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<?php
/**
* Recursively build RDFa <meta> elements used for Open Graph protocol
*
* @since 1.0
* @param string $property whitespace separated list of CURIEs placed in a property attribute
* @param mixed content attribute value for the given property. use an array for array property values or structured properties
*/
function fb_output_og_protocol( $property, $content ) {
if ( empty( $property ) || empty( $content ) )
return;
// array of property values or structured property
if ( is_array( $content ) ) {
foreach( $content as $structured_property => $content_value ) {
// handle numeric keys from regular arrays
// account for the special structured property of url which is equivalent to the root tag and sets up the structure
if ( ! is_string( $structured_property ) || $structured_property === 'url' )
fb_output_og_protocol( $property, $content_value );
else
fb_output_og_protocol( $property . ':' . $structured_property, $content_value );
}
}
else {
echo "<meta property=\"$property\" content=\"" . esc_attr( $content ) . "\" />\n";
}
}
function fb_strip_and_format_desc( $post ) {
$desc_no_html = "";
$desc_no_html = strip_shortcodes( $desc_no_html ); // Strip shortcodes first in case there is HTML inside the shortcode
$desc_no_html = wp_strip_all_tags( $desc_no_html ); // Strip all html
$desc_no_html = trim( $desc_no_html ); // Trim the final string, we may have stripped everything out of the post so this will make the value empty if that's the case
// Check if empty, may be that the strip functions above made excerpt empty, doubhtful but we want to be 100% sure.
if( empty($desc_no_html) ) {
$desc_no_html = $post->post_content; // Start over, this time with the post_content
$desc_no_html = strip_shortcodes( $desc_no_html ); // Strip shortcodes first in case there is HTML inside the shortcode
$desc_no_html = str_replace(']]>', ']]&gt;', $desc_no_html); // Angelo Recommendation, if for some reason ]]> happens to be in the_content, rare but We've seen it happen
$desc_no_html = wp_strip_all_tags($desc_no_html);
$desc_length = strlen($desc_no_html);
$desc_no_html = substr($desc_no_html, 0, 255);
if ( $desc_no_html > $desc_length ) {
$desc_no_html .= '...';
}
$desc_no_html = trim($desc_no_html); // Trim the final string, we may have stripped everything out of the post so this will make the value empty if that's the case
}
$desc_no_html = str_replace( array( "\r\n", "\r", "\n" ), ' ',$desc_no_html); // I take it Facebook doesn't like new lines?
return $desc_no_html;
}
/**
* Add Open Graph protocol markup to <head>
*
* @since 1.0
*/
function fb_add_og_protocol() {
global $post;
$meta_tags = array(
'http://ogp.me/ns#locale' => fb_get_locale(),
'http://ogp.me/ns#site_name' => get_bloginfo( 'name' ),
'http://ogp.me/ns#type' => 'website'
);
if ( is_home() || is_front_page() ) {
$meta_tags['http://ogp.me/ns#title'] = get_bloginfo( 'name' );
$meta_tags['http://ogp.me/ns#description'] = get_bloginfo( 'description' );
} else if ( is_single() ) {
$post_type = get_post_type();
$meta_tags['http://ogp.me/ns#type'] = 'article';
$meta_tags['http://ogp.me/ns#url'] = apply_filters( 'rel_canonical', get_permalink() );
if ( post_type_supports( $post_type, 'title' ) )
$meta_tags['http://ogp.me/ns#title'] = get_the_title();
if ( post_type_supports( $post_type, 'excerpt' ) ) {
// thanks to Angelo Mandato (http://wordpress.org/support/topic/plugin-facebook-plugin-conflicts-with-powerpress?replies=16)
// Strip and format the wordpress way, but don't apply any other filters which adds junk that ends up getitng stripped back out
if ( !post_password_required($post) ) {
// First lets get the post excerpt (shouldn't have any html, but anyone can enter anything...)
$meta_tags['http://ogp.me/ns#description'] = fb_strip_and_format_desc ( $post );
}
}
$meta_tags['http://ogp.me/ns/article#published_time'] = get_the_date('c');
$meta_tags['http://ogp.me/ns/article#modified_time'] = get_the_modified_date('c');
if ( post_type_supports( $post_type, 'author' ) && isset( $post->post_author ) )
$meta_tags['http://ogp.me/ns/article#author'] = get_author_posts_url( $post->post_author );
// add the first category as a section. all other categories as tags
$cat_ids = get_the_category();
if ( ! empty( $cat_ids ) ) {
$cat = get_category( $cat_ids[0] );
if ( ! empty( $cat ) )
$meta_tags['http://ogp.me/ns/article#section'] = $cat->name;
//output the rest of the categories as tags
unset( $cat_ids[0] );
if ( ! empty( $cat_ids ) ) {
$meta_tags['http://ogp.me/ns/article#tag'] = array();
foreach( $cat_ids as $cat_id ) {
$cat = get_category( $cat_id );
$meta_tags['http://ogp.me/ns/article#tag'][] = $cat->name;
unset( $cat );
}
}
}
// add tags. treat tags as lower priority than multiple categories
$tags = get_the_tags();
if ( $tags ) {
if ( ! array_key_exists( 'http://ogp.me/ns/article#tag', $meta_tags ) )
$meta_tags['http://ogp.me/ns/article#tag'] = array();
foreach ( $tags as $tag ) {
$meta_tags['http://ogp.me/ns/article#tag'][] = $tag->name;
}
}
// does current post type and the current theme support post thumbnails?
if ( post_type_supports( $post_type, 'thumbnail' ) && function_exists( 'has_post_thumbnail' ) && has_post_thumbnail() ) {
list( $post_thumbnail_url, $post_thumbnail_width, $post_thumbnail_height ) = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
if ( ! empty( $post_thumbnail_url ) ) {
$image = array( 'url' => $post_thumbnail_url );
if ( ! empty( $post_thumbnail_width ) )
$image['width'] = absint( $post_thumbnail_width );
if ( ! empty($post_thumbnail_height) )
$image['height'] = absint( $post_thumbnail_height );
$meta_tags['http://ogp.me/ns#image'] = array( $image );
}
}
}
else if ( is_author() && isset( $post->post_author ) ) {
$meta_tags['http://ogp.me/ns#type'] = 'profile';
$meta_tags['http://ogp.me/ns/profile#first_name'] = get_the_author_meta( 'first_name', $post->post_author );
$meta_tags['http://ogp.me/ns/profile#last_name'] = get_the_author_meta( 'last_name', $post->post_author );
if ( is_multi_author() )
$meta_tags['http://ogp.me/ns/profile#username'] = get_the_author_meta( 'login', $post->post_author );
}
else if ( is_page() ) {
$meta_tags['http://ogp.me/ns#type'] = 'article';
$meta_tags['http://ogp.me/ns#title'] = get_the_title();
$meta_tags['http://ogp.me/ns#url'] = apply_filters( 'rel_canonical', get_permalink() );
}
$options = get_option( 'fb_options' );
if ( ! empty( $options['app_id'] ) )
$meta_tags['http://ogp.me/ns/fb#app_id'] = $options['app_id'];
$meta_tags = apply_filters( 'fb_meta_tags', $meta_tags, $post );
foreach ( $meta_tags as $property => $content ) {
fb_output_og_protocol( $property, $content );
}
}
add_action( 'wp_head', 'fb_add_og_protocol' );
?>