panels.module

<?php

/**
 * @file panels.module
 *
 * Core functionality for the Panels engine.
 */

define('PANELS_REQUIRED_CTOOLS_API', '2.0.9');

/**
 * The current working panels version.
 *
 * In a release, it should be 7.x-3.x, which should match what drush make will
 * create. In a dev format, it should be 7.x-3.(x+1)-dev, which will allow
 * modules depending on new features in panels to depend on panels > 7.x-3.x.
 *
 * To define a specific version of Panels as a dependency for another module,
 * simply include a dependency line in that module's info file, e.g.:
 *   ; Requires Panels v7.x-3.4 or newer.
 *   dependencies[] = panels (>=3.4)
 */
define('PANELS_VERSION', '7.x-3.8');


define('PANELS_TITLE_FIXED', 0); // Hide title use to be true/false. So false remains old behavior.
define('PANELS_TITLE_NONE', 1); // And true meant no title.
define('PANELS_TITLE_PANE', 2); // And this is the new behavior, where the title field will pick from a pane.

/**
 * Returns the API version of Panels. This didn't exist in 1.
 *
 * @todo -- this should work more like the CTools API version.
 *
 * @return An array with the major and minor versions
 */
function panels_api_version() {
  return array(3, 1);
}

// --------------------------------------------------------------------------
// Core Drupal hook implementations

/**
 * Implementation of hook_theme()
 */
function panels_theme() {
  // Safety: go away if CTools is not at an appropriate version.
  if (!module_invoke('ctools', 'api_version', PANELS_REQUIRED_CTOOLS_API)) {
    return array();
  }

  $theme = array();
  $theme['panels_layout_link'] = array(
    'variables' => array('title' => NULL, 'id' => NULL, 'image' => NULL, 'link' => NULL, 'class' => NULL),
  );
  $theme['panels_layout_icon'] = array(
    'variables' => array('id' => NULL, 'image' => NULL, 'title' => NULL),
  );
  $theme['panels_pane'] = array(
    'variables' => array('content' => array(), 'pane' => array(), 'display' => array()),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'template' => 'panels-pane',
  );
  $theme['panels_common_content_list'] = array(
    'variables' => array('display' => NULL),
    'file' => 'includes/common.inc',
  );
  $theme['panels_render_display_form'] = array(
    'render element' => 'element',
  );

  $theme['panels_dashboard'] = array(
    'variables' => array(),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'file' => '../includes/callbacks.inc',
    'template' => 'panels-dashboard',
  );

  $theme['panels_dashboard_link'] = array(
    'variables' => array('link' => array()),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'file' => '../includes/callbacks.inc',
    'template' => 'panels-dashboard-link',
  );

  $theme['panels_dashboard_block'] = array(
    'variables' => array('block' => array()),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'file' => '../includes/callbacks.inc',
    'template' => 'panels-dashboard-block',
  );

  $theme['panels_add_content_modal'] = array(
    'variables' => array('renderer' => NULL, 'categories' => array(), 'region' => NULL, 'category' => NULL, 'column_count' => 2),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'file' => '../includes/add-content.inc',
    'template' => 'panels-add-content-modal',
  );

  $theme['panels_add_content_link'] = array(
    'variables' => array('renderer' => NULL, 'region' => NULL, 'content_type' => NULL),
    'path' => drupal_get_path('module', 'panels') . '/templates',
    'file' => '../includes/add-content.inc',
    'template' => 'panels-add-content-link',
  );

  // We don't need layout and style themes in maintenance mode.
  // Disabling this: See http://drupal.org/node/979912 for information.
//  if (defined('MAINTENANCE_MODE')) {
//    return $theme;
//  }

  // Register layout and style themes on behalf of all of these items.
  ctools_include('plugins', 'panels');

  // No need to worry about files; the plugin has to already be loaded for us
  // to even know what the theme function is, so files will be auto included.
  $layouts = panels_get_layouts();
  foreach ($layouts as $name => $data) {
    foreach (array('theme', 'admin theme') as $callback) {
      if (!empty($data[$callback])) {
        $theme[$data[$callback]] = array(
          'variables' => array('css_id' => NULL, 'content' => NULL, 'settings' => NULL, 'display' => NULL, 'layout' => NULL, 'renderer' => NULL),
          'path' => $data['path'],
          'file' => $data['file'],
        );

