From b7e7a9b3ba7df61d2906aa8b2427fc9b6a22f36c Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Sat, 4 Aug 2012 16:45:11 +0200
Subject: [PATCH] Add zoom to/from anchor

---
 src/ol/control/control.js        | 33 ++++++++++++++++++++++++++------
 src/ol/control/dblclickzoom.js   |  3 ++-
 src/ol/control/keyboardzoom.js   |  3 ++-
 src/ol/control/mousewheelzoom.js |  3 ++-
 4 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/ol/control/control.js b/src/ol/control/control.js
index b8eefd1b31..9195848924 100644
--- a/src/ol/control/control.js
+++ b/src/ol/control/control.js
@@ -80,15 +80,36 @@ ol.Control.prototype.setResolution = function(map, resolution) {
 
 /**
  * @param {ol.Map} map Map.
+ * @param {number|undefined} resolution Resolution.
  * @param {number} delta Delta.
  * @param {ol.Coordinate=} opt_anchor Anchor.
  */
-ol.Control.prototype.zoom = function(map, delta, opt_anchor) {
-  //if (false && goog.isDef(opt_anchor)) {
-    // FIXME
-  //} else {
-    var resolution = map.getResolution();
+ol.Control.prototype.zoom = function(map, resolution, delta, opt_anchor) {
+  if (goog.isDefAndNotNull(opt_anchor)) {
+    var mapCenter = /** @type {!ol.Coordinate} */ map.getCenter();
+    var mapResolution = map.getResolution();
+    resolution = this.constraints.resolution(resolution, delta);
+    var center;
+    if (resolution < mapResolution) {
+      center = opt_anchor.clone();
+      center.subtract(mapCenter);
+      center.scale(resolution / mapResolution);
+      center.add(mapCenter);
+    } else if (resolution == mapResolution) {
+      center = mapCenter;
+    } else {
+      center = mapCenter.clone();
+      center.subtract(opt_anchor);
+      center.scale(resolution / mapResolution);
+      center.add(opt_anchor);
+    }
+    center = this.constraints.center(center, resolution, ol.Coordinate.ZERO);
+    map.withFrozenRendering(function() {
+      map.setCenter(center);
+      map.setResolution(resolution);
+    });
+  } else {
     resolution = this.constraints.resolution(resolution, delta);
     map.setResolution(resolution);
-  //}
+  }
 };
diff --git a/src/ol/control/dblclickzoom.js b/src/ol/control/dblclickzoom.js
index 1ffef392f7..0241916588 100644
--- a/src/ol/control/dblclickzoom.js
+++ b/src/ol/control/dblclickzoom.js
@@ -25,9 +25,10 @@ ol.control.DblClickZoom.prototype.handleMapBrowserEvent =
     function(mapBrowserEvent) {
   if (mapBrowserEvent.type == goog.events.EventType.DBLCLICK) {
     var map = mapBrowserEvent.map;
+    var resolution = map.getResolution();
     var delta = mapBrowserEvent.browserEvent.shiftKey ? -1 : 1;
     var anchor = mapBrowserEvent.getCoordinate();
-    this.zoom(map, delta, anchor);
+    this.zoom(map, resolution, delta, anchor);
     mapBrowserEvent.preventDefault();
   }
 };
diff --git a/src/ol/control/keyboardzoom.js b/src/ol/control/keyboardzoom.js
index c6cb3e2076..97dff8658b 100644
--- a/src/ol/control/keyboardzoom.js
+++ b/src/ol/control/keyboardzoom.js
@@ -29,8 +29,9 @@ ol.control.KeyboardZoom.prototype.handleMapBrowserEvent =
     var charCode = keyEvent.charCode;
     if (charCode == '+'.charCodeAt(0) || charCode == '-'.charCodeAt(0)) {
       var map = mapBrowserEvent.map;
+      var resolution = map.getResolution();
       var delta = charCode == '+'.charCodeAt(0) ? 1 : -1;
-      this.zoom(map, delta);
+      this.zoom(map, resolution, delta);
       keyEvent.preventDefault();
       mapBrowserEvent.preventDefault();
     }
diff --git a/src/ol/control/mousewheelzoom.js b/src/ol/control/mousewheelzoom.js
index 849a633cb4..9b55cab962 100644
--- a/src/ol/control/mousewheelzoom.js
+++ b/src/ol/control/mousewheelzoom.js
@@ -31,8 +31,9 @@ ol.control.MouseWheelZoom.prototype.handleMapBrowserEvent =
     goog.asserts.assert(mouseWheelEvent instanceof goog.events.MouseWheelEvent);
     if (mouseWheelEvent.deltaY !== 0) {
       var delta = mouseWheelEvent.deltaY < 0 ? 1 : -1;
+      var resolution = map.getResolution();
       var anchor = mapBrowserEvent.getCoordinate();
-      this.zoom(map, delta, anchor);
+      this.zoom(map, resolution, delta, anchor);
       mapBrowserEvent.preventDefault();
       mouseWheelEvent.preventDefault();
     }