Populate Envira Gallery with ACF gallery field

functions.php

/*
 * Populate Envira Gallery with ACF gallery field
 *
 * Filters the gallery $data and replaces with the image data for our images in the ACF gallery field.
 *
 * @uses ACF Pro
 * @uses Envira Gallery
 * @param $data
 * @param $gallery_id
 */
function envira_acf_gallery( $data, $gallery_id ) {
	
	// Target desired Envira gallery using ID
	if ( $data[ "id" ] == 1020 ) {
		
		//Setup new array to populate Envira gallery
		$newdata = array();

		// Don't lose the original gallery id and configuration
		$newdata[ "id" ] = $data[ "id" ];
		$newdata[ "config" ] = $data[ "config" ];
		
		if ( function_exists( 'get_field' ) )
		// Get array of images data from desired ACF gallery field
			$image_ids = get_field( 'gallery_m3_gal', 'options' );

		// Check to make sure array has images
		if( is_array( $image_ids ) ) {

			// Populate the Envira gallery with meta from the ACF gallery
			foreach( $image_ids as $image_id ) {
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "status" ] = 'active';	
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "src" ] = $image_id["url"];
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "title" ] = $image_id["title"];
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "link" ] = $image_id["url"];
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "alt" ] = $image_id["alt"];
				$newdata[ "gallery" ][ ( $image_id["id"] ) ][ "thumb" ] = $image_id["sizes"]["thumbnail"];
			}
		}
		// Return the new array of images
		return $newdata;
	}
	
}
// Add new image data to the envira gallery
add_filter( 'envira_gallery_pre_data', 'envira_acf_gallery', 10, 2);

Thanks for this but I'm having trouble getting it to output anything. I've created an Envira Gallery with a single image - it doesn't matter what, correct? Saved my configuration and gotten the Envira Gallery ID which is 56 in my case.

I have a gallery field in my post called 'gallery' and there are images in it. I've updated your function with my Envira Gallery ID (56) as well as updated the get_field() call to grab my 'gallery' field.

I'm calling the function in my single.php file but what do we supply as parameters for $data and $gallery_id? It won't run as-is without supplying those.

Or am I missing something else?

Thanks!