        // if no theme function exists, assume template.
        if (!function_exists("theme_$data[theme]")) {
          $theme[$data[$callback]]['template'] = str_replace('_', '-', $data[$callback]);
          $theme[$data[$callback]]['file'] = $data['file']; // for preprocess.
        }
      }
    }
  }

  $styles = panels_get_styles();
  foreach ($styles as $name => $data) {
    if (!empty($data['render pane'])) {
      $theme[$data['render pane']] = array(
        'variables' => array('content' => NULL, 'pane' => NULL, 'display' => NULL, 'style' => NULL, 'settings' => NULL),
        'path' => $data['path'],
        'file' => $data['file'],
      );
    }
    if (!empty($data['render region'])) {
      $theme[$data['render region']] = array(
        'variables' => array('display' => NULL, 'owner_id' => NULL, 'panes' => NULL, 'settings' => NULL, 'region_id' => NULL, 'style' => NULL),
        'path' => $data['path'],
        'file' => $data['file'],
      );
    }

    if (!empty($data['hook theme'])) {
      if (is_array($data['hook theme'])) {
        $theme += $data['hook theme'];
      }
      else if (function_exists($data['hook theme'])) {
        $data['hook theme']($theme, $data);
      }
    }
  }

  return $theme;
}

/**
 * Implementation of hook_menu
 */
function panels_menu() {
  // Safety: go away if CTools is not at an appropriate version.
  if (!module_invoke('ctools', 'api_version', PANELS_REQUIRED_CTOOLS_API)) {
    return array();
  }
  $items = array();

  // Base AJAX router callback.
  $items['panels/ajax'] = array(
    'access arguments' => array('access content'),
    'page callback' => 'panels_ajax_router',
    'theme callback' => 'ajax_base_page_theme',
    'delivery callback' => 'ajax_deliver',
    'type' => MENU_CALLBACK,
  );

  $admin_base = array(
    'file' => 'includes/callbacks.inc',
    'access arguments' => array('use panels dashboard'),
  );
  // Provide a nice location for a panels admin panel.
  $items['admin/structure/panels'] = array(
    'title' => 'Panels',
    'page callback' => 'panels_admin_page',
    'description' => 'Get a bird\'s eye view of items related to Panels.',
  ) + $admin_base;

  $items['admin/structure/panels/dashboard'] = array(
    'title' => 'Dashboard',
    'page callback' => 'panels_admin_page',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  ) + $admin_base;

  $items['admin/structure/panels/settings'] = array(
    'title' => 'Settings',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('panels_admin_settings_page'),
    'type' => MENU_LOCAL_TASK,
  ) + $admin_base;

  $items['admin/structure/panels/settings/general'] = array(
    'title' => 'General',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('panels_admin_settings_page'),
    'access arguments' => array('administer page manager'),
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  ) + $admin_base;

  if (module_exists('page_manager')) {
    $items['admin/structure/panels/settings/panel-page'] = array(
      'title' => 'Panel pages',
      'page callback' => 'panels_admin_panel_context_page',
      'type' => MENU_LOCAL_TASK,
      'weight' => -10,
    ) + $admin_base;
  }

  ctools_include('plugins', 'panels');
  $layouts = panels_get_layouts();
  foreach ($layouts as $name => $data) {
    if (!empty($data['hook menu'])) {
      if (is_array($data['hook menu'])) {
        $items += $data['hook menu'];
      }
      else if (function_exists($data['hook menu'])) {
        $data['hook menu']($items, $data);
      }
    }
  }


  return $items;
}

/**
 * Menu loader function to load a cache item for Panels AJAX.
 *
 * This load all of the includes needed to perform AJAX, and loads the
 * cache object and makes sure it is valid.
 */
function panels_edit_cache_load($cache_key) {
  ctools_include('display-edit', 'panels');
  ctools_include('plugins', 'panels');
  ctools_include('ajax');
  ctools_include('modal');
  ctools_include('context');

  return panels_edit_cache_get($cache_key);
}

/**
 * Implementation of hook_init()
 */
function panels_init() {
  // Safety: go away if CTools is not at an appropriate version.
  if (!module_invoke('ctools', 'api_version', PANELS_REQUIRED_CTOOLS_API)) {
    if (user_access('administer site configuration')) {
      drupal_set_message(t('Panels is enabled but CTools is out of date. All Panels modules are disabled until CTools is updated. See the status page for more information.'), 'error');
    }
    return;
  }

