#33: media_send_to_editor

media_send_to_editor.php

<?php
/**
 * Disallow inserting 'full' sizes images into the editor.
 * 
 * @see wp_ajax_send_attachment_to_editor(), media_upload_form_handler()
 * 
 * @param string $html The unslashed HTML to send to the editor.
 * @param in $id The attachment id.
 * @param array $attachment An array of attachment attributes.
 *
 * @return string The filtered HTML sent to the editor.
 */
function wpdocs_no_full_images( $html, $id, $attachment ) {
	$post = get_post( $id );
	// If it's an image and size is 'full', pass 'large' instead
	if ( 'image' == substr( $post->post_mime_type, 0, 5 ) ) {
		if ( ! empty( $attachment['image-size'] ) && 'full' == $attachment['image-size'] ) {
			$url = $attachment['url'];
			$align = ! empty( $attachment['align'] ) ? $attachment['align'] : 'none';
			$size = 'large';
			$alt = ! empty( $attachment['image_alt'] ) ? $attachment['image_alt'] : '';
			$rel = ( $url == get_attachment_link( $attachment_id ) );

			return get_image_send_to_editor( $id, $attachment['post_excerpt'], $attachment['post_title'], $align, $url, $rel, $size, $alt );
		}
	}

	return $html;
}
add_filter( 'media_send_to_editor', 'wpdocs_no_full_images', 10, 3 );