java - 防止用户超出 map 边界

Question

我试图阻止用户移出谷歌地图中的某个区域。然而，似乎没有一种简单的方法可以做到这一点。第一次在这里问，请手下留情。

我尝试了以下方法，试图在用户滚动时进行轮询，但问题是 OnCameraChange 触发的频率不够高，因此它工作时不稳定且不准确。我知道一定有某种方法可以做到这一点，因为它看起来是一个简单而重要的功能。

private static final LatLng NEBOUND = new LatLng(47.670606, -117.393344);
private static final LatLng SWBOUND = new LatLng(47.661283, -117.411052);
private static final LatLngBounds MAPBOUNDARY = new LatLngBounds(SWBOUND, NEBOUND);
private LatLng lastCenter = new LatLng(47.667454, -117.402309);

  private final OnCameraChangeListener mOnCameraChangeListener = 
            new OnCameraChangeListener() {
        @Override
        public void onCameraChange(CameraPosition cameraPosition) {
            LatLngBounds visibleBounds = guMap.getProjection().getVisibleRegion().latLngBounds;
            if(!MAPBOUNDARY.contains(visibleBounds.northeast) || !MAPBOUNDARY.contains(visibleBounds.southwest)){
                guMap.moveCamera(CameraUpdateFactory.newLatLng(lastCenter));
            }
            else
                lastCenter = guMap.getCameraPosition().target;
            centerLoc.setText(lastCenter.toString());
        }
    };

Answer 1

感谢 MaciejGórski 的帮助，我实现了该解决方案 即使 5 毫秒的轮询也相当不稳定，但它有效 请注意，根据边界的形状和用户屏幕的形状，他们可能无法缩小到足够远以查看整个区域。

private static final LatLng NEBOUND = new LatLng(47.671781, -117.393352);
private static final LatLng SWBOUND = new LatLng(47.661283, -117.411052);
private static final LatLngBounds MAPBOUNDARY = new LatLngBounds(SWBOUND, NEBOUND);
private LatLng lastCenter = new LatLng(47.667454, -117.402309);
GoogleMap guMap;
private Handler mHandler;

private void checkBoundaries(){
    LatLng tempCenter = guMap.getCameraPosition().target;
    LatLngBounds visibleBounds = guMap.getProjection().getVisibleRegion().latLngBounds;
    if(!MAPBOUNDARY.contains(visibleBounds.northeast) || !MAPBOUNDARY.contains(visibleBounds.southwest)){
        guMap.moveCamera(CameraUpdateFactory.newLatLng(lastCenter));
    }
    else
        lastCenter = tempCenter;
}

private void setUpHandler(){
    mHandler = new Handler(){
            public void handleMessage(Message msg){
                checkBoundaries();
                sendEmptyMessageDelayed(0, 5);
            }
        };
}