resize new uploads to fit max dimensions

resize-original-upload.php

<?php
/*
Plugin Name: Resize Original Upload
*/

add_filter('wp_handle_upload', 'max_dims_for_new_uploads', 10, 2 );

function max_dims_for_new_uploads( $array, $context ) {
	// $array = array( 'file' => $new_file, 'url' => $url, 'type' => $type )
	// $context = 'upload' || 'sideload'
	$ok = array( 'image/jpeg', 'image/gif', 'image/png' );
	if ( ! in_array( $array['type'], $ok ) ) return $array;

	$editor = wp_get_image_editor( $array['file'] );
	if ( is_wp_error( $editor ) )
		return $editor;

	$editor->set_quality( 90 );
	$editor->resize( 1500, 1500 ); // (int) max width, (int) max height[, (bool) crop]
	$editor->save( $array['file'] );
	return $array;

}