/*
* $RCSfile: WarpQuadratic.java,v $
*
* Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
*
* Use is subject to license terms.
*
* $Revision: 1.1 $
* $Date: 2005/02/11 04:57:25 $
* $State: Exp $
*/
package com.lightcrafts.mediax.jai;
import java.awt.geom.Point2D;
/**
* A quadratic-based description of an image warp.
*
* <p> The source position (x', y') of a point (x, y) is given by the
* quadratic bivariate polynomials:
*
* <pre>
* x' = p(x, y) = c1 + c2*x + c3*y + c4*x^2 + c5*x*y + c6*y^2
* y' = q(x, y) = c7 + c8*x + c9*y + c10*x^2 + c11*x*y + c12*y^2
* </pre>
*
* <p> <code>WarpQuadratic</code> is marked final so that it may be
* more easily inlined.
*
* @see WarpPolynomial
*
*/
public final class WarpQuadratic extends WarpPolynomial {
private float c1, c2, c3, c4, c5, c6; // coefficients for X
private float c7, c8, c9, c10, c11, c12; // coefficients for Y
/**
* Constructs a <code>WarpQuadratic</code> with a given transform mapping
* destination pixels into source space. Note that this is
* a backward mapping as opposed to the forward mapping used in
* AffineOpImage. The coeffs arrays must each contain 6 floats
* corresponding to the coefficients c1, c2, etc. as shown in the
* class comment.
*
* @param xCoeffs The six destination to source transform coefficients for
* the X coordinate.
* @param yCoeffs The six destination to source transform coefficients for
* the Y coordinate.
* @param preScaleX The scale factor to apply to input (dest) X positions.
* @param preScaleY The scale factor to apply to input (dest) Y positions.
* @param postScaleX The scale factor to apply to the result of the
* X polynomial evaluation
* @param postScaleY The scale factor to apply to the result of the
* Y polynomial evaluation
* @throws IllegalArgumentException if the xCoeff and yCoeff arrays
* do not each have size entries.
*/
public WarpQuadratic(float[] xCoeffs, float[] yCoeffs,
float preScaleX, float preScaleY,
float postScaleX, float postScaleY) {
super(xCoeffs, yCoeffs, preScaleX, preScaleY, postScaleX, postScaleY);
if (xCoeffs.length != 6 || yCoeffs.length != 6) {
throw new IllegalArgumentException(JaiI18N.getString("WarpQuadratic0"));
}
c1 = xCoeffs[0];
c2 = xCoeffs[1];
c3 = xCoeffs[2];
c4 = xCoeffs[3];
c5 = xCoeffs[4];
c6 = xCoeffs[5];
c7 = yCoeffs[0];
c8 = yCoeffs[1];
c9 = yCoeffs[2];
c10 = yCoeffs[3];
c11 = yCoeffs[4];
c12 = yCoeffs[5];
}
/**
* Constructs a <code>WarpQuadratic</code> with pre- and
* post-scale factors of 1.
*
* @param xCoeffs The 6 destination to source transform coefficients for
* the X coordinate.
* @param yCoeffs The 6 destination to source transform coefficients for
* the Y coordinate.
* @throws IllegalArgumentException if the xCoeff and yCoeff arrays
* do not each have size entries.
*/
public WarpQuadratic(float[] xCoeffs, float[] yCoeffs) {
this(xCoeffs, yCoeffs, 1.0F, 1.0F, 1.0F, 1.0F);
}
/**
* Computes the source subpixel positions for a given rectangular
* destination region, subsampled with an integral period. The
* destination region is specified using normal integral (full
* pixel) coordinates. The source positions returned by the
* method are specified in floating point.
*
* @param x The minimum X coordinate of the destination region.
* @param y The minimum Y coordinate of the destination region.
* @param width The width of the destination region.
* @param height The height of the destination region.
* @param periodX The horizontal sampling period.
* @param periodY The vertical sampling period.
