SiteListPartView.php

<?php
/**
 * @license http://www.yiiframework.com/license/
 */

namespace frontend\widgets;

/**
 * The ListView widget is used to display data from data
 * provider. Each data model is rendered using the view
 * specified.
 *
 */
class SiteListPartView extends SiteListView
{
    /**
     * @var string
     */
    public $partLayout = '<div class="row">{part}</div>';

    /**
     * @var array
     */
    public $showBanners = true;

    /**
     * @var string
     */
    public $bannerView = '';

    /**
     * @var string
     */
    public $countInPart = 2;
    /**
     * @var string
     */
    public $defaultItemLayout = '';

    /**
     * Renders all data models.
     * @return string the rendering result
     */
    public function renderItems()
    {
        $models = $this->dataProvider->getModels();
        $keys = $this->dataProvider->getKeys();

        $partRows = [];
        $parts = array_chunk($models,$this->countInPart);

        $cnt = 1;
        $lastPartIndex = count($parts) - 1;
        foreach ($parts as $partKey => $part){
            $rows = [];
            foreach ($part as $index => $model) {
                $key = $keys[$index] + $partKey;
                if (($before = $this->renderBeforeItem($model, $key, $index)) !== null) {
                    $rows[] = $before;
                }

                $rows[] = $this->renderItem($model, $key, $index);

                if (($after = $this->renderAfterItem($model, $key, $index)) !== null) {
                    $rows[] = $after;
                }
            }
            $cntRows =  count($rows);
            if($partKey == $lastPartIndex && ($num  = $this->countInPart - $cntRows) > 0){
                $rows = array_merge($rows, array_fill($cntRows, $num, $this->defaultItemLayout));
            }
            $partRows[$partKey] = strtr($this->partLayout, [
                '{part}' => implode($this->separator, $rows),
            ]);

//            if($this->showBanners && $cnt % $this->countInPart == 0){
            if($this->showBanners && $cnt % 4 == 0){
                $partRows[$partKey] .= BannerArticleWidget::widget();
            }
            $cnt++;
        }

        return implode($this->separator, $partRows);
    }
}