Override templates support for themes provided in WordPress plugin

Clay_Templates.php

<?php

class Clay_Template {

	public $override_dir;
	public $hook_prefix;

	public function __construct( $override_dir, $hook_prefix ) {

		$this->override_dir = $override_dir;
		$this->hook_prefix 	= $hook_prefix;

	}

	/**
	 * Get template.
	 *
	 * Search for the template and include the file.
	 *
	 * @since 1.0.0
	 *
	 * @see wcpt_locate_template()
	 *
	 * @param string 	$template_name			Template to load.
	 * @param array 	$args					Args passed for the template file.
	 * @param string 	$string $template_path	Path to templates.
	 * @param string	$default_path			Default path to template files.
	 */
	public function parse_template( $template_name, $args = array(), $template_path = '', $default_path = '' ) {

		ob_start();
		$this->get_template( $template_name, $args, $template_path, $default_path );
		$contents = ob_get_contents();
		ob_end_clean();
		return $contents;

	}

	/**
	 * Get template.
	 *
	 * Search for the template and include the file.
	 *
	 * @since 1.0.0
	 *
	 * @see wcpt_locate_template()
	 *
	 * @param string 	$template_name			Template to load.
	 * @param array 	$args					Args passed for the template file.
	 * @param string 	$string $template_path	Path to templates.
	 * @param string	$default_path			Default path to template files.
	 */
	public function get_template( $template_name, $args = array(), $template_path = '', $default_path = '' ) {

		if ( is_array( $args ) && isset( $args )) {
			extract( $args );
		}

		$template_file = $this->locate_template( $template_name . '.php', $template_path, $default_path );

		if ( ! file_exists( $template_file ) ) :
			_doing_it_wrong( __FUNCTION__, sprintf( '<code>%s</code> does not exist.', $template_file ), '1.0.0' );
			return;
		endif;

		include $template_file;

	}

	/**
	 * Locate template.
	 *
	 * Locate the called template.
	 * Search Order:
	 * 1. /themes/theme/$override_dir/$template_name
	 * 2. /themes/theme/$template_name
	 * 3. /plugins/[gravity-perk]/templates/$template_name.
	 *
	 * @since 1.0.0
	 *
	 * @param 	string 	$template_name	Template to load.
	 * @param 	string 	$template_path	Path to templates.
	 * @param 	string	$default_path		Default path to template files.
	 * @return 	string 									Path to the template file.
	 */
	public function locate_template( $template_name, $template_path = '', $default_path = '' ) {

		// Set variable to search in override directory of theme.
		if ( ! $template_path ) {
			$template_path = $this->override_dir . '/';
		} else {
			$template_path = $template_path . '/';
		}

		// Set default plugin templates path.
		if ( ! $default_path ) :
			$dir = plugin_dir_path( __FILE__ );
			$dir = str_replace( 'src/', '', $dir );
			$default_path = $dir . 'templates/'; // Path to the template folder
		endif;
		// Search template file in theme folder.

		$template = locate_template( array(
			$template_path . $template_name,
			$template_name
		) );
		// Get plugins template file.
		if ( ! $template ) :
			$template = $default_path . $template_name;
		endif;

		return apply_filters( $this->hook_prefix . '_locate_template', $template, $template_name, $template_path, $default_path );
	}

}

This class can be used in any plugin development project for WordPress. It is currently used in QuizMaster, and Gravity Perks as well numerous other plugin projects. Make sure to rename the class for your project so it doesn't conflict with other plugins that may be using it, for instance if your plugin is named "Cats" rename to "Cats_Template". This template loading system will check both the WordPress active theme and child themes, looking for the prefix you specify when loading the class. For instance if the override directory is "cats", and the active theme is "avada" it will look for override templates at /avada/cats/. Templates found in the theme should maintain any directory structure found in the plugin.