gravity.php

<?php
add_filter( 'gform_pre_render', 'populate_civicrm_localization' );
add_filter( 'gform_pre_validation', 'populate_civicrm_localization' );
add_filter( 'gform_pre_submission_filter', 'populate_civicrm_localization' );
add_filter( 'gform_admin_pre_render', 'populate_civicrm_localization' );
function populate_civicrm_localization( $form ) {

    foreach ( $form['fields'] as &$field ) {
    	// CIVICRM COUNTRY FIELD
    	// If field is dropdown and has class "civicrm-country" populate it with Civi data
        if ( $field->type === 'select' && $field->cssClass === 'civicrm-country' ) {
            // Initialize Civi
            if ( !civi_wp()->initialize() ) return;
            // Get Civi countries through API
	        $countries = civicrm_api3('Country', 'get', array(
	    		'sequential' => 1,
				'options' => array('limit' => 0),
			));
	        // Prepare array to hold country data
	        $choices = array();
	        // Loop thorugh returned countries from Civi
	        foreach ( $countries['values'] as $key=>$country ) {
	            $choices[] = array( 'text' => $country['name'], 'value' => $country['id'] );
	        }

	        $field->placeholder = 'Select a Country';
	        $field->choices = $choices;
        }

        // CIVICRM STATE/PROVINCE FIELD
    	// If field is dropdown and has class "civicrm-state-province" populate it with Civi data
        if ( $field->type === 'select' && $field->cssClass === 'civicrm-state-province' ) {
            // Initialize Civi
            if ( !civi_wp()->initialize() ) return;
            // Get Civi state/provinces
            // Prepare query
            $query = "SELECT name,id,country_id FROM civicrm_state_province";
	        $dao = CRM_Core_DAO::executeQuery($query);
	        // Prepare array to hold state data
	        $states = array();
	        while ( $dao->fetch() ) {
	            $states[$dao->id] = array('name' => $dao->name, 'country_id' => $dao->country_id );
	        }

	        $choices = array();
	        // Loop thorugh returned states from Civi
	        foreach ( $states as $state_id=>$state ) {
	        	// I dont't think the $field object supports 'attributes' 
	            $choices[] = array( 'text' => $state['name'], 'value' => $state_id, 'attributes' => array( 'data-country-id' => $state['country_id'] ) ); 
	        }

	        $field->placeholder = 'Select a State/Province';
	        $field->choices = $choices;
        }
    }
    return $form;
}