Nette\Forms\Rendering\DefaultFormRenderer::render PHP Method

    public function render(Nette\Forms\Form $form, $mode = NULL)
    {
        if ($this->form !== $form) {
            $this->form = $form;
        }
        $s = '';
        if (!$mode || $mode === 'begin') {
            $s .= $this->renderBegin();
        }
        if (!$mode || strtolower($mode) === 'ownerrors') {
            $s .= $this->renderErrors();
        } elseif ($mode === 'errors') {
            $s .= $this->renderErrors(NULL, FALSE);
        }
        if (!$mode || $mode === 'body') {
            $s .= $this->renderBody();
        }
        if (!$mode || $mode === 'end') {
            $s .= $this->renderEnd();
        }
        return $s;
    }

 /**
  * @param \Nette\Forms\Form $form
  * @param string|null $mode
  * @return string
  */
 public function render(Nette\Forms\Form $form, $mode = null)
 {
     $form->getElementPrototype()->class[] = 'form-horizontal';
     foreach ($form->getControls() as $control) {
         if ($control instanceof Controls\Button) {
             $control->setAttribute('class', empty($usedPrimary) ? 'btn btn-primary' : 'btn btn-default');
             $usedPrimary = true;
         } elseif ($control instanceof Controls\TextBase || $control instanceof Controls\SelectBox || $control instanceof Controls\MultiSelectBox) {
             $control->setAttribute('class', 'form-control');
         } elseif ($control instanceof Controls\Checkbox || $control instanceof Controls\CheckboxList || $control instanceof Controls\RadioList) {
             $control->getSeparatorPrototype()->setName('div')->class($control->getControlPrototype()->type);
         }
     }
     return parent::render($form, $mode);
 }