VolatileImageBackgroundPainterStrategy.java

/*
 * 01/22/2005
 *
 * VolatileImageBackgroundPainterStrategy.java - Renders an RTextAreaBase's
 * background as an image using VolatileImages.
 * Copyright (C) 2005 Robert Futrell
 * robert_futrell at users.sourceforge.net
 * http://fifesoft.com/rsyntaxtextarea
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA.
 */
package org.fife.ui.rtextarea;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.VolatileImage;

/**
 * A strategy for painting the background of an <code>RTextAreaBase</code> as an image. The image is always stretched to
 * completely fill the <code>RTextAreaBase</code>.
 * <p>
 * 
 * A <code>java.awt.image.VolatileImage</code> is used for rendering; theoretically, this should be the best image
 * format for performance.
 * <p>
 * 
 * You can set the scaling hint used when stretching/skewing the image to fit in the <code>RTextAreaBase</code>'s
 * background via the <code>setScalingHint</code> method, but keep in mind the more accurate the scaling hint, the less
 * responsive your application will be when stretching the window (as that's the only time the image's size is
 * recalculated).
 * 
 * @author Robert Futrell
 * @version 0.1
 * @see org.fife.ui.rtextarea.ImageBackgroundPainterStrategy
 * @see org.fife.ui.rtextarea.BufferedImageBackgroundPainterStrategy
 */
public class VolatileImageBackgroundPainterStrategy
        extends ImageBackgroundPainterStrategy {

    private VolatileImage bgImage;

    /**
     * Constructor.
     * 
     * @param ta
     *            The text area whose background we'll be painting.
     */
    public VolatileImageBackgroundPainterStrategy(RTextAreaBase ta) {
        super(ta);
    }

    /**
     * Paints the image at the specified location. This method assumes scaling has already been done, and simply paints
     * the background image "as-is."
     * 
     * @param g
     *            The graphics context.
     * @param x
     *            The x-coordinate at which to paint.
     * @param y
     *            The y-coordinate at which to paint.
     */
    protected void paintImage(Graphics g, int x, int y) {
        if (bgImage != null) {
            do {
                int rc = bgImage.validate(null);// getGraphicsConfiguration());
                if (rc == VolatileImage.IMAGE_RESTORED) {
                    // FIXME: If the image needs to be restored are its width
                    // and height still valid?? If not, we'll need to cache
                    // these values...
                    renderImage(bgImage.getWidth(), bgImage.getHeight(),
                            getScalingHint());
                }
                g.drawImage(bgImage, x, y, null);
            } while (bgImage.contentsLost());
        }
    }

    /**
     * Renders the image at the proper size into <code>bgImage</code>. This method assumes that <code>bgImage</code> is
     * not <code>null</code>.
     * 
     * @param width
     *            The width of the volatile image to render into.
     * @param height
     *            The height of the volatile image to render into.
     * @param hint
     *            The scaling hint to use.
     */
    protected void renderImage(int width, int height, int hint) {
        Image master = getMasterImage();
        if (master != null) {
            do {
                Image i = master.getScaledInstance(width, height, hint);
                tracker.addImage(i, 1);
                try {
                    tracker.waitForID(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                    bgImage = null;
                    return;
                } finally {
                    tracker.removeImage(i, 1);
                }
                bgImage.getGraphics().drawImage(i, 0, 0, null);
                tracker.addImage(bgImage, 0);
                try {
                    tracker.waitForID(0);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                    bgImage = null;
                    return;
                } finally {
                    tracker.removeImage(bgImage, 0);
                }
            } while (bgImage.contentsLost());
        } // End of if (master!=null).
        else {
            bgImage = null;
        }
    }

    /**
     * Rescales the displayed image to be the specified size.
     * 
     * @param width
     *            The new width of the image.
     * @param height
     *            The new height of the image.
     * @param hint
     *            The scaling hint to use.
     */
    protected void rescaleImage(int width, int height, int hint) {
        bgImage = getRTextAreaBase().createVolatileImage(width, height);
        if (bgImage != null)
            renderImage(width, height, hint);
    }

}