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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 *
 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package javax.swing.plaf.nimbus;

import java.awt.AlphaComposite;
import java.awt.Graphics2D;
import java.awt.Transparency;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.awt.image.ColorModel;

EffectUtils
Author:
Created by Jasper Potts (Jun 18, 2007)/**
 * EffectUtils
 *
 * @author Created by Jasper Potts (Jun 18, 2007)
 */
class EffectUtils {

    
Clear a transparent image to 100% transparent
Params:
img – The image to clear/**
     * Clear a transparent image to 100% transparent
     *
     * @param img The image to clear
     */
    static void clearImage(BufferedImage img) {
        Graphics2D g2 = img.createGraphics();
        g2.setComposite(AlphaComposite.Clear);
        g2.fillRect(0, 0, img.getWidth(), img.getHeight());
        g2.dispose();
    }

    // =================================================================================================================
    // Blur

    
Apply Gaussian Blur to Image
Params:
src –    The image tp
dst –    The destination image to draw blured src image into, null if you want a new one created
radius – The blur kernel radius
Returns:
The blured image/**
     * Apply Gaussian Blur to Image
     *
     * @param src    The image tp
     * @param dst    The destination image to draw blured src image into, null if you want a new one created
     * @param radius The blur kernel radius
     * @return The blured image
     */
    static BufferedImage gaussianBlur(BufferedImage src, BufferedImage dst, int radius) {
        int width = src.getWidth();
        int height = src.getHeight();
        if (dst == null || dst.getWidth() != width || dst.getHeight() != height || src.getType() != dst.getType()) {
            dst = createColorModelCompatibleImage(src);
        }
        float[] kernel = createGaussianKernel(radius);
        if (src.getType() == BufferedImage.TYPE_INT_ARGB) {
            int[] srcPixels = new int[width * height];
            int[] dstPixels = new int[width * height];
            getPixels(src, 0, 0, width, height, srcPixels);
            // horizontal pass
            blur(srcPixels, dstPixels, width, height, kernel, radius);
            // vertical pass
            //noinspection SuspiciousNameCombination
            blur(dstPixels, srcPixels, height, width, kernel, radius);
            // the result is now stored in srcPixels due to the 2nd pass
            setPixels(dst, 0, 0, width, height, srcPixels);
        } else if (src.getType() == BufferedImage.TYPE_BYTE_GRAY) {
            byte[] srcPixels = new byte[width * height];
            byte[] dstPixels = new byte[width * height];
            getPixels(src, 0, 0, width, height, srcPixels);
            // horizontal pass
            blur(srcPixels, dstPixels, width, height, kernel, radius);
            // vertical pass
            //noinspection SuspiciousNameCombination
            blur(dstPixels, srcPixels, height, width, kernel, radius);
            // the result is now stored in srcPixels due to the 2nd pass
            setPixels(dst, 0, 0, width, height, srcPixels);
        } else {
            throw new IllegalArgumentException("EffectUtils.gaussianBlur() src image is not a supported type, type=[" +
                    src.getType() + "]");
        }
        return dst;
    }

    
Blurs the source pixels into the destination pixels. The force of the blur is specified by the radius which
must be greater than 0.
 
The source and destination pixels arrays are expected to be in the INT_ARGB
format.
 
After this method is executed, dstPixels contains a transposed and filtered copy of
srcPixels.
Params:
srcPixels – the source pixels
dstPixels – the destination pixels
width –     the width of the source picture
height –    the height of the source picture
kernel –    the kernel of the blur effect
radius –    the radius of the blur effect/**
     * <p>Blurs the source pixels into the destination pixels. The force of the blur is specified by the radius which
     * must be greater than 0.</p> <p>The source and destination pixels arrays are expected to be in the INT_ARGB
     * format.</p> <p>After this method is executed, dstPixels contains a transposed and filtered copy of
     * srcPixels.</p>
     *
     * @param srcPixels the source pixels
     * @param dstPixels the destination pixels
     * @param width     the width of the source picture
     * @param height    the height of the source picture
     * @param kernel    the kernel of the blur effect
     * @param radius    the radius of the blur effect
     */
    private static void blur(int[] srcPixels, int[] dstPixels,
                             int width, int height,
                             float[] kernel, int radius) {
        float a;
        float r;
        float g;
        float b;

