How to retrieve media images urls in different sizes?

Question

I am trying to retrieve just the urls, not the whole image objects, from a gallery. I am stuck, because I can either get only the full size of images via:

wp_get_attachment_url

because this doesn't accept any parameters, or get the whole img tag with all kinds of stuff via:

wp_get_attachment_image

Is there a way to get the urls? My code right now looks like this:

<?php
    $query_images_args = array(
                               'post_type' => 'attachment',
                               'post_mime_type' => 'image',
                               'post_status' => 'inherit',
                               'posts_per_page' => -1,);

    $query_images = new WP_Query( $query_images_args );

    class image {
        public $thumbnail_url;
        public $full_url;
    }
    $images = array();
    foreach ( $query_images->posts as $picture ) {
        $image = new image();
        $image->thumbnail_url = wp_get_attachment_image( $picture->ID, 'thumbnail' );
        $image->full_url = wp_get_attachment_image( $picture->ID, 'full' );
        array_push($images, $image);
    }

    foreach($images as $image) {
        $thumbnail_url = $image->thumbnail_url;
        $full_url = $image->full_url;
?>

I want to be able to fill this correctly:

<li><img data-full-url="<?php echo $full_url ?>" src="<?php echo $thumbnail_url; ?>" /></li>

Answer 1

I don't understand your code in full (how your foreach's actually fill your list item), but, as for the specific question, I think that the function you want is wp_get_attachment_image_src();

So (illustratively):

   $thumbnail_src = wp_get_attachment_image_src( $picture->ID );
   $image->thumbnail_url = $thumbnail_src[0];
   $full_src = wp_get_attachment_image_src( $picture->ID, 'full' );
   $image->full_url = $full_src[0];