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package java.awt;

import java.awt.image.ImageProducer;
import java.awt.image.ImageObserver;
import java.awt.image.ImageFilter;
import java.awt.image.FilteredImageSource;
import java.awt.image.AreaAveragingScaleFilter;
import java.awt.image.ReplicateScaleFilter;

import sun.awt.image.SurfaceManager;



The abstract class Image is the superclass of all classes that represent graphical images. The image must be obtained in a platform-specific manner. 
Author:     Sami Shaio,      Arthur van Hoff
Since:      1.0
/**
 * The abstract class {@code Image} is the superclass of all
 * classes that represent graphical images. The image must be
 * obtained in a platform-specific manner.
 *
 * @author      Sami Shaio
 * @author      Arthur van Hoff
 * @since       1.0
 */
public abstract class Image {

    
convenience object; we can use this single static object for
all images that do not create their own image caps; it holds the
default (unaccelerated) properties.

/**
     * convenience object; we can use this single static object for
     * all images that do not create their own image caps; it holds the
     * default (unaccelerated) properties.
     */
    private static ImageCapabilities defaultImageCaps =
        new ImageCapabilities(false);

    
Priority for accelerating this image. Subclasses are free to set different default priorities and applications are free to set the priority for specific images via the setAccelerationPriority(float) method. 
Since:1.5
/**
     * Priority for accelerating this image.  Subclasses are free to
     * set different default priorities and applications are free to
     * set the priority for specific images via the
     * {@code setAccelerationPriority(float)} method.
     * @since 1.5
     */
    protected float accelerationPriority = .5f;

    
Determines the width of the image. If the width is not yet known, this method returns -1 and the specified ImageObserver object is notified later. 
Params:
  • observer –   an object waiting for the image to be loaded.
See Also:
Returns: the width of this image, or -1 if the width is not yet known.
/**
     * Determines the width of the image. If the width is not yet known,
     * this method returns {@code -1} and the specified
     * {@code ImageObserver} object is notified later.
     * @param     observer   an object waiting for the image to be loaded.
     * @return    the width of this image, or {@code -1}
     *                   if the width is not yet known.
     * @see       java.awt.Image#getHeight
     * @see       java.awt.image.ImageObserver
     */
    public abstract int getWidth(ImageObserver observer);

    
Determines the height of the image. If the height is not yet known, this method returns -1 and the specified ImageObserver object is notified later. 
Params:
  • observer –   an object waiting for the image to be loaded.
See Also:
Returns: the height of this image, or -1 if the height is not yet known.
/**
     * Determines the height of the image. If the height is not yet known,
     * this method returns {@code -1} and the specified
     * {@code ImageObserver} object is notified later.
     * @param     observer   an object waiting for the image to be loaded.
     * @return    the height of this image, or {@code -1}
     *                   if the height is not yet known.
     * @see       java.awt.Image#getWidth
     * @see       java.awt.image.ImageObserver
     */
    public abstract int getHeight(ImageObserver observer);

    
Gets the object that produces the pixels for the image.
This method is called by the image filtering classes and by
methods that perform image conversion and scaling.

See Also:
Returns:    the image producer that produces the pixels
                                 for this image.
/**
     * Gets the object that produces the pixels for the image.
     * This method is called by the image filtering classes and by
     * methods that perform image conversion and scaling.
     * @return     the image producer that produces the pixels
     *                                  for this image.
     * @see        java.awt.image.ImageProducer
     */
    public abstract ImageProducer getSource();

    
Creates a graphics context for drawing to an off-screen image.
This method can only be called for off-screen images.

Throws:
See Also:
Returns: a graphics context to draw to the off-screen image.
/**
     * Creates a graphics context for drawing to an off-screen image.
     * This method can only be called for off-screen images.
     * @return  a graphics context to draw to the off-screen image.
     * @exception UnsupportedOperationException if called for a
     *            non-off-screen image.
     * @see     java.awt.Graphics
     * @see     java.awt.Component#createImage(int, int)
     */
    public abstract Graphics getGraphics();

    
Gets a property of this image by name.

