如何使用yii ECSVExport扩展在csv文件中附加图像

Question

Yii::import('application.extensions..ECSVExport');

$filename = 'filename.csv';
$csv = new ECSVExport($sheet_generation);

$csv->setOutputFile($outputFile);

$content = $csv->toCSV();   

Yii::app()->getRequest()->sendFile($filename, $content, "text/csv", false);