# Bezier.java :  » Graphic-Library » jgraph » org » jgraph » util » Java Open Source

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 jgraph » org » jgraph » util » Bezier.java ``````/* * Copyright (c) 2005 David Benson * * See LICENSE file in distribution for licensing details of this source file */ package org.jgraph.util; import java.awt.Point; import java.awt.geom.Point2D; /** * Interpolates given points by a bezier curve. The first * and the last two points are interpolated by a quadratic * bezier curve; the other points by a cubic bezier curve. * * Let p a list of given points and b the calculated bezier points, * then one get the whole curve by: * * sharedPath.moveTo(p[0]) * sharedPath.quadTo(b[0].x, b[0].getY(), p[1].x, p[1].getY()); * * for(int i = 2; i < p.length - 1; i++ ) { * Point b0 = b[2*i-3]; * Point b1 = b[2*i-2]; * sharedPath.curveTo(b0.x, b0.getY(), b1.x, b1.getY(), p[i].x, p[i].getY()); * } * * sharedPath.quadTo(b[b.length-1].x, b[b.length-1].getY(), p[n - 1].x, p[n - 1].getY()); * * @author krueger */ public class Bezier { private static final float AP = 0.5f; private Point2D[] bPoints; /** * Creates a new Bezier curve. * @param points */ public Bezier(Point2D[] points) { int n = points.length; if (n < 3) { // Cannot create bezier with less than 3 points return; } bPoints = new Point[2 * (n - 2)]; double paX, paY; double pbX = points[0].getX(); double pbY = points[0].getY(); double pcX = points[1].getX(); double pcY = points[1].getY(); for (int i = 0; i < n - 2; i++) { paX = pbX; paY = pbY; pbX = pcX; pbY = pcY; pcX = points[i + 2].getX(); pcY = points[i + 2].getY(); double abX = pbX - paX; double abY = pbY - paY; double acX = pcX - paX; double acY = pcY - paY; double lac = Math.sqrt(acX * acX + acY * acY); acX = acX /lac; acY = acY /lac; double proj = abX * acX + abY * acY; proj = proj < 0 ? -proj : proj; double apX = proj * acX; double apY = proj * acY; double p1X = pbX - AP * apX; double p1Y = pbY - AP * apY; bPoints[2 * i] = new Point((int) p1X, (int) p1Y); acX = -acX; acY = -acY; double cbX = pbX - pcX; double cbY = pbY - pcY; proj = cbX * acX + cbY * acY; proj = proj < 0 ? -proj : proj; apX = proj * acX; apY = proj * acY; double p2X = pbX - AP * apX; double p2Y = pbY - AP * apY; bPoints[2 * i + 1] = new Point((int) p2X, (int) p2Y); } } /** * Returns the calculated bezier points. * @return the calculated bezier points */ public Point2D[] getPoints() { return bPoints; } /** * Returns the number of bezier points. * @return number of bezier points */ public int getPointCount() { return bPoints.length; } /** * Returns the bezier points at position i. * @param i * @return the bezier point at position i */ public Point2D getPoint(int i) { return bPoints[i]; } } ``````