bfi_image_resize_dimensions

	function bfi_image_resize_dimensions( $payload, $orig_w, $orig_h, $dest_w, $dest_h, $crop = false ) {
		$aspect_ratio = $orig_w / $orig_h;

		$new_w = $dest_w;
		$new_h = $dest_h;

		if ( empty( $new_w ) || $new_w < 0 ) {
			$new_w = intval( $new_h * $aspect_ratio );
		}

		if ( empty( $new_h ) || $new_h < 0 ) {
			$new_h = intval( $new_w / $aspect_ratio );
		}

		$size_ratio = max( $new_w / $orig_w, $new_h / $orig_h );

		$crop_w = round( $new_w / $size_ratio );
		$crop_h = round( $new_h / $size_ratio );
		$s_x = floor( ( $orig_w - $crop_w ) / 2 );
		$s_y = floor( ( $orig_h - $crop_h ) / 2 );

		// Safe guard against super large or zero images which might cause 500 errors
		if ( $new_w > 5000 || $new_h > 5000 || $new_w <= 0 || $new_h <= 0 ) {
			return null;
		}

		// the return array matches the parameters to imagecopyresampled()
		// int dst_x, int dst_y, int src_x, int src_y, int dst_w, int dst_h, int src_w, int src_h
		return array( 0, 0, (int) $s_x, (int) $s_y, (int) $new_w, (int) $new_h, (int) $crop_w, (int) $crop_h );
	}