FRP GUI proof of concept (bkase#2)

Machinery in place to use future-signals to drive a GUI

Cargo.toml

@@ -14,6 +14,12 @@ cfg-if = "0.1.2"
 wasm-bindgen = "0.2"
 packed_struct = "0.3"
 packed_struct_codegen = "0.3"
+js-sys = "0.3.17"
+virtual-dom-rs = "0.6.7"
+css-rs-macro = "0.1"
+futures-preview = "0.3.0-alpha.13"
+futures-util-preview = "0.3.0-alpha.13"
+futures-signals = "0.3.4"
 
 # The `console_error_panic_hook` crate provides better debugging of panics by
 # logging them with `console.error`. This is great for development, but requires
@@ -32,6 +38,8 @@ wee_alloc = { version = "0.4.2", optional = true }
 version = "0.3.4"
 features = [
   'Document',
+  'MouseEvent',
+  'console',
   'Element',
   'HtmlElement',
   'HtmlCanvasElement',

src/debug_gui.rs

@@ -0,0 +1,24 @@
+use futures::{Future, FutureExt};
+use futures_signals::signal::{Signal, SignalExt};
+use virtual_dom_rs::prelude::*;
+use web_utils;
+
+fn sample_view<In: Signal<Item = u32>>(model: In) -> impl Signal<Item = VirtualNode> {
+    model.map(|m| {
+        let greetings = format!("Hello, World! {}", m);
+        html! { <div> { greetings } </div> }
+    })
+}
+
+pub fn run<In: Signal<Item = u32>>(rx: In) -> impl Future<Output = ()> {
+    let start_view = html! { <div> Hello </div> };
+
+    let body = web_utils::document().body().unwrap();
+
+    let mut dom_updater = DomUpdater::new_append_to_mount(start_view, &body);
+
+    sample_view(rx)
+        .map(move |vdom| dom_updater.update(vdom))
+        .to_future()
+        .map(|_| ())
+}

src/future_driver.rs

@@ -0,0 +1,11 @@
+use futures::task::Poll;
+use futures::Future;
+use std::cell::RefCell;
+use std::rc::Rc;
+
+pub fn tick<F: Future + Unpin>(f: Rc<RefCell<F>>) -> Poll<F::Output> {
+    let waker = futures_util::task::noop_waker();
+    // TODO: Is this safe?
+    let mut pin = unsafe { std::pin::Pin::new_unchecked(f.borrow_mut()) };
+    pin.as_mut().poll(&waker)
+}

src/lib.rs

@@ -1,5 +1,17 @@
+// hello world
+
+#![feature(proc_macro_hygiene)]
+#![feature(futures_api)]
+
 extern crate console_error_panic_hook;
+extern crate css_rs_macro;
+extern crate futures;
+extern crate futures_signals;
+extern crate futures_util;
+extern crate js_sys;
+extern crate virtual_dom_rs;
 extern crate wasm_bindgen;
+extern crate web_sys;
 
 extern crate packed_struct;
 #[macro_use]
@@ -12,6 +24,8 @@ pub mod test {
 
 mod alu;
 mod cpu;
+mod debug_gui;
+mod future_driver;
 mod instr;
 mod mem;
 mod ppu;
@@ -21,12 +35,12 @@ mod tile_debug;
 mod utils;
 mod web_utils;
 
+use futures::task::Poll;
+use futures_signals::signal::Mutable;
 use std::cell::RefCell;
 use std::rc::Rc;
-
 use wasm_bindgen::prelude::*;
 use wasm_bindgen::{Clamped, JsCast};
-
 use web_utils::*;
 
 fn draw_frame(data: &mut Vec<u8>, width: u32, height: u32, i: u32) {
@@ -73,8 +87,17 @@ pub fn run() -> Result<(), JsValue> {
     let mut i = 0;
     let mut data = vec![0; (height * width * 4) as usize];
 
+    let state: Mutable<u32> = Mutable::new(0);
+    let signal_future = Rc::new(RefCell::new(debug_gui::run(state.signal())));
+
     let mut last = performance_now();
-    *g.borrow_mut() = Some(Closure::wrap(Box::new(move || {
+    let closure = move || {
+        {
+            // Change the state
+            let mut lock = state.lock_mut();
+            *lock = i;
+        }
+
         // Stop after 500 frames
         if i > 500 {
             // Drop our handle to this closure so that it will get cleaned
@@ -104,9 +127,16 @@ pub fn run() -> Result<(), JsValue> {
         // Increment once per call
         i += 1;
 
+        // Drive our GUI
+        match future_driver::tick(signal_future.clone()) {
+            Poll::Pending => (),
+            Poll::Ready(()) => panic!("The signal should never end!"),
+        };
+
         // Schedule ourself for another requestAnimationFrame callback.
         request_animation_frame(f.borrow().as_ref().unwrap());
-    }) as Box<FnMut()>));
+    };
+    *g.borrow_mut() = Some(Closure::wrap(Box::new(closure) as Box<FnMut()>));
 
     request_animation_frame(g.borrow().as_ref().unwrap());
     Ok(())