From de9fa90facd751a7b3a931c89108b38209c0782d Mon Sep 17 00:00:00 2001
From: Ian Gilman <ian@iangilman.com>
Date: Thu, 18 Feb 2016 15:44:00 -0800
Subject: [PATCH] Viewport.zoomTo and zoomBy now respect ref point even when
 immediately = true

---
 src/viewport.js | 55 +++++++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 22 deletions(-)

diff --git a/src/viewport.js b/src/viewport.js
index 63b4dcaf..edbd13a6 100644
--- a/src/viewport.js
+++ b/src/viewport.js
@@ -765,7 +765,9 @@ $.Viewport.prototype = {
             null;
 
         if ( immediately ) {
-            this.zoomSpring.resetTo( zoom );
+            this._updateZoom({
+                resetTo: zoom
+            });
         } else {
             this.zoomSpring.springTo( zoom );
         }
@@ -891,27 +893,7 @@ $.Viewport.prototype = {
      * @function
      */
     update: function() {
-        var oldZoomPixel,
-            newZoomPixel,
-            deltaZoomPixels,
-            deltaZoomPoints;
-
-        if (this.zoomPoint) {
-            oldZoomPixel = this.pixelFromPoint( this.zoomPoint, true );
-        }
-
-        this.zoomSpring.update();
-
-        if (this.zoomPoint && this.zoomSpring.current.value != this._oldZoom) {
-            newZoomPixel    = this.pixelFromPoint( this.zoomPoint, true );
-            deltaZoomPixels = newZoomPixel.minus( oldZoomPixel );
-            deltaZoomPoints = this.deltaPointsFromPixels( deltaZoomPixels, true );
-
-            this.centerSpringX.shiftBy( deltaZoomPoints.x );
-            this.centerSpringY.shiftBy( deltaZoomPoints.y );
-        } else {
-            this.zoomPoint = null;
-        }
+        this._updateZoom();
 
         this.centerSpringX.update();
         this.centerSpringY.update();
@@ -927,6 +909,35 @@ $.Viewport.prototype = {
         return changed;
     },
 
+    // private
+    _updateZoom: function(options) {
+        var oldZoomPixel,
+            newZoomPixel,
+            deltaZoomPixels,
+            deltaZoomPoints;
+
+        if (this.zoomPoint) {
+            oldZoomPixel = this.pixelFromPoint( this.zoomPoint, true );
+        }
+
+        if (options && options.resetTo) {
+            this.zoomSpring.resetTo(options.resetTo);
+        } else {
+            this.zoomSpring.update();
+        }
+
+        if (this.zoomPoint && this.zoomSpring.current.value != this._oldZoom) {
+            newZoomPixel    = this.pixelFromPoint( this.zoomPoint, true );
+            deltaZoomPixels = newZoomPixel.minus( oldZoomPixel );
+            deltaZoomPoints = this.deltaPointsFromPixels( deltaZoomPixels, true );
+
+            this.centerSpringX.shiftBy( deltaZoomPoints.x );
+            this.centerSpringY.shiftBy( deltaZoomPoints.y );
+        } else {
+            this.zoomPoint = null;
+        }
+    },
+
     /**
      * Convert a delta (translation vector) from viewport coordinates to pixels
      * coordinates. This method does not take rotation into account.