path: root/java/awt/image/ConvolveOp.java

/* 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
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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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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
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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
executable, regardless of the license terms of these independent
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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.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;
  }
}