//
// $Id: ImageUtil.java,v 1.4 2002/02/24 02:20:44 mdb Exp $

package com.threerings.media.util;

import java.awt.Image;
import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Transparency;
import java.awt.image.BufferedImage;

/**
 * Image related utility functions.
 */
public class ImageUtil
{
    /**
     * Extracts a subimage from the supplied image with the specified
     * dimensions. If the supplied image is an instance of {@link
     * BufferedImage}, then the subimage will simply reference the main
     * image. If it is not, the subimage will be created and the data will
     * be rendered into the newly created image.
     *
     * @param source the source image.
     * @param x the left coordinate of the sub-image.
     * @param y the top coordinate of the sub-image.
     * @param width the sub-image width.
     * @param height the sub-image height.
     *
     * @return the desired subimage.
     */
    public static Image getSubimage (
        Image source, int x, int y, int width, int height)
    {
        if (source instanceof BufferedImage) {
            return ((BufferedImage)source).getSubimage(x, y, width, height);

        } else {
            BufferedImage target = createImage(width, height);
            Graphics g = target.getGraphics();
            g.drawImage(source, 0, 0, width, height,
                        x, y, x+width, y+height, null);
            g.dispose();
            return target;
        }
    }

    /**
     * Creates a new blank image with the given dimensions and
     * transparency set to {@link Transparency#BITMASK}.  The format of
     * the created image is compatible with the graphics configuration of
     * the default screen device, such that no format conversion will be
     * necessary when rendering the image to that device.
     *
     * @param width the desired image width.
     * @param height the desired image height.
     *
     * @return the blank image.
     */
    public static BufferedImage createImage (int width, int height)
    {
        return createImage(width, height, Transparency.BITMASK);
    }

    /**
     * Creates a new blank image with the given dimensions and
     * transparency.  The format of the created image is compatible with
     * the graphics configuration of the default screen device, such that
     * no format conversion will be necessary when rendering the image to
     * that device.
     *
     * @param width the desired image width.
     * @param height the desired image height.
     * @param transparency the desired image transparency; one of the
     * constants in {@link java.awt.Transparency}.
     *
     * @return the blank image.
     */
    public static BufferedImage createImage (
        int width, int height, int transparency)
    {
        return _gc.createCompatibleImage(width, height, transparency);
    }

    /** The graphics configuration for the default screen device. */
    protected static GraphicsConfiguration _gc;
    static {
        // obtain information on our graphics environment
        GraphicsEnvironment env =
            GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice gd = env.getDefaultScreenDevice();
        _gc = gd.getDefaultConfiguration();
    };
}