[Chapter 21] 21.8 java.awt.image.ImageObserver (JDK 1.0)
Author: David Flanagan
Date: Thu Jul 31 16:15:45 1997

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| Chapter 21 The java.awt.image Package |

## 21.8 java.awt.image.ImageObserver (JDK 1.0)

###

This interface defines a method and associated constants used by classes that want to receive information asynchronously about the status of an image. Many methods that query information about an image take an `ImageObserver` as an argument. If the specified information is not available when requested, it is passed to the `ImageObserver` when it becomes available. `Component` implements this interface, and components are the most commonly used image observers.

    public abstract interface ImageObserver {
        // Constants
                public static final int ABORT;
                public static final int ALLBITS;
                public static final int ERROR;
                public static final int FRAMEBITS;
                public static final int HEIGHT;
                public static final int PROPERTIES;
                public static final int SOMEBITS;
                public static final int WIDTH;
        // Public Instance Methods
                public abstract boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height);
    }

### Implemented By:

`Component`

### Passed To:

`Component.checkImage(), Component.prepareImage(), ComponentPeer.checkImage(), ComponentPeer.prepareImage(), Graphics.drawImage(), Image.getHeight(), Image.getProperty(), Image.getWidth(), Toolkit.checkImage(), Toolkit.prepareImage()`

java.awt.image.ImageFilter (JDK 1.0) |  | java.awt.image.ImageProducer (JDK 1.0)