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/* Copyright (C) 2004, 2006  Free Software Foundation

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath 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 for more details.

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along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

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As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

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terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

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this exception to your version of the library, but you are not

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exception statement from your version. */

package java.awt.image;

import java.awt.RenderingHints;

import java.awt.geom.Point2D;

import java.awt.geom.Rectangle2D;

import java.util.Arrays;

/**

 * RescaleOp is a filter that changes each pixel by a scaling factor and offset.

 *

 * For filtering Rasters, either one scaling factor and offset can be specified,

 * which will be applied to all bands; or a scaling factor and offset can be

 * specified for each band.

 *

 * For BufferedImages, the scaling may apply to both color and alpha components.

 * If only one scaling factor is provided, or if the number of factors provided

 * equals the number of color components, the scaling is performed on all color

 * components.  Otherwise, the scaling is performed on all components including

 * alpha.  Alpha premultiplication is ignored.

 *

 * After filtering, if color conversion is necessary, the conversion happens,

 * taking alpha premultiplication into account.

 *

 * @author Jerry Quinn (jlquinn@optonline.net)

 * @author Francis Kung (fkung@redhat.com)

 */

public class RescaleOp implements BufferedImageOp, RasterOp

{

  private float[] scale;

  private float[] offsets;

  private RenderingHints hints = null;

  /**

   * Create a new RescaleOp object using the given scale factors and offsets.

   *

   * The length of the arrays must be equal to the number of bands (or number of

   * data or color components) of the raster/image that this Op will be used on,

   * otherwise an IllegalArgumentException will be thrown when calling the

   * filter method.

   *

   * @param scaleFactors an array of scale factors.

   * @param offsets an array of offsets.

   * @param hints any rendering hints to use (can be null).

   * @throws NullPointerException if the scaleFactors or offsets array is null.

   */

  public RescaleOp(float[] scaleFactors,

                   float[] offsets,

                   RenderingHints hints)

  {

    int length = Math.min(scaleFactors.length, offsets.length);

    scale = new float[length];

    System.arraycopy(scaleFactors, 0, this.scale, 0, length);

    this.offsets = new float[length];

    System.arraycopy(offsets, 0, this.offsets, 0, length);

    this.hints = hints;

  }

  /**

   * Create a new RescaleOp object using the given scale factor and offset.

   *

   * The same scale factor and offset will be used on all bands/components.

   *

   * @param scaleFactor the scale factor to use.

   * @param offset the offset to use.

   * @param hints any rendering hints to use (can be null).

   */

  public RescaleOp(float scaleFactor,

                   float offset,

                   RenderingHints hints)

  {

    scale = new float[]{ scaleFactor };

    offsets = new float[]{offset};

    this.hints = hints;

  }

  /**

   * Returns the scaling factors.  This method accepts an optional array, which

   * will be used to store the factors if not null (this avoids allocating a

   * new array).  If this array is too small to hold all the scaling factors,

   * the array will be filled and the remaining factors discarded.

   *

   * @param scaleFactors array to store the scaling factors in (can be null).

   * @return an array of scaling factors.

   */

  public final float[] getScaleFactors(float[] scaleFactors)

  {

    if (scaleFactors == null)

      scaleFactors = new float[scale.length];

    System.arraycopy(scale, 0, scaleFactors, 0, Math.min(scale.length,

                                                         scaleFactors.length));

    return scaleFactors;

  }

  /**

   * Returns the offsets.  This method accepts an optional array, which

   * will be used to store the offsets if not null (this avoids allocating a

   * new array).  If this array is too small to hold all the offsets, the array

   * will be filled and the remaining factors discarded.

   *

   * @param offsets array to store the offsets in (can be null).

   * @return an array of offsets.