 Individual property names are defined by the various image formats. If a property is not defined for a particular image, this method returns the UndefinedProperty object. 
 If the properties for this image are not yet known, this method returns null, and the ImageObserver object is notified later. 
 The property name "comment" should be used to store an optional comment which can be presented to the application as a description of the image, its source, or its author. 
Params:
  • name –   a property name.
  • observer –   an object waiting for this image to be loaded.
Throws:
See Also:
Returns:     the value of the named property.
/**
     * Gets a property of this image by name.
     * <p>
     * Individual property names are defined by the various image
     * formats. If a property is not defined for a particular image, this
     * method returns the {@code UndefinedProperty} object.
     * <p>
     * If the properties for this image are not yet known, this method
     * returns {@code null}, and the {@code ImageObserver}
     * object is notified later.
     * <p>
     * The property name {@code "comment"} should be used to store
     * an optional comment which can be presented to the application as a
     * description of the image, its source, or its author.
     * @param       name   a property name.
     * @param       observer   an object waiting for this image to be loaded.
     * @return      the value of the named property.
     * @throws      NullPointerException if the property name is null.
     * @see         java.awt.image.ImageObserver
     * @see         java.awt.Image#UndefinedProperty
     */
    public abstract Object getProperty(String name, ImageObserver observer);

    
The UndefinedProperty object should be returned whenever a property which was not defined for a particular image is fetched. 
/**
     * The {@code UndefinedProperty} object should be returned whenever a
     * property which was not defined for a particular image is fetched.
     */
    public static final Object UndefinedProperty = new Object();

    
Creates a scaled version of this image. A new Image object is returned which will render the image at the specified width and height by default. The new Image object may be loaded asynchronously even if the original source image has already been loaded completely. 
 If either width or height is a negative number then a value is substituted to maintain the aspect ratio of the original image dimensions. If both width and height are negative, then the original image dimensions are used. 
Params:
  • width – the width to which to scale the image.
  • height – the height to which to scale the image.
  • hints – flags to indicate the type of algorithm to use
for image resampling.
Throws:
See Also:
Returns:    a scaled version of the image.
Since:     1.1
/**
     * Creates a scaled version of this image.
     * A new {@code Image} object is returned which will render
     * the image at the specified {@code width} and
     * {@code height} by default.  The new {@code Image} object
     * may be loaded asynchronously even if the original source image
     * has already been loaded completely.
     *
     * <p>
     *
     * If either {@code width}
     * or {@code height} is a negative number then a value is
     * substituted to maintain the aspect ratio of the original image
     * dimensions. If both {@code width} and {@code height}
     * are negative, then the original image dimensions are used.
     *
     * @param width the width to which to scale the image.
     * @param height the height to which to scale the image.
     * @param hints flags to indicate the type of algorithm to use
     * for image resampling.
     * @return     a scaled version of the image.
     * @exception IllegalArgumentException if {@code width}
     *             or {@code height} is zero.
     * @see        java.awt.Image#SCALE_DEFAULT
     * @see        java.awt.Image#SCALE_FAST
     * @see        java.awt.Image#SCALE_SMOOTH
     * @see        java.awt.Image#SCALE_REPLICATE
     * @see        java.awt.Image#SCALE_AREA_AVERAGING
     * @since      1.1
     */
    public Image getScaledInstance(int width, int height, int hints) {
        ImageFilter filter;
        if ((hints & (SCALE_SMOOTH | SCALE_AREA_AVERAGING)) != 0) {
            filter = new AreaAveragingScaleFilter(width, height);
        } else {
            filter = new ReplicateScaleFilter(width, height);
        }
        ImageProducer prod;
        prod = new FilteredImageSource(getSource(), filter);
        return Toolkit.getDefaultToolkit().createImage(prod);
    }

    
Use the default image-scaling algorithm.

Since:1.1
/**
     * Use the default image-scaling algorithm.
     * @since 1.1
     */
    public static final int SCALE_DEFAULT = 1;

    
Choose an image-scaling algorithm that gives higher priority
to scaling speed than smoothness of the scaled image.

Since:1.1
/**
     * Choose an image-scaling algorithm that gives higher priority
     * to scaling speed than smoothness of the scaled image.
     * @since 1.1
     */
    public static final int SCALE_FAST = 2;

    
Choose an image-scaling algorithm that gives higher priority
to image smoothness than scaling speed.

