Use this action to check if required WordPress plugins are already installed.

check-plugin.php

<?php
/**
* 因為在開發佈景主題的時候，會使用其他外掛的 shortcodes 來輔助。
* 掛在佈景主題的 functions.php 裡面，可以提醒使用者安裝相容的外掛。
*/
add_action( 'admin_init', 'check_plugin');
function check_plugin() {
    $plugins = array(
        'plugin-name' => array( 
            'name' => 'plugin-name',
            'path' => 'plugin-directory/plugin-file.php',
            'url'  => 'https://plugin.url/',
        ),
    );
    foreach ($plugins as $plugin){
        if ( !is_plugin_active( $plugin['path'] ) ) {
            add_action( 'admin_notices', function() use( $plugin ) {?>
                <div class="notice notice-warning is-dismissible"><p><?php esc_html_e('To fully apply this theme, please install required plugin: ','text-domain'); ?><a href="<?php echo $plugin['url']; ?>" title="<?php echo $plugin['name']; ?>"><?php echo $plugin['name']; ?></a></p></div>
            <?php } );
        }
    }
}