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package dropShadow;

import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.awt.GraphicsConfiguration;
import java.awt.Transparency;
import java.awt.Graphics;
import java.awt.GraphicsEnvironment;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;

/**
 * <p>
 * <code>GraphicsUtilities</code> contains a set of tools to perform common
 * graphics operations easily. These operations are divided into several themes,
 * listed below.</p>
 * <h2>Compatible Images</h2>
 * <p>
 * Compatible images can, and should, be used to increase drawing performance.
 * This class provides a number of methods to load compatible images directly
 * from files or to convert existing images to compatibles images.</p>
 * <h2>Creating Thumbnails</h2>
 * <p>
 * This class provides a number of methods to easily scale down images. Some of
 * these methods offer a trade-off between speed and result quality and shouuld
 * be used all the time. They also offer the advantage of producing compatible
 * images, thus automatically resulting into better runtime performance.</p>
 * <p>
 * All these methodes are both faster than
 * {@link java.awt.Image#getScaledInstance(int, int, int)} and produce
 * better-looking results than the various <code>drawImage()</code> methods in
 * {@link java.awt.Graphics}, which can be used for image scaling.</p>
 * <h2>Image Manipulation</h2>
 * <p>
 * This class provides two methods to get and set pixels in a buffered image.
 * These methods try to avoid unmanaging the image in order to keep good
 * performance.</p>
 *
 * @author Romain Guy <romain.guy@mac.com>
 */
public class GraphicsUtilities {

    private GraphicsUtilities() {
    }

    // Returns the graphics configuration for the primary screen
    private static GraphicsConfiguration getGraphicsConfiguration() {
        return GraphicsEnvironment.getLocalGraphicsEnvironment().
                getDefaultScreenDevice().getDefaultConfiguration();
    }

    /**
     * <p>
     * Returns a new <code>BufferedImage</code> using the same color model as
     * the image passed as a parameter. The returned image is only compatible
     * with the image passed as a parameter. This does not mean the returned
     * image is compatible with the hardware.</p>
     *
     * @param image the reference image from which the color model of the new
     * image is obtained
     * @return a new <code>BufferedImage</code>, compatible with the color model
     * of <code>image</code>
     */
    public static BufferedImage createColorModelCompatibleImage(BufferedImage image) {
        ColorModel cm = image.getColorModel();
        return new BufferedImage(cm,
                cm.createCompatibleWritableRaster(image.getWidth(),
                        image.getHeight()),
                cm.isAlphaPremultiplied(), null);
    }

    /**
     * <p>
     * Returns a new compatible image with the same width, height and
     * transparency as the image specified as a parameter.</p>
     *
     * @see java.awt.Transparency
     * @see #createCompatibleImage(int, int)
     * @see #createCompatibleImage(java.awt.image.BufferedImage, int, int)
     * @see #createCompatibleTranslucentImage(int, int)
     * @see #loadCompatibleImage(java.net.URL)
     * @see #toCompatibleImage(java.awt.image.BufferedImage)
     * @param image the reference image from which the dimension and the
     * transparency of the new image are obtained
     * @return a new compatible <code>BufferedImage</code> with the same
     * dimension and transparency as <code>image</code>
     */
    public static BufferedImage createCompatibleImage(BufferedImage image) {
        return createCompatibleImage(image, image.getWidth(), image.getHeight());
    }

    /**
     * <p>
     * Returns a new compatible image of the specified width and height, and the
     * same transparency setting as the image specified as a parameter.</p>
     *
     * @see java.awt.Transparency
     * @see #createCompatibleImage(java.awt.image.BufferedImage)
     * @see #createCompatibleImage(int, int)
     * @see #createCompatibleTranslucentImage(int, int)
     * @see #loadCompatibleImage(java.net.URL)
     * @see #toCompatibleImage(java.awt.image.BufferedImage)
     * @param width the width of the new image
     * @param height the height of the new image
     * @param image the reference image from which the transparency of the new
     * image is obtained
     * @return a new compatible <code>BufferedImage</code> with the same
     * transparency as <code>image</code> and the specified dimension
     */
    public static BufferedImage createCompatibleImage(BufferedImage image,
            int width, int height) {
        return getGraphicsConfiguration().createCompatibleImage(width, height,
                image.getTransparency());
    }