Since:1.1
/**
     * Choose an image-scaling algorithm that gives higher priority
     * to image smoothness than scaling speed.
     * @since 1.1
     */
    public static final int SCALE_SMOOTH = 4;

    
Use the image scaling algorithm embodied in the ReplicateScaleFilter class. The Image object is free to substitute a different filter that performs the same algorithm yet integrates more efficiently into the imaging infrastructure supplied by the toolkit. 
See Also:
Since:     1.1
/**
     * Use the image scaling algorithm embodied in the
     * {@code ReplicateScaleFilter} class.
     * The {@code Image} object is free to substitute a different filter
     * that performs the same algorithm yet integrates more efficiently
     * into the imaging infrastructure supplied by the toolkit.
     * @see        java.awt.image.ReplicateScaleFilter
     * @since      1.1
     */
    public static final int SCALE_REPLICATE = 8;

    
Use the Area Averaging image scaling algorithm.  The
image object is free to substitute a different filter that
performs the same algorithm yet integrates more efficiently
into the image infrastructure supplied by the toolkit.

See Also:
  • AreaAveragingScaleFilter
Since:1.1
/**
     * Use the Area Averaging image scaling algorithm.  The
     * image object is free to substitute a different filter that
     * performs the same algorithm yet integrates more efficiently
     * into the image infrastructure supplied by the toolkit.
     * @see java.awt.image.AreaAveragingScaleFilter
     * @since 1.1
     */
    public static final int SCALE_AREA_AVERAGING = 16;

    
Flushes all reconstructable resources being used by this Image object.
This includes any pixel data that is being cached for rendering to
the screen as well as any system resources that are being used
to store data or pixels for the image if they can be recreated.
The image is reset to a state similar to when it was first created
so that if it is again rendered, the image data will have to be
recreated or fetched again from its source.


Examples of how this method affects specific types of Image object:

    

  • 
BufferedImage objects leave the primary Raster which stores their
pixels untouched, but flush any information cached about those
pixels such as copies uploaded to the display hardware for
accelerated blits.

  • 
Image objects created by the Component methods which take a
width and height leave their primary buffer of pixels untouched,
but have all cached information released much like is done for
BufferedImage objects.

  •  VolatileImage objects release all of their pixel resources including their primary copy which is typically stored on the display hardware where resources are scarce. These objects can later be restored using their validate method. 
  •  Image objects created by the Toolkit and Component classes which are loaded from files, URLs or produced by an ImageProducer are unloaded and all local resources are released. These objects can later be reloaded from their original source as needed when they are rendered, just as when they were first created. 


/**
     * Flushes all reconstructable resources being used by this Image object.
     * This includes any pixel data that is being cached for rendering to
     * the screen as well as any system resources that are being used
     * to store data or pixels for the image if they can be recreated.
     * The image is reset to a state similar to when it was first created
     * so that if it is again rendered, the image data will have to be
     * recreated or fetched again from its source.
     * <p>
     * Examples of how this method affects specific types of Image object:
     * <ul>
     * <li>
     * BufferedImage objects leave the primary Raster which stores their
     * pixels untouched, but flush any information cached about those
     * pixels such as copies uploaded to the display hardware for
     * accelerated blits.
     * <li>
     * Image objects created by the Component methods which take a
     * width and height leave their primary buffer of pixels untouched,
     * but have all cached information released much like is done for
     * BufferedImage objects.
     * <li>
     * VolatileImage objects release all of their pixel resources
     * including their primary copy which is typically stored on
     * the display hardware where resources are scarce.
     * These objects can later be restored using their
     * {@link java.awt.image.VolatileImage#validate validate}
     * method.
     * <li>
     * Image objects created by the Toolkit and Component classes which are
     * loaded from files, URLs or produced by an {@link ImageProducer}
     * are unloaded and all local resources are released.
     * These objects can later be reloaded from their original source
     * as needed when they are rendered, just as when they were first
     * created.
     * </ul>
     */
    public void flush() {
        if (surfaceManager != null) {
            surfaceManager.flush();
        }
    }

    
Returns an ImageCapabilities object which can be
inquired as to the capabilities of this
Image on the specified GraphicsConfiguration.
This allows programmers to find
out more runtime information on the specific Image
object that they have created.  For example, the user
might create a BufferedImage but the system may have
no video memory left for creating an image of that
size on the given GraphicsConfiguration, so although the object
may be acceleratable in general, it
does not have that capability on this GraphicsConfiguration.

