var filename: String?
The filename for the exported data if the exportType is not ImageExportType.DATA_URL.
The correct filename extension will be automatically added
based on the selected export format. It can be an absolute path or file URL or a relative
path.
If some relative path is chosen it will be created in a temporary system directory and
overwritten
if the corresponding file already exists. If the value is null an new temporary file
will be
created for every export.