/* Copyright (C) 2005-2011 Fabio Riccardi */
package com.lightcrafts.ui.region.curves;
import java.util.ArrayList;
import java.awt.geom.GeneralPath;
import java.awt.geom.Point2D;
import java.awt.*;
/** A CubicBasisSpline whose updateShape() actually generates a closed cubic
* rational B-spline. It uses Polynomial.createRationalShape(), which
* performs flattening.
*/
public class CubicRationalSpline extends CubicBasisSpline {
// private final static double[] Weights = new double[] {
// };
private final static double Weight = 1;
// Update "shape" and "segments" from the current value of "points":
void updateShape() {
if (points.size() < 2) {
shape = null;
segments.clear();
return;
}
// Pad out the control point list using wraparound,
// to make a closed spline:
ArrayList extraPoints = new ArrayList(points);
extraPoints.add(0, points.get(points.size() - 2));
extraPoints.add(1, points.get(points.size() - 1));
extraPoints.add(points.get(0));
extraPoints.add(points.get(1));
// Rotate the padded points so generated segment indices will align
// with indices in the points ArrayList:
Object first = extraPoints.get(0);
extraPoints.remove(0);
extraPoints.add(first);
GeneralPath path = new GeneralPath();
int m = extraPoints.size();
ensureBases(m);
segments.clear();
// Iterate over segments:
for (int i=3; i<m-1; i++) {
Polynomial xNum = new Polynomial(0);
Polynomial yNum = new Polynomial(0);
Polynomial xDen = new Polynomial(0);
Polynomial yDen = new Polynomial(0);
// Iterate over control points:
for (int j=0; j<m; j++) {
Point2D p = (Point2D) extraPoints.get(j);
BasisFunction basis = (BasisFunction) Bases.get(j);
double px = p.getX();
double py = p.getY();
Polynomial xSegNum = basis.getSegment(i).multiply(px * Weight);
Polynomial ySegNum = basis.getSegment(i).multiply(py * Weight);
Polynomial xSegDen = basis.getSegment(i).multiply(Weight);
Polynomial ySegDen = basis.getSegment(i).multiply(Weight);
xNum = xNum.add(xSegNum);
yNum = yNum.add(ySegNum);
xDen = xDen.add(xSegDen);
yDen = yDen.add(ySegDen);
}
Shape curve = Polynomial.createRationalShape(
xNum, xDen, yNum, yDen, i, i + 1, .1
);
segments.add(curve);
path.append(curve, true);
}
path.closePath();
shape = path;
}
}