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Chapter 19 java.awt Reference |
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Image
Name
Image
![[Graphic: Figure from the text]](./figs/image.gif)
Description
The Image class represents a displayable object maintained in memory. Because Image is an abstract class, you never work with the Image class itself, but with a platform specific subclass. However, you should never need to know what that subclass is. To draw on an Image, get its graphics context.
Class Definition
public abstract class java.awt.Image
extends java.lang.Object
implements java.io.Serializable {
// Constants
public final static int SCALE_AREA_AVERAGING; 
public final static int SCALE_DEFAULT;
public final static int SCALE_FAST;
public final static int SCALE_REPLICATE;
public final static int SCALE_SMOOTH;
public final static Object UndefinedProperty;
// Instance Methods
public abstract void flush();
public abstract Graphics getGraphics();
public abstract int getHeight (ImageObserver observer);
public abstract Object getProperty (String name, ImageObserver observer);
public Image getScaledInstance (int width, int height, int hints);
public abstract ImageProducer getSource();
public abstract int getWidth (ImageObserver observer);
}
Constants
SCALE_AREA_AVERAGING
public final static int SCALE_AREA_AVERAGING
Flag that requests use of AreaAveragingScaleFilter.
SCALE_DEFAULT
public final static int SCALE_DEFAULT
Flag that requests use of the default image scaling algorithm.
SCALE_FAST
public final static int SCALE_FAST
Flag that requests use of an image scaling algorithm that is faster rather than smoother.
SCALE_REPLICATE
public final static int SCALE_REPLICATE
Flag that requests use of ReplicateScaleFilter.
SCALE_SMOOTH
public final static int SCALE_SMOOTH
Flag that requests use of an image scaling algorithm that is smoother rather than faster.
UndefinedProperty
public final static Object UndefinedProperty
Possible return object from getProperty().
Instance Methods
flush
public abstract void flush()
- Description
-
Resets image to initial state.
getGraphics
public abstract Graphics getGraphics()
- Throws
-
- ClassCastException
-
If image created from file or URL.
- ClassCastException
- Returns
-
The graphics context of the image.
- Description
-
Gets the graphics context of the image for drawing.
getHeight
public abstract int getHeight (ImageObserver observer)
- Parameters
-
- observer
-
An image observer; usually the Component on which the image is rendered.
- observer
- Returns
-
Image height, or -1 if the height is not yet available.
getProperty
public abstract Object getProperty (String name, ImageObserver observer)
- Parameters
-
- name
-
Name of the property to fetch.
- observer
-
An image observer; usually the Component on which the image is rendered.
- name
- Returns
-
Object representing the requested property, null, or UndefinedProperty.
- Throws
-
- ArrayIndexOutOfBoundsException
-
If offset or length is invalid.
- ArrayIndexOutOfBoundsException
- Description
-
Retrieves a property from the image's private property list.
getScaledInstance
public Image getScaledInstance (int width, int height, int hints)
- Parameters
-
- width
-
The width for the scaled image. Use -1 to preserve the aspect ratio with reference to height.
- height
-
The height for the scaled image. Use -1 to preserve the aspect ratio with reference to width.
- hints
-
One or more of the SCALE_ constants.
- width
- Returns
-
The scaled image. It may be loaded asynchronously, even if the original image was fully loaded.
- Description
-
Creates a copy of an image, scaled to width x height and using an algorithm chosen based on the hints given.
getSource
public abstract ImageProducer getSource()
- Returns
-
The ImageProducer of the image.
getWidth
public abstract int getWidth (ImageObserver observer)
- Parameters
-
- observer
-
An image observer; usually the Component on which the image is rendered.
- observer
- Returns
-
Image width, or -1 if the width is not yet available.
See Also
Graphics, ImageObserver, ImageProducer, Object, Properties, String
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