/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.awt.image;

import java.util.Hashtable;
import java.awt.image.ImageProducer;
import java.awt.image.ImageConsumer;
import java.awt.image.ColorModel;
import java.awt.Image;

/**
 * The PixelGrabber class implements an ImageConsumer which can be attached
 * to an Image or ImageProducer object to retrieve a subset of the pixels
 * in that image.  Here is an example:
 * <pre>{@code
 *
 * public void handlesinglepixel(int x, int y, int pixel) {
 *      int alpha = (pixel >> 24) & 0xff;
 *      int red   = (pixel >> 16) & 0xff;
 *      int green = (pixel >>  8) & 0xff;
 *      int blue  = (pixel      ) & 0xff;
 *      // Deal with the pixel as necessary...
 * }
 *
 * public void handlepixels(Image img, int x, int y, int w, int h) {
 *      int[] pixels = new int[w * h];
 *      PixelGrabber pg = new PixelGrabber(img, x, y, w, h, pixels, 0, w);
 *      try {
 *          pg.grabPixels();
 *      } catch (InterruptedException e) {
 *          System.err.println("interrupted waiting for pixels!");
 *          return;
 *      }
 *      if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
 *          System.err.println("image fetch aborted or errored");
 *          return;
 *      }
 *      for (int j = 0; j < h; j++) {
 *          for (int i = 0; i < w; i++) {
 *              handlesinglepixel(x+i, y+j, pixels[j * w + i]);
 *          }
 *      }
 * }
 *
 * }</pre>
 *
 * @see ColorModel#getRGBdefault
 *
 * @author      Jim Graham
 */
public class PixelGrabber implements ImageConsumer {
    ImageProducer producer;

    int dstX;
    int dstY;
    int dstW;
    int dstH;

    ColorModel imageModel;
    byte[] bytePixels;
    int[] intPixels;
    int dstOff;
    int dstScan;

    private boolean grabbing;
    private int flags;

    private static final int GRABBEDBITS = (ImageObserver.FRAMEBITS
                                            | ImageObserver.ALLBITS);
    private static final int DONEBITS = (GRABBEDBITS
                                         | ImageObserver.ERROR);

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the specified image into the given array.
     * The pixels are stored into the array in the default RGB ColorModel.
     * The RGB data for pixel (i, j) where (i, j) is inside the rectangle
     * (x, y, w, h) is stored in the array at
     * {@code pix[(j - y) * scansize + (i - x) + off]}.
     * @see ColorModel#getRGBdefault
     * @param img the image to retrieve pixels from
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param pix the array of integers which are to be used to hold the
     * RGB pixels retrieved from the image
     * @param off the offset into the array of where to store the first pixel
     * @param scansize the distance from one row of pixels to the next in
     * the array
     */
    public PixelGrabber(Image img, int x, int y, int w, int h,
                        int[] pix, int off, int scansize) {
        this(img.getSource(), x, y, w, h, pix, off, scansize);
    }

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the image produced by the specified
     * ImageProducer into the given array.
     * The pixels are stored into the array in the default RGB ColorModel.
     * The RGB data for pixel (i, j) where (i, j) is inside the rectangle
     * (x, y, w, h) is stored in the array at
     * {@code pix[(j - y) * scansize + (i - x) + off]}.
     * @param ip the {@code ImageProducer} that produces the
     * image from which to retrieve pixels
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param pix the array of integers which are to be used to hold the
     * RGB pixels retrieved from the image
     * @param off the offset into the array of where to store the first pixel
     * @param scansize the distance from one row of pixels to the next in
     * the array
     * @see ColorModel#getRGBdefault
     */
    public PixelGrabber(ImageProducer ip, int x, int y, int w, int h,
                        int[] pix, int off, int scansize) {
        producer = ip;
        dstX = x;
        dstY = y;
        dstW = w;
        dstH = h;
        dstOff = off;
        dstScan = scansize;
        intPixels = pix;
        imageModel = ColorModel.getRGBdefault();
    }

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the specified image.  The pixels are
     * accumulated in the original ColorModel if the same ColorModel
     * is used for every call to setPixels, otherwise the pixels are
     * accumulated in the default RGB ColorModel.  If the forceRGB
     * parameter is true, then the pixels will be accumulated in the
     * default RGB ColorModel anyway.  A buffer is allocated by the
     * PixelGrabber to hold the pixels in either case.  If {@code (w < 0)} or
     * {@code (h < 0)}, then they will default to the remaining width and
     * height of the source data when that information is delivered.
     * @param img the image to retrieve the image data from
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param forceRGB true if the pixels should always be converted to
     * the default RGB ColorModel
     */
    public PixelGrabber(Image img, int x, int y, int w, int h,
                        boolean forceRGB)
    {
        producer = img.getSource();
        dstX = x;
        dstY = y;
        dstW = w;
        dstH = h;
        if (forceRGB) {
            imageModel = ColorModel.getRGBdefault();
        }
    }

