clip Polygon - Java 2D Graphics

Java examples for 2D Graphics:Polygon

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Description

clip Polygon

Demo Code


import java.util.ArrayList;
import java.util.List;

public class Main{
    public static List<Point> clipPolygon(List<Point> points, Bounds bounds) {
        List<Point> clippedPoints;

        int[] edges = { 1, 4, 2, 8 };
        /*/*w w  w  . j a  va 2  s  .c om*/
        i, j, k,
                a, b,
                len, edge, p,
                lu = L.LineUtil;   */

        final int len = points.size();

        for (Point point : points) {
            point.setCode(LineUtil.getBitCode(point, bounds));
        }

        // for each edge (left, bottom, right, top)
        for (int k = 0; k < 4; k++) {
            int edge = edges[k];
            clippedPoints = new ArrayList<Point>();

            int j = len - 1;

            int pointsLen = points.size();

            for (int i = 0; i < pointsLen; j = i++) {

                Point a = points.get(i);
                Point b = points.get(j);
                int acode = a.getCode();
                int bcode = b.getCode();

                // if a is inside the clip window
                if ((acode & edge) == 0) {
                    // if b is outside the clip window (a->b goes out of screen)
                    if ((bcode & edge) != 0) {
                        Point p = getEdgeIntersection(b, a, edge, bounds);
                        p.setCode(LineUtil.getBitCode(p, bounds));
                        clippedPoints.add(p);
                    }
                    clippedPoints.add(a);

                    // else if b is inside the clip window (a->b enters the screen)
                } else if ((bcode & edge) == 0) {
                    Point p = getEdgeIntersection(b, a, edge, bounds);
                    p.setCode(LineUtil.getBitCode(p, bounds));
                    clippedPoints.add(p);
                }
            }
            points = clippedPoints;
        }

        return points;
    }
}

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