From f35947361ca0a5c1d69a4a645d007167559d7604 Mon Sep 17 00:00:00 2001
From: Victor Woeltjen <victor.woeltjen@nasa.gov>
Date: Mon, 23 May 2016 15:32:48 -0700
Subject: [PATCH] [Timeline] Remain centered during zoom

#936
---
 platform/features/timeline/res/templates/timeline.html        | 4 ++--
 .../timeline/src/controllers/TimelineZoomController.js        | 4 +++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/platform/features/timeline/res/templates/timeline.html b/platform/features/timeline/res/templates/timeline.html
index 41a1c67a87..fc2e779a36 100644
--- a/platform/features/timeline/res/templates/timeline.html
+++ b/platform/features/timeline/res/templates/timeline.html
@@ -104,14 +104,14 @@
         <div class="split-pane-component l-timeline-pane t-pane-h l-pane-top t-timeline-gantt l-timeline-gantt s-timeline-gantt">
             <div class="l-hover-btns-holder s-hover-btns-holder t-btns-zoom">
                 <a class="t-btn l-btn s-btn"
-                   ng-click="zoomController.zoom(-1)"
+                   ng-click="zoomController.zoom(-1, scroll)"
                    ng-show="true"
                    title="Zoom in">
                     <span class="ui-symbol icon zoom-in">X</span>
                 </a>
 
                 <a class="t-btn l-btn s-btn"
-                   ng-click="zoomController.zoom(1)"
+                   ng-click="zoomController.zoom(1, scroll)"
                    ng-show="true"
                    title="Zoom out">
                     <span class="ui-symbol icon zoom-out">Y</span>
diff --git a/platform/features/timeline/src/controllers/TimelineZoomController.js b/platform/features/timeline/src/controllers/TimelineZoomController.js
index 4c8acd0061..4208a7465c 100644
--- a/platform/features/timeline/src/controllers/TimelineZoomController.js
+++ b/platform/features/timeline/src/controllers/TimelineZoomController.js
@@ -80,11 +80,13 @@ define(
                  * @returns {number} current zoom level (as the size of a
                  *          major tick mark, in pixels)
                  */
-                zoom: function (amount) {
+                zoom: function (amount, bounds) {
                     // Update the zoom level if called with an argument
                     if (arguments.length > 0 && !isNaN(amount)) {
+                        var center = this.toMillis(bounds.x + bounds.width / 2);
                         setZoomLevel(zoomIndex + amount);
                         storeZoom(zoomIndex);
+                        bounds.x = this.toPixels(center) - bounds.width / 2;
                     }
                     return zoomLevels[zoomIndex];
                 },