Create a custom element fo visual Composer Grid Builder

add-vc-grid-element.php

// _dt_fancy_header_bg_image

add_filter( 'vc_gitem_template_attribute_fancy_image', 'vc_gitem_template_attribute_fancy_image', 10, 2 );

function vc_gitem_template_attribute_fancy_image( $value, $data ) {
    /**
     * @var Wp_Post $post
     * @var string $data
     */
    global $post;
    $output = '';
    $postID = $post->ID;
    $fancy_head_ID = get_post_meta( $post->ID, '_dt_fancy_header_bg_image', true );
    $image_string = wp_get_attachment_image( $fancy_head_ID[0], 'medium' );

    $output .= "\n\t" . '<div class="' . $css_class . '">';
    $output .= "\n\t\t" . '<div class="wpb_wrapper">';
    $output .= "\n\t\t\t" . $image_string;
    $output .= "\n\t\t" . '</div> ';
    $output .= "\n\t" . '</div> ';
    // return a template for featured_image variable
    //return vc_include_template( 'params/vc_grid_item/attributes/fancy_image.php', array(
        //'post' => $post,
        //'data' => $data
    //) );
    return $output;
}

add_filter( 'vc_grid_item_shortcodes', 'my_module_add_grid_shortcodes' );
function my_module_add_grid_shortcodes( $shortcodes ) {
    $shortcodes['vc_batt_image'] = array(
        'name' => __( 'Post Image2', 'js_composer' ),
        'base' => 'vc_batt_image',
        'icon' => 'vc_icon-vc-gitem-image',
        'category' => __( 'Post', 'js_composer' ),
        'description' => __( 'Featured image', 'js_composer' ),
        'post_type' => Vc_Grid_Item_Editor::postType(),
    );
    return $shortcodes;
}

add_shortcode( 'vc_batt_image', 'vc_gitem_fancy_image_render' );
function vc_gitem_fancy_image_render( $atts ) {
    return '{{fancy_image: }}';
}