getPermissions method
Gets the current document's permissions. There are three types of permissions: No restrictions: CPDFDocumentPermissions.none If the document has an open password and an owner password, using the open password will grant CPDFDocumentPermissions.user permissions, and using the owner password will grant CPDFDocumentPermissions.owner permissions.
example:
var permissions = await document.getPermissions();
Implementation
Future<CPDFDocumentPermissions> getPermissions() async {
int permissionId = await _channel.invokeMethod('get_permissions');
return CPDFDocumentPermissions.values[permissionId];
}