1 /* 2 * Copyright (c) 1997, 1998, 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 */ 25 26 package java.awt; 27 28 import java.awt.image.ColorModel; 29 30 /** 31 * The {@code Composite} interface, along with 32 * {@link CompositeContext}, defines the methods to compose a draw 33 * primitive with the underlying graphics area. 34 * After the {@code Composite} is set in the 35 * {@link Graphics2D} context, it combines a shape, text, or an image 36 * being rendered with the colors that have already been rendered 37 * according to pre-defined rules. The classes 38 * implementing this interface provide the rules and a method to create 39 * the context for a particular operation. 40 * {@code CompositeContext} is an environment used by the 41 * compositing operation, which is created by the {@code Graphics2D} 42 * prior to the start of the operation. {@code CompositeContext} 43 * contains private information and resources needed for a compositing 44 * operation. When the {@code CompositeContext} is no longer needed, 45 * the {@code Graphics2D} object disposes of it in order to reclaim 46 * resources allocated for the operation. 47 * <p> 48 * Instances of classes implementing {@code Composite} must be 49 * immutable because the {@code Graphics2D} does not clone 50 * these objects when they are set as an attribute with the 51 * {@code setComposite} method or when the {@code Graphics2D} 52 * object is cloned. This is to avoid undefined rendering behavior of 53 * {@code Graphics2D}, resulting from the modification of 54 * the {@code Composite} object after it has been set in the 55 * {@code Graphics2D} context. 56 * <p> 57 * Since this interface must expose the contents of pixels on the 58 * target device or image to potentially arbitrary code, the use of 59 * custom objects which implement this interface when rendering directly 60 * to a screen device is governed by the {@code readDisplayPixels} 61 * {@link AWTPermission}. The permission check will occur when such 62 * a custom object is passed to the {@code setComposite} method 63 * of a {@code Graphics2D} retrieved from a {@link Component}. 64 * @see AlphaComposite 65 * @see CompositeContext 66 * @see Graphics2D#setComposite 67 */ 68 public interface Composite { 69 70 /** 71 * Creates a context containing state that is used to perform 72 * the compositing operation. In a multi-threaded environment, 73 * several contexts can exist simultaneously for a single 74 * {@code Composite} object. 75 * @param srcColorModel the {@link ColorModel} of the source 76 * @param dstColorModel the {@code ColorModel} of the destination 77 * @param hints the hint that the context object uses to choose between 78 * rendering alternatives 79 * @return the {@code CompositeContext} object used to perform the 80 * compositing operation. 81 */ 82 public CompositeContext createContext(ColorModel srcColorModel, 83 ColorModel dstColorModel, 84 RenderingHints hints); 85 86 }