From 897a237807d8cbd427b18674750859aca363453f Mon Sep 17 00:00:00 2001
From: Ian Gilman <ian@iangilman.com>
Date: Tue, 20 Jan 2015 11:23:34 -0800
Subject: [PATCH] Added viewport-change event; fixed spring reset

---
 changelog.txt     |  2 ++
 src/spring.js     |  6 ++----
 src/tiledimage.js |  3 ---
 src/viewer.js     | 26 +++++++++++++++++++-------
 4 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/changelog.txt b/changelog.txt
index 671a9edd..d3a20e31 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -44,6 +44,8 @@ OPENSEADRAGON CHANGELOG
 * Added union() to OpenSeadragon.Rect
 * Fixed an error in fitBounds if the new and old bounds were extremely close in size
 * Added ajaxWithCredentials option (#543)
+* Added viewport-change event for after the viewport changes but before it's drawn
+* A spring's current value is now updated immediately on reset (#524)
 
 1.2.1: (in progress)
 
diff --git a/src/spring.js b/src/spring.js
index 4f92dfcb..3320ecc2 100644
--- a/src/spring.js
+++ b/src/spring.js
@@ -117,10 +117,8 @@ $.Spring.prototype = /** @lends OpenSeadragon.Spring.prototype */{
      * @param {Number} target
      */
     resetTo: function( target ) {
-        this.target.value = target;
-        this.target.time  = this.current.time;
-        this.start.value  = this.target.value;
-        this.start.time   = this.target.time;
+        this.start.value = this.target.value = this.current.value = target;
+        this.start.time = this.target.time = this.current.time = $.now();
     },
 
     /**
diff --git a/src/tiledimage.js b/src/tiledimage.js
index fc444b83..db52c66c 100644
--- a/src/tiledimage.js
+++ b/src/tiledimage.js
@@ -409,8 +409,6 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
 
             this._xSpring.resetTo(position.x);
             this._ySpring.resetTo(position.y);
-            this._xSpring.update();
-            this._ySpring.update();
         } else {
             if (sameTarget) {
                 return;
@@ -454,7 +452,6 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
             }
 
             this._scaleSpring.resetTo(scale);
-            this._scaleSpring.update();
             this._updateForScale();
         } else {
             if (sameTarget) {
diff --git a/src/viewer.js b/src/viewer.js
index f48eea97..8a291e50 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -2798,13 +2798,10 @@ function updateMulti( viewer ) {
 
 function updateOnce( viewer ) {
 
-    var containerSize,
-        animated;
-
     //viewer.profiler.beginUpdate();
 
     if ( viewer.autoResize ) {
-        containerSize = _getSafeElemSize( viewer.container );
+        var containerSize = _getSafeElemSize( viewer.container );
         if ( !containerSize.equals( THIS[ viewer.hash ].prevContainerSize ) ) {
             // maintain image position
             var oldBounds = viewer.viewport.getBounds();
@@ -2815,8 +2812,22 @@ function updateOnce( viewer ) {
         }
     }
 
-    animated = viewer.viewport.update();
-    animated = viewer.world.update() || animated;
+    var viewportChange = viewer.viewport.update();
+    var animated = viewer.world.update() || viewportChange;
+
+    if (viewportChange) {
+        /**
+         * Raised when any spring animation update occurs (zoom, pan, etc.),
+         * before the viewer has drawn the new location.
+         *
+         * @event viewport-change
+         * @memberof OpenSeadragon.Viewer
+         * @type {object}
+         * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised this event.
+         * @property {?Object} userData - Arbitrary subscriber-defined object.
+         */
+        viewer.raiseEvent('viewport-change');
+    }
 
     if( viewer.referenceStrip ){
         animated = viewer.referenceStrip.update( viewer.viewport ) || animated;
@@ -2847,7 +2858,8 @@ function updateOnce( viewer ) {
 
         if (animated) {
             /**
-             * Raised when any spring animation update occurs (zoom, pan, etc.).
+             * Raised when any spring animation update occurs (zoom, pan, etc.),
+             * after the viewer has drawn the new location.
              *
              * @event animation
              * @memberof OpenSeadragon.Viewer