自学HarmonyOS应用开发（51）- 获取瓦片地图数据（续）

//https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
int getTileCol(double long_deg, int zoom){
    int total_cols = (int)Math.pow(2, zoom);
    return (int)((long_deg + 180)/360 * total_cols);
}

int getTileRow(double lat_deg, int zoom){
    double tan = Math.tan(Math.toRadians(lat_deg));
    double asinh = Math.log(tan + Math.sqrt(tan * tan + 1));
    return (int)((1.0 - asinh / Math.PI) * Math.pow(2, zoom - 1));
}

public void loadMapTile(){
    getContext().getGlobalTaskDispatcher(TaskPriority.DEFAULT).asyncDispatch(new Runnable() {
        @Override
        public void run() {
            int tileCol = getTileCol(longtitude, zoom);
            int tileRow = getTileRow(latitude, zoom);
            String urlString = String.format(getMapUrlString(), tileCol, tileRow, zoom);
            PixelMap map = getImagePixmap(urlString);
            tile = new PixelMapHolder(map);
            getContext().getUITaskDispatcher().asyncDispatch(new Runnable() {
                @Override
                public void run() {
                    TileMap.this.invalidate();
                }
            });
        }
    });
}

public final String getMapUrlString(){
    // 高德地图 - 矢量
    final String GAODE_V_MAP_URL = "https://webrd02.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=2&style=8&x=%d&y=%d&z=%d";
    // 高德地图 - 道路
    final String GAODE_R_MAP_URL = "https://webst02.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=2&style=8&x=%d&y=%d&z=%d";
    // 高德地图 - 卫星
    final String GAODE_S_MAP_URL = "https://webst01.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=2&style=6&x=%d&y=%d&z=%d";
    switch(mapSource){
        case GAODE_VECTOR:
            return GAODE_V_MAP_URL;
        case GAODE_ROAD:
            return GAODE_R_MAP_URL;
        case GAODE_SATELLITE:
            return GAODE_S_MAP_URL;
        default:
            return null;
    }
}

public static PixelMap getImagePixmap(String urlString) {
    try {
        URL url = new URL(urlString);
        URLConnection con = url.openConnection();
        con.setConnectTimeout(500*1000);
        InputStream is = con.getInputStream();
        ImageSource source = ImageSource.create(is, new ImageSource.SourceOptions());
        ImageSource.DecodingOptions options = new ImageSource.DecodingOptions();
        options.desiredSize = new Size(513,513);
        PixelMap pixelMap = source.createPixelmap(options);
        is.close();
        return pixelMap;
    } catch (Exception e) {
        return null;
    }
}