1. /*

  2.  * @(#)Image.java	1.33 03/01/23

  3.  *

  4.  * Copyright 2003 Sun Microsystems, Inc. All rights reserved.

  5.  * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

  6.  */

  7. package java.awt;

  8. 

  9. import java.awt.image.ImageProducer;

  10. import java.awt.image.ImageObserver;

  11. import java.awt.image.ImageFilter;

  12. import java.awt.image.FilteredImageSource;

  13. import java.awt.image.AreaAveragingScaleFilter;

  14. import java.awt.image.ReplicateScaleFilter;

  15. 

  16. /**

  17.  * The abstract class <code>Image</code> is the superclass of all 

  18.  * classes that represent graphical images. The image must be 

  19.  * obtained in a platform-specific manner.

  20.  *

  21.  * @version 	1.33, 01/23/03

  22.  * @author 	Sami Shaio

  23.  * @author 	Arthur van Hoff

  24.  * @since       JDK1.0

  25.  */

  26. public abstract class Image {

  27.     /**

  28.      * Determines the width of the image. If the width is not yet known, 

  29.      * this method returns <code>-1</code> and the specified   

  30.      * <code>ImageObserver</code> object is notified later.

  31.      * @param     observer   an object waiting for the image to be loaded.

  32.      * @return    the width of this image, or <code>-1</code> 

  33.      *                   if the width is not yet known.

  34.      * @see       java.awt.Image#getHeight

  35.      * @see       java.awt.image.ImageObserver

  36.      */

  37.     public abstract int getWidth(ImageObserver observer);

  38. 

  39.     /**

  40.      * Determines the height of the image. If the height is not yet known, 

  41.      * this method returns <code>-1</code> and the specified  

  42.      * <code>ImageObserver</code> object is notified later.

  43.      * @param     observer   an object waiting for the image to be loaded.

  44.      * @return    the height of this image, or <code>-1</code> 

  45.      *                   if the height is not yet known.

  46.      * @see       java.awt.Image#getWidth

  47.      * @see       java.awt.image.ImageObserver

  48.      */

  49.     public abstract int getHeight(ImageObserver observer);

  50. 

  51.     /**

  52.      * Gets the object that produces the pixels for the image.

  53.      * This method is called by the image filtering classes and by 

  54.      * methods that perform image conversion and scaling.

  55.      * @return     the image producer that produces the pixels 

  56.      *                                  for this image.

  57.      * @see        java.awt.image.ImageProducer

  58.      */

  59.     public abstract ImageProducer getSource();

  60. 

  61.     /**

  62.      * Creates a graphics context for drawing to an off-screen image. 

  63.      * This method can only be called for off-screen images. 

  64.      * @return  a graphics context to draw to the off-screen image. 

  65.      * @see     java.awt.Graphics

  66.      * @see     java.awt.Component#createImage(int, int)

  67.      */

  68.     public abstract Graphics getGraphics();

  69. 

  70.     /**

  71.      * Gets a property of this image by name. 

  72.      * <p>

  73.      * Individual property names are defined by the various image 

  74.      * formats. If a property is not defined for a particular image, this 

  75.      * method returns the <code>UndefinedProperty</code> object. 

  76.      * <p>

  77.      * If the properties for this image are not yet known, this method 

  78.      * returns <code>null</code>, and the <code>ImageObserver</code> 

  79.      * object is notified later. 

  80.      * <p>

  81.      * The property name <code>"comment"</code> should be used to store 

  82.      * an optional comment which can be presented to the application as a 

  83.      * description of the image, its source, or its author. 

  84.      * @param       name   a property name.

  85.      * @param       observer   an object waiting for this image to be loaded.

  86.      * @return      the value of the named property.

  87.      * @see         java.awt.image.ImageObserver

  88.      * @see         java.awt.Image#UndefinedProperty

  89.      */

  90.     public abstract Object getProperty(String name, ImageObserver observer);

  91. 

  92.     /**

  93.      * The <code>UndefinedProperty</code> object should be returned whenever a

  94.      * property which was not defined for a particular image is fetched.

  95.      */

  96.     public static final Object UndefinedProperty = new Object();

  97. 

  98.     /**

  99.      * Creates a scaled version of this image.

