From 40efb59a34c9e5bd9b7cb0aaee5e0fc77cf00303 Mon Sep 17 00:00:00 2001
From: Monica Kozbial <kozbial@google.com>
Date: Fri, 10 Jul 2020 17:34:53 -0700
Subject: [PATCH] Unbind event handlers in dispose of zoom controls. (#4031)

* Unbind event handlers in dispose of zoom controls.

* Move event handler references to constructor.
---
 core/zoom_controls.js | 40 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/core/zoom_controls.js b/core/zoom_controls.js
index 4b1edadec..98e431f7f 100644
--- a/core/zoom_controls.js
+++ b/core/zoom_controls.js
@@ -29,6 +29,30 @@ Blockly.ZoomControls = function(workspace) {
    * @private
    */
   this.workspace_ = workspace;
+
+  /**
+   * A handle to use to unbind the mouse down event handler for zoom reset
+   *    button. Opaque data returned from Blockly.bindEventWithChecks_.
+   * @type {?Blockly.EventData}
+   * @private
+   */
+  this.onZoomResetWrapper_ = null;
+
+  /**
+   * A handle to use to unbind the mouse down event handler for zoom in button.
+   * Opaque data returned from Blockly.bindEventWithChecks_.
+   * @type {?Blockly.EventData}
+   * @private
+   */
+  this.onZoomInWrapper_ = null;
+
+  /**
+   * A handle to use to unbind the mouse down event handler for zoom out button.
+   * Opaque data returned from Blockly.bindEventWithChecks_.
+   * @type {?Blockly.EventData}
+   * @private
+   */
+  this.onZoomOutWrapper_ = null;
 };
 
 /**
@@ -80,6 +104,7 @@ Blockly.ZoomControls.prototype.left_ = 0;
  */
 Blockly.ZoomControls.prototype.top_ = 0;
 
+
 /**
  * Create the zoom controls.
  * @return {!SVGElement} The zoom controls SVG group.
@@ -122,6 +147,15 @@ Blockly.ZoomControls.prototype.dispose = function() {
   if (this.svgGroup_) {
     Blockly.utils.dom.removeNode(this.svgGroup_);
   }
+  if (this.onZoomResetWrapper_) {
+    Blockly.unbindEvent_(this.onZoomResetWrapper_);
+  }
+  if (this.onZoomInWrapper_) {
+    Blockly.unbindEvent_(this.onZoomInWrapper_);
+  }
+  if (this.onZoomOutWrapper_) {
+    Blockly.unbindEvent_(this.onZoomOutWrapper_);
+  }
 };
 
 /**
@@ -209,7 +243,7 @@ Blockly.ZoomControls.prototype.createZoomOutSvg_ = function(rnd) {
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
 
   // Attach listener.
-  Blockly.bindEventWithChecks_(
+  this.onZoomOutWrapper_ = Blockly.bindEventWithChecks_(
       zoomoutSvg, 'mousedown', null, this.zoom_.bind(this, -1));
 };
 
@@ -256,7 +290,7 @@ Blockly.ZoomControls.prototype.createZoomInSvg_ = function(rnd) {
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
 
   // Attach listener.
-  Blockly.bindEventWithChecks_(
+  this.onZoomInWrapper_ = Blockly.bindEventWithChecks_(
       zoominSvg, 'mousedown', null, this.zoom_.bind(this, 1));
 };
 
@@ -320,7 +354,7 @@ Blockly.ZoomControls.prototype.createZoomResetSvg_ = function(rnd) {
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
 
   // Attach event listeners.
-  Blockly.bindEventWithChecks_(
+  this.onZoomResetWrapper_ = Blockly.bindEventWithChecks_(
       zoomresetSvg, 'mousedown', null, this.resetZoom_.bind(this));
 };