build_post_featured_image() runs unnecessarily

[paulschreiber]

build_post_featured_image() runs unnecessarily, whether or not the featured image is shown in the template.

We have postmeta that determines whether to hide/show the image.

Result: if the featured image is a gif, amp-anim gets added to amp_component_scripts, which generates a warning in the AMP validator.

[paulschreiber]

It would be helpful to be able to filter this i.e. if ( apply_filters( 'amp_featured_image_is_visible', true ) ) { ... } .

[westonruter]

How are you turning off a featured image from being displayed? Are you doing something like:

add_filter( 'amp_post_template_data', function( $data ) {
    $data['featured_image'] = false;
    return $data;
} );

If so, then it would seem to me that the scripts returned by AMP_Img_Sanitizer should get queued up after the filter applies, not before.

[paulschreiber]

How are you turning off a featured image from being displayed? Are you doing something like:

We have a metabox with a checkbox titled "Show image on article page." When the box is not checked, we save some postmeta to indicate suppression.

In the template itself, we retrieve the value of the postmeta, put it in $show_featured_image, and call something like this:

if ( $show_featured_image ) {
   get_template_part( 'template-parts/featured-image-embed' );
}

In the amp_post_template_data filter, we have code like this:

// Workaround for https://github.com/Automattic/amp-wp/issues/732
//
// Suppress amp-anim if:
// (a) no GIFs in body
// (b) featured image is a GIF
// (c) suppress featured image checkbox is checked
//
if ( ! preg_match( '/<amp-anim.+src=".+\.gif/', $data['post_amp_content'] ) ) { // query params may be present after gif; no close quote
	$featured_image_url = get_the_post_thumbnail_url( $post->ID );
	$url_parts = wp_parse_url( $featured_image_url );
	$file_extension = strtolower( pathinfo( $url_parts['path'], PATHINFO_EXTENSION ) );
	if ( 'gif' === $file_extension ) {
		$show_featured_image  = get_post_meta( $post->ID, ...

		if ( ! $show_featured_image ) {
			unset( $data['amp_component_scripts']['amp-anim'] );
		}
	}
}

[westonruter]

This should be made obsolete by #2202 in that we can move to constructing the Reader mode templates in a more traditional way, and then only the AMP components that are actually used in the page will then be among the scripts included on the page.

[westonruter]

Fixed by #3781. Now only the required component scripts are included on the rendered page, as needed.