Bezier.java

package com.marshalchen.common.uimodule.signaturepad.utils;

public class Bezier {

	public TimedPoint startPoint;
    public TimedPoint control1;
    public TimedPoint control2;
    public TimedPoint endPoint;

	public Bezier(TimedPoint startPoint, TimedPoint control1,
			TimedPoint control2, TimedPoint endPoint) {
		this.startPoint = startPoint;
		this.control1 = control1;
		this.control2 = control2;
		this.endPoint = endPoint;
	}

	public float length() {
		int steps = 10, length = 0;
		int i;
		float t;
        double cx, cy, px = 0, py = 0, xdiff, ydiff;

		for (i = 0; i <= steps; i++) {
			t = i / steps;
			cx = point(t, this.startPoint.x, this.control1.x,
					this.control2.x, this.endPoint.x);
			cy = point(t, this.startPoint.y, this.control1.y,
					this.control2.y, this.endPoint.y);
			if (i > 0) {
				xdiff = cx - px;
				ydiff = cy - py;
				length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
			}
			px = cx;
			py = cy;
		}
		return length;

	}

	public double point(float t, float start, float c1, float c2, float end) {
		return start * (1.0 - t) * (1.0 - t)  * (1.0 - t)
	               + 3.0 *  c1    * (1.0 - t) * (1.0 - t)  * t
	               + 3.0 *  c2    * (1.0 - t) * t          * t
	               +        end   * t         * t          * t;
	}

}