gcc/libjava/classpath/java/awt/image/BandCombineOp.java

/* Copyright (C) 2004  Free Software Foundation

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
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02110-1301 USA.

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package java.awt.image;

import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

/**
 * Filter Raster pixels by applying a matrix.
 * 
 * BandCombineOp applies a matrix to each pixel to produce new pixel values.
 * The width of the matrix must be the same or one more than the number of
 * bands in the source Raster.  If one more, the pixels in the source are
 * assumed to contain an implicit 1.0 at the end.
 * 
 * The rows of the matrix are multiplied by the pixel to produce the values
 * for the destination.  Therefore the destination Raster must contain the
 * same number of bands as the number of rows in the filter matrix.
 * 
 * @author Jerry Quinn (jlquinn@optonline.net)
 */
public class BandCombineOp implements RasterOp
{
  private RenderingHints hints;
  private float[][] matrix;
  
  /**
   * Construct a BandCombineOp.
   * 
   * @param matrix The matrix to filter pixels with.
   * @param hints Rendering hints to apply.  Ignored.
   */
  public BandCombineOp(float[][] matrix, RenderingHints hints)
  {
    this.matrix = matrix;
    this.hints = hints;
  }

  /**
   * Filter Raster pixels through a matrix.
   * 
   * Applies the Op matrix to source pixes to produce dest pixels.  Each row
   * of the matrix is multiplied by the src pixel components to produce the
   * dest pixel.  If matrix is one more than the number of bands in the src,
   * the last element is implicitly multiplied by 1, i.e. added to the sum
   * for that dest component.
   * 
   * If dest is null, a suitable Raster is created.  This implementation uses
   * createCompatibleDestRaster.  
   * 
   * @param src The source Raster.
   * @param dest  The destination Raster, or null.
   * @returns The destination Raster or an allocated Raster.
   * @see java.awt.image.RasterOp#filter(java.awt.image.Raster,
   *java.awt.image.WritableRaster)
   */
  public WritableRaster filter(Raster src, WritableRaster dest) {
    if (dest == null)
      dest = createCompatibleDestRaster(src);
    
    // Filter the pixels
    float[] spix = new float[matrix[0].length];
    float[] dpix = new float[matrix.length];
    for (int y = src.getMinY(); y < src.getHeight() + src.getMinY(); y++)
      for (int x = src.getMinX(); x < src.getWidth() + src.getMinX(); x++)
      {
        // In case matrix rows have implicit translation
        spix[spix.length - 1] = 1.0f;
        src.getPixel(x, y, spix);
        for (int i = 0; i < matrix.length; i++)
        {
          dpix[i] = 0;
          for (int j = 0; j < matrix[0].length; j++)
            dpix[i] += spix[j] * matrix[i][j];
        }
        dest.setPixel(x, y, dpix);
      }

    return dest;
  }

  /* (non-Javadoc)
   * @see java.awt.image.RasterOp#getBounds2D(java.awt.image.Raster)
   */
  public Rectangle2D getBounds2D(Raster src)
  {
    return src.getBounds();
  }

  /**
   * Creates a new WritableRaster that can be used as the destination for this
   * Op.  This implementation creates a Banded Raster with data type FLOAT.
   * @see
   *java.awt.image.RasterOp#createCompatibleDestRaster(java.awt.image.Raster) 
   */
  public WritableRaster createCompatibleDestRaster(Raster src)
  {
    return Raster.createBandedRaster(DataBuffer.TYPE_FLOAT, src.getWidth(),
        src.getHeight(), matrix.length,
        new Point(src.getMinX(), src.getMinY()));
  }

  /** Return corresponding destination point for source point.
   * 
   * LookupOp 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 Point2D getPoint2D(Point2D src, Point2D dst)
  {
    if (dst == null) return (Point2D)src.clone();
    dst.setLocation(src);
    return dst;
  }

  /* (non-Javadoc)
   * @see java.awt.image.RasterOp#getRenderingHints()
   */
  public RenderingHints getRenderingHints()
  {
    return hints;
  }
  
  /** Return the matrix for this Op. */
  public float[][] getMatrix()
  {
    return matrix;
  }

}