Java example source code file (StrokeBorder.java)

This example Java source code file (StrokeBorder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractborder, awt, basicstroke, bean, constructorproperties, geometry, graphics2d, insets, javabean, nullpointerexception, override, paint, strokeborder

The StrokeBorder.java Java example source code

/*
 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package javax.swing.border;

import java.awt.BasicStroke;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.Paint;
import java.awt.RenderingHints;
import java.awt.geom.Rectangle2D;
import java.beans.ConstructorProperties;

/**
 * A class which implements a border of an arbitrary stroke.
 * <p>
 * <strong>Warning:
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI
 * between applications running the same version of Swing.
 * As of 1.4, support for long term storage of all JavaBeans™
 * has been added to the <code>java.beans package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Sergey A. Malenkov
 *
 * @since 1.7
 */
public class StrokeBorder extends AbstractBorder {
    private final BasicStroke stroke;
    private final Paint paint;

    /**
     * Creates a border of the specified {@code stroke}.
     * The component's foreground color will be used to render the border.
     *
     * @param stroke  the {@link BasicStroke} object used to stroke a shape
     *
     * @throws NullPointerException if the specified {@code stroke} is {@code null}
     */
    public StrokeBorder(BasicStroke stroke) {
        this(stroke, null);
    }

    /**
     * Creates a border of the specified {@code stroke} and {@code paint}.
     * If the specified {@code paint} is {@code null},
     * the component's foreground color will be used to render the border.
     *
     * @param stroke  the {@link BasicStroke} object used to stroke a shape
     * @param paint   the {@link Paint} object used to generate a color
     *
     * @throws NullPointerException if the specified {@code stroke} is {@code null}
     */
    @ConstructorProperties({ "stroke", "paint" })
    public StrokeBorder(BasicStroke stroke, Paint paint) {
        if (stroke == null) {
            throw new NullPointerException("border's stroke");
        }
        this.stroke = stroke;
        this.paint = paint;
    }

    /**
     * Paints the border for the specified component
     * with the specified position and size.
     * If the border was not specified with a {@link Paint} object,
     * the component's foreground color will be used to render the border.
     * If the component's foreground color is not available,
     * the default color of the {@link Graphics} object will be used.
     *
     * @param c       the component for which this border is being painted
     * @param g       the paint graphics
     * @param x       the x position of the painted border
     * @param y       the y position of the painted border
     * @param width   the width of the painted border
     * @param height  the height of the painted border
     *
     * @throws NullPointerException if the specified {@code g} is {@code null}
     */
    @Override
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        float size = this.stroke.getLineWidth();
        if (size > 0.0f) {
            g = g.create();
            if (g instanceof Graphics2D) {
                Graphics2D g2d = (Graphics2D) g;
                g2d.setStroke(this.stroke);
                g2d.setPaint(this.paint != null ? this.paint : c == null ? null : c.getForeground());
                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                                     RenderingHints.VALUE_ANTIALIAS_ON);
                g2d.draw(new Rectangle2D.Float(x + size / 2, y + size / 2, width - size, height - size));
            }
            g.dispose();
        }
    }

    /**
     * Reinitializes the {@code insets} parameter
     * with this border's current insets.
     * Every inset is the smallest (closest to negative infinity) integer value
     * that is greater than or equal to the line width of the stroke
     * that is used to paint the border.
     *
     * @param c       the component for which this border insets value applies
     * @param insets  the {@code Insets} object to be reinitialized
     * @return the reinitialized {@code insets} parameter
     *
     * @throws NullPointerException if the specified {@code insets} is {@code null}
     *
     * @see Math#ceil
     */
    @Override
    public Insets getBorderInsets(Component c, Insets insets) {
        int size = (int) Math.ceil(this.stroke.getLineWidth());
        insets.set(size, size, size, size);
        return insets;
    }

    /**
     * Returns the {@link BasicStroke} object used to stroke a shape
     * during the border rendering.
     *
     * @return the {@link BasicStroke} object
     */
    public BasicStroke getStroke() {
        return this.stroke;
    }

    /**
     * Returns the {@link Paint} object used to generate a color
     * during the border rendering.
     *
     * @return the {@link Paint} object or {@code null}
     *         if the {@code paint} parameter is not set
     */
    public Paint getPaint() {
        return this.paint;
    }
}