Wordpress pagrindinių funkcijų paketimas

Tai va norėčiau pakeisti dvi funkcijas iš failo: wp-admin/includes/media.php

Nekeičiant pačio failo ir po wordpress atnaujinimo, kad niekas nesusigadintu noriu panaudoti pluginą. Tačiau nelabai iki galo supratau kaip padaryti taip, kad jei pluginas aktyvuotas naudotu funkciją iš mano plugino, o ne iš media.php.

Gal kas galėtu pabandyti paaiškinti man ką reiktu daryti kitaip?

Plugino kodas:

<?php
/*
Plugin Name: img
Plugin URI: http://test.com
*/

add_filter( 'image_attachment_fields_to_edit', 'my_image_attachment_fields_to_edit', 1, 2);
add_filter( 'media_handle_upload', 'my_media_handle_upload', 1, 4);

function my_media_handle_upload($file_id, $post_id, $post_data = array(), $overrides = array( 'test_form' => false )) {

$time = current_time('mysql');
if ( $post = get_post($post_id) ) {
	if ( substr( $post->post_date, 0, 4 ) > 0 )
		$time = $post->post_date;
}

$name = $_FILES[$file_id]['name'];
$file = wp_handle_upload($_FILES[$file_id], $overrides, $time);

if ( isset($file['error']) )
	return new WP_Error( 'upload_error', $file['error'] );

$name_parts = pathinfo($name);
$name = trim( substr( $name, 0, -(1 + strlen($name_parts['extension'])) ) );

$url = $file['url'];
$type = $file['type'];
$file = $file['file'];
$title = $name; 
$content = "";

// use image exif/iptc data for title and caption defaults if possible
if ( $image_meta = @wp_read_image_metadata($file) ) {
	if ( trim( $image_meta['title'] ) && ! is_numeric( sanitize_title( $image_meta['title'] ) ) )
		$title = $image_meta['title'];
	if ( trim( $image_meta['caption'] ) )
		$content = $image_meta['caption'];
}

// Construct the attachment array
$attachment = array_merge( array(
	'post_mime_type' => $type,
	'guid' => $url,
	'post_parent' => $post_id,
	'post_title' => $title,
	'post_content' => $content,
), $post_data );

// This should never be set as it would then overwrite an existing attachment.
if ( isset( $attachment['ID'] ) )
	unset( $attachment['ID'] );

// Save the data
$id = wp_insert_attachment($attachment, $file, $post_id);
if ( !is_wp_error($id) ) {
	wp_update_attachment_metadata( $id, wp_generate_attachment_metadata( $id, $file ) );
}

return $id;

}
function my_image_attachment_fields_to_edit($form_fields, $post) {
if ( substr($post->post_mime_type, 0, 5) == 'image' ) {
	$alt = get_post_meta($post->ID, '_wp_attachment_image_alt', true);
	if ( empty($alt) )
		$alt = '';

	$form_fields['post_title']['required'] = true;

	$form_fields['image_alt'] = array(
		'value' => $alt,
		'label' => __('Alternate Text'),
		'helps' => __('Alt text for the image, e.g. “The Mona Lisa”')
	);

	$form_fields['align'] = array(
		'label' => __('Alignment'),
		'input' => 'html',
		'html'  => image_align_input_fields($post, get_option('image_default_align')),
	);

	$form_fields['image-size'] = image_size_input_fields( $post, get_option('image_default_size', 'medium') );

} else {
	unset( $form_fields['image_alt'] );
}
return $form_fields;
}
?>