    /**
     * Request the PixelGrabber to start fetching the pixels.
     */
    public synchronized void startGrabbing() {
        if ((flags & DONEBITS) != 0) {
            return;
        }
        if (!grabbing) {
            grabbing = true;
            flags &= ~(ImageObserver.ABORT);
            producer.startProduction(this);
        }
    }

    /**
     * Request the PixelGrabber to abort the image fetch.
     */
    public synchronized void abortGrabbing() {
        imageComplete(IMAGEABORTED);
    }

    /**
     * Request the Image or ImageProducer to start delivering pixels and
     * wait for all of the pixels in the rectangle of interest to be
     * delivered.
     * @return true if the pixels were successfully grabbed, false on
     * abort, error or timeout
     * @exception InterruptedException
     *            Another thread has interrupted this thread.
     */
    public boolean grabPixels() throws InterruptedException {
        return grabPixels(0);
    }

    /**
     * Request the Image or ImageProducer to start delivering pixels and
     * wait for all of the pixels in the rectangle of interest to be
     * delivered or until the specified timeout has elapsed.  This method
     * behaves in the following ways, depending on the value of
     * {@code ms}:
     * <ul>
     * <li> If {@code ms == 0}, waits until all pixels are delivered
     * <li> If {@code ms > 0}, waits until all pixels are delivered
     * as timeout expires.
     * <li> If {@code ms < 0}, returns {@code true} if all pixels
     * are grabbed, {@code false} otherwise and does not wait.
     * </ul>
     * @param ms the number of milliseconds to wait for the image pixels
     * to arrive before timing out
     * @return true if the pixels were successfully grabbed, false on
     * abort, error or timeout
     * @exception InterruptedException
     *            Another thread has interrupted this thread.
     */
    public synchronized boolean grabPixels(long ms)
        throws InterruptedException
    {
        if ((flags & DONEBITS) != 0) {
            return (flags & GRABBEDBITS) != 0;
        }
        long end = ms + System.currentTimeMillis();
        if (!grabbing) {
            grabbing = true;
            flags &= ~(ImageObserver.ABORT);
            producer.startProduction(this);
        }
        while (grabbing) {
            long timeout;
            if (ms == 0) {
                timeout = 0;
            } else {
                timeout = end - System.currentTimeMillis();
                if (timeout <= 0) {
                    break;
                }
            }
            wait(timeout);
        }
        return (flags & GRABBEDBITS) != 0;
    }

    /**
     * Return the status of the pixels.  The ImageObserver flags
     * representing the available pixel information are returned.
     * @return the bitwise OR of all relevant ImageObserver flags
     * @see ImageObserver
     */
    public synchronized int getStatus() {
        return flags;
    }

    /**
     * Get the width of the pixel buffer (after adjusting for image width).
     * If no width was specified for the rectangle of pixels to grab then
     * then this information will only be available after the image has
     * delivered the dimensions.
     * @return the final width used for the pixel buffer or -1 if the width
     * is not yet known
     * @see #getStatus
     */
    public synchronized int getWidth() {
        return (dstW < 0) ? -1 : dstW;
    }

    /**
     * Get the height of the pixel buffer (after adjusting for image height).
     * If no width was specified for the rectangle of pixels to grab then
     * then this information will only be available after the image has
     * delivered the dimensions.
     * @return the final height used for the pixel buffer or -1 if the height
     * is not yet known
     * @see #getStatus
     */
    public synchronized int getHeight() {
        return (dstH < 0) ? -1 : dstH;
    }

    /**
     * Get the pixel buffer.  If the PixelGrabber was not constructed
     * with an explicit pixel buffer to hold the pixels then this method
     * will return null until the size and format of the image data is
     * known.
     * Since the PixelGrabber may fall back on accumulating the data
     * in the default RGB ColorModel at any time if the source image
     * uses more than one ColorModel to deliver the data, the array
     * object returned by this method may change over time until the
     * image grab is complete.
     * @return either a byte array or an int array
     * @see #getStatus
     * @see #setPixels(int, int, int, int, ColorModel, byte[], int, int)
     * @see #setPixels(int, int, int, int, ColorModel, int[], int, int)
     */
    public synchronized Object getPixels() {
        return (bytePixels == null)
            ? ((Object) intPixels)
            : ((Object) bytePixels);
    }

