Android Google Maps PolygonOptions 未根据给定的坐标集绘制

Question

我正在尝试围绕一条路线绘制一个复杂的多边形，按照给定半径的步骤进行。为此，我在路线的每一步(坐标)周围绘制了 50 条边的均匀多边形(实际上是圆形)。现在我获得了路线周围所有绘制圆圈的一组坐标，我可以在 map 上看到它们，但它们是重叠的，这不是很好看，在上面添加如此大量的叠加层不是一个好习惯 map 。

所以我现在需要做的是将我现在拥有的所有多边形合并为一个多边形并将其绘制在 map 上。

我尝试删除每两个多边形的交点(测试 polygon1 的点是否位于 polygon2 内部，反之亦然)并将所有其余坐标合并到一个数组中，然后构建我的新多边形，但它没有用。这是我如何执行此操作的代码 fragment :

public ArrayList<PolygonOptions> polygons = new ArrayList<>();

// lineOptions is the set of route coordinates
    for (int i = 0; i < lineOptions.getPoints().size() - 1; i++) {
        // Draw a circle around each point of the route
        PolygonOptions circle1 = drawCircle(lineOptions.getPoints().get(i), 0.1);
        PolygonOptions circle2 = drawCircle(lineOptions.getPoints().get(i + 1), 0.1);
        // Draw a convex hull between every two successive circles
        PolygonOptions convexHull = convexHull(circle1, circle2);

        convexHull.strokeWidth(0);
        convexHull.fillColor(0x7F729E47);
        activity.range.add(activity.mMap.addPolygon(convexHull));
        polygons.add(convexHull);
    }


if (polygons.size() == 1) {
        pts.addAll(polygons.get(0).getPoints());
    } else {
        for (int i = 0; i < polygons.size() - 1; i++) {
            ArrayList<LatLng> pts1 = new ArrayList<>();
            ArrayList<LatLng> pts2 = new ArrayList<>();
            pts1.addAll(polygons.get(i).getPoints());
            pts2.addAll(polygons.get(i + 1).getPoints());

            for (int j = 0; j < pts1.size(); j++) {
                if (pointInPolygon(pts1.get(j), pts2)) {
                    pts1.remove(j);
                }
            }

            for (int j = 0; j < pts2.size(); j++) {
                if (pointInPolygon(pts2.get(j), pts1)) {
                    pts2.remove(j);
                }
            }

            pts.addAll(pts1);
            pts.addAll(pts2);
        }
    }

// This part didn't work
// PolygonOptions range = new PolygonOptions();
// range.addAll(pts);
// range.strokeWidth(0);
// range.fillColor(0x7F729E47);
// activity.range.add(activity.mMap.addPolygon(range));

Answer 1

按照@antonio 的指示，并使用 JTS Topology Suit，我能够在路线周围绘制一个具有定义半径的多边形(缓冲路线)。当我使用 JTS 库中的缓冲区函数时，我获得了路线的缓冲区，但上限是椭圆形的，我读到了它，发生这种情况是因为计算的坐标投影在不平坦的地球 map 上，上限变得更椭圆当路线靠近地球两极时，当靠近赤道线(0º 纬度)时更圆。无论如何，我使用了库中的另一个功能来联合我的问题中已有的所有多边形，结果如下:

    public ArrayList<Polygon> polys = new ArrayList<>();

    //lineOptions is the set of route coordinates
    for (int i = 0; i < lineOptions.getPoints().size() - 1; i++) {
        // Draw a circle around each point of the route
        PolygonOptions circle1 = drawCircle(lineOptions.getPoints().get(i), 0.1);
        PolygonOptions circle2 = drawCircle(lineOptions.getPoints().get(i + 1), 0.1);


        // Draw a convex hull between every two successive circles
        PolygonOptions convexHull = convexHull(circle1, circle2);



        List<LatLng> latLngs = convexHull.getPoints();
        List<Coordinate> coords = new ArrayList<>();

        for (int j=0; j<latLngs.size(); j++) {
            coords.add(new Coordinate(latLngs.get(j).latitude, latLngs.get(j).longitude));
            if(j==latLngs.size()-1)
                coords.add(new Coordinate(latLngs.get(0).latitude, latLngs.get(0).longitude));
        }

        Coordinate[] coordinates = coords.toArray(new Coordinate[coords.size()]);

        GeometryFactory fact = new GeometryFactory();
        LinearRing linear = new GeometryFactory().createLinearRing(coordinates);
        Polygon poly = new Polygon(linear, null, fact);

        polys.add(poly);

    }


    PolygonOptions combine = combineIntoOnePolygon(polys);
    combine.strokeWidth(0);
    combine.fillColor(0x7F729E47);
    activity.range = activity.mMap.addPolygon(combine);

合并函数:

static PolygonOptions combineIntoOnePolygon(Collection<Polygon> geometries ){
    Geometry all = null;
    PolygonOptions allPolygon = new PolygonOptions();

    for(Iterator<Polygon> i = geometries.iterator(); i.hasNext(); ){
        Polygon geometry = i.next();
        if( geometry == null ) continue;
        if( all == null ){
            all = geometry;
        }
        else {
            all = all.union( geometry );
        }
    }

    List<Coordinate> bufferCoordinates = Arrays.asList(all.getCoordinates());

    for (Coordinate c : bufferCoordinates) {
        allPolygon.add(new LatLng(c.x, c.y));
    }

    return allPolygon;
}