Wordpress: Pull any image file and get it's thumbnail in any size/crop dynamically without the need for add_image_size()

dynamic_img_src.php

<?php
/**
 * Call any image file (URI or ABSPATH) or image ID
 * and get it's thumbnail in any size/crop dynamically
 * 
 * Usage: <?php 
 *        echo dynamic_img_src( 'http://yoursite.com/images/image.png', 'width=800&height=600&crop=true' );
 *        echo dynamic_img_src( 38, array( 'width'=>800, 'height'=>600, 'crop'=>true ) );
 * 
 * @author  Michael Niles <github@blindmikey.com>
 * @version 1.0.0
 */
function dynamic_img_src( $original_src, $args )
{
    if ( is_numeric( $original_src ) )
    {
        $original_src = wp_get_attachment_image_src( $original_src, 'large' );
        $original_src = $original_src[0];
    }

    $path = str_replace( get_bloginfo('url').'/', ABSPATH, urldecode( $original_src ) );

    $settings = wp_parse_args( $args, array(
        'width'  => 150,
        'height' => 150,
        'crop'   => false
    ));
    $settings['src']  = $original_src;
    $settings['path'] = $path;

    if ( ! file_exists( $path ) )
    {
        trigger_error( 'File "'.$path.'" does not exist.' );
        return false;
    }

    $ext           = '.'.pathinfo( $settings['src'], PATHINFO_EXTENSION );
    $new_src_check = str_replace( $ext, '', $settings['path'] ) . '-' . $settings['width'] . 'x' . $settings['height'] . $ext;
    $new_src       = str_replace( $ext, '', $settings['src']  ) . '-' . $settings['width'] . 'x' . $settings['height'] . $ext;

    if ( file_exists( $new_src_check ) )
    {
        return $new_src;
    }

    $image = wp_get_image_editor( $settings['path'] );

    if ( is_wp_error( $image ) )
    {
        trigger_error( $image->get_error_message() );
        return false;
    }

    $image->resize( $settings['width'], $settings['height'],
        filter_var( $settings['crop'], FILTER_VALIDATE_BOOLEAN ) );

    $image->save( $new_src_check );

    return $new_src;
}

Next improvement planned: update WP's attachment metadata so that when the image is removed via WP admin, our copy gets nuked as well.