.
 746    if (empty($subtype_info['required context'])) {
 747      return;
 748    }
 749  
 750    if (empty($conf['context'])) {
 751      return;
 752    }
 753  
 754    $context = ctools_context_select($contexts, $subtype_info['required context'], $conf['context']);
 755  
 756    return $context;
 757  }