From 81213595edeb5eee572956c0774b33053311759a Mon Sep 17 00:00:00 2001
From: Fabian Kessler <fabian.kessler@optimaize.com>
Date: Sun, 21 Apr 2013 02:57:18 +0300
Subject: [PATCH] Render start and stop callbacks for all cases.

Rendering can happen on demand (by calling start()) but also when adding/removing nodes and relations. I also need to be informed when rendering starts in my use case. I have a re-arrange button that needs to be toggled whenever rendering is in progress, and with these events it's nice and clean.
When the event callbacks are passed in to the Springy.Renderer start() method only (as in my previous commit) then all the other cases are left out (adding/removing nodes/relations).
---
 springy.js | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/springy.js b/springy.js
index fdda419..baf6e97 100644
--- a/springy.js
+++ b/springy.js
@@ -487,12 +487,14 @@
 	 * Start simulation if it's not running already.
 	 * In case it's running then the call is ignored, and none of the callbacks passed is ever executed.
 	 */
-	Layout.ForceDirected.prototype.start = function(render, done) {
+	Layout.ForceDirected.prototype.start = function(render, onRenderStart, onRenderStop) {
 		var t = this;
 
 		if (this._started) return;
 		this._started = true;
 		this._stop = false;
+		
+		if (onRenderStart !== undefined) { onRenderStart(); }
 
 		Springy.requestAnimationFrame(function step() {
 			t.applyCoulombsLaw();
@@ -508,7 +510,7 @@
 			// stop simulation when energy of the system goes below a threshold
 			if (t._stop || t.totalEnergy() < 0.01) {
 				t._started = false;
-				if (done !== undefined) { done(); }
+				if (onRenderStop !== undefined) { onRenderStop(); }
 			} else {
 				Springy.requestAnimationFrame(step);
 			}
@@ -628,12 +630,18 @@
 	// 	return Math.abs(ac.x * n.x + ac.y * n.y);
 	// };
 
-	// Renderer handles the layout rendering loop
-	var Renderer = Springy.Renderer = function(layout, clear, drawEdge, drawNode) {
+	/**
+	 * Renderer handles the layout rendering loop
+	 * @param onRenderStart optional callback function that gets executed whenever rendering starts.
+	 * @param onRenderStop optional callback function that gets executed whenever rendering stops.
+	 */
+	var Renderer = Springy.Renderer = function(layout, clear, drawEdge, drawNode, onRenderStart, onRenderStop) {
 		this.layout = layout;
 		this.clear = clear;
 		this.drawEdge = drawEdge;
 		this.drawNode = drawNode;
+        	this.onRenderStart = onRenderStart;
+		this.onRenderStop  = onRenderStop;
 
 		this.layout.graph.addGraphListener(this);
 	}
@@ -664,7 +672,7 @@
 			t.layout.eachNode(function(node, point) {
 				t.drawNode(node, point.p);
 			});
-		}, done);
+		}, this.onRenderStart, this.onRenderStop);
 	};
 
 	Renderer.prototype.stop = function() {