    /**
     * <p>
     * Returns a new opaque compatible image of the specified width and
     * height.</p>
     *
     * @see #createCompatibleImage(java.awt.image.BufferedImage)
     * @see #createCompatibleImage(java.awt.image.BufferedImage, int, int)
     * @see #createCompatibleTranslucentImage(int, int)
     * @see #loadCompatibleImage(java.net.URL)
     * @see #toCompatibleImage(java.awt.image.BufferedImage)
     * @param width the width of the new image
     * @param height the height of the new image
     * @return a new opaque compatible <code>BufferedImage</code> of the
     * specified width and height
     */
    public static BufferedImage createCompatibleImage(int width, int height) {
        return getGraphicsConfiguration().createCompatibleImage(width, height);
    }

    /**
     * <p>
     * Returns a new translucent compatible image of the specified width and
     * height.</p>
     *
     * @see #createCompatibleImage(java.awt.image.BufferedImage)
     * @see #createCompatibleImage(java.awt.image.BufferedImage, int, int)
     * @see #createCompatibleImage(int, int)
     * @see #loadCompatibleImage(java.net.URL)
     * @see #toCompatibleImage(java.awt.image.BufferedImage)
     * @param width the width of the new image
     * @param height the height of the new image
     * @return a new translucent compatible <code>BufferedImage</code> of the
     * specified width and height
     */
    public static BufferedImage createCompatibleTranslucentImage(int width,
            int height) {
        return getGraphicsConfiguration().createCompatibleImage(width, height,
                Transparency.TRANSLUCENT);
    }

    /**
     * <p>
     * Returns a new compatible image from a URL. The image is loaded from the
     * specified location and then turned, if necessary into a compatible
     * image.</p>
     *
     * @see #createCompatibleImage(java.awt.image.BufferedImage)
     * @see #createCompatibleImage(java.awt.image.BufferedImage, int, int)
     * @see #createCompatibleImage(int, int)
     * @see #createCompatibleTranslucentImage(int, int)
     * @see #toCompatibleImage(java.awt.image.BufferedImage)
     * @param resource the URL of the picture to load as a compatible image
     * @return a new translucent compatible <code>BufferedImage</code> of the
     * specified width and height
     * @throws java.io.IOException if the image cannot be read or loaded
     */
    public static BufferedImage loadCompatibleImage(URL resource)
            throws IOException {
        BufferedImage image = ImageIO.read(resource);
        return toCompatibleImage(image);
    }

    /**
     * <p>
     * Return a new compatible image that contains a copy of the specified
     * image. This method ensures an image is compatible with the hardware, and
     * therefore optimized for fast blitting operations.</p>
     *
     * @see #createCompatibleImage(java.awt.image.BufferedImage)
     * @see #createCompatibleImage(java.awt.image.BufferedImage, int, int)
     * @see #createCompatibleImage(int, int)
     * @see #createCompatibleTranslucentImage(int, int)
     * @see #loadCompatibleImage(java.net.URL)
     * @param image the image to copy into a new compatible image
     * @return a new compatible copy, with the same width and height and
     * transparency and content, of <code>image</code>
     */
    public static BufferedImage toCompatibleImage(BufferedImage image) {
        if (image.getColorModel().equals(
                getGraphicsConfiguration().getColorModel())) {
            return image;
        }

        BufferedImage compatibleImage
                = getGraphicsConfiguration().createCompatibleImage(
                        image.getWidth(), image.getHeight(),
                        image.getTransparency());
        Graphics g = compatibleImage.getGraphics();
        g.drawImage(image, 0, 0, null);
        g.dispose();

        return compatibleImage;
    }

    /**
     * <p>
     * Returns a thumbnail of a source image. <code>newSize</code> defines the
     * length of the longest dimension of the thumbnail. The other dimension is
     * then computed according to the dimensions ratio of the original
     * picture.</p>
     * <p>
     * This method favors speed over quality. When the new size is less than
     * half the longest dimension of the source image,
     * {@link #createThumbnail(BufferedImage, int)} or
     * {@link #createThumbnail(BufferedImage, int, int)} should be used instead
     * to ensure the quality of the result without sacrificing too much
     * performance.</p>
     *
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int, int)
     * @param image the source image
     * @param newSize the length of the largest dimension of the thumbnail
     * @return a new compatible <code>BufferedImage</code> containing a
     * thumbnail of <code>image</code>
     * @throws IllegalArgumentException if <code>newSize</code> is larger than
     * the largest dimension of <code>image</code> or &lt;= 0
     */
    public static BufferedImage createThumbnailFast(BufferedImage image,
            int newSize) {
        float ratio;
        int width = image.getWidth();
        int height = image.getHeight();

        if (width > height) {
            if (newSize >= width) {
                throw new IllegalArgumentException("newSize must be lower than"
                        + " the image width");
            } else if (newSize <= 0) {
                throw new IllegalArgumentException("newSize must"
                        + " be greater than 0");
            }

            ratio = (float) width / (float) height;
            width = newSize;
            height = (int) (newSize / ratio);
        } else {
            if (newSize >= height) {
                throw new IllegalArgumentException("newSize must be lower than"
                        + " the image height");
            } else if (newSize <= 0) {
                throw new IllegalArgumentException("newSize must"
                        + " be greater than 0");
            }

            ratio = (float) height / (float) width;
            height = newSize;
            width = (int) (newSize / ratio);
        }

