renderableimage.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

/*
 * @(#)RenderableImage.java	1.16 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/* ********************************************************************
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 *** COPYRIGHT (c) Eastman Kodak Company, 1997                      ***
 *** As  an unpublished  work pursuant to Title 17 of the United    ***
 *** States Code.  All rights reserved.                             ***
 **********************************************************************
 **********************************************************************
 **********************************************************************/

package java.awt.image.renderable;
import java.util.Vector;
import java.awt.RenderingHints;
import java.awt.image.*;

/**
 * A RenderableImage is a common interface for rendering-independent
 * images (a notion which subsumes resolution independence).  That is,
 * images which are described and have operations applied to them
 * independent of any specific rendering of the image.  For example, a
 * RenderableImage can be rotated and cropped in
 * resolution-independent terms.  Then, it can be rendered for various
 * specific contexts, such as a draft preview, a high-quality screen
 * display, or a printer, each in an optimal fashion.
 * 
 * <p> A RenderedImage is returned from a RenderableImage via the
 * createRendering() method, which takes a RenderContext.  The
 * RenderContext specifies how the RenderedImage should be
 * constructed.  Note that it is not possible to extract pixels
 * directly from a RenderableImage.
 * 
 * <p> The createDefaultRendering() and createScaledRendering() methods are
 * convenience methods that construct an appropriate RenderContext
 * internally.  All of the rendering methods may return a reference to a
 * previously produced rendering.
 */
public interface RenderableImage {
  
    /**
     * String constant that can be used to identify a property on
     * a RenderedImage obtained via the createRendering or
     * createScaledRendering methods.  If such a property exists,
     * the value of the propoery will be a RenderingHints object
     * specifying which hints were observed in creating the rendering.
     */
     static final String HINTS_OBSERVED = "HINTS_OBSERVED";

    /** 
     * Returns a vector of RenderableImages that are the sources of
     * image data for this RenderableImage. Note that this method may
     * return an empty vector, to indicate that the image has no sources,
     * or null, to indicate that no information is available.
     *
     * @return a (possibly empty) Vector of RenderableImages, or null.
     */
    Vector<RenderableImage> getSources();
    
    /**
     * Gets a property from the property set of this image.
     * If the property name is not recognized, java.awt.Image.UndefinedProperty
     * will be returned.
     *
     * @param name the name of the property to get, as a String.
     * @return a reference to the property Object, or the value
     *         java.awt.Image.UndefinedProperty.
     */
    Object getProperty(String name);

    /** 
     * Returns a list of names recognized by getProperty. 
     * @return a list of property names.
     */
    String[] getPropertyNames();
    
    /**
     * Returns true if successive renderings (that is, calls to
     * createRendering() or createScaledRendering()) with the same arguments
     * may produce different results.  This method may be used to
     * determine whether an existing rendering may be cached and
     * reused.  It is always safe to return true.
     * @return <code>true</code> if successive renderings with the
     *         same arguments might produce different results;
     *         <code>false</code> otherwise.
     */
    boolean isDynamic();

    /** 
     * Gets the width in user coordinate space.  By convention, the
     * usual width of a RenderableImage is equal to the image's aspect
     * ratio (width divided by height).
     *
     * @return the width of the image in user coordinates.
     */
    float getWidth();
  
    /**
     * Gets the height in user coordinate space.  By convention, the
     * usual height of a RenderedImage is equal to 1.0F.
     *
     * @return the height of the image in user coordinates.
     */
    float getHeight();
    
    /** 
     * Gets the minimum X coordinate of the rendering-independent image data.
     * @return the minimum X coordinate of the rendering-independent image
     * data.
     */
    float getMinX();
  
    /** 
     * Gets the minimum Y coordinate of the rendering-independent image data.
     * @return the minimum Y coordinate of the rendering-independent image
     * data.
     */
    float getMinY();

    /**
     * Creates a RenderedImage instance of this image with width w, and
     * height h in pixels.  The RenderContext is built automatically
     * with an appropriate usr2dev transform and an area of interest
     * of the full image.  All the rendering hints come from hints
     * passed in.
     *
     * <p> If w == 0, it will be taken to equal
     * Math.round(h*(getWidth()/getHeight())).
     * Similarly, if h == 0, it will be taken to equal
     * Math.round(w*(getHeight()/getWidth())).  One of
     * w or h must be non-zero or else an IllegalArgumentException 
     * will be thrown.
     *
     * <p> The created RenderedImage may have a property identified
     * by the String HINTS_OBSERVED to indicate which RenderingHints
     * were used to create the image.  In addition any RenderedImages
     * that are obtained via the getSources() method on the created
     * RenderedImage may have such a property.
     *
     * @param w the width of rendered image in pixels, or 0.
     * @param h the height of rendered image in pixels, or 0.
     * @param hints a RenderingHints object containg hints.
     * @return a RenderedImage containing the rendered data.
     */
    RenderedImage createScaledRendering(int w, int h, RenderingHints hints);
  
    /** 
     * Returnd a RenderedImage instance of this image with a default
     * width and height in pixels.  The RenderContext is built
     * automatically with an appropriate usr2dev transform and an area
     * of interest of the full image.  The rendering hints are
     * empty.  createDefaultRendering may make use of a stored
     * rendering for speed.
     *
     * @return a RenderedImage containing the rendered data.
     */
    RenderedImage createDefaultRendering();
  
    /** 
     * Creates a RenderedImage that represented a rendering of this image
     * using a given RenderContext.  This is the most general way to obtain a
     * rendering of a RenderableImage.
     *
     * <p> The created RenderedImage may have a property identified
     * by the String HINTS_OBSERVED to indicate which RenderingHints
     * (from the RenderContext) were used to create the image.
     * In addition any RenderedImages
     * that are obtained via the getSources() method on the created
     * RenderedImage may have such a property.
     *
     * @param renderContext the RenderContext to use to produce the rendering.
     * @return a RenderedImage containing the rendered data.
     */
    RenderedImage createRendering(RenderContext renderContext);
}