magento2/app/code/Magento/Email/Block/Adminhtml/Template.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

/**
 * Adminhtml system templates page content block
 *
 * @author      Magento Core Team <core@magentocommerce.com>
 */
namespace Magento\Email\Block\Adminhtml;

/**
 * @api
 * @since 100.0.2
 */
class Template extends \Magento\Backend\Block\Template implements \Magento\Backend\Block\Widget\ContainerInterface
{
    /**
     * Template list
     *
     * @var string
     */
    protected $_template = 'Magento_Email::template/list.phtml';

    /**
     * @var \Magento\Backend\Block\Widget\Button\ButtonList
     */
    protected $buttonList;

    /**
     * @var \Magento\Backend\Block\Widget\Button\ToolbarInterface
     */
    protected $toolbar;

    /**
     * @param \Magento\Backend\Block\Template\Context $context
     * @param \Magento\Backend\Block\Widget\Button\ButtonList $buttonList
     * @param \Magento\Backend\Block\Widget\Button\ToolbarInterface $toolbar
     * @param array $data
     */
    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Backend\Block\Widget\Button\ButtonList $buttonList,
        \Magento\Backend\Block\Widget\Button\ToolbarInterface $toolbar,
        array $data = []
    ) {
        $this->buttonList = $buttonList;
        $this->toolbar = $toolbar;
        parent::__construct($context, $data);
    }

    /**
     * {@inheritdoc}
     */
    public function updateButton($buttonId, $key, $data)
    {
        $this->buttonList->update($buttonId, $key, $data);
        return $this;
    }

    /**
     * Create add button and grid blocks
     *
     * @return \Magento\Framework\View\Element\AbstractBlock
     */
    protected function _prepareLayout()
    {
        $this->buttonList->add(
            'add',
            [
                'label' => __('Add New Template'),
                'onclick' => "window.location='" . $this->getCreateUrl() . "'",
                'class' => 'add primary add-template'
            ]
        );
        $this->toolbar->pushButtons($this, $this->buttonList);
        return parent::_prepareLayout();
    }

    /**
     * Get URL for create new email template
     *
     * @return string
     */
    public function getCreateUrl()
    {
        return $this->getUrl('adminhtml/*/new');
    }

    /**
     * {@inheritdoc}
     */
    public function addButton($buttonId, $data, $level = 0, $sortOrder = 0, $region = 'toolbar')
    {
        $this->buttonList->add($buttonId, $data, $level, $sortOrder, $region);
        return $this;
    }

    /**
     * Get transactional emails page header text
     *
     * @return \Magento\Framework\Phrase
     */
    public function getHeaderText()
    {
        return __('Transactional Emails');
    }

    /**
     * {@inheritdoc}
     */
    public function removeButton($buttonId)
    {
        $this->buttonList->remove($buttonId);
        return $this;
    }

    /**
     * Get Add New Template button html
     *
     * @return string
     */
    protected function getAddButtonHtml()
    {
        $out = '';
        foreach ($this->buttonList->getItems() as $buttons) {
            /** @var \Magento\Backend\Block\Widget\Button\Item $item */
            foreach ($buttons as $item) {
                $out .= $this->getChildHtml($item->getButtonKey());
            }
        }
        return $out;
    }

    /**
     * {@inheritdoc}
     */
    public function canRender(\Magento\Backend\Block\Widget\Button\Item $item)
    {
        return !$item->isDeleted();
    }
}