kartik\grid\ExpandRowColumn::renderHeaderCellContent PHP Méthode

    protected function renderHeaderCellContent()
    {
        if ($this->header !== null) {
            return parent::renderHeaderCellContent();
        }
        $icon = $this->expandIcon;
        $css = 'kv-expand-header-icon kv-state-collapsed';
        if ($this->defaultHeaderState === GridView::ROW_EXPANDED) {
            $icon = $this->collapseIcon;
            $css = 'kv-expand-header-icon kv-state-expanded';
        }
        return "<div class='{$css}'>{$icon}</div>";
    }