Force wordpress to generate a square intermediate image resize without hard crop (wp crops image, but i don't need this, I need some extra white space outside)

wp_square_images.php

<?php

add_filter('wp_generate_attachment_metadata', 'custom_crop');
function custom_crop($metadata) {

	$square_image_size = 320;

	$uploads = wp_upload_dir();

	$file = path_join( $uploads['basedir'], $metadata['file'] ); // original image file

	list( $year, $month, $filename ) = explode( '/', $metadata['file'] );
	list( $fname, $fext ) = explode( '.', $filename );
	$crop_filename = "{$fname}-{$square_image_size}-square-crop.{$fext}";

	$target = path_join( $uploads['basedir'], "{$year}/{$month}/{$crop_filename}" ); // intermediate size file

	// find the long edge
	$image_long_edge = $metadata['width'] >= $metadata['height'] ? $metadata['width'] : $metadata['height'];
	$image_long_ratio = $image_long_edge / $square_image_size;

	if ($fext === 'jpg' || $fext === 'jpeg') {
		$image = imagecreatefromjpeg($file); // original image resource
	} else if ($fext === 'png') {
		$image = imagecreatefrompng($file); // original image resource
	}

	if ($image) {
		// create a blank image to fill
		$image_target = wp_imagecreatetruecolor( $square_image_size, $square_image_size );

		if ($fext === 'png') {
			// Fill the image with transparent color
			imagesavealpha($image_target, true);
			// set background to transparent
			$background_color = imagecolorallocatealpha( $image_target, 0, 0, 0, 127 );
		} else {
			// set background to white
			$background_color = imagecolorallocate($image_target, 255, 255, 255);
		}

		imagefill($image_target, 0, 0, $background_color);

		if ($metadata['width'] >= $metadata['height']) {
			imagecopyresampled($image_target, $image, 0, (($square_image_size - ($metadata['height'] / $image_long_ratio))/2), 0, 0, $square_image_size, ($metadata['height'] / $image_long_ratio), $metadata['width'], $metadata['height'] );
		} else {
			imagecopyresampled($image_target, $image, (($square_image_size - ($metadata['width'] / $image_long_ratio))/2), 0, 0, 0, ($metadata['width'] / $image_long_ratio), $square_image_size,$metadata['width'], $metadata['height'] );
		}
	}

	// write the square crop image to disk
	if ($fext === 'jpg' || $fext === 'jpeg') {
		imagejpeg( $image_target, $target, apply_filters( 'jpeg_quality', 90, 'image_resize' ) );
	} else if ($fext === 'png') {
		imagepng( $image_target, $target );
	}

  // override photo generated meta 
	$metadata['sizes']['square-crop']['file'] = $crop_filename;
	$metadata['sizes']['square-crop']['width'] = $square_image_size;
	$metadata['sizes']['square-crop']['height'] = $square_image_size;

	// Destroy image
	imagedestroy($image_target);

	return $metadata;
}


add_filter( 'image_size_names_choose', 'square_custom_size' );
function square_custom_size( $sizes ) {
	return array_merge( $sizes, array(
		'square-crop' => __( 'Square Crop' ),
	) );
}