use dicom-rs with wasm bindgen

[vampolo]

Hey,

I'm trying to use dicom-rs with wasm bindgen for a subassembly app. So far I have something like this function to load a dicom file using JS fetch

pub async fn load_url(url: String) -> Result<(), JsValue> {
    let mut opts = RequestInit::new();
    opts.method("GET");
    opts.mode(RequestMode::Cors);

    let request = Request::new_with_str_and_init(&url, &opts)?;

    let window = web_sys::window().unwrap();
    let resp_value = JsFuture::from(window.fetch_with_request(&request)).await?;

    // `resp_value` is a `Response` object.
    assert!(resp_value.is_instance_of::<Response>());
    let resp: Response = resp_value.dyn_into().unwrap();

    // Convert this other `Promise` into a rust `Future`.
    let array_buffer = JsFuture::from(resp.array_buffer()?).await?;

    let typebuf: js_sys::Uint8Array = js_sys::Uint8Array::new(&array_buffer);

    let mut slice = vec![0; typebuf.length() as usize];
    typebuf.copy_to(&mut slice[..]);

    let mut file = Cursor::new(slice);

    let obj = from_reader(&mut file).unwrap();

    // let patient_name = obj.element_by_name("PatientName").unwrap().to_str().unwrap();

    // console::log_1(&patient_name.to_string().into());

    Ok(())
}

Problem is the line let obj = from_reader(&mut file).unwrap() fails with :

I'm using the latest master. Not sure if the function I'm calling on the dicom-rs side is the right one. The import is the following: use dicom_object::from_reader;

[Enet4]

Thank you for the example! from_reader does not expect a preamble, which is probably what made the operation fail. Can you try and skip the first 128 bytes before calling from_reader?

I agree that the ergonomics of this API can be improved here. At some point the options builder pattern might be more interesting here.

[vampolo]

Thank you @Enet4

Yeah dropping the first 128 bytes did it

    let mut file = Cursor::new(&slice[128..]);

    let obj = from_reader(&mut file).unwrap();

    let patient_name = obj.element_by_name("PatientName").unwrap().to_str().unwrap();

    console::log_1(&patient_name.to_string().into());

[Enet4]

Closing, as the main concern appears to have been resolved, and the current behavior of the API is by design. Improvements to the API can be suggested in #43.