   */

  public final float[] getOffsets(float[] offsets)

  {

    if (offsets == null)

      offsets = new float[this.offsets.length];

    System.arraycopy(this.offsets, 0, offsets, 0, Math.min(this.offsets.length,

                                                           offsets.length));

    return offsets;

  }

  /**

   * Returns the number of scaling factors / offsets.

   *

   * @return the number of scaling factors / offsets.

   */

  public final int getNumFactors()

  {

    return scale.length;

  }

  /* (non-Javadoc)

   * @see java.awt.image.BufferedImageOp#getRenderingHints()

   */

  public final RenderingHints getRenderingHints()

  {

    return hints;

  }

  /**

   * Converts the source image using the scale factors and offsets specified in

   * the constructor.  The resulting image is stored in the destination image if

   * one is provided; otherwise a new BufferedImage is created and returned.

   *

   * The source image cannot use an IndexColorModel, and the destination image

   * (if one is provided) must have the same size.

   *

   * If the final value of a sample is beyond the range of the color model, it

   * will be clipped to the appropriate maximum / minimum.

   *

   * @param src The source image.

   * @param dst The destination image.

   * @throws IllegalArgumentException if the rasters and/or color spaces are

   *            incompatible.

   * @return The rescaled image.

   */

  public final BufferedImage filter(BufferedImage src, BufferedImage dst)

  {

    // Initial checks

    if (scale.length != 1

        && scale.length != src.getColorModel().getNumComponents()

        && (scale.length != src.getColorModel().getNumColorComponents()))

      throw new IllegalArgumentException("Source image has wrong number of "

                                         + "bands for these scaling factors.");

    if (dst == null)

      dst = createCompatibleDestImage(src, null);

    else if (src.getHeight() != dst.getHeight()

             || src.getWidth() != dst.getWidth())

      throw new IllegalArgumentException("Source and destination images are "

                                         + "different sizes.");

    // Prepare for possible colorspace conversion

    BufferedImage dst2 = dst;

    if (dst.getColorModel().getColorSpace().getType() != src.getColorModel().getColorSpace().getType())

      dst2 = createCompatibleDestImage(src, src.getColorModel());

    // Figure out how many bands to scale

    int numBands = scale.length;

    if (scale.length == 1)

      numBands = src.getColorModel().getNumColorComponents();

    boolean[] bands = new boolean[numBands];

    // this assumes the alpha, if present, is the last band

    Arrays.fill(bands, true);

    // Perform rescaling

    filter(src.getRaster(), dst2.getRaster(), bands);

    // Copy alpha band if needed (ie if it exists and wasn't scaled)

    // NOTE: This assumes the alpha component is the last band!

    if (src.getColorModel().hasAlpha()

        && numBands == src.getColorModel().getNumColorComponents())

      {

        dst2.getRaster().setSamples(0, 0, src.getWidth(), src.getHeight(),

                                    numBands,

                                    src.getRaster().getSamples(0, 0,

                                                               src.getWidth(),

                                                               src.getHeight(),

                                                               numBands,

                                                               (int[]) null));

      }

    // Perform colorspace conversion if needed

    if (dst != dst2)

      new ColorConvertOp(hints).filter(dst2, dst);

    return dst;

  }

  /* (non-Javadoc)

   * @see java.awt.image.RasterOp#filter(java.awt.image.Raster, java.awt.image.WritableRaster)

   */

  public final WritableRaster filter(Raster src, WritableRaster dest)

  {

    // Required sanity checks

    if (scale.length != 1 && scale.length != src.numBands)

      throw new IllegalArgumentException("Number of rasters is incompatible "

                                             + "with the number of scaling "

                                             + "factors provided.");

    if (dest == null)

      dest = src.createCompatibleWritableRaster();

    else if (src.getHeight() != dest.getHeight()

             || src.getWidth() != dest.getWidth())

      throw new IllegalArgumentException("Source and destination rasters are "

                                         + "different sizes.");

    else if (src.numBands != dest.numBands)

      throw new IllegalArgumentException("Source and destination rasters "

                                         + "are incompatible.");

    // Filter all bands

    boolean[] bands = new boolean[src.getNumBands()];

    Arrays.fill(bands, true);

    return filter(src, dest, bands);

  }

  /**

   * Perform raster-based filtering on a selected number of bands.