  ctools_add_css('panels', 'panels');
}

/**
 * Implementation of hook_permission().
 *
 * @todo Almost all of these need to be moved into pipelines.
 */
function panels_permission() {
  return array(
    'use panels dashboard' => array(
      'title' => t("Use Panels Dashboard"),
      'description' => t('Allows a user to access the <a href="@url">Panels Dashboard</a>.', array('@url' => url('admin/structure/panels'))),
    ),
    'view pane admin links' => array( // @todo
      'title' => t("View administrative links on Panel panes"),
      'description' => t(""),
    ),
    'administer pane access' => array( // @todo should we really have a global perm for this, or should it be moved into a pipeline question?
      'title' => t("Configure access settings on Panel panes"),
      'description' => t("Access rules (often also called visibility rules) can be configured on a per-pane basis. This permission allows users to configure those settings."),
    ),
    'use panels in place editing' => array(
      'title' => t("Use the Panels In-Place Editor"),
      'description' => t("Allows a user to utilize Panels' In-Place Editor."),
    ),
    'change layouts in place editing' => array(
      'title' => t("Change layouts with the Panels In-Place Editor"),
      'description' => t("Allows a user to change layouts with the IPE."),
    ),
    'bypass access in place editing' => array(
      'title' => t("Bypass access checks when using Panels In-Place Editor"),
      'description' => t("Allows using IPE even if user does not have additional permissions granted by other modules."),
      'restrict access' => TRUE,
    ),
    'administer advanced pane settings' => array(
      'title' => t("Configure advanced settings on Panel panes"),
      'description' => t(""),
    ),
    'administer panels layouts' => array(
      'title' => t("Administer Panels layouts"),
      'description' => t("Allows a user to administer exported Panels layout plugins & instances."),
    ),
    'administer panels styles' => array(
      'title' => t("Administer Panels styles"),
      'description' => t("DEPRECATED: Modules using this permission should use specific style permissions. See Issue #2329419 for more info."),
    ),
    'administer panels display styles' => array(
      'title' => t("Administer Panels display styles"),
      'description' => t("Allows a user to administer the styles of Panel displays."),
    ),
    'administer panels pane styles' => array(
      'title' => t("Administer Panels pane styles"),
      'description' => t("Allows a user to administer the styles of Panel panes."),
    ),
    'administer panels region styles' => array(
      'title' => t("Administer Panels region styles"),
      'description' => t("Allows a user to administer the styles of Panel regions."),
    ),
    'use panels caching features' => array(
      'title' => t("Configure caching settings on Panels"),
      'description' => t("Allows a user to configure caching on Panels displays and panes."),
    ),
    'use panels locks' => array(
      'title' => t('Use panel locks'),
      'description' => t('Allows a user to lock and unlock panes in a panel display.'),
    ),
    'use ipe with page manager' => array(
      'title' => t("Use the Panels In-Place Editor with Page Manager"),
      'description' => t('Allows users with access to the In-Place editor to administer page manager pages. This permission is only needed for users without "use page manager" access.'),
    ),
  );
}

/**
 * Implements hook_flush_caches().
 */
function panels_flush_caches() {
  if (db_table_exists('cache_panels')) {
    return array('cache_panels');
  }
}

// ---------------------------------------------------------------------------
// CTools hook implementations
//
// These aren't core Drupal hooks but they are just as important.

/**
 * Implementation of hook_ctools_plugin_directory() to let the system know
 * we implement task and task_handler plugins.
 */
function panels_ctools_plugin_directory($module, $plugin) {
  // Safety: go away if CTools is not at an appropriate version.
  if (!module_invoke('ctools', 'api_version', PANELS_REQUIRED_CTOOLS_API)) {
    return;
  }