Params:
  • gc – a GraphicsConfiguration object. A value of null for this parameter will result in getting the image capabilities for the default GraphicsConfiguration.
See Also:
Returns:an ImageCapabilities object that contains the capabilities of this Image on the specified GraphicsConfiguration.
Since:1.5
/**
     * Returns an ImageCapabilities object which can be
     * inquired as to the capabilities of this
     * Image on the specified GraphicsConfiguration.
     * This allows programmers to find
     * out more runtime information on the specific Image
     * object that they have created.  For example, the user
     * might create a BufferedImage but the system may have
     * no video memory left for creating an image of that
     * size on the given GraphicsConfiguration, so although the object
     * may be acceleratable in general, it
     * does not have that capability on this GraphicsConfiguration.
     * @param gc a {@code GraphicsConfiguration} object.  A value of null
     * for this parameter will result in getting the image capabilities
     * for the default {@code GraphicsConfiguration}.
     * @return an {@code ImageCapabilities} object that contains
     * the capabilities of this {@code Image} on the specified
     * GraphicsConfiguration.
     * @see java.awt.image.VolatileImage#getCapabilities()
     * VolatileImage.getCapabilities()
     * @since 1.5
     */
    public ImageCapabilities getCapabilities(GraphicsConfiguration gc) {
        if (surfaceManager != null) {
            return surfaceManager.getCapabilities(gc);
        }
        // Note: this is just a default object that gets returned in the
        // absence of any more specific information from a surfaceManager.
        // Subclasses of Image should either override this method or
        // make sure that they always have a non-null SurfaceManager
        // to return an ImageCapabilities object that is appropriate
        // for their given subclass type.
        return defaultImageCaps;
    }

    
Sets a hint for this image about how important acceleration is.
This priority hint is used to compare to the priorities of other
Image objects when determining how to use scarce acceleration
resources such as video memory.  When and if it is possible to
accelerate this Image, if there are not enough resources available
to provide that acceleration but enough can be freed up by
de-accelerating some other image of lower priority, then that other
Image may be de-accelerated in deference to this one.  Images
that have the same priority take up resources on a first-come,
first-served basis.

Params:
  • priority – a value between 0 and 1, inclusive, where higher
values indicate more importance for acceleration.  A value of 0
means that this Image should never be accelerated.  Other values
are used simply to determine acceleration priority relative to other
Images.
Throws:
Since:1.5
/**
     * Sets a hint for this image about how important acceleration is.
     * This priority hint is used to compare to the priorities of other
     * Image objects when determining how to use scarce acceleration
     * resources such as video memory.  When and if it is possible to
     * accelerate this Image, if there are not enough resources available
     * to provide that acceleration but enough can be freed up by
     * de-accelerating some other image of lower priority, then that other
     * Image may be de-accelerated in deference to this one.  Images
     * that have the same priority take up resources on a first-come,
     * first-served basis.
     * @param priority a value between 0 and 1, inclusive, where higher
     * values indicate more importance for acceleration.  A value of 0
     * means that this Image should never be accelerated.  Other values
     * are used simply to determine acceleration priority relative to other
     * Images.
     * @throws IllegalArgumentException if {@code priority} is less
     * than zero or greater than 1.
     * @since 1.5
     */
    public void setAccelerationPriority(float priority) {
        if (priority < 0 || priority > 1) {
            throw new IllegalArgumentException("Priority must be a value " +
                                               "between 0 and 1, inclusive");
        }
        accelerationPriority = priority;
        if (surfaceManager != null) {
            surfaceManager.setAccelerationPriority(accelerationPriority);
        }
    }

    
Returns the current value of the acceleration priority hint.

See Also:
  • setAccelerationPriority
Returns:value between 0 and 1, inclusive, which represents the current
priority value
Since:1.5
/**
     * Returns the current value of the acceleration priority hint.
     * @see #setAccelerationPriority(float priority) setAccelerationPriority
     * @return value between 0 and 1, inclusive, which represents the current
     * priority value
     * @since 1.5
     */
    public float getAccelerationPriority() {
        return accelerationPriority;
    }

    SurfaceManager surfaceManager;

    static {
        SurfaceManager.setImageAccessor(new SurfaceManager.ImageAccessor() {
            public SurfaceManager getSurfaceManager(Image img) {
                return img.surfaceManager;
            }
            public void setSurfaceManager(Image img, SurfaceManager mgr) {
                img.surfaceManager = mgr;
            }
        });
    }
}