lfjeff/AppExtension.php

## AppExtension.php
<?php

// src/Twig/AppExtension.php

namespace App\Twig;

use Twig\Extension\AbstractExtension;
use Twig\TwigFunction;

class AppExtension extends AbstractExtension
{
    private $imageProcUrl;

    public function __construct(?string $imageProcUrl)
    {
        $this->imageProcUrl = $imageProcUrl;    // value from config parameter app.image_proc_url
    }

    public function getFunctions()
    {
        return [
            new TwigFunction('image_proc', [$this, 'imageProc']),
        ];
    }

    /**
     * Process images according to $queryOpts values.
     *
     * For details on how this works, see https://images.weserv.nl
     *
     */
    public function imageProc(string $imageUrl, string $queryOpts = '', $processLocalFiles = false)
    {
        if (!trim($this->imageProcUrl)) {
            // bypass if imageProcUrl is blank
            return $imageUrl;
        }

        $imageProcUrl = $this->imageProcUrl;

        //
        // add host if missing (only for local files)
        //
        if (!preg_match('~^(//|https?://)~', $imageUrl)) {

            if (!$processLocalFiles) {
                return $imageUrl;
            }

            $dir = '';
            if (!preg_match('~^/~', $imageUrl)) {
                $dir = dirname($_SERVER['REQUEST_URI']);
            }

            if ((!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
                || $_SERVER['SERVER_PORT'] == 443) {
                $imageUrl = "https://$_SERVER[SERVER_NAME]$dir$imageUrl";
            } else {
                $imageUrl = "http://$_SERVER[SERVER_NAME]$dir$imageUrl";
            }
        }

        // if webp is not supported, remove any output option
        if (false === stripos($_SERVER['HTTP_ACCEPT'], 'image/webp')) {
            $queryOpts = preg_replace('/&?output=webp/', '', $queryOpts);
        }

        $imageUrl = preg_replace(['~^//~', '~^http://~', '~^https://~'], ['', '', 'ssl:'], $imageUrl);

        return "$imageProcUrl/?url=$imageUrl&$queryOpts";
    }
}

## example.html.twig
{# example of how to use image_proc() function in a template #}
<html>
<body>
<img width="100" src="{{ image_proc('https://images.mysafetysign.com/img/lg/S/danger-high-voltage-area-sign-s-8285.png', 'w=100') }}" />
</body>
</html>

## services.yaml
#  config/services.yaml
#
#  Add these parameters to your services.yaml file
#
parameters:
    # URL of image processing service (used by Twig image_proc() function)
    # if blank, disable image processing
    app.image_proc_url: '//images.weserv.nl'

services:
    # default configuration for services in *this* file
    _defaults:
        autowire: true      # Automatically injects dependencies in your services.
        autoconfigure: true # Automatically registers your services as commands, event subscribers, etc.
        public: false       # Allows optimizing the container by removing unused services; this also means
                            # fetching services directly from the container via $container->get() won't work.
                            # The best practice is to be explicit about your dependencies anyway.

        bind:               # set up special global autowiring rules
            $imageProcUrl: '%app.image_proc_url%'
	<?php

	// src/Twig/AppExtension.php

	namespace App\Twig;

	use Twig\Extension\AbstractExtension;
	use Twig\TwigFunction;

	class AppExtension extends AbstractExtension
	{
	private $imageProcUrl;

	public function __construct(?string $imageProcUrl)
	{
	$this->imageProcUrl = $imageProcUrl; // value from config parameter app.image_proc_url
	}

	public function getFunctions()
	{
	return [
	new TwigFunction('image_proc', [$this, 'imageProc']),
	];
	}

	/**
	* Process images according to $queryOpts values.
	*
	* For details on how this works, see https://images.weserv.nl
	*
	*/
	public function imageProc(string $imageUrl, string $queryOpts = '', $processLocalFiles = false)
	{
	if (!trim($this->imageProcUrl)) {
	// bypass if imageProcUrl is blank
	return $imageUrl;
	}

	$imageProcUrl = $this->imageProcUrl;

	//
	// add host if missing (only for local files)
	//
	if (!preg_match('~^(//\|https?://)~', $imageUrl)) {

	if (!$processLocalFiles) {
	return $imageUrl;
	}

	$dir = '';
	if (!preg_match('~^/~', $imageUrl)) {
	$dir = dirname($_SERVER['REQUEST_URI']);
	}

	if ((!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
	\|\| $_SERVER['SERVER_PORT'] == 443) {
	$imageUrl = "https://$_SERVER[SERVER_NAME]$dir$imageUrl";
	} else {
	$imageUrl = "http://$_SERVER[SERVER_NAME]$dir$imageUrl";
	}
	}

	// if webp is not supported, remove any output option
	if (false === stripos($_SERVER['HTTP_ACCEPT'], 'image/webp')) {
	$queryOpts = preg_replace('/&?output=webp/', '', $queryOpts);
	}

	$imageUrl = preg_replace(['~^//~', '~^http://~', '~^https://~'], ['', '', 'ssl:'], $imageUrl);

	return "$imageProcUrl/?url=$imageUrl&$queryOpts";
	}
	}
	{# example of how to use image_proc() function in a template #}
	<html>
	<body>
	<img width="100" src="{{ image_proc('https://images.mysafetysign.com/img/lg/S/danger-high-voltage-area-sign-s-8285.png', 'w=100') }}" />
	</body>
	</html>
	# config/services.yaml
	#
	# Add these parameters to your services.yaml file
	#
	parameters:
	# URL of image processing service (used by Twig image_proc() function)
	# if blank, disable image processing
	app.image_proc_url: '//images.weserv.nl'

	services:
	# default configuration for services in this file
	_defaults:
	autowire: true # Automatically injects dependencies in your services.
	autoconfigure: true # Automatically registers your services as commands, event subscribers, etc.
	public: false # Allows optimizing the container by removing unused services; this also means
	# fetching services directly from the container via $container->get() won't work.
	# The best practice is to be explicit about your dependencies anyway.

	bind: # set up special global autowiring rules
	$imageProcUrl: '%app.image_proc_url%'