1/* 2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25package javax.swing; 26 27import java.awt.Graphics2D; 28 29/** 30 * <p>A painting delegate. The Painter interface defines exactly one method, 31 * <code>paint</code>. It is used in situations where the developer can change 32 * the painting routine of a component without having to resort to subclassing 33 * the component. It is also generically useful when doing any form of painting 34 * delegation.</p> 35 * 36 * <p><code>Painter</code>s are simply encapsulations of Java2D code and make 37 * it fairly trivial to reuse existing <code>Painter</code>s or to combine 38 * them together. Implementations of this interface are also trivial to write, 39 * such that if you can't find a <code>Painter</code> that does what you need, 40 * you can write one with minimal effort. Writing a <code>Painter</code> requires 41 * knowledge of Java2D.</p> 42 * 43 * <p>A <code>Painter</code> may be created with a type parameter. This type will be 44 * expected in the <code>paint</code> method. For example, you may wish to write a 45 * <code>Painter</code> that only works with subclasses of {@link java.awt.Component}. 46 * In that case, when the <code>Painter</code> is declared, you may declare that 47 * it requires a <code>Component</code>, allowing the paint method to be type safe. Ex: 48 * <pre> 49 * {@code 50 * Painter<Component> p = new Painter<Component>() { 51 * public void paint(Graphics2D g, Component c, int width, int height) { 52 * g.setColor(c.getBackground()); 53 * //and so forth 54 * } 55 * } 56 * } 57 * </pre> 58 * 59 * <p>This interface makes no guarantees of threadsafety.</p> 60 * 61 * @author rbair 62 * @since 1.7 63 */ 64public interface Painter<T> { 65 /** 66 * <p>Renders to the given {@link java.awt.Graphics2D} object. Implementations 67 * of this method <em>may</em> modify state on the <code>Graphics2D</code>, and are not 68 * required to restore that state upon completion. In most cases, it is recommended 69 * that the caller pass in a scratch graphics object. The <code>Graphics2D</code> 70 * must never be null.</p> 71 * 72 * <p>State on the graphics object may be honored by the <code>paint</code> method, 73 * but may not be. For instance, setting the antialiasing rendering hint on the 74 * graphics may or may not be respected by the <code>Painter</code> implementation.</p> 75 * 76 * <p>The supplied object parameter acts as an optional configuration argument. 77 * For example, it could be of type <code>Component</code>. A <code>Painter</code> 78 * that expected it could then read state from that <code>Component</code> and 79 * use the state for painting. For example, an implementation may read the 80 * backgroundColor and use that.</p> 81 * 82 * <p>Generally, to enhance reusability, most standard <code>Painter</code>s ignore 83 * this parameter. They can thus be reused in any context. The <code>object</code> 84 * may be null. Implementations must not throw a NullPointerException if the object 85 * parameter is null.</p> 86 * 87 * <p>Finally, the <code>width</code> and <code>height</code> arguments specify the 88 * width and height that the <code>Painter</code> should paint into. More 89 * specifically, the specified width and height instruct the painter that it should 90 * paint fully within this width and height. Any specified clip on the 91 * <code>g</code> param will further constrain the region.</p> 92 * 93 * <p>For example, suppose I have a <code>Painter</code> implementation that draws 94 * a gradient. The gradient goes from white to black. It "stretches" to fill the 95 * painted region. Thus, if I use this <code>Painter</code> to paint a 500 x 500 96 * region, the far left would be black, the far right would be white, and a smooth 97 * gradient would be painted between. I could then, without modification, reuse the 98 * <code>Painter</code> to paint a region that is 20x20 in size. This region would 99 * also be black on the left, white on the right, and a smooth gradient painted 100 * between.</p> 101 * 102 * @param g The Graphics2D to render to. This must not be null. 103 * @param object an optional configuration parameter. This may be null. 104 * @param width width of the area to paint. 105 * @param height height of the area to paint. 106 */ 107 public void paint(Graphics2D g, T object, int width, int height); 108} 109