bundles/org.eclipse.ui.forms/src/org/eclipse/ui/internal/forms/widgets/PixelConverter.java

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.forms.widgets;

import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Control;

public class PixelConverter {
	/**
	 * Number of horizontal dialog units per character, value <code>4</code>.
	 */
	private static final int HORIZONTAL_DIALOG_UNIT_PER_CHAR = 4;

	private FontMetrics fFontMetrics;

	public PixelConverter(Control control) {
		GC gc = new GC(control);
		gc.setFont(control.getFont());
		fFontMetrics = gc.getFontMetrics();
		gc.dispose();
	}

	/**
	 * @see DialogPage#convertHorizontalDLUsToPixels
	 */
	public int convertHorizontalDLUsToPixels(int dlus) {
		// round to the nearest pixel
		return (fFontMetrics.getAverageCharWidth() * dlus + HORIZONTAL_DIALOG_UNIT_PER_CHAR / 2)
				/ HORIZONTAL_DIALOG_UNIT_PER_CHAR;
	}
}