        BufferedImage temp = createCompatibleImage(image, width, height);
        Graphics2D g2 = temp.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2.drawImage(image, 0, 0, temp.getWidth(), temp.getHeight(), null);
        g2.dispose();

        return temp;
    }

    /**
     * <p>
     * Returns a thumbnail of a source image.</p>
     * <p>
     * This method favors speed over quality. When the new size is less than
     * half the longest dimension of the source image,
     * {@link #createThumbnail(BufferedImage, int)} or
     * {@link #createThumbnail(BufferedImage, int, int)} should be used instead
     * to ensure the quality of the result without sacrificing too much
     * performance.</p>
     *
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int, int)
     * @param image the source image
     * @param newWidth the width of the thumbnail
     * @param newHeight the height of the thumbnail
     * @return a new compatible <code>BufferedImage</code> containing a
     * thumbnail of <code>image</code>
     * @throws IllegalArgumentException if <code>newWidth</code> is larger than
     * the width of <code>image</code> or if code>newHeight</code> is larger
     * than the height of <code>image</code> or if one of the dimensions is
     * &lt;= 0
     */
    public static BufferedImage createThumbnailFast(BufferedImage image,
            int newWidth, int newHeight) {
        if (newWidth >= image.getWidth()
                || newHeight >= image.getHeight()) {
            throw new IllegalArgumentException("newWidth and newHeight cannot"
                    + " be greater than the image"
                    + " dimensions");
        } else if (newWidth <= 0 || newHeight <= 0) {
            throw new IllegalArgumentException("newWidth and newHeight must"
                    + " be greater than 0");
        }

        BufferedImage temp = createCompatibleImage(image, newWidth, newHeight);
        Graphics2D g2 = temp.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2.drawImage(image, 0, 0, temp.getWidth(), temp.getHeight(), null);
        g2.dispose();

        return temp;
    }

    /**
     * <p>
     * Returns a thumbnail of a source image. <code>newSize</code> defines the
     * length of the longest dimension of the thumbnail. The other dimension is
     * then computed according to the dimensions ratio of the original
     * picture.</p>
     * <p>
     * This method offers a good trade-off between speed and quality. The result
     * looks better than
     * {@link #createThumbnailFast(java.awt.image.BufferedImage, int)} when the
     * new size is less than half the longest dimension of the source image, yet
     * the rendering speed is almost similar.</p>
     *
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int, int)
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int, int)
     * @param image the source image
     * @param newSize the length of the largest dimension of the thumbnail
     * @return a new compatible <code>BufferedImage</code> containing a
     * thumbnail of <code>image</code>
     * @throws IllegalArgumentException if <code>newSize</code> is larger than
     * the largest dimension of <code>image</code> or &lt;= 0
     */
    public static BufferedImage createThumbnail(BufferedImage image,
            int newSize) {
        int width = image.getWidth();
        int height = image.getHeight();

        boolean isWidthGreater = width > height;

        if (isWidthGreater) {
            if (newSize >= width) {
                throw new IllegalArgumentException("newSize must be lower than"
                        + " the image width");
            }
        } else if (newSize >= height) {
            throw new IllegalArgumentException("newSize must be lower than"
                    + " the image height");
        }

        if (newSize <= 0) {
            throw new IllegalArgumentException("newSize must"
                    + " be greater than 0");
        }

        float ratioWH = (float) width / (float) height;
        float ratioHW = (float) height / (float) width;

        BufferedImage thumb = image;

        do {
            if (isWidthGreater) {
                width /= 2;
                if (width < newSize) {
                    width = newSize;
                }
                height = (int) (width / ratioWH);
            } else {
                height /= 2;
                if (height < newSize) {
                    height = newSize;
                }
                width = (int) (height / ratioHW);
            }

