newsupernova/app/code/Magefan/Blog/Block/Adminhtml/Post/Edit/Tab/Meta.php

<?php
/**
 * Copyright © 2015 Ihor Vansach (ihor@magefan.com). All rights reserved.
 * See LICENSE.txt for license details (http://opensource.org/licenses/osl-3.0.php).
 *
 * Glory to Ukraine! Glory to the heroes!
 */

namespace Magefan\Blog\Block\Adminhtml\Post\Edit\Tab;

/**
 * Admin blog post edit form meta tab
 */
class Meta extends \Magento\Backend\Block\Widget\Form\Generic implements \Magento\Backend\Block\Widget\Tab\TabInterface
{
    /**
     * Prepare form
     *
     * @return $this
     */
    protected function _prepareForm()
    {
        /* @var $model \Magefan\Blog\Model\Category */
        $model = $this->_coreRegistry->registry('current_model');

        /*
         * Checking if user have permissions to save information
         */
        $isElementDisabled = !$this->_isAllowedAction('Magefan_Blog::post');

        /** @var \Magento\Framework\Data\Form $form */
        $form = $this->_formFactory->create();

        $form->setHtmlIdPrefix('post_');

        $fieldset = $form->addFieldset(
            'meta_fieldset',
            ['legend' => __('Meta Data'), 'class' => 'fieldset-wide']
        );

        $fieldset->addField(
            'meta_keywords',
            'textarea',
            [
                'name' => 'post[meta_keywords]',
                'label' => __('Keywords'),
                'title' => __('Meta Keywords'),
                'disabled' => $isElementDisabled
            ]
        );

        $fieldset->addField(
            'meta_description',
            'textarea',
            [
                'name' => 'post[meta_description]',
                'label' => __('Description'),
                'title' => __('Meta Description'),
                'disabled' => $isElementDisabled
            ]
        );

        $this->_eventManager->dispatch('magefan_blog_post_edit_tab_meta_prepare_form', ['form' => $form]);

        $form->setValues($model->getData());

        $this->setForm($form);

        return parent::_prepareForm();
    }

    /**
     * Prepare label for tab
     *
     * @return \Magento\Framework\Phrase
     */
    public function getTabLabel()
    {
        return __('Meta Data');
    }

    /**
     * Prepare title for tab
     *
     * @return \Magento\Framework\Phrase
     */
    public function getTabTitle()
    {
        return __('Meta Data');
    }

    /**
     * Returns status flag about this tab can be shown or not
     *
     * @return bool
     */
    public function canShowTab()
    {
        return true;
    }

    /**
     * Returns status flag about this tab hidden or not
     *
     * @return bool
     */
    public function isHidden()
    {
        return false;
    }

    /**
     * Check permission for passed action
     *
     * @param string $resourceId
     * @return bool
     */
    protected function _isAllowedAction($resourceId)
    {
        return $this->_authorization->isAllowed($resourceId);
    }
}