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_glium/src/backend.rs

@@ -177,9 +177,6 @@ pub fn run(mut app: Box<dyn epi::App>, native_options: epi::NativeOptions) {
     #[allow(unused_mut)]
     let mut storage = create_storage(app.name());
 
-    #[cfg(feature = "http")]
-    let http = std::sync::Arc::new(crate::http::GliumHttp {});
-
     let window_settings = deserialize_window_settings(&storage);
     let mut event_loop = glutin::event_loop::EventLoop::with_user_event();
     let icon = native_options.icon_data.clone().and_then(load_icon);
@@ -198,8 +195,6 @@ pub fn run(mut app: Box<dyn epi::App>, native_options: epi::NativeOptions) {
         let mut frame = epi::backend::FrameBuilder {
             info: integration_info(&display, None),
             tex_allocator: painter,
-            #[cfg(feature = "http")]
-            http: http.clone(),
             output: &mut app_output,
             repaint_signal: repaint_signal.clone(),
         }
@@ -222,8 +217,6 @@ pub fn run(mut app: Box<dyn epi::App>, native_options: epi::NativeOptions) {
         let mut frame = epi::backend::FrameBuilder {
             info: integration_info(&display, None),
             tex_allocator: painter,
-            #[cfg(feature = "http")]
-            http: http.clone(),
             output: &mut app_output,
             repaint_signal: repaint_signal.clone(),
         }
@@ -319,8 +312,6 @@ pub fn run(mut app: Box<dyn epi::App>, native_options: epi::NativeOptions) {
             let mut frame = epi::backend::FrameBuilder {
                 info: integration_info(&display, previous_frame_time),
                 tex_allocator: painter,
-                #[cfg(feature = "http")]
-                http: http.clone(),
                 output: &mut app_output,
                 repaint_signal: repaint_signal.clone(),
             }

egui_glium/src/http.rs

@@ -1,70 +0,0 @@
-use std::collections::BTreeMap;
-
-pub use epi::http::{Request, Response};
-
-/// NOTE: Ok(..) is returned on network error.
-/// Err is only for failure to use the fetch api.
-pub fn fetch_blocking(request: &Request) -> Result<Response, String> {
-    let mut req = ureq::request(&request.method, &request.url);
-
-    for header in &request.headers {
-        req = req.set(header.0, header.1);
-    }
-
-    let resp = if request.body.is_empty() {
-        req.call()
-    } else {
-        req.send_bytes(&request.body)
-    };
-
-    let (ok, resp) = match resp {
-        Ok(resp) => (true, resp),
-        Err(ureq::Error::Status(_, resp)) => (false, resp), // Still read the body on e.g. 404
-        Err(ureq::Error::Transport(error)) => return Err(error.to_string()),
-    };
-
-    let url = resp.get_url().to_owned();
-    let status = resp.status();
-    let status_text = resp.status_text().to_owned();
-    let mut headers = BTreeMap::new();
-    for key in &resp.headers_names() {
-        if let Some(value) = resp.header(key) {
-            // lowercase for easy lookup
-            headers.insert(key.to_ascii_lowercase(), value.to_owned());
-        }
-    }
-
-    let mut reader = resp.into_reader();
-    let mut bytes = vec![];
-    use std::io::Read;
-    reader
-        .read_to_end(&mut bytes)
-        .map_err(|err| err.to_string())?;
-
-    let response = Response {
-        url,
-        ok,
-        status,
-        status_text,
-        bytes,
-        headers,
-    };
-    Ok(response)
-}
-
-// ----------------------------------------------------------------------------
-
-pub(crate) struct GliumHttp {}
-
-impl epi::backend::Http for GliumHttp {
-    fn fetch_dyn(
-        &self,
-        request: Request,
-        on_done: Box<dyn FnOnce(Result<Response, String>) + Send>,
-    ) {
-        std::thread::spawn(move || {
-            let result = crate::http::fetch_blocking(&request);
-            on_done(result)
-        });
-    }
-}

egui_glium/src/lib.rs

@@ -19,8 +19,6 @@
 #![allow(clippy::manual_range_contains, clippy::single_match)]
 
 mod backend;
-#[cfg(feature = "http")]
-pub mod http;
 mod painter;
 #[cfg(feature = "persistence")]
 pub mod persistence;