get approximate Area - Java 2D Graphics

Java examples for 2D Graphics:Area

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Description

get approximate Area

Demo Code


//package com.java2s;
import static java.lang.Double.NaN;
import java.awt.geom.*;

public class Main {
    private static final AffineTransform identity = new AffineTransform();

    public static double approxArea(Area area) {
        PathIterator i = area.getPathIterator(identity);
        return approxArea(i);
    }// ww w  .  j  a va2  s .  c  o  m

    public static double approxArea(GeneralPath p) {
        PathIterator i = p.getPathIterator(identity);
        return approxArea(i);
    }

    public static double approxArea(PathIterator i) {
        double a = 0.0;
        double[] coords = new double[6];
        double startX = NaN, startY = NaN;
        Line2D segment = new Line2D.Double(NaN, NaN, NaN, NaN);
        while (!i.isDone()) {
            int segType = i.currentSegment(coords);
            double x = coords[0], y = coords[1];
            switch (segType) {
            case PathIterator.SEG_CLOSE:
                segment.setLine(segment.getX2(), segment.getY2(), startX,
                        startY);
                a += hexArea(segment);
                startX = startY = NaN;
                segment.setLine(NaN, NaN, NaN, NaN);
                break;
            case PathIterator.SEG_LINETO:
                segment.setLine(segment.getX2(), segment.getY2(), x, y);
                a += hexArea(segment);
                break;
            case PathIterator.SEG_MOVETO:
                startX = x;
                startY = y;
                segment.setLine(NaN, NaN, x, y);
                break;
            default:
                throw new IllegalArgumentException(
                        "PathIterator contains curved segments");
            }
            i.next();
        }
        if (Double.isNaN(a)) {
            throw new IllegalArgumentException(
                    "PathIterator contains an open path");
        } else {
            return 0.5 * Math.abs(a);
        }
    }

    private static double hexArea(Line2D seg) {
        return seg.getX1() * seg.getY2() - seg.getX2() * seg.getY1();
    }
}

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