jdk/src/share/classes/java/awt/image/ImageObserver.java
changeset 2 90ce3da70b43
child 5506 202f599c92aa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/awt/image/ImageObserver.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,170 @@
+/*
+ * Copyright 1995-1999 Sun Microsystems, Inc.  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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.awt.image;
+
+import java.awt.Image;
+
+/**
+ * An asynchronous update interface for receiving notifications about
+ * Image information as the Image is constructed.
+ *
+ * @author      Jim Graham
+ */
+public interface ImageObserver {
+    /**
+     * This method is called when information about an image which was
+     * previously requested using an asynchronous interface becomes
+     * available.  Asynchronous interfaces are method calls such as
+     * getWidth(ImageObserver) and drawImage(img, x, y, ImageObserver)
+     * which take an ImageObserver object as an argument.  Those methods
+     * register the caller as interested either in information about
+     * the overall image itself (in the case of getWidth(ImageObserver))
+     * or about an output version of an image (in the case of the
+     * drawImage(img, x, y, [w, h,] ImageObserver) call).
+     *
+     * <p>This method
+     * should return true if further updates are needed or false if the
+     * required information has been acquired.  The image which was being
+     * tracked is passed in using the img argument.  Various constants
+     * are combined to form the infoflags argument which indicates what
+     * information about the image is now available.  The interpretation
+     * of the x, y, width, and height arguments depends on the contents
+     * of the infoflags argument.
+     * <p>
+     * The <code>infoflags</code> argument should be the bitwise inclusive
+     * <b>OR</b> of the following flags: <code>WIDTH</code>,
+     * <code>HEIGHT</code>, <code>PROPERTIES</code>, <code>SOMEBITS</code>,
+     * <code>FRAMEBITS</code>, <code>ALLBITS</code>, <code>ERROR</code>,
+     * <code>ABORT</code>.
+     *
+     * @param     img   the image being observed.
+     * @param     infoflags   the bitwise inclusive OR of the following
+     *               flags:  <code>WIDTH</code>, <code>HEIGHT</code>,
+     *               <code>PROPERTIES</code>, <code>SOMEBITS</code>,
+     *               <code>FRAMEBITS</code>, <code>ALLBITS</code>,
+     *               <code>ERROR</code>, <code>ABORT</code>.
+     * @param     x   the <i>x</i> coordinate.
+     * @param     y   the <i>y</i> coordinate.
+     * @param     width    the width.
+     * @param     height   the height.
+     * @return    <code>false</code> if the infoflags indicate that the
+     *            image is completely loaded; <code>true</code> otherwise.
+     *
+     * @see #WIDTH
+     * @see #HEIGHT
+     * @see #PROPERTIES
+     * @see #SOMEBITS
+     * @see #FRAMEBITS
+     * @see #ALLBITS
+     * @see #ERROR
+     * @see #ABORT
+     * @see Image#getWidth
+     * @see Image#getHeight
+     * @see java.awt.Graphics#drawImage
+     */
+    public boolean imageUpdate(Image img, int infoflags,
+                               int x, int y, int width, int height);
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * the width of the base image is now available and can be taken
+     * from the width argument to the imageUpdate callback method.
+     * @see Image#getWidth
+     * @see #imageUpdate
+     */
+    public static final int WIDTH = 1;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * the height of the base image is now available and can be taken
+     * from the height argument to the imageUpdate callback method.
+     * @see Image#getHeight
+     * @see #imageUpdate
+     */
+    public static final int HEIGHT = 2;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * the properties of the image are now available.
+     * @see Image#getProperty
+     * @see #imageUpdate
+     */
+    public static final int PROPERTIES = 4;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * more pixels needed for drawing a scaled variation of the image
+     * are available.  The bounding box of the new pixels can be taken
+     * from the x, y, width, and height arguments to the imageUpdate
+     * callback method.
+     * @see java.awt.Graphics#drawImage
+     * @see #imageUpdate
+     */
+    public static final int SOMEBITS = 8;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * another complete frame of a multi-frame image which was previously
+     * drawn is now available to be drawn again.  The x, y, width, and height
+     * arguments to the imageUpdate callback method should be ignored.
+     * @see java.awt.Graphics#drawImage
+     * @see #imageUpdate
+     */
+    public static final int FRAMEBITS = 16;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * a static image which was previously drawn is now complete and can
+     * be drawn again in its final form.  The x, y, width, and height
+     * arguments to the imageUpdate callback method should be ignored.
+     * @see java.awt.Graphics#drawImage
+     * @see #imageUpdate
+     */
+    public static final int ALLBITS = 32;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * an image which was being tracked asynchronously has encountered
+     * an error.  No further information will become available and
+     * drawing the image will fail.
+     * As a convenience, the ABORT flag will be indicated at the same
+     * time to indicate that the image production was aborted.
+     * @see #imageUpdate
+     */
+    public static final int ERROR = 64;
+
+    /**
+     * This flag in the infoflags argument to imageUpdate indicates that
+     * an image which was being tracked asynchronously was aborted before
+     * production was complete.  No more information will become available
+     * without further action to trigger another image production sequence.
+     * If the ERROR flag was not also set in this image update, then
+     * accessing any of the data in the image will restart the production
+     * again, probably from the beginning.
+     * @see #imageUpdate
+     */
+    public static final int ABORT = 128;
+}