  // We don't support the 'ctools' 'cache' plugin and pretending to causes
  // errors when they're in use.
  if ($module == 'ctools' && $plugin == 'cache') {
    return;
    // if we did we'd make a plugin/ctools_cache or something.
  }

  if ($module == 'page_manager' || $module == 'panels' || $module == 'ctools' || $module == 'stylizer') {
    // Panels and CTools both implement a 'cache' plugin but we don't implement
    // the CTools version.
    if ($module == 'ctools' && $plugin == 'cache') {
      return;
    }

    return 'plugins/' . $plugin;
  }
}

/**
 * Implements hook_ctools_plugin_type().
 *
 * Register layout, style, cache, and display_renderer plugin types, declaring
 * relevant plugin type information as necessary.
 */
function panels_ctools_plugin_type() {
  return array(
    'layouts' => array(
      'load themes' => TRUE, // Can define layouts in themes
      'process' => 'panels_layout_process',
      'child plugins' => TRUE,
    ),
    'styles' => array(
      'load themes' => TRUE,
      'process' => 'panels_plugin_styles_process',
      'child plugins' => TRUE,
    ),
    'cache' => array(),
    'display_renderers' => array(
      'classes' => array('renderer'),
    ),
    'panels_storage' => array(),
  );
}

/**
 * Ensure a layout has a minimal set of data.
 */
function panels_layout_process(&$plugin) {
  $plugin += array(
    'category' => t('Miscellaneous'),
    'description' => '',
  );
}

/**
 * Implementation of hook_ctools_plugin_api().
 *
 * Inform CTools about version information for various plugins implemented by
 * Panels.
 *
 * @param string $owner
 *   The system name of the module owning the API about which information is
 *   being requested.
 * @param string $api
 *   The name of the API about which information is being requested.
 */
function panels_ctools_plugin_api($owner, $api) {
  if ($owner == 'panels' && $api == 'styles') {
    // As of 6.x-3.6, Panels has a slightly new system for style plugins.
    return array('version' => 2.0);
  }

  if ($owner == 'panels' && $api == 'pipelines') {
    return array(
      'version' => 1,
      'path' => drupal_get_path('module', 'panels') . '/includes',
    );
  }
}

/**
 * Implementation of hook_views_api().
 */
function panels_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'panels') . '/plugins/views',
  );
}

/**
 * Perform additional processing on a style plugin.
 *
 * Currently this is only being used to apply versioning information to style
 * plugins in order to ensure the legacy renderer passes the right type of
 * parameters to a style plugin in a hybrid environment of both new and old
 * plugins.
 *
 * @see _ctools_process_data()
 *
 * @param array $plugin
 *   The style plugin that is being processed.
 * @param array $info
 *   The style plugin type info array.
 */
function panels_plugin_styles_process(&$plugin, $info) {
  $plugin += array(
    'weight' => 0,
  );

  $compliant_modules = ctools_plugin_api_info('panels', 'styles', 2.0, 2.0);
  $plugin['version'] = empty($compliant_modules[$plugin['module']]) ? 1.0 : $compliant_modules[$plugin['module']]['version'];
}

/**
 * Declare what style types Panels uses.
 */
function panels_ctools_style_base_types() {
  return array(
    'region' => array(
      'title' => t('Panel region'),
      'preview' => 'panels_stylizer_region_preview',
      'theme variables' => array('settings' => NULL, 'class' => NULL, 'content' => NULL),
    ),
    'pane' => array(
      'title' => t('Panel pane'),
      'preview' => 'panels_stylizer_pane_preview',
      'theme variables' => array('settings' => NULL, 'content' => NULL, 'pane' => NULL, 'display' => NULL),
    ),
  );
}

function panels_stylizer_lipsum() {
  return "
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus at velit dolor. Donec egestas tellus sit amet urna rhoncus adipiscing. Proin nec porttitor sem. Maecenas aliquam, purus nec tempus dignissim, nulla arcu aliquam diam, non tincidunt massa ante vel dolor. Aliquam sapien sapien, tincidunt id tristique at, pretium sagittis libero.</p>

    <p>Nulla facilisi. Curabitur lacinia, tellus sed tristique consequat, diam lorem scelerisque felis, at dictum purus augue facilisis lorem. Duis pharetra dignissim rutrum. Curabitur ac elit id dui dapibus tincidunt. Nulla eget sem quam, non eleifend eros. Cras porttitor tempus lectus ac scelerisque. Curabitur vehicula bibendum lorem, vitae ornare ligula venenatis ut.</p>
  ";
}

/**
 * Generate a preview given the current settings.
 */
function panels_stylizer_region_preview($plugin, $settings) {
  ctools_stylizer_add_css($plugin, $settings);
  return theme($plugin['theme'], array('settings' => $settings, 'class' => ctools_stylizer_get_css_class($plugin, $settings), 'content' => panels_stylizer_lipsum()));
}

