Replace all http code in epi/eframe/egui_glium/egui_web with ehttp (#697)

I've extracted all the http request code and turned it
into its own crate at <https://github.com/emilk/ehttp>.

There was never a reason for the HTTP request library to be part of
`eframe`. Much better to have it as its own crate!

egui_web/src/backend.rs

@@ -137,8 +137,6 @@ pub struct AppRunner {
     prefer_dark_mode: Option<bool>,
     last_save_time: f64,
     screen_reader: crate::screen_reader::ScreenReader,
-    #[cfg(feature = "http")]
-    http: Arc<http::WebHttp>,
     pub(crate) last_text_cursor_pos: Option<egui::Pos2>,
 }
 
@@ -165,8 +163,6 @@ impl AppRunner {
             prefer_dark_mode,
             last_save_time: now_sec(),
             screen_reader: Default::default(),
-            #[cfg(feature = "http")]
-            http: Arc::new(http::WebHttp {}),
             last_text_cursor_pos: None,
         };
 
@@ -175,8 +171,6 @@ impl AppRunner {
             let mut frame = epi::backend::FrameBuilder {
                 info: runner.integration_info(),
                 tex_allocator: runner.web_backend.painter.as_tex_allocator(),
-                #[cfg(feature = "http")]
-                http: runner.http.clone(),
                 output: &mut app_output,
                 repaint_signal: runner.needs_repaint.clone(),
             }
@@ -247,8 +241,6 @@ impl AppRunner {
         let mut frame = epi::backend::FrameBuilder {
             info: self.integration_info(),
             tex_allocator: self.web_backend.painter.as_tex_allocator(),
-            #[cfg(feature = "http")]
-            http: self.http.clone(),
             output: &mut app_output,
             repaint_signal: self.needs_repaint.clone(),
         }

egui_web/src/http.rs

@@ -1,97 +0,0 @@
-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(format!("{:#?}", err)))
-}
-
-/// 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> {
-    // https://rustwasm.github.io/wasm-bindgen/examples/fetch.html
-    // https://github.com/seanmonstar/reqwest/blob/master/src/wasm/client.rs
-
-    use wasm_bindgen::JsCast;
-    use wasm_bindgen_futures::JsFuture;
-
-    let mut opts = web_sys::RequestInit::new();
-    opts.method(&request.method);
-    opts.mode(web_sys::RequestMode::Cors);
-
-    if !request.body.is_empty() {
-        let body_bytes: &[u8] = &request.body;
-        let body_array: js_sys::Uint8Array = body_bytes.into();
-        let js_value: &JsValue = body_array.as_ref();
-        opts.body(Some(js_value));
-    }
-
-    let js_request = web_sys::Request::new_with_str_and_init(&request.url, &opts)?;
-
-    for h in &request.headers {
-        js_request.headers().set(h.0, h.1)?;
-    }
-
-    let window = web_sys::window().unwrap();
-    let response = JsFuture::from(window.fetch_with_request(&js_request)).await?;
-    let response: web_sys::Response = response.dyn_into()?;
-
-    let array_buffer = JsFuture::from(response.array_buffer()?).await?;
-    let uint8_array = js_sys::Uint8Array::new(&array_buffer);
-    let bytes = uint8_array.to_vec();
-
-    // https://developer.mozilla.org/en-US/docs/Web/API/Headers
-    // "Note: When Header values are iterated over, [...] values from duplicate header names are combined."
-    let mut headers = std::collections::BTreeMap::<String, String>::new();
-    let js_headers: web_sys::Headers = response.headers();
-    let js_iter = js_sys::try_iter(&js_headers)
-        .expect("headers try_iter")
-        .expect("headers have an iterator");
-
-    for item in js_iter {
-        let item = item.expect("headers iterator");
-        let array: js_sys::Array = item.into();
-        let v: Vec<JsValue> = array.to_vec();
-
-        let mut key = v[0]
-            .as_string()
-            .ok_or_else(|| JsValue::from_str("headers name"))?;
-        let value = v[1]
-            .as_string()
-            .ok_or_else(|| JsValue::from_str("headers value"))?;
-
-        // for easy lookup
-        key.make_ascii_lowercase();
-        headers.insert(key, value);
-    }
-
-    Ok(Response {
-        url: response.url(),
-        ok: response.ok(),
-        status: response.status(),
-        status_text: response.status_text(),
-        bytes,
-        headers,
-    })
-}
-
-// ----------------------------------------------------------------------------
-
-pub(crate) struct WebHttp {}
-
-impl epi::backend::Http for WebHttp {
-    fn fetch_dyn(
-        &self,
-        request: Request,
-        on_done: Box<dyn FnOnce(Result<Response, String>) + Send>,
-    ) {
-        crate::spawn_future(async move {
-            let result = crate::http::fetch_async(&request).await;
-            on_done(result)
-        });
-    }
-}

egui_web/src/lib.rs

@@ -22,8 +22,6 @@
 #![warn(clippy::all, rust_2018_idioms)]
 
 pub mod backend;
-#[cfg(feature = "http")]
-pub mod http;
 mod painter;
 pub mod screen_reader;
 pub mod webgl1;