Android tap hit tester for lines, quadratic bezier curves, cubic bezier curves

CurveHitTester.java

import android.graphics.PointF;

public class CurveHitTester {

    private static final float FLT_EPSILON = 1.1920928955078125E-7f;
    private static final float PI_2 = (float) Math.PI / 2.0f;

    public static boolean hitTestLine(PointF point, PointF origin, PointF destination, float lineWidth) {
        PointF[] vertices = new PointF[]{ origin, destination };
        return hitTestCurve(point, vertices, 1, lineWidth);
    }

    public static boolean hitTestQuad(PointF point, PointF origin, PointF control1, PointF destination, int segments, float lineWidth) {
        if (segments <= 0) {
            return false;
        }

        PointF[] vertices = new PointF[segments + 1];
        float t = 0;
        for (int i = 0; i < segments; i++) {
            float u = 1 - t;
            float x = u * u * origin.x + 2.0f * u * t * control1.x + t * t * destination.x;
            float y = u * u * origin.y + 2.0f * u * t * control1.y + t * t * destination.y;
            vertices[i] = new PointF(x, y);
            t += 1.0f / segments;
        }
        vertices[segments] = destination

        return hitTestCurve(point, vertices, segments, lineWidth);
    }

    public static boolean hitTestCubic(PointF point, PointF origin, PointF control1, PointF control2, PointF destination, int segments, float lineWidth) {
        if (segments <= 0) {
            return false;
        }

        PointF[] vertices = new PointF[segments + 1];
        float t = 0;
        for (int i = 0; i < segments; i++) {
            float u = 1 - t;
            float x = u * u * u * origin.x + 3.0f * u * u * t * control1.x + 3.0f * u * t * t * control2.x + t * t * t * destination.x;
            float y = u * u * u * origin.y + 3.0f * u * u * t * control1.y + 3.0f * u * t * t * control2.y + t * t * t * destination.y;
            vertices[i] = new PointF(x, y);
            t += 1.0f / segments;
        }
        vertices[segments] = destination;

        return hitTestCurve(point, vertices, segments, lineWidth);
    }

    private static boolean hitTestCurve(PointF point, PointF[] vertices, int segments, float lineWidth) {
        for (int i = 0; i < segments; i++) {
            PointF from = vertices[i];
            PointF to = vertices[i + 1];
            PointF center = new PointF((from.x + to.x) / 2, (from.y + to.y) / 2);
            PointF pa = new PointF(point.x - center.x, point.y - center.y);
            float l = (float) Math.sqrt(pa.x*pa.x + pa.y*pa.y);
            float r = PI_2;
            if (Math.abs(to.x - from.x) > FLT_EPSILON) {
                r = (float) Math.tan((to.y - from.y) / (to.x - from.x));
            }
            float r1 = PI_2;
            if (Math.abs(pa.x) > FLT_EPSILON) {
                r1 = (float) Math.tan(pa.y / pa.x);
            }
            float r2 = r1 - r;
            PointF point_ = new PointF((float) (l * Math.cos(r2)), (float) (l * Math.sin(r2)));
            float w = (float) Math.sqrt(Math.pow(center.x - from.x, 2) + Math.pow(center.y - from.y, 2));
            if (-w < point_.x && w > point_.x) {
                if (-lineWidth / 2 < point_.y && lineWidth / 2 > point_.y) {
                    return true;
                }
            }
        }

        return false;
    }

}