java.awt.image.ImageObserver Maven / Gradle / Ivy

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This work corresponds to the API signatures of JSR 217: Personal Basis Profile 1.1. In the event of a discrepency between this work and the JSR 217 specification, which is available at http://www.jcp.org/en/jsr/detail?id=217, the latter takes precedence. */ package java.awt.image; import java.awt.Image; /** * An asynchronous update interface for receiving notifications about * Image information as the Image is constructed. * * @version 1.26 01/23/03 * @author Jim Graham */ public interface ImageObserver { /** * 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; /** * 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). * *

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. *