/**
 * Generate a preview given the current settings.
 */
function panels_stylizer_pane_preview($plugin, $settings) {
  ctools_stylizer_add_css($plugin, $settings);
  $pane = new stdClass();

  $content = new stdClass;
  $content->title = t('Lorem ipsum');
  $content->content = panels_stylizer_lipsum();
  $content->type = 'dummy';
  $content->subtype = 'dummy';

  $content->css_class = ctools_stylizer_get_css_class($plugin, $settings);

  $display = new panels_display();

  if (!empty($plugin['theme'])) {
    return theme($plugin['theme'], array('settings' => $settings, 'content' => $content, 'pane' => $pane, 'display' => $display));
  }
  else {
    return theme('panels_pane', array('content' => $content, 'pane' => $pane, 'display' => $display));
  }
}

// ---------------------------------------------------------------------------
// Panels display editing

/**
 * @defgroup mainapi Functions comprising the main panels API
 * @{
 */

/**
 * Main API entry point to edit a panel display.
 *
 * Sample implementations utiltizing the the complex $destination behavior can be found
 * in panels_page_edit_content() and, in a separate contrib module, OG Blueprints
 * (http://drupal.org/project/og_blueprints), og_blueprints_blueprint_edit().
 *
 * @ingroup mainapi
 *
 * @param object $display instanceof panels_display \n
 *  A fully loaded panels $display object, as returned from panels_load_display().
 *  Merely passing a did is NOT sufficient. \n
 *  Note that 'fully loaded' means the $display must already be loaded with any contexts
 *  the caller wishes to have set for the display.
 * @param mixed $destination \n
 *  The redirect destination that the user should be taken to on form submission or
 *  cancellation. With panels_edit, $destination has complex effects on the return
 *  values of panels_edit() once the form has been submitted. See the explanation of
 *  the return value below to understand the different types of values returned by panels_edit()
 *  at different stages of FAPI. Under most circumstances, simply passing in
 *  drupal_get_destination() is all that's necessary.
 * @param array $content_types \n
 *  An associative array of allowed content types, typically as returned from
 *  panels_common_get_allowed_types(). Note that context partially governs available content types,
 *  so you will want to create any relevant contexts using panels_create_context() or
 *  panels_create_context_empty() to make sure all the appropriate content types are available.
 *
 * @return
 *  Because the functions called by panels_edit() invoke the form API, this function
 *  returns different values depending on the stage of form submission we're at. In Drupal 5,
 *  the phase of form submission is indicated by the contents of $_POST['op']. Here's what you'll
 *  get at different stages:
 *    -# If !$_POST['op']: then we're on on the initial passthrough and the form is being
 *       rendered, so it's the $form itself that's being returned. Because negative margins,
 *       a common CSS technique, bork the display editor's ajax drag-and-drop, it's important
 *       that the $output be printed, not returned. Use this syntax in the caller function: \n
 *          print theme('page', panels_edit($display, $destination, $content_types), FALSE); \n
 *    -# If $_POST['op'] == t('Cancel'): form submission has been cancelled. If empty($destination) == FALSE,
 *       then there is no return value and the panels API takes care of redirecting to $destination.
 *       If empty($destination) == TRUE, then there's still no return value, but the caller function
 *       has to take care of form redirection.
 *    -# If $_POST['op'] == ('Save'): the form has been submitted successfully and has run through
 *        panels_edit_display_submit(). $output depends on the value of $destination:
 *      - If empty($destination) == TRUE: $output contains the modified $display
 *        object, and no redirection will occur. This option is useful if the caller
 *        needs to perform additional operations on or with the modified $display before
 *        the page request is complete. Using hook_form_alter() to add an additional submit
 *        handler is typically the preferred method for something like this, but there
 *        are certain use cases where that is infeasible and $destination = NULL should
 *        be used instead. If this method is employed, the caller will need to handle form
 *        redirection. Note that having $_REQUEST['destination'] set, whether via
 *        drupal_get_destination() or some other method, will NOT interfere with this
 *        functionality; consequently, you can use drupal_get_destination() to safely store
 *        your desired redirect in the caller function, then simply use drupal_goto() once
 *        panels_edit() has done its business.
 *      - If empty($destination) == FALSE: the form will redirect to the URL string
 *        given in $destination and NO value will be returned.
 */
function panels_edit($display, $destination = NULL, $content_types = NULL, $title = FALSE) {
  ctools_include('display-edit', 'panels');
  ctools_include('ajax');
  ctools_include('plugins', 'panels');
  return _panels_edit($display, $destination, $content_types, $title);
}

/**
 * API entry point for selecting a layout for a given display.
 *
 * Layout selection is nothing more than a list of radio items encompassing the available
 * layouts for this display, as defined by .inc files in the panels/layouts subdirectory.
 * The only real complexity occurs when a user attempts to change the layout of a display
 * that has some content in it.
 *
 * @param object $display instanceof panels_display \n
 *  A fully loaded panels $display object, as returned from panels_load_display().
 *  Merely passing a did is NOT sufficient.
 * @param string $finish
 *  A string that will be used for the text of the form submission button. If no value is provided,
 *  then the form submission button will default to t('Save').
 * @param mixed $destination
 *  Basic usage is a string containing the URL that the form should redirect to upon submission.
 *  For a discussion of advanced usages, see panels_edit().
 * @param mixed $allowed_layouts
 *  Allowed layouts has three different behaviors that depend on which of three value types
 *  are passed in by the caller:
 *    #- if $allowed_layouts instanceof panels_allowed_layouts (includes subclasses): the most
 *       complex use of the API. The caller is passing in a loaded panels_allowed_layouts object
 *       that the client module previously created and stored somewhere using a custom storage
 *       mechanism.
 *    #- if is_string($allowed_layouts): the string will be used in a call to variable_get() which
 *       will call the $allowed_layouts . '_allowed_layouts' var. If the data was stored properly
 *       in the system var, the $allowed_layouts object will be unserialized and recreated.
 *       @see panels_common_set_allowed_layouts()
 *    #- if is_null($allowed_layouts): the default behavior, which also provides backwards
 *       compatibility for implementations of the Panels2 API written before beta4. In this case,
 *       a dummy panels_allowed_layouts object is created which does not restrict any layouts.
 *       Subsequent behavior is indistinguishable from pre-beta4 behavior.
 *
 * @return
 *  Can return nothing, or a modified $display object, or a redirection string; return values for the
 *  panels_edit* family of functions are quite complex. See panels_edit() for detailed discussion.
 * @see panels_edit()
 */
function panels_edit_layout($display, $finish, $destination = NULL, $allowed_layouts = NULL) {
  ctools_include('display-layout', 'panels');
  ctools_include('plugins', 'panels');
  return _panels_edit_layout($display, $finish, $destination, $allowed_layouts);
}

// ---------------------------------------------------------------------------
// Panels database functions

/**
 * Forms the basis of a panel display
 */
class panels_display {
  var $args = array();
  var $content = array();
  var $panels = array();
  var $incoming_content = NULL;
  var $css_id = NULL;
  var $context = array();
  var $did = 'new';
  var $renderer = 'standard';

  function add_pane(&$pane, $location = NULL) {
    // If no location specified, use what's set in the pane.
    if (empty($location)) {
      $location = $pane->panel;
    }
    else {
      $pane->panel = $location;
    }

    // Generate a permanent uuid for this pane, and use
    // it as a temporary pid.
    $pane->uuid = ctools_uuid_generate();
    $pane->pid = 'new-' . $pane->uuid;

    // Add the pane to the approprate spots.
    $this->content[$pane->pid] = &$pane;
    $this->panels[$location][] = $pane->pid;
  }

  function duplicate_pane($pid, $location = FALSE) {
    $pane = $this->clone_pane($pid);
    $this->add_pane($pane, $location);
  }

  function clone_pane($pid) {
    $pane = clone $this->content[$pid];
    $pane->uuid = ctools_uuid_generate();
    return $pane;
  }

  /**
   * Get the title from a display.
   *
   * The display must have already been rendered, or the setting to set the
   * display's title from a pane's title will not have worked.
   *
   * @return
   *   The title to use. If NULL, this means to let any default title that may be in use
   *   pass through. i.e, do not actually set the title.
   */
  function get_title() {
    switch ($this->hide_title) {
      case PANELS_TITLE_NONE:
        return '';

      case PANELS_TITLE_PANE:
        return isset($this->stored_pane_title) ? $this->stored_pane_title : '';

      case PANELS_TITLE_FIXED:
      case FALSE; // For old exported panels that are not in the database.
        if (!empty($this->title)) {
          return filter_xss_admin(ctools_context_keyword_substitute($this->title, array(), $this->context));
        }
        return NULL;
    }
  }

  /**
   * Render this panels display.
   *
   * After checking to ensure the designated layout plugin is valid, a
   * display renderer object is spawned and runs its rendering logic.
   *
   * @param mixed $renderer
   *    An instantiated display renderer object, or the name of a display
   *    renderer plugin+class to be fetched. Defaults to NULL. When NULL, the
   *    predesignated display renderer will be used.
   */
  function render($renderer = NULL) {
    $layout = panels_get_layout($this->layout);
    if (!$layout) {
      return NULL;
    }

    // If we were not given a renderer object, load it.
    if (!is_object($renderer)) {
      // If the renderer was not specified, default to $this->renderer
      // which is either standard or was already set for us.
      $renderer = panels_get_renderer_handler(!empty($renderer) ? $renderer : $this->renderer, $this);
      if (!$renderer) {
        return NULL;
      }
    }

    $output = '';
    // Let modules act just prior to render.
    foreach (module_implements('panels_pre_render') as $module) {
      $function = $module . '_panels_pre_render';
      $output .= $function($this, $renderer);
    }

    $output .= $renderer->render();

    // Let modules act just after render.
    foreach (module_implements('panels_post_render') as $module) {
      $function = $module . '_panels_post_render';
      $output .= $function($this, $renderer);
    }
    return $output;
  }

  /**
   * Determine if the given user can perform the requested operation.
   *
   * @param string $op
   *   An operation like: create, read, update, or delete.
   * @param object $account
   *   (optional) The account to check access for.
   *
   * @return bool
   *   TRUE if access is granted; otherwise FALSE.
   */
  function access($op, $account = NULL) {
    global $user;

    if (!$account) {
      $account = $user;
    }

    // Even administrators need to go through the access system. However, to
    // support legacy plugins, user 1 gets full access no matter what.
    if ($account->uid == 1) {
      return TRUE;
    }

    if (!in_array($op, array('create', 'read', 'update', 'delete', 'change layout'))) {
      return FALSE;
    }

    if (empty($this->storage_type) || empty($this->storage_id)) {
      return FALSE;
    }

    if ($this->storage_type == 'unknown') {
      return FALSE;
    }

    $storage_plugin = panels_get_panels_storage_plugin($this->storage_type);
    if (!$storage_plugin) {
      return FALSE;
    }

    $access_callback = panels_plugin_get_function('panels_storage', $storage_plugin, 'access callback');
    if (!$access_callback) {
      return FALSE;
    }

    return $access_callback($this->storage_type, $this->storage_id, $op, $account);
  }
}

/**
 * }@ End of 'defgroup mainapi', although other functions are specifically added later
 */

/**
 * Creates a new display, setting the ID to our magic new id.
 */
function panels_new_display() {
  ctools_include('export');
  $display = ctools_export_new_object('panels_display', FALSE);
  $display->did = 'new';
  return $display;
}

/**
 * Create a new pane.
 *
 * @todo -- use schema API for some of this?
 */
function panels_new_pane($type, $subtype, $set_defaults = FALSE) {
  ctools_include('export');
  $pane = ctools_export_new_object('panels_pane', FALSE);
  $pane->pid = 'new';
  $pane->type = $type;
  $pane->subtype = $subtype;
  if ($set_defaults) {
    ctools_include('content');
    $content_type = ctools_get_content_type($type);
    $content_subtype = ctools_content_get_subtype($content_type, $subtype);
    $pane->configuration = ctools_content_get_defaults($content_type, $content_subtype);
  }
  drupal_alter('panels_new_pane', $pane);

  return $pane;
}

/**
 * Load and fill the requested $display object(s).
 *
 * Helper function primarily for for panels_load_display().
 *
 * @param array $dids
 *  An indexed array of dids to be loaded from the database.
 *
 * @return $displays
 *  An array of displays, keyed by their display dids.
 *
 * @todo schema API can drasticly simplify this code.
 */
function panels_load_displays($dids) {
  $displays = array();
  if (empty($dids) || !is_array($dids)) {
    return $displays;
  }

  $result = db_query("SELECT * FROM {panels_display} WHERE did IN (:dids)", array(':dids' => $dids));

  ctools_include('export');
  foreach ($result as $obj) {
    $displays[$obj->did] = ctools_export_unpack_object('panels_display', $obj);
    // Modify the hide_title field to go from a bool to an int if necessary.
  }

  $result = db_query("SELECT * FROM {panels_pane} WHERE did IN (:dids) ORDER BY did, panel, position", array(':dids' => $dids));
  foreach ($result as $obj) {
    $pane = ctools_export_unpack_object('panels_pane', $obj);

    $displays[$pane->did]->panels[$pane->panel][] = $pane->pid;
    $displays[$pane->did]->content[$pane->pid] = $pane;
  }

  return $displays;
}

/**
 * Load a single display.
 *
 * @ingroup mainapi
 *
 * @param int $did
 *  The display id (did) of the display to be loaded.
 *
 * @return object $display instanceof panels_display \n
 *  Returns a partially-loaded panels_display object. $display objects returned from
 *  from this function have only the following data:
 *    - $display->did (the display id)
 *    - $display->name (the 'name' of the display, where applicable - it often isn't)
 *    - $display->layout (a string with the system name of the display's layout)
 *    - $display->panel_settings (custom layout style settings contained in an associative array; NULL if none)
 *    - $display->layout_settings (panel size and configuration settings for Flexible layouts; NULL if none)
 *    - $display->css_id (the special css_id that has been assigned to this display, if any; NULL if none)
 *    - $display->content (an array of pane objects, keyed by pane id (pid))
 *    - $display->panels (an associative array of panel regions, each an indexed array of pids in the order they appear in that region)
 *    - $display->cache (any relevant data from panels_simple_cache)
 *    - $display->args
 *    - $display->incoming_content
 *
 * While all of these members are defined, $display->context is NEVER defined in the returned $display;
 * it must be set using one of the ctools_context_create() functions.
 */
function panels_load_display($did) {
  $displays = panels_load_displays(array($did));
  if (!empty($displays)) {
    return array_shift($displays);
  }
}

/**
 * Save a display object.
 *
 * @ingroup mainapi
 *
 * Note that a new $display only receives a real did once it is run through
 * this function, and likewise for the pid of any new pane.
 *
 * Until then, a new display uses a string placeholder, 'new', in place of
 * a real did, and a new pane (whether on a new $display or not) appends a
 * universally-unique identifier (which is stored permanently in the 'uuid'
 * field). This format is also used in place of the real pid for exports.
 *
 * @param object $display instanceof panels_display \n
 *  The display object to be saved. Passed by reference so the caller need not use
 *  the return value for any reason except convenience.
 *
 * @return object $display instanceof panels_display \n
 */
function panels_save_display(&$display) {
  $update = (isset($display->did) && is_numeric($display->did)) ? array('did') : array();
  if (empty($display->uuid) || !ctools_uuid_is_valid($display->uuid)) {
    $display->uuid = ctools_uuid_generate();
  }
  drupal_write_record('panels_display', $display, $update);

  $pids = array();
  if ($update) {
    // Get a list of all panes currently in the database for this display so we can know if there
    // are panes that need to be deleted. (i.e, aren't currently in our list of panes).
    $result = db_query("SELECT pid FROM {panels_pane} WHERE did = :did", array(':did' => $display->did));
    foreach ($result as $pane) {
      $pids[$pane->pid] = $pane->pid;
    }
  }

  // update all the panes
  ctools_include('plugins', 'panels');
  ctools_include('content');

  foreach ($display->panels as $id => $panes) {
    $position = 0;
    $new_panes = array();
    foreach ((array) $panes as $pid) {
      if (!isset($display->content[$pid])) {
        continue;
      }
      $pane = $display->content[$pid];
      $type = ctools_get_content_type($pane->type);

      $pane->position = $position++;
      $pane->did = $display->did;

      $old_pid = $pane->pid;

      if (empty($pane->uuid) || !ctools_uuid_is_valid($pane->uuid)) {
        $pane->uuid = ctools_uuid_generate();
      }

      drupal_write_record('panels_pane', $pane, is_numeric($pid) ? array('pid') : array());

      // Allow other modules to take action after a pane is saved.
      if ($pane->pid == $old_pid) {
        module_invoke_all('panels_pane_update', $pane);