/* ConvolveOp.java --
   Copyright (C) 2004, 2005, 2006, Free Software Foundation -- ConvolveOp

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
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
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.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

/**
 * Convolution filter.
 * 
 * ConvolveOp convolves the source image with a Kernel to generate a
 * destination image.  This involves multiplying each pixel and its neighbors
 * with elements in the kernel to compute a new pixel.
 * 
 * Each band in a Raster is convolved and copied to the destination Raster.
 * 
 * For BufferedImages, convolution is applied to all components.  If the
 * source is not premultiplied, the data will be premultiplied before
 * convolving.  Premultiplication will be undone if the destination is not
 * premultiplied.  Color conversion will be applied if needed.
 * 
 * @author jlquinn@optonline.net
 */
public class ConvolveOp implements BufferedImageOp, RasterOp
{
  /** Edge pixels are set to 0. */
  public static final int EDGE_ZERO_FILL = 0;
  
  /** Edge pixels are copied from the source. */
  public static final int EDGE_NO_OP = 1;
  
  private Kernel kernel;
  private int edge;
  private RenderingHints hints;

  /**
   * Construct a ConvolveOp.
   * 
   * The edge condition specifies that pixels outside the area that can be
   * filtered are either set to 0 or copied from the source image.
   * 
   * @param kernel The kernel to convolve with.
   * @param edgeCondition Either EDGE_ZERO_FILL or EDGE_NO_OP.
   * @param hints Rendering hints for color conversion, or null.
   */
  public ConvolveOp(Kernel kernel,
      				int edgeCondition,
      				RenderingHints hints)
  {
    this.kernel = kernel;
    edge = edgeCondition;
    this.hints = hints;
  }
  
  /**
   * Construct a ConvolveOp.
   * 
   * The edge condition defaults to EDGE_ZERO_FILL.
   * 
   * @param kernel The kernel to convolve with.
   */
  public ConvolveOp(Kernel kernel)
  {
    this.kernel = kernel;
    edge = EDGE_ZERO_FILL;
    hints = null;
  }

  
  /* (non-Javadoc)
   * @see java.awt.image.BufferedImageOp#filter(java.awt.image.BufferedImage,
   * java.awt.image.BufferedImage)
   */
  public final BufferedImage filter(BufferedImage src, BufferedImage dst)
  {
    if (src == dst)
      throw new IllegalArgumentException();
    
    if (dst == null)
      dst = createCompatibleDestImage(src, src.getColorModel());
    
    // Make sure source image is premultiplied
    BufferedImage src1 = src;
    if (!src.isPremultiplied)
    {
      src1 = createCompatibleDestImage(src, src.getColorModel());
      src.copyData(src1.getRaster());
      src1.coerceData(true);
    }

    BufferedImage dst1 = dst;
    if (!src.getColorModel().equals(dst.getColorModel()))
      dst1 = createCompatibleDestImage(src, src.getColorModel());

    filter(src1.getRaster(), dst1.getRaster());
    
    if (dst1 != dst)
    {
      // Convert between color models.
      // TODO Check that premultiplied alpha is handled correctly here.
      Graphics2D gg = dst.createGraphics();
      gg.setRenderingHints(hints);
      gg.drawImage(dst1, 0, 0, null);
      gg.dispose();
    }
    
    return dst;
  }

  /* (non-Javadoc)
   * @see
   * java.awt.image.BufferedImageOp#createCompatibleDestImage(java.awt.image.BufferedImage,
   * java.awt.image.ColorModel)
   */
  public BufferedImage createCompatibleDestImage(BufferedImage src,
						 ColorModel dstCM)
  {
    // FIXME: set properties to those in src
    return new BufferedImage(dstCM,
			     src.getRaster().createCompatibleWritableRaster(),
			     src.isPremultiplied, null);
  }

  /* (non-Javadoc)
   * @see java.awt.image.RasterOp#getRenderingHints()
   */
  public final RenderingHints getRenderingHints()
  {
    return hints;
  }
  
  /**
   * @return The edge condition.
   */
  public int getEdgeCondition()
  {
    return edge;
  }
  
  /**
   * Returns (a clone of) the convolution kernel.
   *
   * @return The convolution kernel.
   */
  public final Kernel getKernel()
  {
    return (Kernel) kernel.clone();
  }

