src/main/java/org/apache/log4j/chainsaw/components/elements/TabIconHandler.java

package org.apache.log4j.chainsaw.components.elements;

import org.apache.log4j.chainsaw.EventCountListener;
import org.apache.log4j.chainsaw.components.tabbedpane.ChainsawTabbedPane;
import org.apache.log4j.chainsaw.icons.ChainsawIcons;
import org.apache.log4j.chainsaw.icons.LineIconFactory;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public  class TabIconHandler implements EventCountListener, ChangeListener {
    //the tabIconHandler is associated with a new tab, and a new tab always
    //shows the 'new events' icon
    private boolean newEvents = true;
    private boolean seenEvents = false;
    private final String ident;
    private ChainsawTabbedPane tabbedPane;
    ImageIcon NEW_EVENTS = new ImageIcon(ChainsawIcons.ANIM_RADIO_TOWER);
    ImageIcon HAS_EVENTS = new ImageIcon(ChainsawIcons.INFO);
    Icon SELECTED = LineIconFactory.createBlankIcon();

    public TabIconHandler(String identifier, ChainsawTabbedPane tabbedPane) {
        ident = identifier;
        this.tabbedPane = tabbedPane;

        new Thread(
            () -> {
                while (true) {
                    //if this tab is active, remove the icon
                    //don't process undocked tabs
                    if (tabbedPane.indexOfTab(ident) > -1 &&
                        tabbedPane.getSelectedIndex() == tabbedPane
                            .indexOfTab(ident)) {
                        tabbedPane.setIconAt(
                            tabbedPane.indexOfTab(ident), SELECTED);
                        newEvents = false;
                        seenEvents = true;
                    } else if (tabbedPane.indexOfTab(ident) > -1) {
                        if (newEvents) {
                            tabbedPane.setIconAt(
                                tabbedPane.indexOfTab(ident), NEW_EVENTS);
                            newEvents = false;
                            seenEvents = false;
                        } else if (!seenEvents) {
                            tabbedPane.setIconAt(
                                tabbedPane.indexOfTab(ident), HAS_EVENTS);
                        }
                    }

                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException ie) {
                    }
                }
            }).start();
    }

    @Override
    public void eventCountChanged(int currentCount, int totalCount) {
        newEvents = true;
    }

    @Override
    public void stateChanged(ChangeEvent event) {
        if (
            tabbedPane.indexOfTab(ident) > -1 && tabbedPane.indexOfTab(ident) == tabbedPane.getSelectedIndex()) {
            tabbedPane.setIconAt(tabbedPane.indexOfTab(ident), SELECTED);
        }
    }
}