sunset-theme

<?php


// in functions-admin.php
// ==================
// we can get all the post formats by get_post_format_slugs() function
// it returns all formats including 'standard' format which we don't need
// 'standard' is always on the top so its index is zero
// so we can ignore it by a if condition if( $i != 0)

function post_formats_callback() {

    $formats = get_post_format_slugs();
    $options =  get_option( 'post_formats' );
    $output = '';
    $i = 0;

    foreach( $formats as $format ) {

        if( $i != 0) {

            $checked = ( @$options[$format] == $format ? 'checked' : '' );
            $output .= '<label><input type="checkbox" name="post_formats['.$format.']" '.$checked.' value="'.$format.'">' . $format . "</label><br>";
            }
            $i++;
    }
    echo $output;
}


// in theme-support.php
// =================
$options =  get_option( 'post_formats' );
if( ! empty( $options ) ){
    add_theme_support( 'post-formats', $options );
}