Bug 549496 - VisibleLinesTracker is activated twice inI20190723-1800

LineNumberRulerColumn

Tracker is activated enabled twice but only deactivated once. At the
same time the Tracker should use ListenerList for its listeners.

Change-Id: I310dc8cfc5068e329d81e7bd668b9f0646d2873b
Signed-off-by: Paul Pazderski <paul-eclipse@ppazderski.de>

2 files changed, 6 insertions, 13 deletions

diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/source/LineNumberRulerColumn.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/source/LineNumberRulerColumn.java
index 1e41584ccc7..0f98abf8bbd 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/source/LineNumberRulerColumn.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/source/LineNumberRulerColumn.java
@@ -644,15 +644,11 @@ public class LineNumberRulerColumn implements IVerticalRulerColumn {
 		fCanvas.addMouseMoveListener(fMouseHandler);
 		fCanvas.addMouseWheelListener(fMouseHandler);
 
-		if (fCachedTextViewer != null) {
-			VisibleLinesTracker.track(fCachedTextViewer, lineHeightChangeHandler);
-			fCachedTextViewer.addTextListener(fInternalListener);
-
+		fCachedTextViewer.addTextListener(fInternalListener);
 
-			if (fFont == null) {
-				if (fCachedTextWidget != null && !fCachedTextWidget.isDisposed())
-					fFont= fCachedTextWidget.getFont();
-			}
+		if (fFont == null) {
+			if (!fCachedTextWidget.isDisposed())
+				fFont= fCachedTextWidget.getFont();
 		}
 
 		if (fFont != null)
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/source/VisibleLinesTracker.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/source/VisibleLinesTracker.java
index 3f6b3815965..4f8c2dfd37d 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/source/VisibleLinesTracker.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/source/VisibleLinesTracker.java
@@ -13,8 +13,7 @@
  */
 package org.eclipse.jface.text.source;
 
-import java.util.ArrayList;
-import java.util.Collection;
+import java.util.LinkedHashSet;
 import java.util.function.Consumer;
 
 import org.eclipse.swt.custom.StyledText;
@@ -48,10 +47,9 @@ class VisibleLinesTracker implements PaintListener {
 	private int oldBottomPixel;
 
 	/**
-	 *
 	 * List of handler to call when a visible line height change.
 	 */
-	private final Collection<Consumer<StyledText>> handlers;
+	private final LinkedHashSet<Consumer<StyledText>> handlers= new LinkedHashSet<>();
 
 	/**
 	 * Constructor to track line height change of visible lines of the {@link StyledText} of the
@@ -61,7 +59,6 @@ class VisibleLinesTracker implements PaintListener {
 	 */
 	private VisibleLinesTracker(ITextViewer viewer) {
 		this.viewer= viewer;
-		this.handlers= new ArrayList<>();
 	}
 
 	@Override