Fix Colocalisation_Test window crash on multiple runs

If a script uses Colocalisation_Test, and closes the result window,
subsequent attempts to run Colocalisation_Test will crash because the
reference to the window will still be there, but the attempts to write
to the window will crash because the window was closed. To verify,
revert changes to Colocalisation_Test.java & run the new test case added
- the 2nd attempt to run coloc will fail.

The solution was to cleanup the window ref when a window is closed.

Signed-off-by: Curtis Rueden <[email protected]>

src/main/java/sc/fiji/coloc/Colocalisation_Test.java

@@ -45,6 +45,8 @@
 import ij.text.TextWindow;
 
 import java.awt.Rectangle;
+import java.awt.event.WindowEvent;
+import java.awt.event.WindowListener;
 import java.text.DecimalFormat;
 
 public class Colocalisation_Test implements PlugIn
@@ -701,10 +703,29 @@ public void correlate(ImagePlus imp1, ImagePlus imp2, ImagePlus imp3)
 		"\t" +df0.format(iterations)+
 		"\t" + randMethod+
 		"\t" +strPSF;
-	if (textWindow == null)
+	if (textWindow == null) {
 		textWindow = new TextWindow("Results",
-		Headings2, str, 400, 250);
-	else {
+				Headings2, str, 400, 250);
+				textWindow.addWindowListener(new WindowListener() {
+					@Override
+					public void windowClosed(WindowEvent arg0) {
+						textWindow = null;
+					}
+
+					@Override
+					public void windowActivated(WindowEvent arg0) {}
+					@Override
+					public void windowClosing(WindowEvent arg0) {}
+					@Override
+					public void windowDeactivated(WindowEvent arg0) {}
+					@Override
+					public void windowDeiconified(WindowEvent arg0) {}
+					@Override
+					public void windowIconified(WindowEvent arg0) {}
+					@Override
+					public void windowOpened(WindowEvent arg0) {}
+				});
+	} else {
 		textWindow.getTextPanel().setColumnHeadings(Headings2);
 		textWindow.getTextPanel().appendLine(str);
 	}

src/test/java/sc/fiji/coloc/tests/ColocalisationGUITest.java

@@ -0,0 +1,41 @@
+package sc.fiji.coloc.tests;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.awt.Window;
+import java.awt.event.WindowEvent;
+
+import org.junit.Test;
+
+import ij.IJ;
+import ij.ImagePlus;
+import ij.WindowManager;
+import ij.plugin.ChannelSplitter;
+import sc.fiji.coloc.Colocalisation_Test;
+
+public class ColocalisationGUITest extends ColocalisationTest {
+	@Test
+	public void testThatWindowRefIsCleanedUpIfClosed() {		
+		ImagePlus img = IJ.openImage("http://imagej.net/images/FluorescentCells.zip");
+		ImagePlus[] splitImg = ChannelSplitter.split(img);
+		Colocalisation_Test colocalisationTest = new Colocalisation_Test();
+
+		// run module once, it'll open results textWindow
+		colocalisationTest.correlate(splitImg[0], splitImg[1], splitImg[2]);
+
+		// check textWindow is open, and close it
+		Window resultsWindow = WindowManager.getWindow("Results");
+		assertTrue(resultsWindow.isVisible());
+		resultsWindow.dispatchEvent(new WindowEvent(resultsWindow, WindowEvent.WINDOW_CLOSING));
+		assertFalse(resultsWindow.isVisible());
+
+		// run module again
+		colocalisationTest.correlate(splitImg[0], splitImg[1], splitImg[2]);
+
+		// check textWindow is open, .correlate didnt crash!
+		resultsWindow = WindowManager.getWindow("Results");
+		assertTrue(resultsWindow.isVisible());
+
+	} 
+}