Dynamic OG images for WordPress using Microlink

functions.php

<?php

/**
 * The following goes in your child theme's functions.php file
 */
 
/**
 * Generate custom Open Graph images for your blog posts
 *
 * @param  string $url URL of OG image in HTML Meta.
 * @return string $url URL of OG image in HTML Meta.
 */
function mb_generate_og_image_url( $url = '' ) {

	// Admin can throw errors, so let's just skip that
	if ( is_admin() ) {
		return $url;
	}

	// Optional: If $url is not empty, you have already uploaded a custom OG image
	// to the post. If you would like to override previously uploaded images,
	// remove the following 3 lines. This applies to Yoast and Rankmath.
	if ( ! empty( $url ) ) {
		return $url;
	}

	if ( is_singular( 'post' ) ) {
		$id = get_the_ID();

		// The array keys here should match the possible values found on the Microlink card
		$ogArgs = [
			'preset' => 'quote',
			'avatar' => 'https://unavatar.io/calgarywebdev', // Unavatar.io is a great way to keep your image up to date
			'text'   => get_the_title( $id ),
			'author' => 'michaelbourne.ca',
			'job'    => 'Michael Bourne',
		];

		$api = 'https://i.microlink.io/';
		$cardUrl = 'https://cards.microlink.io/?' . http_build_query( $ogArgs );
		$url = $api . rawurlencode( $cardUrl );
	}

	// Fallback
	return $url;
}

/**
 * Yoast
 */
add_filter( 'wpseo_opengraph_image', 'mb_generate_og_image_url', 20 );
add_filter( 'wpseo_twitter_image', 'mb_generate_og_image_url', 20 );

/**
 * RankMath
 */
add_filter( 'rank_math/opengraph/facebook/image', 'mb_generate_og_image_url', 20 );
add_filter( 'rank_math/opengraph/twitter/image', 'mb_generate_og_image_url', 20 );

/**
 * SEO Framework. We have to get creative to support their filters.
 */
add_filter( 'the_seo_framework_image_generation_params', function( $params = [], $args = null, $context = 'social' ) {

	// Let's not mess with non-social sharing images.
	if ( 'social' !== $context ) return $params;

	if ( null === $args ) {
		// In the loop.
		if ( is_singular( 'post' ) ) {
			// Append. Use array_unshift() on 'cbs' to prepend.
			$params['cbs']['custom'] = 'mb_tsf_custom_singular_image_generator';
		}
	}

	return $params;
}, 10, 3 );

function mb_tsf_custom_singular_image_generator( $args = null, $size = 'full' ) {

	$url = mb_generate_og_image_url();
	$id  = '';

	// Since our function can return a blank URL, check for that.
	if ( ! empty( $url ) ) {
		yield [
			'url' => $url,
			'id'  => $id, // Optional. Used for alt-tag and dimension fetching.
		];
	}
}

/**
 * SEOPress. Similar as above, we have to use their filter in combination with out URL function.
 */
function mb_sp_social_og_thumb($html) { 

	//you can add here all your conditions like if is_page(), is_category() etc.. 
	if ( is_singular( 'post' ) ) {
		$url = mb_generate_og_image_url();
		$html = '<meta property="og:image" content="' . esc_url( $url ) . '" />';
	}

	return $html;
}
add_filter('seopress_social_og_thumb', 'mb_sp_social_og_thumb');