isotope/core — pull request #1311 by tristanlins (2014-11-17 12:26:02+00:00)
Title: Add download file hook.

Allow developers to hook into the download file process.
In my case, I need to stamp PDFs with licensee informations before download.

The hook synopsis:
```php
public function myDownloadFile(
\FilesModel $objFileModel,
\Isotope\Model\Download $objDownload,
\Isotope\Model\ProductCollectionDownload $objCollectionDownload
);
```