   *

   * The length of the bands array should equal the number of bands; a true

   * element indicates filtering should happen on the corresponding band, while

   * a false element will skip the band.

   *

   * The rasters are assumed to be compatible and non-null.

   *

   * @param src the source raster.

   * @param dest the destination raster.

   * @param bands an array indicating which bands to filter.

   * @throws NullPointerException if any parameter is null.

   * @throws ArrayIndexOutOfBoundsException if the bands array is too small.

   * @return the destination raster.

   */

  private WritableRaster filter(Raster src, WritableRaster dest, boolean[] bands)

  {

    int[] values = new int[src.getHeight() * src.getWidth()];

    float scaleFactor, offset;

    // Find max sample value, to be used for clipping later

    int[] maxValue = src.getSampleModel().getSampleSize();

    for (int i = 0; i < maxValue.length; i++)

      maxValue[i] = (int)Math.pow(2, maxValue[i]) - 1;

    // TODO: can this be optimized further?

    // Filter all samples of all requested bands

    for (int band = 0; band < bands.length; band++)

      if (bands[band])

        {

          values = src.getSamples(src.getMinX(), src.getMinY(), src.getWidth(),

                                  src.getHeight(), band, values);

          if (scale.length == 1)

            {

              scaleFactor = scale[0];

              offset = offsets[0];

            }

          else

            {

              scaleFactor = scale[band];

              offset = offsets[band];

            }

          for (int i = 0; i < values.length; i++)

            {

              values[i] = (int) (values[i] * scaleFactor + offset);

              // Clip if needed

              if (values[i] < 0)

                values[i] = 0;

              if (values[i] > maxValue[band])

                values[i] = maxValue[band];

            }

          dest.setSamples(dest.getMinX(), dest.getMinY(), dest.getWidth(),

                          dest.getHeight(), band, values);

        }

    return dest;

  }

  /*

   * (non-Javadoc)

   *

   * @see java.awt.image.BufferedImageOp#createCompatibleDestImage(java.awt.image.BufferedImage,

   *      java.awt.image.ColorModel)

   */

  public BufferedImage createCompatibleDestImage(BufferedImage src,

                                                 ColorModel dstCM)

  {

    if (dstCM == null)

      return new BufferedImage(src.getWidth(), src.getHeight(), src.getType());

    return new BufferedImage(dstCM,

                             src.getRaster().createCompatibleWritableRaster(),

                             src.isAlphaPremultiplied(), null);

  }

  /* (non-Javadoc)

   * @see java.awt.image.RasterOp#createCompatibleDestRaster(java.awt.image.Raster)

   */

  public WritableRaster createCompatibleDestRaster(Raster src)

  {

    return src.createCompatibleWritableRaster();

  }

  /* (non-Javadoc)

   * @see java.awt.image.BufferedImageOp#getBounds2D(java.awt.image.BufferedImage)

   */

  public final Rectangle2D getBounds2D(BufferedImage src)

  {

    return src.getRaster().getBounds();

  }

  /* (non-Javadoc)

   * @see java.awt.image.RasterOp#getBounds2D(java.awt.image.Raster)

   */

  public final Rectangle2D getBounds2D(Raster src)

  {

    return src.getBounds();

  }

  /* (non-Javadoc)

   * @see java.awt.image.BufferedImageOp#getPoint2D(java.awt.geom.Point2D, java.awt.geom.Point2D)

   */

  public final Point2D getPoint2D(Point2D src, Point2D dst)

  {

    if (dst == null)

      dst = (Point2D) src.clone();

    else

      dst.setLocation(src);

    return dst;

  }

}