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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 都会通过该invalidate()功能重新绘制图块和覆盖项目。无论如何，正如这里所说，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；我重用了官方 MapsForge 示例活动中的一些代码：

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
    }
}
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1 回答 1

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添加叠加项目后尝试添加叠加控制器

事实上，我发现你可以只使用另一个函数。

例子：

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

希望这可以帮助！

于 2013-01-03T06:40:47.503 回答