Media gallery – inserting full size images without link

UPDATE

I’ve just submitted a core patch to add link="none" support to the shortcode.

ORIGINAL ANSWER

You don’t need to hack core to do what you want to do; just use the appropriate shortcode parameters, e.g.:

If you want to change the defaults, then use the post_gallery filter:

function mytheme_gallery_shortcode_defaults( $output, $attr ) {
    global $post;
    $attr = array(
        'columns' => '0',
        'size' => 'full'
    );
    return $output;
}
add_filter( 'post_gallery', 'mytheme_gallery_shortcode_defaults', 10, 2 );

The only way to remove the link is to clear the image link field in the Media Library, or you can do some involved code replacement.

EDIT

I’m somewhat guessing here, as I’m not fully familiar with filtering the gallery output. I’ve made a couple of modifications, including passing both variables to the callback, correcting the add_filter() call to accommodate both variables, and returning $output rather than $attr.

EDIT 2

Okay, so it looks like, currently, the only way to override th shortcode attributes is to rewrite the entire walker. See this Trac Ticket for details.

So, basically, this:

function mytheme_gallery_shortcode( $output, $attr ) {
    global $post, $wp_locale;

    static $instance = 0;
    $instance++;

    // Allow plugins/themes to override the default gallery template.
    $output = apply_filters('post_gallery', '', $attr);
    if ( $output != '' )
        return $output;

    // We're trusting author input, so let's at least make sure it looks like a valid orderby statement
    if ( isset( $attr['orderby'] ) ) {
        $attr['orderby'] = sanitize_sql_orderby( $attr['orderby'] );
        if ( !$attr['orderby'] )
            unset( $attr['orderby'] );
    }

    extract(shortcode_atts(array(
        'order'      => 'ASC',
        'orderby'    => 'menu_order ID',
        'id'         => $post->ID,
        'itemtag'    => 'dl',
        'icontag'    => 'dt',
        'captiontag' => 'dd',
        'columns'    => 0,
        'size'       => 'full',
        'include'    => '',
        'exclude'    => '',
                'link'       => 'none'
    ), $attr));

    $id = intval($id);
    if ( 'RAND' == $order )
        $orderby = 'none';

    if ( !empty($include) ) {
        $include = preg_replace( '/[^0-9,]+/', '', $include );
        $_attachments = get_posts( array('include' => $include, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );

        $attachments = array();
        foreach ( $_attachments as $key => $val ) {
            $attachments[$val->ID] = $_attachments[$key];
        }
    } elseif ( !empty($exclude) ) {
        $exclude = preg_replace( '/[^0-9,]+/', '', $exclude );
        $attachments = get_children( array('post_parent' => $id, 'exclude' => $exclude, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );
    } else {
        $attachments = get_children( array('post_parent' => $id, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );
    }

    if ( empty($attachments) )
        return '';

    if ( is_feed() ) {
        $output = "\n";
        foreach ( $attachments as $att_id => $attachment )
            $output .= wp_get_attachment_link($att_id, $size, true) . "\n";
        return $output;
    }

    $itemtag = tag_escape($itemtag);
    $captiontag = tag_escape($captiontag);
    $columns = intval($columns);
    $itemwidth = $columns > 0 ? floor(100/$columns) : 100;
    $float = is_rtl() ? 'right' : 'left';

    $selector = "gallery-{$instance}";

    $gallery_style = $gallery_div = '';
    if ( apply_filters( 'use_default_gallery_style', true ) )
        $gallery_style = "
        <style type="text/css">
            #{$selector} {
                margin: auto;
            }
            #{$selector} .gallery-item {
                float: {$float};
                margin-top: 10px;
                text-align: center;
                width: {$itemwidth}%;
            }
            #{$selector} img {
                border: 2px solid #cfcfcf;
            }
            #{$selector} .gallery-caption {
                margin-left: 0;
            }
        </style>
        <!-- see gallery_shortcode() in wp-includes/media.php -->";
    $size_class = sanitize_html_class( $size );
    $gallery_div = "<div id='$selector' class="gallery galleryid-{$id} gallery-columns-{$columns} gallery-size-{$size_class}">";
    $output = apply_filters( 'gallery_style', $gallery_style . "\n\t\t" . $gallery_div );

    $i = 0;
    foreach ( $attachments as $id => $attachment ) {
                $image = wp_get_attachment_image( $id, $size, false );
        $link = isset($attr['link']) && 'file' == $attr['link'] ? wp_get_attachment_link($id, $size, false, false) : wp_get_attachment_link($id, $size, true, false);
                $image_output = ( 'none' == $attr['link'] ? $image : $link );

        $output .= "<{$itemtag} class="gallery-item">";
        $output .= "
            <{$icontag} class="gallery-icon">
                $image_output
            </{$icontag}>";
        if ( $captiontag && trim($attachment->post_excerpt) ) {
            $output .= "
                <{$captiontag} class="wp-caption-text gallery-caption">
                " . wptexturize($attachment->post_excerpt) . "
                </{$captiontag}>";
        }
        $output .= "</{$itemtag}>";
        if ( $columns > 0 && ++$i % $columns == 0 )
            $output .= '<br style="clear: both" />';
    }

    $output .= "
            <br style="clear: both;" />
        </div>\n";

    return $output;
}
add_filter( 'post_gallery', 'mytheme_gallery_shortcode', 10, 2 );