MapsForge 动态添加的叠加项目不会重绘答案

【问题标题】：MapsForge dynamically added overlay items do not redrawMapsForge 动态添加的叠加项目不会重绘
【发布时间】：2012-12-21 15:00:16
【问题描述】：

我想在运行时向 MapsForge 添加一些 Overlay 项目；我可以成功添加它们，但它们只有在我移动或缩放地图后才会出现。实际上应该如此，因为每次移动或缩放时，MapsForge 都会通过invalidate() 函数重新绘制图块和覆盖项目。无论如何，as it is stated here，这是自 MapsForge 0.2.0 版以来已经修复的问题：MapView 类应该能够在添加新项目时自动重绘。

我正在使用 MapsForge 0.3.1。要么我做错了，要么这个问题在当前版本中再次出现。这是我的代码；我重用了the official MapsForge Sample activities的一些代码：

public class MyMapView extends MapView{

    //I brought some variables outside the Sample's function in order to add new items dynamically to the lists
    ListOverlay mListOverlay;
    List<OverlayItem> mOverlayItems;
    Polyline mPolyline;
    Circle mLastPosition;

    //Basically here I do the same actions shown in the MapsForge samples. These items appear at once, with the onCreate() functions of the Activity
    public void addInitialOverlays(){
        Circle circle = createCircle(CENTRAL_STATION);
        Polygon polygon = createPolygon(Arrays.asList(VICTORY_COLUMN, CENTRAL_STATION, BRANDENBURG_GATE));
        mPolyline = createPolyline(Arrays.asList(BRANDENBURG_GATE, VICTORY_COLUMN));
        Marker marker1 = createMarker(R.drawable.marker_red, VICTORY_COLUMN);
        Marker marker2 = createMarker(R.drawable.marker_green, BRANDENBURG_GATE);

        mLastPosition = createCircle(VICTORY_COLUMN);

        mOverlayItems.add(circle);
        mOverlayItems.add(polygon);
        mOverlayItems.add(mPolyline);
        mOverlayItems.add(marker1);
        mOverlayItems.add(marker2);
        mOverlayItems.add(mLastPosition);
        getOverlays().add(mListOverlay);
    }

    //Here is the relevant part. This is called periodically from the main Activity
    public void addPointToRoute(double latitude, double longitude) {

        GeoPoint newPoint = new GeoPoint(latitude, longitude);
        //Tried both removing the list from the overlays and re-adding it, and leaving it where it is; same result
        //getOverlays().remove(mListOverlay);
        mOverlayItems.remove(mPolyline);
        List<GeoPoint> oldPolyline = mPolyline.getPolygonalChain().getGeoPoints();
        oldPolyline.add(newPoint);
        mPolyline = createPolyline(oldPolyline);
        mOverlayItems.add(mPolyline);
        mLastPosition.setGeoPoint(newPoint);
        //getOverlays().add(mListOverlay);

        invalidateOnUiThread();//This MapView function calls either invalidate() or postInvalidate(), depending on the situation
    }
}

【问题讨论】：

标签： android android-mapview openstreetmap

【解决方案1】：

添加叠加项目后尝试添加叠加控制器

事实上我发现你可以使用另一个函数来代替。

示例：

mapView.getOverlays().add(listOverlay);
//redraw once overlay items have been added/removed
mapView.getOverlayController().redrawOverlays(); //method 1
/**OR**/
mapView.redraw(); //method 2

希望这会有所帮助！

【讨论】：