我在我的应用程序中使用 osmdroid 3.0.5 jar 来显示地图视图。我正在叠加一个覆盖层，由水平线和垂直线组成。我注意到仅在某些位置，在高缩放级别下，某些线条会消失，然后在拖动地图时重新出现。
我制作了一个最小的示例应用程序，它演示了在真实设备和模拟器（Gingerbread 2.3.3）上都出现的问题。
完整的代码如下所示 - （'transform' 方法在真实应用程序中是必需的，尽管它们似乎不在这个最小示例中）：
public class DemoMap extends Activity implements MapViewConstants {
private MapView mapView;
private MapController mapController;
private MapOverlay mmapOverlay = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.copymain);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setTileSource(TileSourceFactory.MAPNIK);
mapView.setBuiltInZoomControls(true);
mapView.setMultiTouchControls(true);
mapController = mapView.getController();
mapController.setZoom(17);
// Only shows the bug at ceratin lat/lon positions, this is one
GeoPoint point2 = new GeoPoint(39191699, -120102561);
mapController.setCenter(point2);
mmapOverlay = new MapOverlay(this);
List<Overlay> listOfOverlays = mapView.getOverlays();
listOfOverlays.add(mmapOverlay);
mapView.invalidate();
}
public class MapOverlay extends org.osmdroid.views.overlay.Overlay {
public MapOverlay(Context ctx) {super(ctx); }
private int mVpl;// viewport left, top, right, bottom
private int mVpt;
private int mVpr;
private int mVpb;
private MapView mMv = null;
// Two routines to transform and scale between viewport and mapview
private float transformX(float in, MapView mv) {
float out;
out = ((mVpr - mVpl) * in) / (mv.getRight() - mv.getLeft())
+ mVpl;
return out;
}
private float transformY(float in, MapView mv) {
float out;
out = ((mVpb - mVpt) * in) / (mv.getBottom() - mv.getTop())
+ mVpt;
return out;
}
@Override
protected void draw(Canvas pC, MapView mapV, boolean shadow) {
if (shadow)
return;
Paint paint;
paint = new Paint();
paint.setColor(Color.RED);
paint.setAntiAlias(true);
paint.setStyle(Style.STROKE);
paint.setStrokeWidth(1);
paint.setTextAlign(Paint.Align.LEFT);
paint.setTextSize(12);
final Rect viewportRect = new Rect();
final Projection projection = mapV.getProjection();
viewportRect.set(projection.getScreenRect());
mVpl = viewportRect.left;
mVpt = viewportRect.top;
mVpr = viewportRect.right;
mVpb = viewportRect.bottom;
// draw two lines to split screen into 2x2 quarters
// drag the map left and right and the vertical line disappears,
// then reappears! It's OK at one less zoom level
pC.drawLine(transformX(mapV.getWidth()/2, mapV), transformY(0, mapV),
transformX(mapV.getWidth()/2, mapV),
transformY(mapV.getHeight(), mapV), paint);
pC.drawLine(transformX(0, mapV), transformY(mapV.getHeight()/2, mapV),
transformX(mapV.getWidth(), mapV),
transformY(mapV.getHeight()/2, mapV), paint);
}
}
}
有趣的是，如果在我的真实应用程序中，如果我对屏幕外位图进行绘图，然后在 Overlay 绘制结束时一次性绘制，线条不会消失就可以了。
任何帮助都感激不尽。