/*

 * Copyright 2004-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.swing;

import java.awt.*;

import java.awt.image.*;

import java.util.*;

/**

 * A base class used for icons or images that are expensive to paint.

 * A subclass will do the following:

 * <ol>

 * <li>Invoke <code>paint</code> when you want to paint the image,

 *     if you are implementing <code>Icon</code> you'll invoke this from

 *     <code>paintIcon</code>.

 *     The args argument is useful when additional state is needed.

 * <li>Override <code>paintToImage</code> to render the image.  The code that

 *     lives here is equivalent to what previously would go in

 *     <code>paintIcon</code>, for an <code>Icon</code>.

 * </ol>

 * The two ways to use this class are:

 * <ol>

 * <li>Invoke <code>paint</code> to draw the cached reprensentation at

 *     the specified location.

 * <li>Invoke <code>getImage</code> to get the cached reprensentation and

 *     draw the image yourself.  This is primarly useful when you are not

 *     using <code>VolatileImage</code>.

 * </ol>

 *

 *

 */

public abstract class CachedPainter {

    // CacheMap maps from class to ImageCache.

    private static final Map<Object,ImageCache> cacheMap =

                   new HashMap<Object,ImageCache>();

    private static ImageCache getCache(Object key) {

        synchronized(CachedPainter.class) {

            ImageCache cache = cacheMap.get(key);

            if (cache == null) {

                cache = new ImageCache(1);

                cacheMap.put(key, cache);

            }

            return cache;

        }

    }

    /**

     * Creates an instance of <code>CachedPainter</code> that will cache up

     * to <code>cacheCount</code> images of this class.

     *

     * @param cacheCount Max number of images to cache

     */

    public CachedPainter(int cacheCount) {

        getCache(getClass()).setMaxCount(cacheCount);

    }

    /**

     * Renders the cached image to the the passed in <code>Graphic</code>.

     * If there is no cached image <code>paintToImage</code> will be invoked.

     * <code>paintImage</code> is invoked to paint the cached image.

     *

     * @param c Component rendering to, this may be null.

     * @param g Graphics to paint to

     * @param x X-coordinate to render to

     * @param y Y-coordinate to render to

     * @param w Width to render in

     * @param h Height to render in

     * @param arg Variable arguments that will be passed to paintToImage

     */

    public void paint(Component c, Graphics g, int x,

                         int y, int w, int h, Object... args) {

        if (w <= 0 || h <= 0) {

            return;

        }

        if (c != null) {

            synchronized(c.getTreeLock()) {

                synchronized(CachedPainter.class) {

                    // If c is non-null, synchronize on the tree lock.

                    // This is necessary because asking for the

                    // GraphicsConfiguration will grab a tree lock.

                    paint0(c, g, x, y, w, h, args);

                }

            }

        }

        else {

            synchronized(CachedPainter.class) {

                paint0(c, g, x, y, w, h, args);

            }

        }

    }

    private void paint0(Component c, Graphics g, int x,

                         int y, int w, int h, Object... args) {

        Object key = getClass();

        GraphicsConfiguration config = getGraphicsConfiguration(c);

        ImageCache cache = getCache(key);

        Image image = cache.getImage(key, config, w, h, args);

        int attempts = 0;

        do {

            boolean draw = false;

            if (image instanceof VolatileImage) {

                // See if we need to recreate the image

                switch (((VolatileImage)image).validate(config)) {

                case VolatileImage.IMAGE_INCOMPATIBLE:

                    ((VolatileImage)image).flush();

                    image = null;

                    break;

                case VolatileImage.IMAGE_RESTORED:

                    draw = true;

                    break;

                }

            }

            if (image == null) {

                // Recreate the image

                image = createImage(c, w, h, config, args);

                cache.setImage(key, config, w, h, args, image);

                draw = true;

            }

            if (draw) {

                // Render to the Image

                Graphics g2 = image.getGraphics();

                paintToImage(c, image, g2, w, h, args);

                g2.dispose();

            }

            // Render to the passed in Graphics

            paintImage(c, g, x, y, w, h, image, args);

            // If we did this 3 times and the contents are still lost

            // assume we're painting to a VolatileImage that is bogus and

            // give up.  Presumably we'll be called again to paint.

        } while ((image instanceof VolatileImage) &&

                 ((VolatileImage)image).contentsLost() && ++attempts < 3);

    }

    /**

     * Paints the representation to cache to the supplied Graphics.

     *

     * @param c Component painting to, may be null.

     * @param image Image to paint to

     * @param g Graphics to paint to, obtained from the passed in Image.

     * @param w Width to paint to

     * @param h Height to paint to

     * @param args Arguments supplied to <code>paint</code>

     */

    protected abstract void paintToImage(Component c, Image image, Graphics g,

                                         int w, int h, Object[] args);

    /**

     * Paints the image to the specified location.

     *

     * @param c Component painting to

     * @param g Graphics to paint to

     * @param x X coordinate to paint to

     * @param y Y coordinate to paint to

     * @param w Width to paint to

     * @param h Height to paint to

     * @param image Image to paint

     * @param args Arguments supplied to <code>paint</code>

     */

    protected void paintImage(Component c, Graphics g,

                              int x, int y, int w, int h, Image image,

                              Object[] args) {

        g.drawImage(image, x, y, null);

    }

    /**

     * Creates the image to cache.  This returns an opaque image, subclasses

     * that require translucency or transparency will need to override this

     * method.

     *

     * @param c Component painting to

     * @param w Width of image to create

     * @param h Height to image to create

     * @param config GraphicsConfiguration that will be

     *        rendered to, this may be null.

     * @param args Arguments passed to paint

     */

    protected Image createImage(Component c, int w, int h,

                                GraphicsConfiguration config, Object[] args) {

        if (config == null) {

            return new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);

        }

        return config.createCompatibleVolatileImage(w, h);

    }

    /**

     * Clear the image cache

     */

    protected void flush() {

        synchronized(CachedPainter.class) {

            getCache(getClass()).flush();

        }

    }

    private GraphicsConfiguration getGraphicsConfiguration(Component c) {

        if (c == null) {

            return null;

        }

        return c.getGraphicsConfiguration();

    }

}