Responsive images

use SomehowDigital\ImgProxy\Url;

$base = Url::create()->source('https://example.com/photos/cat.jpg');

A srcset

Build one URL for each width.

use SomehowDigital\ImgProxy\Option\Quality;
use SomehowDigital\ImgProxy\Option\Width;

$srcset = implode(', ', array_map(
    static fn(int $width): string => sprintf(
        'https://imgproxy.example.com/%s %dw',
        $base->options(new Width($width), new Quality(75))->build('avif'),
        $width,
    ),
    [320, 640, 1280],
));
// https://imgproxy.example.com/_/w:320/q:75/plain/…@avif 320w, …

HiDPI

Dpr multiplies the size, so you describe the image in CSS pixels.

use SomehowDigital\ImgProxy\Option\Dpr;
use SomehowDigital\ImgProxy\Option\Width;

$base->options(new Width(300), new Dpr(2))->build();
// _/w:300/dpr:2/plain/https%3A%2F%2Fexample.com%2Fphotos%2Fcat.jpg