  100.      * A new <code>Image</code> object is returned which will render 

  101.      * the image at the specified <code>width</code> and 

  102.      * <code>height</code> by default.  The new <code>Image</code> object

  103.      * may be loaded asynchronously even if the original source image

  104.      * has already been loaded completely.  If either the <code>width</code> 

  105.      * or <code>height</code> is a negative number then a value is 

  106.      * substituted to maintain the aspect ratio of the original image 

  107.      * dimensions.

  108.      * @param width the width to which to scale the image.

  109.      * @param height the height to which to scale the image.

  110.      * @param hints flags to indicate the type of algorithm to use

  111.      * for image resampling.

  112.      * @return     a scaled version of the image.

  113.      * @see        java.awt.Image#SCALE_DEFAULT

  114.      * @see        java.awt.Image#SCALE_FAST 

  115.      * @see        java.awt.Image#SCALE_SMOOTH

  116.      * @see        java.awt.Image#SCALE_REPLICATE

  117.      * @see        java.awt.Image#SCALE_AREA_AVERAGING

  118.      * @since      JDK1.1

  119.      */

  120.     public Image getScaledInstance(int width, int height, int hints) {

  121. 	ImageFilter filter;

  122. 	if ((hints & (SCALE_SMOOTH | SCALE_AREA_AVERAGING)) != 0) {

  123. 	    filter = new AreaAveragingScaleFilter(width, height);

  124. 	} else {

  125. 	    filter = new ReplicateScaleFilter(width, height);

  126. 	}

  127. 	ImageProducer prod;

  128. 	prod = new FilteredImageSource(getSource(), filter);

  129. 	return Toolkit.getDefaultToolkit().createImage(prod);

  130.     }

  131. 

  132.     /**

  133.      * Use the default image-scaling algorithm.

  134.      * @since JDK1.1

  135.      */

  136.     public static final int SCALE_DEFAULT = 1;

  137. 

  138.     /**

  139.      * Choose an image-scaling algorithm that gives higher priority

  140.      * to scaling speed than smoothness of the scaled image.

  141.      * @since JDK1.1

  142.      */

  143.     public static final int SCALE_FAST = 2;

  144. 

  145.     /**

  146.      * Choose an image-scaling algorithm that gives higher priority

  147.      * to image smoothness than scaling speed.

  148.      * @since JDK1.1

  149.      */

  150.     public static final int SCALE_SMOOTH = 4;

  151. 

  152.     /**

  153.      * Use the image scaling algorithm embodied in the 

  154.      * <code>ReplicateScaleFilter</code> class.  

  155.      * The <code>Image</code> object is free to substitute a different filter 

  156.      * that performs the same algorithm yet integrates more efficiently

  157.      * into the imaging infrastructure supplied by the toolkit.

  158.      * @see        java.awt.image.ReplicateScaleFilter

  159.      * @since      JDK1.1

  160.      */

  161.     public static final int SCALE_REPLICATE = 8;

  162. 

  163.     /**

  164.      * Use the Area Averaging image scaling algorithm.  The

  165.      * image object is free to substitute a different filter that

  166.      * performs the same algorithm yet integrates more efficiently

  167.      * into the image infrastructure supplied by the toolkit.

  168.      * @see java.awt.image.AreaAveragingScaleFilter

  169.      * @since JDK1.1

  170.      */

  171.     public static final int SCALE_AREA_AVERAGING = 16;

  172. 

  173.     /**

  174.      * Flushes all resources being used by this Image object.  This

  175.      * includes any pixel data that is being cached for rendering to

  176.      * the screen as well as any system resources that are being used

  177.      * to store data or pixels for the image.  The image is reset to

  178.      * a state similar to when it was first created so that if it is

  179.      * again rendered, the image data will have to be recreated or

  180.      * fetched again from its source.

  181.      * <p>

  182.      * This method always leaves the image in a state such that it can 

  183.      * be reconstructed.  This means the method applies only to cached 

  184.      * or other secondary representations of images such as those that 

  185.      * have been generated from an <tt>ImageProducer</tt> (read from a 

  186.      * file, for example). It does nothing for off-screen images that 

  187.      * have only one copy of their data.

  188.      */

  189.     public abstract void flush();

  190. }