FontMetrics.java

/*******************************************************************************
 * Copyright (c) 2000, 2008 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.swt.graphics;


/**
 * Instances of this class provide measurement information
 * about fonts including ascent, descent, height, leading
 * space between rows, and average character width.
 * <code>FontMetrics</code> are obtained from <code>GC</code>s
 * using the <code>getFontMetrics()</code> method.
 *
 * @see GC#getFontMetrics
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public final class FontMetrics {
	int ascent, descent, averageCharWidth, leading, height;

FontMetrics() {
}

/**
 * Compares the argument to the receiver, and returns true
 * if they represent the <em>same</em> object using a class
 * specific comparison.
 *
 * @param object the object to compare with this object
 * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
 *
 * @see #hashCode
 */
@Override
public boolean equals (Object object) {
	if (object == this) return true;
	if (!(object instanceof FontMetrics)) return false;
	FontMetrics metrics = (FontMetrics)object;
	return ascent == metrics.ascent && descent == metrics.descent &&
		averageCharWidth == metrics.averageCharWidth && leading == metrics.leading &&
		height == metrics.height;
}

/**
 * Returns the ascent of the font described by the receiver. A
 * font's <em>ascent</em> is the distance from the baseline to the 
 * top of actual characters, not including any of the leading area,
 * measured in pixels.
 *
 * @return the ascent of the font
 */
public int getAscent() {
	return ascent;
}

/**
 * Returns the average character width, measured in pixels,
 * of the font described by the receiver.
 *
 * @return the average character width of the font
 */
public int getAverageCharWidth() {
	return averageCharWidth;
}

/**
 * Returns the descent of the font described by the receiver. A
 * font's <em>descent</em> is the distance from the baseline to the
 * bottom of actual characters, not including any of the leading area,
 * measured in pixels.
 *
 * @return the descent of the font
 */
public int getDescent() {
	return descent;
}

/**
 * Returns the height of the font described by the receiver, 
 * measured in pixels. A font's <em>height</em> is the sum of
 * its ascent, descent and leading area.
 *
 * @return the height of the font
 *
 * @see #getAscent
 * @see #getDescent
 * @see #getLeading
 */
public int getHeight() {
	return height;
}

/**
 * Returns the leading area of the font described by the
 * receiver. A font's <em>leading area</em> is the space
 * above its ascent which may include accents or other marks.
 *
 * @return the leading space of the font
 */
public int getLeading() {
	return leading;
}

public static FontMetrics gtk_new(int ascent, int descent, int averageCharWidth, int leading, int height) {
	FontMetrics fontMetrics = new FontMetrics();
	fontMetrics.ascent = ascent;
	fontMetrics.descent = descent;
	fontMetrics.averageCharWidth = averageCharWidth;
	fontMetrics.leading = leading;
	fontMetrics.height = height;
	return fontMetrics;
}

/**
 * Returns an integer hash code for the receiver. Any two 
 * objects that return <code>true</code> when passed to 
 * <code>equals</code> must return the same value for this
 * method.
 *
 * @return the receiver's hash
 *
 * @see #equals
 */
@Override
public int hashCode() {
	return ascent ^ descent ^ averageCharWidth ^ leading ^ height;
}

}