From 5f933b12bbe99c47b6c893431f36475d8597f5df Mon Sep 17 00:00:00 2001
From: Johannes Mueller <johannes.mueller@precipoint.de>
Date: Fri, 5 Jun 2020 12:27:00 +0200
Subject: [PATCH] Clear listeners and nodes to avoid memory leaks

---
 src/button.js      | 14 ++++++++++++++
 src/buttongroup.js | 10 ++++++++++
 src/navigator.js   |  4 ++++
 src/viewer.js      | 20 +++++++++++++++++++-
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/button.js b/src/button.js
index 0ddb919a..ac909933 100644
--- a/src/button.js
+++ b/src/button.js
@@ -396,6 +396,20 @@ $.extend( $.Button.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.
         this.element.disabled = false;
         $.setElementOpacity( this.element, 1.0, true );
         this.notifyGroupEnter();
+    },
+
+    destroy: function() {
+        this.element.removeChild(this.imgRest);
+        this.imgRest = null;
+        this.element.removeChild(this.imgGroup);
+        this.imgGroup = null;
+        this.element.removeChild(this.imgHover);
+        this.imgHover = null;
+        this.element.removeChild(this.imgDown);
+        this.imgDown = null;
+        this.removeAllHandlers();
+        this.tracker.destroy();
+        this.element = null;
     }
 
 });
diff --git a/src/buttongroup.js b/src/buttongroup.js
index 2522d2f0..995f90d3 100644
--- a/src/buttongroup.js
+++ b/src/buttongroup.js
@@ -129,6 +129,16 @@ $.ButtonGroup.prototype = {
      */
     emulateExit: function() {
         this.tracker.exitHandler( { eventSource: this.tracker } );
+    },
+
+    destroy: function() {
+        while (this.buttons.length) {
+            var button = this.buttons.pop();
+            this.element.removeChild(button.element);
+            button.destroy();
+        }
+        this.tracker.destroy();
+        this.element = null;
     }
 };
 
diff --git a/src/navigator.js b/src/navigator.js
index afa3a7f5..6ff112e0 100644
--- a/src/navigator.js
+++ b/src/navigator.js
@@ -406,6 +406,10 @@ $.extend( $.Navigator.prototype, $.EventSource.prototype, $.Viewer.prototype, /*
         return $.Viewer.prototype.addTiledImage.apply(this, [optionsClone]);
     },
 
+    destroy: function() {
+        return $.Viewer.prototype.destroy.apply(this);
+    },
+
     // private
     _getMatchingItem: function(theirItem) {
         var count = this.world.getItemCount();
diff --git a/src/viewer.js b/src/viewer.js
index 20e06186..73b2aca4 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -765,8 +765,23 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             this.drawer.destroy();
         }
 
+        if ( this.navigator ) {
+            this.navigator.destroy();
+            THIS[ this.navigator.hash ] = null;
+            delete THIS[ this.navigator.hash ];
+            this.navigator = null;
+        }
+
         this.removeAllHandlers();
 
+        if (this.buttons) {
+            this.buttons.destroy();
+        }
+
+        if (this.paging) {
+            this.paging.destroy();
+        }
+
         // Go through top element (passed to us) and remove all children
         // Use removeChild to make sure it handles SVG or any non-html
         // also it performs better - http://jsperf.com/innerhtml-vs-removechild/15
@@ -776,6 +791,9 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             }
         }
 
+        this.container.onsubmit = null;
+        this.clearControls();
+
         // destroy the mouse trackers
         if (this.innerTracker){
             this.innerTracker.destroy();
@@ -3261,7 +3279,7 @@ function updateOnce( viewer ) {
 
     //viewer.profiler.beginUpdate();
 
-    if (viewer._opening) {
+    if (viewer._opening || !THIS[viewer.hash]) {
         return;
     }