Wrong image size set when using wp_get_attachment_image() (fix)

[EmilEriksen]

When using this function the image won't be returned with a size-$size class but with an attachment-$size class and thus Picturefill.WP will set an incorrect size. This can easily be fixed though:

add_filter( 'picturefill_wp_initial_image_attributes', 'prefix_get_image_size_attribute' );
function prefix_get_image_size_attribute( $attributes ) {

    if ( empty( $attributes['size'] ) ) {
        if ( preg_match( '/(?:(?:^|\s)attachment-)([\w|-]+)/', $attributes['class'], $size_match ) ) {
            $attributes['size'] = $size_match[1];
        }
    }

    return $attributes;
}

[tychay]

Nice catch.

Looks like WordPress core has a bug where get_image_tag() returns a different class than wp_get_attachment_image(). This shouldn't be a filter though, but patched in the plugin itself given the core spits it out.

Patch:
tychay@c8794c8

Note to upstream: Without this patch, post thumbnails won't get properly sized (not sure they'll get properly sized post patch as I don't use this plugin yet).

I submitted a bug report at https://core.trac.wordpress.org/ticket/32093 but I doubt it will be fixed at this point as post thumbnails have been with us for over three years.

[tychay]

Pull request #64