AS3 Upload: File Filtering

The FileFilter class is used to indicate what files on the user’s system are shown in the file-browsing dialog box that is displayed when FileReference.browse() or FileReferenceList.browse() is called.

The FileFilter instances can also be passed to a browse() function. If you use a FileFilter instance, extensions and file types that aren’t specified in the FileFilter instance are filtered out; that is, they are not available to the user to select for uploading. If no FileFilter object is passed to browse(), all files are shown in the dialog box.
You can use FileFilter instances in one of two ways:

1. A description with Windows file extensions only
2. A description with Windows file extensions and Macintosh file types

The two formats are not interchangeable within a single browse() call. You must use one or the other.

You can pass one or more FileFilter instances to FileReference.browse() or FileReferenceList.browse(). The following examples show different ways to create and pass FileFilter instances to a browse() call (for Windows only). The first example creates FileFilter instances outside of the browse() call:

var imagesFilter:FileFilter = new FileFilter("Images", "*.jpg;*.gif;*.png");
var docFilter:FileFilter = new FileFilter("Documents", "*.pdf;*.doc;*.txt");
var myFileReference:FileReference = new FileReference();
myFileReference.browse([imagesFilter, docFilter]);

The second example creates FileFilter instances within the browse() call:

myFileReference.browse( [ new FileFilter("Images", "*.jpg;*.gif;*.png"), new FileFilter("Flash Movies", "*.swf") ] );

The list of extensions in the FileFilter.extension property is used to filter the files in Windows, depending on the file selected by the user. It is not actually displayed in the dialog box; to display the file types for users, you must list the file types in the description string as well as in the extension list. The description string is displayed in the dialog box in Windows. (It is not used on the Macintosh.) On the Mac, if you supply a list of file types, that list is used to filter the files. If not, the list of Windows extensions is used.

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