WordPress at a glance
function is not described

_delete_attachment_theme_mod() WP 3.0.0

Checks an attachment being deleted to see if it's a header or background image.

If true it removes the theme modification which would be pointing at the deleted attachment.

  • Since 4.3.0 Also removes header_image_data.
  • Since 4.5.0 Also removes custom logo theme mods.

No Hooks.

Return

Nothing (null).

Usage

_delete_attachment_theme_mod( $id );
$id(int) (required)
The attachment id.

Code of delete attachment theme mod: wp-includes/theme.php VER 5.0.3

<?php
function _delete_attachment_theme_mod( $id ) {
	$attachment_image = wp_get_attachment_url( $id );
	$header_image     = get_header_image();
	$background_image = get_background_image();
	$custom_logo_id   = get_theme_mod( 'custom_logo' );

	if ( $custom_logo_id && $custom_logo_id == $id ) {
		remove_theme_mod( 'custom_logo' );
		remove_theme_mod( 'header_text' );
	}

	if ( $header_image && $header_image == $attachment_image ) {
		remove_theme_mod( 'header_image' );
		remove_theme_mod( 'header_image_data' );
	}

	if ( $background_image && $background_image == $attachment_image ) {
		remove_theme_mod( 'background_image' );
	}
}