    /**
     * Get the ColorModel for the pixels stored in the array.  If the
     * PixelGrabber was constructed with an explicit pixel buffer then
     * this method will always return the default RGB ColorModel,
     * otherwise it may return null until the ColorModel used by the
     * ImageProducer is known.
     * Since the PixelGrabber may fall back on accumulating the data
     * in the default RGB ColorModel at any time if the source image
     * uses more than one ColorModel to deliver the data, the ColorModel
     * object returned by this method may change over time until the
     * image grab is complete and may not reflect any of the ColorModel
     * objects that was used by the ImageProducer to deliver the pixels.
     * @return the ColorModel object used for storing the pixels
     * @see #getStatus
     * @see ColorModel#getRGBdefault
     * @see #setColorModel(ColorModel)
     */
    public synchronized ColorModel getColorModel() {
        return imageModel;
    }

    /**
     * The setDimensions method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param width the width of the dimension
     * @param height the height of the dimension
     */
    public void setDimensions(int width, int height) {
        if (dstW < 0) {
            dstW = width - dstX;
        }
        if (dstH < 0) {
            dstH = height - dstY;
        }
        if (dstW <= 0 || dstH <= 0) {
            imageComplete(STATICIMAGEDONE);
        } else if (intPixels == null &&
                   imageModel == ColorModel.getRGBdefault()) {
            intPixels = new int[dstW * dstH];
            dstScan = dstW;
            dstOff = 0;
        }
        flags |= (ImageObserver.WIDTH | ImageObserver.HEIGHT);
    }

    /**
     * The setHints method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param hints a set of hints used to process the pixels
     */
    public void setHints(int hints) {
        return;
    }

    /**
     * The setProperties method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param props the list of properties
     */
    public void setProperties(Hashtable<?,?> props) {
        return;
    }

    /**
     * The setColorModel method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param model the specified {@code ColorModel}
     * @see #getColorModel
     */
    public void setColorModel(ColorModel model) {
        return;
    }

    private void convertToRGB() {
        int size = dstW * dstH;
        int newpixels[] = new int[size];
        if (bytePixels != null) {
            for (int i = 0; i < size; i++) {
                newpixels[i] = imageModel.getRGB(bytePixels[i] & 0xff);
            }
        } else if (intPixels != null) {
            for (int i = 0; i < size; i++) {
                newpixels[i] = imageModel.getRGB(intPixels[i]);
            }
        }
        bytePixels = null;
        intPixels = newpixels;
        dstScan = dstW;
        dstOff = 0;
        imageModel = ColorModel.getRGBdefault();
    }

    /**
     * The setPixels method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param srcX the X coordinate of the upper-left corner
     *        of the area of pixels to be set
     * @param srcY the Y coordinate of the upper-left corner
     *        of the area of pixels to be set
     * @param srcW the width of the area of pixels
     * @param srcH the height of the area of pixels
     * @param model the specified {@code ColorModel}
     * @param pixels the array of pixels
     * @param srcOff the offset into the pixels array
     * @param srcScan the distance from one row of pixels to the next
     *        in the pixels array
     * @see #getPixels
     */
    public void setPixels(int srcX, int srcY, int srcW, int srcH,
                          ColorModel model,
                          byte pixels[], int srcOff, int srcScan) {
        if (srcY < dstY) {
            int diff = dstY - srcY;
            if (diff >= srcH) {
                return;
            }
            srcOff += srcScan * diff;
            srcY += diff;
            srcH -= diff;
        }
        if (srcY + srcH > dstY + dstH) {
            srcH = (dstY + dstH) - srcY;
            if (srcH <= 0) {
                return;
            }
        }
        if (srcX < dstX) {
            int diff = dstX - srcX;
            if (diff >= srcW) {
                return;
            }
            srcOff += diff;
            srcX += diff;
            srcW -= diff;
        }
        if (srcX + srcW > dstX + dstW) {
            srcW = (dstX + dstW) - srcX;
            if (srcW <= 0) {
                return;
            }
        }
        int dstPtr = dstOff + (srcY - dstY) * dstScan + (srcX - dstX);
        if (intPixels == null) {
            if (bytePixels == null) {
                bytePixels = new byte[dstW * dstH];
                dstScan = dstW;
                dstOff = 0;
                imageModel = model;
            } else if (imageModel != model) {
                convertToRGB();
            }
            if (bytePixels != null) {
                for (int h = srcH; h > 0; h--) {
                    System.arraycopy(pixels, srcOff, bytePixels, dstPtr, srcW);
                    srcOff += srcScan;
                    dstPtr += dstScan;
                }
            }
        }
        if (intPixels != null) {
            int dstRem = dstScan - srcW;
            int srcRem = srcScan - srcW;
            for (int h = srcH; h > 0; h--) {
                for (int w = srcW; w > 0; w--) {
                    intPixels[dstPtr++] = model.getRGB(pixels[srcOff++]&0xff);
                }
                srcOff += srcRem;
                dstPtr += dstRem;
            }
        }
        flags |= ImageObserver.SOMEBITS;
    }