        int ca;
        int cr;
        int cg;
        int cb;

        for (int y = 0; y < height; y++) {
            int index = y;
            int offset = y * width;

            for (int x = 0; x < width; x++) {
                a = r = g = b = 0.0f;

                for (int i = -radius; i <= radius; i++) {
                    int subOffset = x + i;
                    if (subOffset < 0 || subOffset >= width) {
                        subOffset = (x + width) % width;
                    }

                    int pixel = srcPixels[offset + subOffset];
                    float blurFactor = kernel[radius + i];

                    a += blurFactor * ((pixel >> 24) & 0xFF);
                    r += blurFactor * ((pixel >> 16) & 0xFF);
                    g += blurFactor * ((pixel >> 8) & 0xFF);
                    b += blurFactor * ((pixel) & 0xFF);
                }

                ca = (int) (a + 0.5f);
                cr = (int) (r + 0.5f);
                cg = (int) (g + 0.5f);
                cb = (int) (b + 0.5f);

                dstPixels[index] = ((ca > 255 ? 255 : ca) << 24) |
                        ((cr > 255 ? 255 : cr) << 16) |
                        ((cg > 255 ? 255 : cg) << 8) |
                        (cb > 255 ? 255 : cb);
                index += height;
            }
        }
    }

    
Blurs the source pixels into the destination pixels. The force of the blur is specified by the radius which
must be greater than 0.
 
The source and destination pixels arrays are expected to be in the BYTE_GREY
format.
 
After this method is executed, dstPixels contains a transposed and filtered copy of
srcPixels.
Params:
srcPixels – the source pixels
dstPixels – the destination pixels
width –     the width of the source picture
height –    the height of the source picture
kernel –    the kernel of the blur effect
radius –    the radius of the blur effect/**
     * <p>Blurs the source pixels into the destination pixels. The force of the blur is specified by the radius which
     * must be greater than 0.</p> <p>The source and destination pixels arrays are expected to be in the BYTE_GREY
     * format.</p> <p>After this method is executed, dstPixels contains a transposed and filtered copy of
     * srcPixels.</p>
     *
     * @param srcPixels the source pixels
     * @param dstPixels the destination pixels
     * @param width     the width of the source picture
     * @param height    the height of the source picture
     * @param kernel    the kernel of the blur effect
     * @param radius    the radius of the blur effect
     */
    static void blur(byte[] srcPixels, byte[] dstPixels,
                            int width, int height,
                            float[] kernel, int radius) {
        float p;
        int cp;
        for (int y = 0; y < height; y++) {
            int index = y;
            int offset = y * width;
            for (int x = 0; x < width; x++) {
                p = 0.0f;
                for (int i = -radius; i <= radius; i++) {
                    int subOffset = x + i;
//                    if (subOffset < 0) subOffset = 0;
//                    if (subOffset >= width) subOffset = width-1;
                    if (subOffset < 0 || subOffset >= width) {
                        subOffset = (x + width) % width;
                    }
                    int pixel = srcPixels[offset + subOffset] & 0xFF;
                    float blurFactor = kernel[radius + i];
                    p += blurFactor * pixel;
                }
                cp = (int) (p + 0.5f);
                dstPixels[index] = (byte) (cp > 255 ? 255 : cp);
                index += height;
            }
        }
    }

    static float[] createGaussianKernel(int radius) {
        if (radius < 1) {
            throw new IllegalArgumentException("Radius must be >= 1");
        }

        float[] data = new float[radius * 2 + 1];

        float sigma = radius / 3.0f;
        float twoSigmaSquare = 2.0f * sigma * sigma;
        float sigmaRoot = (float) Math.sqrt(twoSigmaSquare * Math.PI);
        float total = 0.0f;

        for (int i = -radius; i <= radius; i++) {
            float distance = i * i;
            int index = i + radius;
            data[index] = (float) Math.exp(-distance / twoSigmaSquare) / sigmaRoot;
            total += data[index];
        }

        for (int i = 0; i < data.length; i++) {
            data[i] /= total;
        }

        return data;
    }

    // =================================================================================================================
    // Get/Set Pixels helper methods