*
* @param destRect A <code>float</code> array containing at least
* <code>2*((width+periodX-1)/periodX)*
* ((height+periodY-1)/periodY)</code>
* elements, or <code>null</code>. If <code>null</code>, a
* new array will be constructed.
*
* @return A reference to the <code>destRect</code> parameter if
* it is non-<code>null</code>, or a new
* <code>float</code> array otherwise.
* @throws ArrayBoundsException if destRect is too small
*/
public float[] warpSparseRect(int x, int y,
int width, int height,
int periodX, int periodY,
float[] destRect) {
//XXX: This method should do its calculations in doubles
if (destRect == null) {
destRect = new
float[((width + periodX - 1) / periodX) *
((height + periodY - 1) / periodY) * 2];
}
//
// x' = c1 + c2*x + c3*y + c4*x^2 + c5*x*y + c6*y^2
// y' = c7 + c8*x + c9*y + c10*x^2 + c11*x*y + c12*y^2
//
float px1 = periodX * preScaleX; // powers for periodX
float px2 = px1 * px1;
// Delta delta x for both polys.
float ddx = c4 * 2 * px2;
float ddy = c10 * 2 * px2;
float x1 = (x + 0.5F) * preScaleX; // powers for x
float x2 = x1 * x1;
width += x;
height += y;
int index = 0;
for (int j = y; j < height; j += periodY) {
// Pre-scaled input coordinates and step.
float y1 = (j + 0.5F) * preScaleY; // powers for current y
float y2 = y1 * y1;
// The warped position for the first point of the current line
float wx = c1 + c2 * x1 + c3 * y1 +
c4 * x2 + c5 * x1 * y1 + c6 * y2;
float wy = c7 + c8 * x1 + c9 * y1 +
c10 * x2 + c11 * x1 * y1 + c12 * y2;
// Delta x and delta y
float dx = c2 * px1 + c4 * (2 * x1 * px1 + px2) + c5 * px1 * y1;
float dy = c8 * px1 + c10 * (2 * x1 * px1 + px2) + c11 * px1 * y1;
for (int i = x; i < width; i += periodX) {
destRect[index++] = wx * postScaleX - 0.5F;
destRect[index++] = wy * postScaleY - 0.5F;
wx += dx;
wy += dy;
dx += ddx;
dy += ddy;
}
}
return destRect;
}
/**
* Computes the source point corresponding to the supplied point.
*
* <p>This method returns the value of <code>pt</code> in the following
* code snippet:
*
* <pre>
* double x1 = (destPt.getX() + 0.5F)*preScaleX;
* double x2 = x1*x1;
*
* double y1 = (destPt.getY() + 0.5F)*preScaleY;
* double y2 = y1*y1;
*
* double x = c1 + c2*x1 + c3*y1 + c4*x2 + c5*x1*y1 + c6*y2;
* double y = c7 + c8*x1 + c9*y1 + c10*x2 + c11*x1*y1 + c12*y2;
*
* Point2D pt = (Point2D)destPt.clone();
* pt.setLocation(x*postScaleX - 0.5, y*postScaleY - 0.5);
* </pre>
* </p>
*
* @param destPt the position in destination image coordinates
* to map to source image coordinates.
*
* @return a <code>Point2D</code> of the same class as
* <code>destPt</code>.
*
* @throws IllegalArgumentException if <code>destPt</code> is
* <code>null</code>.
*
* @since JAI 1.1.2
*/
public Point2D mapDestPoint(Point2D destPt) {
if (destPt == null) {
throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
}
double x1 = (destPt.getX() + 0.5F)*preScaleX;
double x2 = x1*x1;
double y1 = (destPt.getY() + 0.5F)*preScaleY;
double y2 = y1*y1;
double x = c1 + c2*x1 + c3*y1 + c4*x2 + c5*x1*y1 + c6*y2;
double y = c7 + c8*x1 + c9*y1 + c10*x2 + c11*x1*y1 + c12*y2;
Point2D pt = (Point2D)destPt.clone();
pt.setLocation(x*postScaleX - 0.5, y*postScaleY - 0.5);
return pt;
}
}