Observe rendering events - ember.js

Question

Are there events that I can observe, similar to ember-data's events around data loading such as isLoaded/isUpdating, for while view/templates are being rendered?
I have a list of ~1000 elements going into a list, and it takes quite some time to even render (the topic of a whole other question). I'd like to show some indication to the user that rendering work is being done.
There are events at a more microcosmic level such as: http://emberjs.com/api/classes/Ember.View.html#event_willClearRender. I'm curious to know if there are events for when any rendering is being performed.

Answer 1

Ember.Instrumentation provides a general purpose way to instrument code and conveniently, by default, Ember emits instrumentation events anytime something is rendered.
Ember.subscribe is used to setup a listener for before and after-- the events are namespaced with periods so subscribing to "render" will get you all render instrumentation calls, which by default is like "render.boundHandlebars", "render.metamorph", "render.view" ...
Here's a little function to help you get started.. you can paste this into the console and click around your app to check it out (or if you want to see all the rendering from the start paste it somewhere in your code so its loaded after ember but before your app).
If no event is passed to beginInstrumentation it'll default to render ...
beginInstrumentation = function(eventName) {
var styles;
if (eventName == null) {
eventName = "render";
}
styles = {
"render.render.metamorph": "color: #a47701;",
"render.render.boundHandlebars": "color: #0f51fe;",
"render.view": "color: #37be02;"
};
Ember.subscribe(eventName, {
before: function(name, ts, payload) {
console.group(name);
return ts;
},
after: function(name, ts, payload, b_ts) {
var elapsed, style;
style = styles[name] || "";
elapsed = (ts - b_ts).toFixed(4);
console.log("%c" + payload.object + ": " + elapsed + "ms", style);
return console.groupEnd();
}
});
};
beginInstrumentation();
Heres the output in chrome when I paste it into the TodoMVC app and click the all/completed/active filters (should work in firefox/firebug as well)