Question

我目前正在使用Android Google地图实用程序库。我通过API调用接收给定区域的geojson，并且需要在地图上显示该区域。

我是通过致电

来这样做的

GeoJsonLayer layer = new GeoJsonLayer(getMap(), geoJsonData);
layer.addLayerToMap()

其中getMap（）返回一个GoogleMap对象，geoJsonData是一个JSONObject。此代码在与geojson关联的区域周围绘制边框。

下面的代码在区域周围绘制一个红色边框，并用黄色填充。

GeoJsonLayer layer = new GeoJsonLayer(getMap(), geoJsonData);            
GeoJsonPolygonStyle polygonStyle = layer.getDefaultPolygonStyle();
polygonStyle.setStrokeColor(ContextCompat.getColor(this, R.color.red));
polygonStyle.setFillColor(ContextCompat.getColor(this, R.color.yellow));
layer.addLayerToMap();

我在尝试设置此GeoJsonLayer的样式时遇到了麻烦，整个地图为黄色，区域边框为红色，区域的填充颜色为正常颜色。

有人能告诉我如何使用GeoJson数据在Android中实现这一目标吗？一种选择是创建我自己的多边形形状。我可以使用覆盖整个地图的坐标声明一个多边形，然后使用geojson返回的坐标添加一个洞。

但我认为必须有一些更简单的东西允许我使用内置的GeoJsonLayer类，并且不需要我自己解析geojson。

Answer 1

您可以使用与您描述的方法相同的方法：

“使用覆盖整个地图的坐标来声明多边形，然后我使用geojson“
返回的坐标添加一个洞

GeoJSON也支持Polygon with "holes"所以，对于GeoJSON，“整个地图”坐标如

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -179.99,
              89.99
            ],
            [
              -179.99,
              0
            ],
            [
              -179.99,
              -89.99
            ],
            [
              0,
              -89.99
            ],
            [
              179.99,
              -89.99
            ],
            [
              179.99,
              0
            ],
            [
              179.99,
              89.99
            ],
            [
              0,
              89.99
            ],
            [
              -179.99,
              89.99
            ]
          ],
          [
            [
              -0.191208,
              51.509869
            ],
            [
              -0.158464,
              51.513287
            ],
            [
              -0.151769,
              51.50554
            ],
            [
              -0.174471,
              51.502178
            ],
            [
              -0.187989,
              51.502444
            ],
            [
              -0.191208,
              51.509869
            ]
          ]
        ],
        "properties": {
          "Territoire": 2
        }
      },
      "properties": {
        "name": "Hyde Park"
      }
    }
  ]
}

你自动得到这样的东西：

如果您无法访问GeoJSON生成的后端，并且只接收目标区域的多边形，则可以添加“整个地图”部分

按照以下代码进入coordinates多边形数组的位置0（目标区域的坐标之前）：

JSONObject featureCollection = geoJsonData;
JSONArray features = featureCollection.getJSONArray("features");
for(int i = 0; i < features.length(); i++) {
    JSONObject feature = features.getJSONObject(i);
    JSONObject geometry = feature.getJSONObject("geometry");
    String geometryType = geometry.getString("type");
    if ("Polygon".equals(geometryType)) {
        JSONArray coordinates = geometry.getJSONArray("coordinates");
        if (coordinates.length() == 1) {
            coordinates.put(coordinates.get(0));
            JSONArray wholeMap = new JSONArray(
                    "[\n" +
                            "            [\n" +
                            "              -179.99,\n" +
                            "              89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              -179.99,\n" +
                            "              0\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              -179.99,\n" +
                            "              -89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              0,\n" +
                            "              -89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              179.99,\n" +
                            "              -89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              179.99,\n" +
                            "              0\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              179.99,\n" +
                            "              89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              0,\n" +
                            "              89.99\n" +
                            "            ],\n" +
                            "            [\n" +
                            "              -179.99,\n" +
                            "              89.99\n" +
                            "            ]\n" +
                            "          ]"
            );
            coordinates.put(0, wholeMap);
        } else {
            Log.d("OAA", "No need insert");
        }
    }
}

其中geoJsonData - 您的GeoJSON数据没有“整个地图”部分，例如：

JSONObject geoJsonData = new JSONObject(
    "{\n" +
            "  \"type\": \"FeatureCollection\",\n" +
            "  \"features\": [\n" +
            "    {\n" +
            "      \"type\": \"Feature\",\n" +
            "      \"geometry\": {\n" +
            "        \"type\": \"Polygon\",\n" +
            "        \"coordinates\": [\n" +
            "          [\n" +
            "            [\n" +
            "              -0.191208,\n" +
            "              51.509869\n" +
            "            ],\n" +
            "            [\n" +
            "              -0.158464,\n" +
            "              51.513287\n" +
            "            ],\n" +
            "            [\n" +
            "              -0.151769,\n" +
            "              51.50554\n" +
            "            ],\n" +
            "            [\n" +
            "              -0.174471,\n" +
            "              51.502178\n" +
            "            ],\n" +
            "            [\n" +
            "              -0.187989,\n" +
            "              51.502444\n" +
            "            ]\n" +
            "          ]\n" +
            "        ],\n" +
            "        \"properties\": {\n" +
            "          \"Territoire\": 2\n" +
            "        }\n" +
            "      },\n" +
            "      \"properties\": {\n" +
            "        \"name\": \"Hyde Park\"\n" +
            "      }\n" +
            "    }\n" +
            "  ]\n" +
            "}"
    );

<强>更新 GeoJSON还支持具有多个“孔”的多边形，GeoJSON显示了Hyde＆amp;的两个“孔”。摄政公园：

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -179.99,
              89.99
            ],
            [
              -179.99,
              0
            ],
            [
              -179.99,
              -89.99
            ],
            [
              0,
              -89.99
            ],
            [
              179.99,
              -89.99
            ],
            [
              179.99,
              0
            ],
            [
              179.99,
              89.99
            ],
            [
              0,
              89.99
            ],
            [
              -179.99,
              89.99
            ]
          ],
          [
            [
              -0.191208,
              51.509869
            ],
            [
              -0.158464,
              51.513287
            ],
            [
              -0.151769,
              51.50554
            ],
            [
              -0.174471,
              51.502178
            ],
            [
              -0.187989,
              51.502444
            ],
            [
              -0.191208,
              51.509869
            ]
          ],
          [
            [
              -0.167685,
              51.530226
            ],
            [
              -0.163737,
              51.534924
            ],
            [
              -0.151849,
              51.537566
            ],
            [
              -0.151849,
              51.537566
            ],
            [
              -0.146914,
              51.535964
            ],
            [
              -0.145625,
              51.525325
            ],
            [
              -0.155538,
              51.523589
            ],
            [
              -0.167685,
              51.530226
            ]
          ]
        ],
        "properties": {
          "Territoire": 2
        }
      },
      "properties": {
        "name": "Hyde Park"
      }
    }
  ]
}

Android谷歌地图GeoJson，如何为整个地图着色一种颜色

1 个答案: