Custom Omeka Exhibit code to skip empty pages / section headers

custom_exhibit_functions.php

/**
 * Check if the provided exhibit page is empty (layout type = text, no text)
 *
 * @param ExhibitPage $exhibitPage
 * @return boolean
 **/
function my_exhibit_builder_exhibit_page_is_empty($exhibitPage)
{
	if ($exhibitPage->layout == 'text') {
		$entries = $exhibitPage->getPageEntries();
		if ($entry = $entries[1]) {
			if (trim($entry->text) == '') {
				return true;
			}
		}
	}
	return false;
}


/**
 * Return the first non-empty page in an exhibit, beginning with provided page
 * If provided page is non-empty, it will be immediately returned; otherwise a search
 * proceeds through the page structure to find the next non-empty page.
 *
 * @param Exhibit $exhibit
 * @param ExhibitPage|null $exhibitPage
 * @return ExhibitPage|null 
 **/
function my_exhibit_builder_get_first_nonempty_page($exhibit, $exhibitPage = null)
{
	// if a page is passed in, start there, otherwise load the first top page	
	if (!$exhibitPage)
	{
		$topPages = $exhibit->getTopPages();
		if (count($topPages) > 0) 
		{
			$exhibitPage = $topPages[0];
		}
		else 
		{
			return null;
		}
	}

	// check if page is text layout, and empty
	if (my_exhibit_builder_exhibit_page_is_empty($exhibitPage)) 
	{
		// page is empty, look for the next page
		$targetPage = null;

		if ($nextPage = $exhibitPage->firstChildOrNext()) 
		{
			$targetPage = $nextPage;
		} 
		elseif ($exhibitPage->parent_id) 
		{
			$parentPage = $exhibitPage->getParent();
			$nextParentPage = $parentPage->next();
			if ($nextParentPage) 
			{
				$targetPage = $nextPage;
			}
		}

		return my_exhibit_builder_get_first_nonempty_page($exhibit, $targetPage);
	}
	
	// page is not empty, so return it
	return $exhibitPage;	
}


/**
 * Return a link to the next exhibit page
 * Customized from ExhibitBuilder 2.0 code
 *
 * @param string $text Link text
 * @param array $props Link attributes
 * @param ExhibitPage $exhibitPage If null, will use the current exhibit page
 * @return string
 */
function my_exhibit_builder_link_to_next_page($text = null, $props = array(), $exhibitPage = null)
{
    if (!$exhibitPage) {
        $exhibitPage = get_current_record('exhibit_page');
    }

    $exhibit = get_record_by_id('Exhibit', $exhibitPage->exhibit_id);

    $targetPage = null;

    // if page object exists, grab link to the first child page if exists. If it doesn't, grab
    // a link to the next page
    if ($nextPage = $exhibitPage->firstChildOrNext()) {
        $targetPage = $nextPage;
    } elseif ($exhibitPage->parent_id) {
        $parentPage = $exhibitPage->getParent();
        $nextParentPage = $parentPage->next();
        if ($nextParentPage) {
            $targetPage = $nextPage;
        }
    }

	// CUSTOM
	// IF PAGE IS EMPTY, SKIP IT!
	// THIS ALLOWS SECTION HEADERS
	if ($targetPage && my_exhibit_builder_exhibit_page_is_empty($targetPage)) {
		return my_exhibit_builder_link_to_next_page($text, $props, $targetPage);
	}

    if ($targetPage) {
        if (!isset($props['class'])) {
            $props['class'] = 'next-page';
        }
        if ($text === null) {
            $text = metadata($targetPage, 'title') . ' »';
        }
        return exhibit_builder_link_to_exhibit($exhibit, $text, $props, $targetPage);
    }

    return null;
}


/**
 * Return a link to the previous exhibit page
 * Customized from ExhibitBuilder 2.0 code
 *
 * @param string $text Link text
 * @param array $props Link attributes
 * @param ExhibitPage $exhibitPage If null, will use the current exhibit page
 * @return string
 */
function my_exhibit_builder_link_to_previous_page($text = null, $props = array(), $exhibitPage = null)
{
    if (!$exhibitPage) {
        $exhibitPage = get_current_record('exhibit_page');
    }
    $exhibit = get_record_by_id('Exhibit', $exhibitPage->exhibit_id);

    // If page object exists, grab link to previous exhibit page if exists. If it doesn't, grab
    // a link to the last page on the previous parent page, or the exhibit if at top level
    if ($previousPage = $exhibitPage->previousOrParent()) {

		// CUSTOM
		// IF PAGE IS EMPTY, SKIP IT!
		// THIS ALLOWS SECTION HEADERS
		if (my_exhibit_builder_exhibit_page_is_empty($previousPage)){
			return my_exhibit_builder_link_to_previous_page($text, $props, $previousPage);
		}

        if(!isset($props['class'])) {
            $props['class'] = 'previous-page';
        }
        if ($text === null) {
            $text = '« ' . metadata($previousPage, 'title');
        }
        return exhibit_builder_link_to_exhibit($exhibit, $text, $props, $previousPage);
    }

    return null;
}


function my_exhibit_builder_is_page_ancestor($page, $parent)
{
	if (!$page) return false;
	
	while ($page->parent_id) 
	{
		$page = $page->getParent();
		if ($page->id == $parent->id)
			return true;
	}
	return false;
}


/**
 * Returns the HTML for a nested navigation for exhibit sections and pages
 * Customized for my from ExhibitBuilder 1.x code, updated for Omeka 2.0
 * Top level pages are treated as "sections" (eliminated in Omeka 2.0)
 *
 * @param Exhibit|null $exhibit If null, will use the current exhibit
 * @param boolean $showAllPages
 * @param integer $cols The number of columns to split the menu
 * @param ExhibitPage $exhibitPage Page to mark as selected
 * @return string
 **/
function my_exhibit_builder_nested_nav($exhibit = null, $showAllPages = false, $cols = 2, $exhibitPage = null)
{
    if (!$exhibit) {
        if (!($exhibit = get_current_record('exhibit'))) {
            return;
        }    
    }
	
	if (!$exhibitPage) {
		$exhibitPage = get_current_record('exhibit_page', 0);
	}

	$tot = count($exhibit->getTopPages());
	if ($tot <= $cols) $cols = 1;
	$ctr = 0;

    $html = '<ul class="exhibit-section-nav">';

    foreach ($exhibit->getTopPages() as $exhibitTopPage) 
	{
		if ($ctr == ceil($tot / $cols))
		{
		    $html .= '</ul><ul class="exhibit-section-nav">';
			$ctr = 1;
		}
		else
		{
			$ctr = $ctr + 1;
		}

		// note that the link is to the next non-empty page if the page is empty
        $html .= '<li class="exhibit-nested-section' . ($exhibitPage->id == $exhibitTopPage->id || my_exhibit_builder_is_page_ancestor($exhibitPage, $exhibitTopPage) ? ' current' : '') . '"><a class="exhibit-section-title" href="' . html_escape(exhibit_builder_exhibit_uri($exhibit, my_exhibit_builder_get_first_nonempty_page($exhibit, $exhibitTopPage))) . '">' . str_replace('/', '/<wbr>', html_escape($exhibitTopPage->title)) . '</a>';

        if ($showAllPages || $exhibitPage->id == $exhibitTopPage->id || my_exhibit_builder_is_page_ancestor($exhibitPage, $exhibitTopPage))
		{
            $html .= my_exhibit_builder_child_page_nav($exhibitTopPage);
        }
        $html .= '</li>';
    }
    $html .= '</ul>';
    // $html = apply_filters('exhibit_builder_nested_nav', $html, $exhibit, $showAllPages);
    return $html;
}


/**
 * Return the markup for the exhibit child page navigation.
 *
 * @param ExhibitPage|null $exhibitPage If null, uses the current exhibit page
 * @return string
 */
function my_exhibit_builder_child_page_nav($exhibitPage = null, $currentPage = null)
{
    if (!$exhibitPage) {
        $exhibitPage = get_current_record('exhibit_page');
    }
	
	if (!$currentPage) {
        $currentPage = get_current_record('exhibit_page', 0);
    }

    $exhibit = $exhibitPage->getExhibit();
    $children = exhibit_builder_child_pages($exhibitPage);
    $html = '<ul class="exhibit-child-nav navigation">' . "\n";
    foreach ($children as $child) {
        $html .= '<li class="' . ((@$currentPage->id == $child->id) ? 'current' : '') . '"><a href="' . html_escape(exhibit_builder_exhibit_uri($exhibit, $child)) . '">' . html_escape($child->title) . '</a></li>';
    }
    $html .= '</ul>' . "\n";
    return $html;
}