wasm: separate update/render for later benching

1 files changed, 11 insertions, 5 deletions

diff --git a/src/render_loop.rs b/src/render_loop.rs
index 628e687..7056493 100644
--- a/src/render_loop.rs
+++ b/src/render_loop.rs
@@ -4,6 +4,8 @@ use std::rc::Rc;
 use log::error;
 use wasm_bindgen::prelude::*;
 
+use crate::JSResult;
+
 /// use `window.requestAnimationFrame()` to schedule calling a
 /// function as long as the function returns true.
 pub struct RenderLoop {
@@ -21,7 +23,7 @@ impl RenderLoop {
     /// `fun` takes a timestamp in the same space as the document
     /// timeline and returns a flag specifying whether we should
     /// schedule another frame..
-    pub fn new<T: FnMut(f64) -> bool + 'static>(mut fun: T) -> Self {
+    pub fn new<T: FnMut(f64) -> JSResult<bool> + 'static>(mut fun: T) -> Self {
         // init with stub closure because rust wants that, then change
         // it later once we have our rc clone.
         let inner = Rc::new(UnsafeCell::new(Closure::new(|_| {})));
@@ -29,11 +31,15 @@ impl RenderLoop {
         let rloop = inner.clone();
         let f = unsafe { &mut *inner.get() };
         *f = Closure::new(move |t| {
-            if fun(t) {
-                let cl = unsafe { &*rloop.get() };
-                if let Err(e) = Self::request_animation_frame(cl) {
-                    error!("couldn't request animation frame: {:?}", e);
+            match fun(t) {
+                Err(e) => error!("render callback error: {:?}", e),
+                Ok(true) => {
+                    let cl = unsafe { &*rloop.get() };
+                    if let Err(e) = Self::request_animation_frame(cl) {
+                        error!("couldn't request animation frame: {:?}", e);
+                    }
                 }
+                Ok(false) => {},
             }
         });