/*******************************************************************************
 * Copyright (c) 2004, 2005 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.gef.examples.text.edit;

import java.util.Hashtable;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;

/**
 * @author Pratik Shah
 * @since 3.1
 */
public class FontCache
{

private static Hashtable table = new Hashtable();

private FontCache() { }

/**
 * Clients should only check in fonts that they checked out from this cache, and should
 * do only one check-in per checkout. If the given font is not found, a null pointer
 * exception will be encountered.
 */
public static void checkIn(Font font) {
	FontData fd = font.getFontData()[0];
	Key key = new Key(fd.getName(), fd.getHeight(), (fd.getStyle() & SWT.BOLD) != 0,
			(fd.getStyle() & SWT.ITALIC) != 0);
	Value value = (Value)table.get(key);
	value.refCount--;
	if (value.refCount == 0) {
		table.remove(key);
		value.font.dispose();
	}
}

public static Font checkOut(String fontName, int fontHeight, 
		boolean isBold, boolean isItalic) {
	Key key = new Key(fontName, fontHeight, isBold, isItalic);
	Value value = (Value)table.get(key);
	if (value == null) {
		value = new Value();
		int style = (isBold ? SWT.BOLD : SWT.NONE) | (isItalic ? SWT.ITALIC : SWT.NONE);
		value.font = new Font(null, new FontData(fontName, fontHeight, style));
		table.put(key, value);
	}
	value.refCount++;
	return value.font;
}

private static class Key {
	private String fontName;
	private int height;
	private boolean isBold, isItalic;
	private Key(String fontName, int height, boolean isBold, boolean isItalic) {
		this.fontName = fontName;
		this.height = height;
		this.isBold = isBold;
		this.isItalic = isItalic;
	}
	public boolean equals(Object obj) {
		boolean result = obj == this;
		if (!result && (obj instanceof Key)) {
			Key key = (Key)obj;
			result = fontName.equalsIgnoreCase(key.fontName)
					&& height == key.height
					&& isBold == key.isBold
					&& isItalic == key.isItalic;
		}
		return result;
	}
	public int hashCode() {
		return fontName.toLowerCase().hashCode() + height;
	}
}

private static class Value {
	private Font font;
	private int refCount;
}

}