WordPress Featured Image Helper

_featured-image.php

<?php
/*
 * Get the featured image of post and return as object similar to ACF image object
 *
 * @param - $post, $sizes
 * 
 * @return - $image (array)
 */
function get_featured_image($post_id=false) {

	if(!$post_id) {
		global $post;
		// $post_thumbnail_id = get_post_thumbnail_id( $post );
	}
	else {
		$post=get_post($post_id);
		setup_postdata( $post );
		// $post_thumbnail_id = $post->ID;
	}

	$sizes = get_intermediate_image_sizes();
	
	$image=false;
	if ( has_post_thumbnail() ) :
 		$image = array(); 
		$post_thumbnail_id = get_post_thumbnail_id( $post );
		$thumb = get_post( $post_thumbnail_id );
	    $image['title'] = $thumb->post_title;
	    $image['alt'] = get_post_meta( $thumb->ID, '_wp_attachment_image_alt', true ); //alt text
	    $image['caption'] = $thumb->post_excerpt;
	    $image['description'] = $thumb->post_content;
	    $image['orientation']='landscape'; 
    	$image['url'] = $thumb->guid;
    	foreach ($sizes as $size) {
			$url_array = wp_get_attachment_image_src($post_thumbnail_id, $size, true);
			$image['sizes'][$size] = $url_array[0]; 
			if ($size==='large') {
		    	$large_width=$url_array[1]; 
		    	$large_height=$url_array[2]; 
		    	if($large_height>$large_width) {
		    		$image['orientation']='portrait'; 
		    	}
			}
    	}
	endif;
	return $image;
}

function the_image($single_post=true, $display_size='large', $image_class='thumbnail') {
	global $post;

	// $sizes = array('medium_large', 'fp-small', 'fp-medium', 'fp-large', 'icon', 'letterbox', 'letterbox-medium' );

	// if ( !$single_post && ( (get_post_format( $post_id ) != 'gallery') && (get_post_format( $post_id ) != 'video') ) ):
		if( !$single_post && get_field('letterbox_image')) {
	        $image = get_field('letterbox_image');
	    	$image_small = $image['sizes']['medium_large'];
	        $image_large = $image['url'];
	        $image_link = $image['original_image']['sizes']['large'];		
		}
		else {
			$image =  get_featured_image(); //$post->ID
			if($image) {
				$image_small = $image['sizes']['medium_large'];
				$image_large = $image['sizes'][$display_size];
				$image_link = $image['sizes']['large'];	
			}	
		}

		if($image): 
			?>
			<div class="text-center">
				<a href="<?php echo $image_link ?>" class="image-popup-vertical-fit" title="<?php the_title() ?><?php echo ($image['caption'] ? ' &vert; '.$image['caption']  : '' ) ?>">
					<img class="<?php echo $image_class ?>"  data-interchange="[<?php echo $image_small ?>, small], [<?php echo $image_large; ?>, medium], [<?php echo $image_large; ?>, large]" alt="<?php echo ($image['alt'] ? $image['alt']  : 'Image'); ?>" title="<?php echo ($image['title'] ? $image['title']  : 'defaultImgTitle' ); ?>">
				</a>
			</div>
			<?php 
		endif;
	// endif; 
}

_usage.php

<?php 
get_template_part( 'template-parts/featured-image-posts' );

featured-image-check.php

<?php 
/*
 * Featured Image Check
 *
 * Only show the image in 1 location (or not at all if it is too small). This is a fix for 
 * people using small images for featured images.
 *
 * Usage: Replace the get_template_part( 'template-parts/featured-image' ) function with the 
 * following and include it again in the header of the main article
 *
 * featured_image_check(0); // Check for hero image
 * featured_image_check(1); // Check for image in main article
 */

if (!function_exists('featured_image_check')) {
	/*
	    	// Usage:
		if (function_exists('featured_image_check')) {
			featured_image_check(0); // Check for hero image
		}
	*/	
	function featured_image_check( $location, $sizes = array( array("size" => "featured-xlarge", "width" => 1920), array("size" => "large", "width" => 700) ) ) {
		global $post;
		if ( has_post_thumbnail( $post->ID ) ) {
			// Thumbnail post 
			$post_thumbnail_id = get_post_thumbnail_id( $post );
			$thumb = get_post( $post_thumbnail_id );

			// X-large image
			$xlarge_image_array = wp_get_attachment_image_src($post_thumbnail_id, $sizes[0]["size"], true);
			$xlarge_width = $xlarge_image_array[1];

			// Large image
			$large_image_array = wp_get_attachment_image_src($post_thumbnail_id, $sizes[1]["size"], true);
			$large_width = $large_image_array[1];

			// Only show the image in 1 location (or not at all)
			if ($location === 0 && $xlarge_width >= $sizes[0]["width"]) {
				get_template_part( 'template-parts/featured-image' );
			}
			elseif ($location === 1 && $xlarge_width < $sizes[0]["width"] ) {
				
				if ( $large_width >= $sizes[1]["width"] ) {
					get_template_part( 'template-parts/featured-image-post' );
				}
				elseif ( $large_width < $sizes[1]["width"] ) {
					$current_user = wp_get_current_user();
					if (user_can( $current_user, 'editor' ) || user_can( $current_user, 'administrator' )) {
					  get_template_part( 'template-parts/featured-image-missing' );
					}
				}
			}
		}
	}
}

featured-image-posts.php

<?php
// If a featured image is set, insert into layout
if ( has_post_thumbnail( $post->ID ) ) : 
	$post_thumbnail_id = get_post_thumbnail_id( $post );
	$thumb = get_post( $post_thumbnail_id );
	$alt = get_post_meta( $thumb->ID, '_wp_attachment_image_alt', true ); //alt text 
	if (!$alt) {
		$alt = get_the_title();
	}
	?>
	<div id="featured-image-posts">
		<div class="gallery-item">
			<?php if (is_single()): ?>
				<a href="<?php echo the_post_thumbnail_url('large'); ?>" class="lightbox"><img class="thumbnail" alt="<?php echo $alt; ?>" src="<?php echo the_post_thumbnail_url('large'); ?>"></a>
			<?php else: ?>
				<a href="<?php echo get_permaLink() ?>"><img class="thumbnail" alt="<?php echo $alt; ?>" src="<?php echo the_post_thumbnail_url('large'); ?>"></a>
			<?php endif ?>
		</div>
	</div>
<?php endif;