core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/CSourcePreviewerUpdater.java

/*******************************************************************************
 * Copyright (c) 2000, 2012 QNX Software Systems and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     QNX Software Systems - Initial API and implementation
 *     Anton Leherbauer (Wind River Systems)
 *******************************************************************************/
package org.eclipse.cdt.internal.ui.preferences;

import org.eclipse.cdt.ui.PreferenceConstants;
import org.eclipse.cdt.ui.text.CSourceViewerConfiguration;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.text.source.SourceViewer;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.graphics.Font;

public class CSourcePreviewerUpdater {

	/**
	 * Handles editor font changes for source preview viewers.
	 *
	 * @param viewer
	 * @param configuration
	 * @param store
	 */
	public CSourcePreviewerUpdater(SourceViewer viewer, CSourceViewerConfiguration configuration,
			IPreferenceStore store) {
		registerPreviewer(viewer, configuration, store);
	}

	/**
	 * Registers a source preview updater for the given viewer, configuration and preference store.
	 *
	 * @param viewer the viewer
	 * @param configuration the configuration
	 * @param preferenceStore the preference store
	 */
	static public void registerPreviewer(final SourceViewer viewer, final CSourceViewerConfiguration configuration,
			final IPreferenceStore preferenceStore) {
		Assert.isNotNull(viewer);
		Assert.isNotNull(configuration);
		Assert.isNotNull(preferenceStore);
		final IPropertyChangeListener fontChangeListener = new IPropertyChangeListener() {
			/*
			 * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent)
			 */
			@Override
			public void propertyChange(PropertyChangeEvent event) {
				if (event.getProperty().equals(PreferenceConstants.EDITOR_TEXT_FONT)) {
					Font font = JFaceResources.getFont(PreferenceConstants.EDITOR_TEXT_FONT);
					viewer.getTextWidget().setFont(font);
				}
			}
		};
		final IPropertyChangeListener propertyChangeListener = new IPropertyChangeListener() {
			/*
			 * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent)
			 */
			@Override
			public void propertyChange(PropertyChangeEvent event) {
				if (configuration.affectsTextPresentation(event)) {
					configuration.handlePropertyChangeEvent(event);
					viewer.invalidateTextPresentation();
				}
			}
		};
		viewer.getTextWidget().addDisposeListener(new DisposeListener() {
			/*
			 * @see org.eclipse.swt.events.DisposeListener#widgetDisposed(org.eclipse.swt.events.DisposeEvent)
			 */
			@Override
			public void widgetDisposed(DisposeEvent e) {
				preferenceStore.removePropertyChangeListener(propertyChangeListener);
				JFaceResources.getFontRegistry().removeListener(fontChangeListener);
			}
		});
		JFaceResources.getFontRegistry().addListener(fontChangeListener);
		preferenceStore.addPropertyChangeListener(propertyChangeListener);
	}

}