Merge pull request #1592 from pygy/async-redraw

Make m.redraw() purely asynchronous, add m.redraw.sync()

api/redraw.js

@@ -4,26 +4,23 @@ var coreRenderer = require("../render/render")
 
 function throttle(callback) {
 	//60fps translates to 16.6ms, round it down since setTimeout requires int
-	var time = 16
+	var delay = 16
 	var last = 0, pending = null
 	var timeout = typeof requestAnimationFrame === "function" ? requestAnimationFrame : setTimeout
 	return function() {
-		var now = Date.now()
-		if (last === 0 || now - last >= time) {
-			last = now
-			callback()
-		}
-		else if (pending === null) {
+		var elapsed = Date.now() - last
+		if (pending === null) {
 			pending = timeout(function() {
 				pending = null
 				callback()
 				last = Date.now()
-			}, time - (now - last))
+			}, delay - elapsed)
 		}
 	}
 }
 
-module.exports = function($window) {
+
+module.exports = function($window, throttleMock) {
 	var renderService = coreRenderer($window)
 	renderService.setEventCallback(function(e) {
 		if (e.redraw === false) e.redraw = undefined
@@ -31,18 +28,24 @@ module.exports = function($window) {
 	})
 
 	var callbacks = []
+	var rendering = false
+
 	function subscribe(key, callback) {
 		unsubscribe(key)
-		callbacks.push(key, throttle(callback))
+		callbacks.push(key, callback)
 	}
 	function unsubscribe(key) {
 		var index = callbacks.indexOf(key)
 		if (index > -1) callbacks.splice(index, 2)
 	}
-	function redraw() {
-		for (var i = 1; i < callbacks.length; i += 2) {
-			callbacks[i]()
-		}
+	function sync() {
+		if (rendering) throw new Error("Nested m.redraw.sync() call")
+		rendering = true
+		for (var i = 1; i < callbacks.length; i+=2) try {callbacks[i]()} catch (e) {/*noop*/}
+		rendering = false
 	}
+
+	var redraw = (throttleMock || throttle)(sync)
+	redraw.sync = sync
 	return {subscribe: subscribe, unsubscribe: unsubscribe, redraw: redraw, render: renderService.render}
 }