Java tutorial
/* * Copyright (c) 1997, 1998, 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 java.awt; import java.awt.image.ColorModel; /** * The {@code Composite} interface, along with * {@link CompositeContext}, defines the methods to compose a draw * primitive with the underlying graphics area. * After the {@code Composite} is set in the * {@link Graphics2D} context, it combines a shape, text, or an image * being rendered with the colors that have already been rendered * according to pre-defined rules. The classes * implementing this interface provide the rules and a method to create * the context for a particular operation. * {@code CompositeContext} is an environment used by the * compositing operation, which is created by the {@code Graphics2D} * prior to the start of the operation. {@code CompositeContext} * contains private information and resources needed for a compositing * operation. When the {@code CompositeContext} is no longer needed, * the {@code Graphics2D} object disposes of it in order to reclaim * resources allocated for the operation. * <p> * Instances of classes implementing {@code Composite} must be * immutable because the {@code Graphics2D} does not clone * these objects when they are set as an attribute with the * {@code setComposite} method or when the {@code Graphics2D} * object is cloned. This is to avoid undefined rendering behavior of * {@code Graphics2D}, resulting from the modification of * the {@code Composite} object after it has been set in the * {@code Graphics2D} context. * <p> * Since this interface must expose the contents of pixels on the * target device or image to potentially arbitrary code, the use of * custom objects which implement this interface when rendering directly * to a screen device is governed by the {@code readDisplayPixels} * {@link AWTPermission}. The permission check will occur when such * a custom object is passed to the {@code setComposite} method * of a {@code Graphics2D} retrieved from a {@link Component}. * @see AlphaComposite * @see CompositeContext * @see Graphics2D#setComposite */ public interface Composite { /** * Creates a context containing state that is used to perform * the compositing operation. In a multi-threaded environment, * several contexts can exist simultaneously for a single * {@code Composite} object. * @param srcColorModel the {@link ColorModel} of the source * @param dstColorModel the {@code ColorModel} of the destination * @param hints the hint that the context object uses to choose between * rendering alternatives * @return the {@code CompositeContext} object used to perform the * compositing operation. */ public CompositeContext createContext(ColorModel srcColorModel, ColorModel dstColorModel, RenderingHints hints); }