如何使用 path2d 绘制多边形并查看点是否在其区域内? [英] How can I draw a polygon using path2d and see if a point is within it's area?

问题描述

我正在尝试使用带有 path2d 的多个顶点绘制任何类型的多边形形状，我想稍后使用 java.awt.geom.Area 查看确定点是否在其区域内

I,m trying to draw a polygon shape of any kind using multiple vertices with path2d and I want to later on see if a determinate point is within its area using java.awt.geom.Area

public static boolean is insideRegion(Region region, Coordinate coord){
Geopoint lastGeopoint = null;
        GeoPoint firstGeopoint = null;
        final Path2D boundary = new Path2D.Double();
        for(GeoPoint geoponto : region.getGeoPoints()){
            if(firstGeopoint == null) firstGeopoint = geoponto;
            if(lastGeopoint != null){
                boundary.moveTo(lastGeopoint.getLatitude(),lastGeopoint.getLongitude());                
                boundary.lineTo(geoponto.getLatitude(),geoponto.getLongitude());                
            }
            lastGeopoint = geoponto;
        }
        boundary.moveTo(lastGeopoint.getLatitude(),lastGeopoint.getLongitude());                
        boundary.lineTo(firstGeopoint.getLatitude(),firstGeopoint.getLongitude());

        final Area area = new Area(boundary);
        Point2D point = new Point2D.Double(coord.getLatitude(),coord.getLongitude());
        if (area.contains(point)) {
            return true;
        }
return false
}

推荐答案

所以我整理了这个非常快速的测试.

So I put together this really quick test.

public class Poly extends JPanel {

    private Path2D prettyPoly;

    public Poly() {

        prettyPoly = new Path2D.Double();
        boolean isFirst = true;
        for (int points = 0; points < (int)Math.round(Math.random() * 100); points++) {
            double x = Math.random() * 300;
            double y = Math.random() * 300;

            if (isFirst) {
                prettyPoly.moveTo(x, y);
                isFirst = false;
            } else {
                prettyPoly.lineTo(x, y);
            }
        }

        prettyPoly.closePath();

        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                Point p = e.getPoint();
                System.out.println(prettyPoly.contains(p));

                repaint();
            }
        });

    }

    @Override
    protected void paintComponent(Graphics g) {

        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g.create();
        g2d.draw(prettyPoly);
        g2d.dispose();

    }
}

这会在随机位置生成随机数量的点.

This generates a random number of points at random locations.

然后使用鼠标点击来确定鼠标点击是否属于该形状

It then uses the mouse click to determine if the mouse click falls within that shape

更新

(注意，我将 g2d.draw 更改为 g2d.fill 以便更容易查看内容区域)

(Note, I changed the g2d.draw to g2d.fill to make it easier to see the content area)

注意，红色的一切都返回真"，其他一切都返回假"...

Note, everything in red returns "true", everything else returns "false"...

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