    /**
     * The setPixels method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param srcX the X coordinate of the upper-left corner
     *        of the area of pixels to be set
     * @param srcY the Y coordinate of the upper-left corner
     *        of the area of pixels to be set
     * @param srcW the width of the area of pixels
     * @param srcH the height of the area of pixels
     * @param model the specified {@code ColorModel}
     * @param pixels the array of pixels
     * @param srcOff the offset into the pixels array
     * @param srcScan the distance from one row of pixels to the next
     *        in the pixels array
     * @see #getPixels
     */
    public void setPixels(int srcX, int srcY, int srcW, int srcH,
                          ColorModel model,
                          int pixels[], int srcOff, int srcScan) {
        if (srcY < dstY) {
            int diff = dstY - srcY;
            if (diff >= srcH) {
                return;
            }
            srcOff += srcScan * diff;
            srcY += diff;
            srcH -= diff;
        }
        if (srcY + srcH > dstY + dstH) {
            srcH = (dstY + dstH) - srcY;
            if (srcH <= 0) {
                return;
            }
        }
        if (srcX < dstX) {
            int diff = dstX - srcX;
            if (diff >= srcW) {
                return;
            }
            srcOff += diff;
            srcX += diff;
            srcW -= diff;
        }
        if (srcX + srcW > dstX + dstW) {
            srcW = (dstX + dstW) - srcX;
            if (srcW <= 0) {
                return;
            }
        }
        if (intPixels == null) {
            if (bytePixels == null) {
                intPixels = new int[dstW * dstH];
                dstScan = dstW;
                dstOff = 0;
                imageModel = model;
            } else {
                convertToRGB();
            }
        }
        int dstPtr = dstOff + (srcY - dstY) * dstScan + (srcX - dstX);
        if (imageModel == model) {
            for (int h = srcH; h > 0; h--) {
                System.arraycopy(pixels, srcOff, intPixels, dstPtr, srcW);
                srcOff += srcScan;
                dstPtr += dstScan;
            }
        } else {
            if (imageModel != ColorModel.getRGBdefault()) {
                convertToRGB();
            }
            int dstRem = dstScan - srcW;
            int srcRem = srcScan - srcW;
            for (int h = srcH; h > 0; h--) {
                for (int w = srcW; w > 0; w--) {
                    intPixels[dstPtr++] = model.getRGB(pixels[srcOff++]);
                }
                srcOff += srcRem;
                dstPtr += dstRem;
            }
        }
        flags |= ImageObserver.SOMEBITS;
    }

    /**
     * The imageComplete method is part of the ImageConsumer API which
     * this class must implement to retrieve the pixels.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being grabbed.  Developers using
     * this class to retrieve pixels from an image should avoid calling
     * this method directly since that operation could result in problems
     * with retrieving the requested pixels.
     * @param status the status of image loading
     */
    public synchronized void imageComplete(int status) {
        grabbing = false;
        switch (status) {
        default:
        case IMAGEERROR:
            flags |= ImageObserver.ERROR | ImageObserver.ABORT;
            break;
        case IMAGEABORTED:
            flags |= ImageObserver.ABORT;
            break;
        case STATICIMAGEDONE:
            flags |= ImageObserver.ALLBITS;
            break;
        case SINGLEFRAMEDONE:
            flags |= ImageObserver.FRAMEBITS;
            break;
        }
        producer.removeConsumer(this);
        notifyAll();
    }

    /**
     * Returns the status of the pixels.  The ImageObserver flags
     * representing the available pixel information are returned.
     * This method and {@link #getStatus() getStatus} have the
     * same implementation, but {@code getStatus} is the
     * preferred method because it conforms to the convention of
     * naming information-retrieval methods with the form
     * "getXXX".
     * @return the bitwise OR of all relevant ImageObserver flags
     * @see ImageObserver
     * @see #getStatus()
     */
    public synchronized int status() {
        return flags;
    }
}