Modify thumbnail output html img src with AMP-img src

Hi there!

Not sure which thumbnail you are looking to modify but have you looked into what image functions WordPress does have? One that comes to mind is:
https://developer.www.ads-software.com/reference/functions/wp_get_attachment_image_src/

If you are looking for just the post thumbnail you can try using the post_thumbnail_html filter:
https://developer.www.ads-software.com/reference/hooks/post_thumbnail_html/

Hope that helps you out a bit!

I have the same question as parazi7u…

I got this snippet… I think I’m close, but not quite there yet. Any idea on how to convert into <amp-img>?

function isa_amp_featured_img( $size = ‘medium’ ) {

global $post;

if ( has_post_thumbnail( $post->ID ) ) {

$thumb_id = get_post_thumbnail_id( $post->ID );
$img = wp_get_attachment_image_src( $thumb_id, $size );
$img_src = $img[0];
$w = $img[1];
$h = $img[2];

$alt = get_post_meta($post->ID, ‘_wp_attachment_image_alt’, true);

if(empty($alt)) {
$attachment = get_post( $thumb_id );
$alt = trim(strip_tags( $attachment->post_title ) );
} ?>
<amp-img id=”feat-img” src=”<?php echo esc_url( $img_src ); ?>” <?php
if ( $img_srcset = wp_get_attachment_image_srcset( $thumb_id, $size ) ) {
?> srcset=”<?php echo esc_attr( $img_srcset ); ?>” <?php
}
?> alt=”<?php echo esc_attr( $alt ); ?>” width=”<?php echo $w; ?>” height=”<?php echo $h; ?>”>
</amp-img>
<?php
}
}

function my_amp_set_custom_template( $file, $type, $post ) {
if ( ‘single’ === $type ) {
$file = get_stylesheet_directory() . ‘/amp/single.php’;
}
return $file;
}
add_filter( ‘amp_post_template_file’, ‘my_amp_set_custom_template’, 10, 3 );