JAL-2608 tidy up OverviewPanel when closed

[jalview.git] / src / jalview / gui / OverviewPanel.java

diff --git a/src/jalview/gui/OverviewPanel.java b/src/jalview/gui/OverviewPanel.java
index 62e7a68..7a4456e 100755 (executable)
--- a/src/jalview/gui/OverviewPanel.java
+++ b/src/jalview/gui/OverviewPanel.java
@@ -147,7 +147,6 @@ public class OverviewPanel extends JPanel implements Runnable,
       }
     });
 
-
     updateOverviewImage();
   }
 
@@ -205,6 +204,14 @@ public class OverviewPanel extends JPanel implements Runnable,
    */
   public void updateOverviewImage()
   {
+    if (oviewCanvas == null)
+    {
+      /*
+       * panel has been disposed
+       */
+      return;
+    }
+
     if ((getWidth() > 0) && (getHeight() > 0))
     {
       od.setWidth(getWidth());
@@ -221,7 +228,6 @@ public class OverviewPanel extends JPanel implements Runnable,
     Thread thread = new Thread(this);
     thread.start();
     repaint();
-
   }
 
   @Override
@@ -251,4 +257,21 @@ public class OverviewPanel extends JPanel implements Runnable,
   {
     setBoxPosition();
   }
+
+  /**
+   * Removes this object as a property change listener, and nulls references
+   */
+  protected void dispose()
+  {
+    try
+    {
+      av.getRanges().removePropertyChangeListener(this);
+    } finally
+    {
+      av = null;
+      oviewCanvas = null;
+      ap = null;
+      od = null;
+    }
+  }
 }