Zero copy

ZeroCopyBuffer<Vec<u8>> (and its friends like ZeroCopyBuffer<Vec<i8>>) sends the data from Rust to Dart without making copies¹. Thus, you save the time of copying data, which can be large if your data is big (such as a high-resolution image).

Example

pub fn draw_tree(tree: Vec<TreeNode>) -> ZeroCopyBuffer<Vec<u8>> { ... }

Becomes:

Future<Uint8List> drawTree({required List<TreeNode> tree});

The generated Dart code looks exactly the same as the case without ZeroCopyBuffer. However, the internal implementation changes and there is no memory copy at all!

Remark: If you are curious about Future, have a look at this.