            BufferedImage temp = createCompatibleImage(image, width, height);
            Graphics2D g2 = temp.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                    RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2.drawImage(thumb, 0, 0, temp.getWidth(), temp.getHeight(), null);
            g2.dispose();

            thumb = temp;
        } while (newSize != (isWidthGreater ? width : height));

        return thumb;
    }

    /**
     * <p>
     * Returns a thumbnail of a source image.</p>
     * <p>
     * This method offers a good trade-off between speed and quality. The result
     * looks better than
     * {@link #createThumbnailFast(java.awt.image.BufferedImage, int)} when the
     * new size is less than half the longest dimension of the source image, yet
     * the rendering speed is almost similar.</p>
     *
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int)
     * @see #createThumbnailFast(java.awt.image.BufferedImage, int, int)
     * @see #createThumbnail(java.awt.image.BufferedImage, int)
     * @param image the source image
     * @param newWidth the width of the thumbnail
     * @param newHeight the height of the thumbnail
     * @return a new compatible <code>BufferedImage</code> containing a
     * thumbnail of <code>image</code>
     * @throws IllegalArgumentException if <code>newWidth</code> is larger than
     * the width of <code>image</code> or if code>newHeight</code> is larger
     * than the height of
     * <code>image or if one the dimensions is not &gt; 0</code>
     */
    public static BufferedImage createThumbnail(BufferedImage image,
            int newWidth, int newHeight) {
        int width = image.getWidth();
        int height = image.getHeight();

        if (newWidth >= width || newHeight >= height) {
            throw new IllegalArgumentException("newWidth and newHeight cannot"
                    + " be greater than the image"
                    + " dimensions");
        } else if (newWidth <= 0 || newHeight <= 0) {
            throw new IllegalArgumentException("newWidth and newHeight must"
                    + " be greater than 0");
        }

        BufferedImage thumb = image;

        do {
            if (width > newWidth) {
                width /= 2;
                if (width < newWidth) {
                    width = newWidth;
                }
            }

            if (height > newHeight) {
                height /= 2;
                if (height < newHeight) {
                    height = newHeight;
                }
            }

            BufferedImage temp = createCompatibleImage(image, width, height);
            Graphics2D g2 = temp.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                    RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2.drawImage(thumb, 0, 0, temp.getWidth(), temp.getHeight(), null);
            g2.dispose();

            thumb = temp;
        } while (width != newWidth || height != newHeight);

        return thumb;
    }

    /**
     * <p>
     * Returns an array of pixels, stored as integers, from a
     * <code>BufferedImage</code>. The pixels are grabbed from a rectangular
     * area defined by a location and two dimensions. Calling this method on an
     * image of type different from <code>BufferedImage.TYPE_INT_ARGB</code> and
     * <code>BufferedImage.TYPE_INT_RGB</code> will unmanage the image.</p>
     *
     * @param img the source image
     * @param x the x location at which to start grabbing pixels
     * @param y the y location at which to start grabbing pixels
     * @param w the width of the rectangle of pixels to grab
     * @param h the height of the rectangle of pixels to grab
     * @param pixels a pre-allocated array of pixels of size w*h; can be null
     * @return <code>pixels</code> if non-null, a new array of integers
     * otherwise
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and
     * of length &lt; w*h
     */
    public static int[] getPixels(BufferedImage img,
            int x, int y, int w, int h, int[] pixels) {
        if (w == 0 || h == 0) {
            return new int[0];
        }

        if (pixels == null) {
            pixels = new int[w * h];
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length"
                    + " >= w*h");
        }

        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_INT_ARGB
                || imageType == BufferedImage.TYPE_INT_RGB) {
            Raster raster = img.getRaster();
            return (int[]) raster.getDataElements(x, y, w, h, pixels);
        }

        // Unmanages the image
        return img.getRGB(x, y, w, h, pixels, 0, w);
    }

    /**
     * <p>
     * Writes a rectangular area of pixels in the destination
     * <code>BufferedImage</code>. Calling this method on an image of type
     * different from <code>BufferedImage.TYPE_INT_ARGB</code> and
     * <code>BufferedImage.TYPE_INT_RGB</code> will unmanage the image.</p>
     *
     * @param img the destination image
     * @param x the x location at which to start storing pixels
     * @param y the y location at which to start storing pixels
     * @param w the width of the rectangle of pixels to store
     * @param h the height of the rectangle of pixels to store
     * @param pixels an array of pixels, stored as integers
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and
     * of length &lt; w*h
     */
    public static void setPixels(BufferedImage img,
            int x, int y, int w, int h, int[] pixels) {
        if (pixels == null || w == 0 || h == 0) {
            return;
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length"
                    + " >= w*h");
        }

        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_INT_ARGB
                || imageType == BufferedImage.TYPE_INT_RGB) {
            WritableRaster raster = img.getRaster();
            raster.setDataElements(x, y, w, h, pixels);
        } else {
            // Unmanages the image
            img.setRGB(x, y, w, h, pixels, 0, w);
        }
    }
}