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*
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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;
}