8302846: IGV: Zoom stuck when zooming out on large graphs

Reviewed-by: rcastanedalo, thartmann

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/ZoomLevelAction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,6 +40,8 @@ public final class ZoomLevelAction extends JComboBox<String> implements ChangedL
 
     private final DiagramViewer diagramScene;
 
+    boolean updateZoomInScene = true;
+
     @Override
     public void actionPerformed(ActionEvent e) {
         EditorTopComponent editor = EditorTopComponent.getActive();
@@ -58,6 +60,9 @@ public void actionPerformed(ActionEvent e) {
             level = Math.max(level, minLevel);
             level = Math.min(level, maxLevel);
             setZoomLevel(level);
+            if (updateZoomInScene) {
+                diagramScene.setZoomPercentage(level);
+            }
         } catch(NumberFormatException exception) {
             changed(diagramScene);
         }
@@ -84,11 +89,12 @@ public ZoomLevelAction(DiagramViewer scene) {
 
     private void setZoomLevel(int zoomLevel) {
         setSelectedItem(zoomLevel + "%");
-        diagramScene.setZoomPercentage(zoomLevel);
     }
 
     @Override
     public void changed(DiagramViewer diagramViewer) {
-        setSelectedItem(diagramViewer.getZoomPercentage() + "%");
+        updateZoomInScene = false;
+        setZoomLevel(diagramViewer.getZoomPercentage());
+        updateZoomInScene = true;
     }
 }