FileDocCategorySizeDatePackage
ImageObserver.javaAPI DocJava SE 5 API6178Fri Aug 26 14:56:54 BST 2005java.awt.image

ImageObserver

public interface ImageObserver
An asynchronous update interface for receiving notifications about Image information as the Image is constructed.
version
1.27 12/19/03
author
Jim Graham

Fields Summary
public static final int
WIDTH
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.
public static final int
HEIGHT
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.
public static final int
PROPERTIES
This flag in the infoflags argument to imageUpdate indicates that the properties of the image are now available.
public static final int
SOMEBITS
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.
public static final int
FRAMEBITS
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.
public static final int
ALLBITS
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.
public static final int
ERROR
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.
public static final int
ABORT
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.
Constructors Summary
Methods Summary
public booleanimageUpdate(java.awt.Image img, int infoflags, int x, int y, int width, int height)
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.

The infoflags argument should be the bitwise inclusive OR of the following flags: WIDTH, HEIGHT, PROPERTIES, SOMEBITS, FRAMEBITS, ALLBITS, ERROR, ABORT.

param
img the image being observed.
param
infoflags the bitwise inclusive OR of the following flags: WIDTH, HEIGHT, PROPERTIES, SOMEBITS, FRAMEBITS, ALLBITS, ERROR, ABORT.
param
x the x coordinate.
param
y the y coordinate.
param
width the width.
param
height the height.
return
false if the infoflags indicate that the image is completely loaded; true 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