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flutterdartcastingstreamtransform

How to transform Stream<List<int>> to Stream<Uint8List> in Flutter

I have a Flutter function from a package that returns a Stream<List<int>> and I want to cast/transform to a Stream<Uint8List>. I'm not very familiar with dart Streams so I will appreciate any help/suggestion on this topic.

I have tried to cast(), as Stream<Uint8List>, but did not work at all.

Solution

  • It's very likely that you have a Stream<List<int>> that already has Uint8List elements. If so, you should be able to cast the elements (not the Stream itself) by using Stream.cast:

    var uint8ListStream = originalStream.cast<Uint8List>();

    If that doesn't work, then you can create a new Stream from the original with Stream.map, copying each List<int> into a new Uint8List:

    var uint8ListStream = originalStream.map((list) => Uint8List.from(list));

    You also could use asUint8List (from the answer I linked to above) to combine the approaches, copying into new Uint8Lists only if necessary:

    var uint8ListStream = originalStream.map((list) => list.asUint8List());