  /* (non-Javadoc)
   * @see java.awt.image.RasterOp#filter(java.awt.image.Raster,
   * java.awt.image.WritableRaster)
   */
  public final WritableRaster filter(Raster src, WritableRaster dest)
  {
    if (src == dest)
      throw new IllegalArgumentException("src == dest is not allowed.");
    if (kernel.getWidth() > src.getWidth() 
        || kernel.getHeight() > src.getHeight())
      throw new ImagingOpException("The kernel is too large.");
    if (dest == null)
      dest = createCompatibleDestRaster(src);
    else if (src.getNumBands() != dest.getNumBands())
      throw new ImagingOpException("src and dest have different band counts.");

    // calculate the borders that the op can't reach...
    int kWidth = kernel.getWidth();
    int kHeight = kernel.getHeight();
    int left = kernel.getXOrigin();
    int right = Math.max(kWidth - left - 1, 0);
    int top = kernel.getYOrigin();
    int bottom = Math.max(kHeight - top - 1, 0);
    
    // process the region that is reachable...
    int regionW = src.width - left - right;
    int regionH = src.height - top - bottom;
    float[] kvals = kernel.getKernelData(null);
    float[] tmp = new float[kWidth * kHeight];

    for (int x = 0; x < regionW; x++)
      {
        for (int y = 0; y < regionH; y++)
          {
            // FIXME: This needs a much more efficient implementation
            for (int b = 0; b < src.getNumBands(); b++)
            {
              float v = 0;
              src.getSamples(x, y, kWidth, kHeight, b, tmp);
              for (int i = 0; i < tmp.length; i++)
                v += tmp[tmp.length - i - 1] * kvals[i];
                // FIXME: in the above line, I've had to reverse the order of 
                // the samples array to make the tests pass.  I haven't worked 
                // out why this is necessary. 
              dest.setSample(x + kernel.getXOrigin(), y + kernel.getYOrigin(), 
                             b, v);
            }
          }
      }
    
    // fill in the top border
    fillEdge(src, dest, 0, 0, src.width, top, edge);
    
    // fill in the bottom border
    fillEdge(src, dest, 0, src.height - bottom, src.width, bottom, edge);
    
    // fill in the left border
    fillEdge(src, dest, 0, top, left, regionH, edge);
    
    // fill in the right border
    fillEdge(src, dest, src.width - right, top, right, regionH, edge);
    
    return dest;  
  }
  
  /**
   * Fills a range of pixels (typically at the edge of a raster) with either
   * zero values (if <code>edgeOp</code> is <code>EDGE_ZERO_FILL</code>) or the 
   * corresponding pixel values from the source raster (if <code>edgeOp</code>
   * is <code>EDGE_NO_OP</code>).  This utility method is called by the 
   * {@link #fillEdge(Raster, WritableRaster, int, int, int, int, int)} method.
   * 
   * @param src  the source raster.
   * @param dest  the destination raster.
   * @param x  the x-coordinate of the top left pixel in the range.
   * @param y  the y-coordinate of the top left pixel in the range.
   * @param w  the width of the pixel range.
   * @param h  the height of the pixel range.
   * @param edgeOp  indicates how to determine the values for the range
   *     (either {@link #EDGE_ZERO_FILL} or {@link #EDGE_NO_OP}).
   */
  private void fillEdge(Raster src, WritableRaster dest, int x, int y, int w, 
                        int h, int edgeOp) 
  {
    if (w <= 0)
      return;
    if (h <= 0)
      return;
    if (edgeOp == EDGE_ZERO_FILL)  // fill region with zeroes
      {
        float[] zeros = new float[src.getNumBands() * w * h];
        dest.setPixels(x, y, w, h, zeros); 
      }
    else  // copy pixels from source
      {
        float[] pixels = new float[src.getNumBands() * w * h];
        src.getPixels(x, y, w, h, pixels);
        dest.setPixels(x, y, w, h, pixels);
      }
  }

  /* (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();
  }

  /** Return corresponding destination point for source point.
   * 
   * ConvolveOp will return the value of src unchanged.
   * @param src The source point.
   * @param dst The destination point.
   * @see java.awt.image.RasterOp#getPoint2D(java.awt.geom.Point2D,
   * java.awt.geom.Point2D)
   */
  public final Point2D getPoint2D(Point2D src, Point2D dst)
  {
    if (dst == null) return (Point2D)src.clone();
    dst.setLocation(src);
    return dst;
  }
}