OSMdroid mapview 的两指旋转答案

【问题标题】：Two finger rotation for OSMdroid mapviewOSMdroid mapview 的两指旋转
【发布时间】：2014-01-20 03:59:49
【问题描述】：

我正在尝试使用 osmdroid 为我的离线地图进行两个手指旋转。我是使用安卓地图的新手。我有一个 geoTIFF，我打算使用 NDK 提取信息，然后将其发送到 JAVA。我还需要使用 geoPoint 使用指南针与 True North Up 对齐。我该如何继续，有什么帮助吗？

我确实试过这个： Android Two finger rotation 例如，但运气不好，我的应用无法检测到任何两指事件。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    mResourceProxy = new DefaultResourceProxyImpl(getApplicationContext());
    setContentView(R.layout.activity_main);
    mapView = (MapView)findViewById(R.id.mapview);

    //Mapview touch utilities
    mapView.setClickable(true);
    mapView.setBuiltInZoomControls(true);
    mapView.setMultiTouchControls(true);

    //set initial zoom-level, depends on your need
    mapView.getController().setZoom(nMyZoom); 

    //Display Position Overlay
    /* Itemized Overlay */
    {
            /* Create a static ItemizedOverlay showing a some Markers on some cities. */
            final ArrayList<OverlayItem> items = new ArrayList<OverlayItem>();
            items.add(new OverlayItem("Fruchthalle", "Kaiserslautern", new GeoPoint(nMyLat, nMyLong)));

            /* OnTapListener for the Markers, shows a simple Toast. */
            this.mMyLocationOverlay = new ItemizedIconOverlay<OverlayItem>(items,
                            new ItemizedIconOverlay.OnItemGestureListener<OverlayItem>() {
                                    @Override
                                    public boolean onItemSingleTapUp(final int index, final OverlayItem item) {
                                            Toast.makeText(
                                                            MainActivity.this,
                                                            "Place '" + item.getTitle()+ "' (index=" + index
                                                                            + ") got single tapped up", Toast.LENGTH_LONG).show();
                                            return true; // We 'handled' this event.
                                    }

                                    @Override
                                    public boolean onItemLongPress(final int index, final OverlayItem item) {
                                            Toast.makeText(
                                                            MainActivity.this,
                                                            "Place '" + item.getTitle() + "' (index=" + index
                                                                            + ") got long pressed", Toast.LENGTH_LONG).show();
                                            return false;
                                    }
                            }, mResourceProxy);
            this.mapView.getOverlays().add(this.mMyLocationOverlay);
    }

【问题讨论】：

标签： android android-ndk android-mapview osmdroid

【解决方案1】：

您看过OpenStreetMapViewer 示例应用程序吗？那里有RotationGestureOverlay 覆盖，专门显示了如何执行此操作。它不像我想要的那样流畅，但它会完成这项工作。

【讨论】：

【解决方案2】：

为简单起见，请使用以下类：

public class RotationGestureDetector {

public interface RotationListener {
    public void onRotate(float deltaAngle);
}

protected float mRotation;
private RotationListener mListener;

public RotationGestureDetector(RotationListener listener) {
    mListener = listener;
}

private float rotation(MotionEvent event) {
    double delta_x = (event.getX(0) - event.getX(1));
    double delta_y = (event.getY(0) - event.getY(1));
    double radians = Math.atan2(delta_y, delta_x);
    return (float) Math.toDegrees(radians);
}

public void onTouch(MotionEvent e) {
    if (e.getPointerCount() != 2)
        return;

    if (e.getActionMasked() == MotionEvent.ACTION_POINTER_DOWN) {
        mRotation = rotation(e);
    }

    float rotation = rotation(e);
    float delta = rotation - mRotation;
    mRotation += delta;
    mListener.onRotate(delta);
}

}

和

public class RotationGestureOverlay extends Overlay implements RotationGestureDetector.RotationListener
{

private final RotationGestureDetector mRotationDetector;
private RotationGestureDetector.RotationListener rotationListener;


public RotationGestureOverlay(Context context, RotationGestureDetector.RotationListener rotationListener)
{
    super(context);
    this.rotationListener = rotationListener;
    mRotationDetector = new RotationGestureDetector(this);
}

@Override
public boolean onTouchEvent(MotionEvent event, MapView mapView)
{
    if (this.isEnabled()) {
        mRotationDetector.onTouch(event);
    }
    return super.onTouchEvent(event, mapView);
}

@Override
public void onRotate(float deltaAngle)
{
    rotationListener.onRotate(deltaAngle);
}

@Override
public void draw(Canvas canvas, MapView mapView, boolean b) {

}

}

添加叠加层：

mapView.getOverlays().add(new RotationGestureOverlay(context,this);

【讨论】：