Add http fetch to eframe and implement it in egui_glium using ureq

egui_web/src/http.rs

@@ -0,0 +1,68 @@
+use wasm_bindgen::prelude::*;
+
+pub use epi::http::{Request, Response};
+
+/// NOTE: Ok(..) is returned on network error.
+/// Err is only for failure to use the fetch api.
+pub async fn fetch_async(request: &Request) -> Result<Response, String> {
+    fetch_jsvalue(request)
+        .await
+        .map_err(|err| err.as_string().unwrap_or_default())
+}
+
+/// NOTE: Ok(..) is returned on network error.
+/// Err is only for failure to use the fetch api.
+async fn fetch_jsvalue(request: &Request) -> Result<Response, JsValue> {
+    let Request { method, url } = request;
+
+    // https://rustwasm.github.io/wasm-bindgen/examples/fetch.html
+
+    use wasm_bindgen::JsCast;
+    use wasm_bindgen_futures::JsFuture;
+
+    let mut opts = web_sys::RequestInit::new();
+    opts.method(method);
+    opts.mode(web_sys::RequestMode::Cors);
+
+    let request = web_sys::Request::new_with_str_and_init(&url, &opts)?;
+    request.headers().set("Accept", "*/*")?;
+
+    let window = web_sys::window().unwrap();
+    let response = JsFuture::from(window.fetch_with_request(&request)).await?;
+    assert!(response.is_instance_of::<web_sys::Response>());
+    let response: web_sys::Response = response.dyn_into().unwrap();
+
+    // // TODO: support binary get
+
+    // let body = JsFuture::from(response.text()?).await?;
+    // let body = body.as_string().unwrap_or_default();
+
+    let array_buffer = JsFuture::from(response.array_buffer()?).await?;
+    let uint8_array = js_sys::Uint8Array::new(&array_buffer);
+    let bytes = uint8_array.to_vec();
+
+    let header_content_type = response
+        .headers()
+        .get("Content-Type")
+        .ok()
+        .flatten()
+        .unwrap_or_default();
+
+    let text = if header_content_type.starts_with("text")
+        || header_content_type == "application/javascript"
+    {
+        String::from_utf8(bytes.clone()).ok()
+    } else {
+        None
+    };
+
+    Ok(Response {
+        status_text: response.status_text(),
+        url: response.url(),
+        ok: response.ok(),
+        status: response.status(),
+        header_content_type,
+        bytes,
+        text,
+    })
+}