    
Returns an array of pixels, stored as integers, from a BufferedImage. 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 BufferedImage.TYPE_INT_ARGB and BufferedImage.TYPE_INT_RGB will unmanage the
image.
Params:
img –    the source image
x –      the x location at which to start grabbing pixels
y –      the y location at which to start grabbing pixels
w –      the width of the rectangle of pixels to grab
h –      the height of the rectangle of pixels to grab
pixels – a pre-allocated array of pixels of size w*h; can be null
Throws:
IllegalArgumentException – is pixels is non-null and of length < w*h
Returns:
pixels if non-null, a new array of integers otherwise/**
     * <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
     */
    static byte[] getPixels(BufferedImage img,
                                   int x, int y, int w, int h, byte[] pixels) {
        if (w == 0 || h == 0) {
            return new byte[0];
        }

        if (pixels == null) {
            pixels = new byte[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_BYTE_GRAY) {
            Raster raster = img.getRaster();
            return (byte[]) raster.getDataElements(x, y, w, h, pixels);
        } else {
            throw new IllegalArgumentException("Only type BYTE_GRAY is supported");
        }
    }

    
Writes a rectangular area of pixels in the destination BufferedImage. Calling this method on an
image of type different from BufferedImage.TYPE_INT_ARGB and BufferedImage.TYPE_INT_RGB
will unmanage the image.
Params:
img –    the destination image
x –      the x location at which to start storing pixels
y –      the y location at which to start storing pixels
w –      the width of the rectangle of pixels to store
h –      the height of the rectangle of pixels to store
pixels – an array of pixels, stored as integers
Throws:
IllegalArgumentException – is pixels is non-null and of length < w*h/**
     * <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
     */
    static void setPixels(BufferedImage img,
                                 int x, int y, int w, int h, byte[] 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_BYTE_GRAY) {
            WritableRaster raster = img.getRaster();
            raster.setDataElements(x, y, w, h, pixels);
        } else {
            throw new IllegalArgumentException("Only type BYTE_GRAY is supported");
        }
    }

    
Returns an array of pixels, stored as integers, from a
BufferedImage. 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 BufferedImage.TYPE_INT_ARGB
and BufferedImage.TYPE_INT_RGB will unmanage the image.
Params:
img – the source image
x – the x location at which to start grabbing pixels
y – the y location at which to start grabbing pixels
w – the width of the rectangle of pixels to grab
h – the height of the rectangle of pixels to grab
pixels – a pre-allocated array of pixels of size w*h; can be null
Throws:
IllegalArgumentException – is pixels is non-null and
  of length < w*h
Returns:
pixels if non-null, a new array of integers
  otherwise/**
     * <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);
    }

    
Writes a rectangular area of pixels in the destination
BufferedImage. Calling this method on
an image of type different from BufferedImage.TYPE_INT_ARGB
and BufferedImage.TYPE_INT_RGB will unmanage the image.
Params:
img – the destination image
x – the x location at which to start storing pixels
y – the y location at which to start storing pixels
w – the width of the rectangle of pixels to store
h – the height of the rectangle of pixels to store
pixels – an array of pixels, stored as integers
Throws:
IllegalArgumentException – is pixels is non-null and
  of length < w*h/**
     * <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);
        }
    }

    
Returns a new BufferedImage 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.
Params:
image – the reference image from which the color model of the new
  image is obtained
Returns:
a new BufferedImage, compatible with the color model
  of image/**
     * <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);
    }

    
Returns a new translucent compatible image of the specified width and
height. That is, the returned BufferedImage is compatible with
the graphics hardware. If the method is called in a headless
environment, then the returned BufferedImage will be compatible with
the source image.
Params:
width – the width of the new image
height – the height of the new image
Returns:
a new translucent compatible BufferedImage of the
  specified width and height/**
     * <p>Returns a new translucent compatible image of the specified width and
     * height. That is, the returned <code>BufferedImage</code> is compatible with
     * the graphics hardware. If the method is called in a headless
     * environment, then the returned BufferedImage will be compatible with
     * the source image.</p>
     *
     * @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 isHeadless() ?
                new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB) :
                getGraphicsConfiguration().createCompatibleImage(width, height,
                                                   Transparency.TRANSLUCENT);
    }

    private static boolean isHeadless() {
        return GraphicsEnvironment.isHeadless();
    }

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

}