java - 如何在同一个 Activity 中切换 View ？

Question

我在我的应用程序中实现了 map 旋转。我想使用一个按钮从普通 map View (无旋转)切换到旋转效果。问题是在 Oncreate 中，setContentView 可以启动或法线贴图，或带旋转的贴图。如何切换 2 个 View ？

这是 map 旋转文件:

public class MapViewCompassDemo extends MapActivity {


private SensorManager mSensorManager;
protected RotateView mRotateView;
private float mHeading = 0;

class RotateView extends ViewGroup  {
        private Matrix mMatrix = new Matrix();
                private float[] mTemp = new float[2]; 
    private static final float SQ2 = 1.414213562373095f;

    public RotateView(Context context) {
        super(context);

    }


    @SuppressWarnings("deprecation")
    @Override
    protected void dispatchDraw(Canvas canvas) {
        canvas.save(Canvas.MATRIX_SAVE_FLAG);
        canvas.rotate(-mHeading, getWidth() * 0.5f, getHeight() * 0.5f);
        canvas.getMatrix().invert(mMatrix);
       super.dispatchDraw(canvas);
        canvas.restore();
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        final int width = getWidth();
        final int height = getHeight();
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View view = getChildAt(i);
            final int childWidth = view.getMeasuredWidth();
            final int childHeight = view.getMeasuredHeight();
            final int childLeft = (width - childWidth) / 2;
            final int childTop = (height - childHeight) / 2;
            view.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int w = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        int h = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        int sizeSpec;
        if (w > h) {
            sizeSpec = MeasureSpec.makeMeasureSpec((int) (w * SQ2), MeasureSpec.EXACTLY);
        } else {
            sizeSpec = MeasureSpec.makeMeasureSpec((int) (h * SQ2), MeasureSpec.EXACTLY);
        }
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            getChildAt(i).measure(sizeSpec, sizeSpec);
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        final float[] temp = mTemp;
        temp[0] = event.getX();
        temp[1] = event.getY();
        mMatrix.mapPoints(temp);
        event.setLocation(temp[0], temp[1]);
        return super.dispatchTouchEvent(event);
    }

 }

@Override
protected void onResume() {
    super.onResume();
    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

    mSensorManager.registerListener(myOrientationListener, mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), SensorManager.SENSOR_DELAY_UI);

}

@Override
protected void onStop() {
    mSensorManager.unregisterListener(myOrientationListener);
    super.onStop();
}

protected boolean isRouteDisplayed() {
    return false;
}

final SensorEventListener myOrientationListener = new SensorEventListener() {
    public void onSensorChanged(SensorEvent sensorEvent) {
        if (sensorEvent.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
            mHeading = sensorEvent.values[0];
            mRotateView.invalidate();
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }
};

}

这是 Activity 的扩展(我用来为 map 构建命令)。

public class CommandActivity extends MapViewCompassDemo{
protected  MapView mapView;
protected MyLocationOverlay myLocationOverlay;


protected static final File MAP_FLORENCE = new File(Environment.getExternalStorageDirectory().getPath() + “/folder/map/", "florence.map");

private static final Byte MIN_ZOOM_LEVEL = new Byte("12");
private static final Byte MAX_ZOOM_LEVEL = new Byte("22");
private static final Byte START_ZOOM_LEVEL = new Byte("12");

private byte zoomLevelMax;
private byte zoomLevelMin;
private byte startZoomLevel;




public void configureMapViewFlorence() {
    FileOpenResult fileOpenResult = this.mapView.setMapFile(MAP_FLORENCE);
    GeoPoint geoPoint = new GeoPoint(43.7874, 11.2499);
    this.mapView.getMapViewPosition().setCenter(geoPoint);

    if (!fileOpenResult.isSuccess()) {
        Toast.makeText(this, fileOpenResult.getErrorMessage(), Toast.LENGTH_LONG).show();

    }

}



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


        zoomLevelMin = MIN_ZOOM_LEVEL;
    zoomLevelMax = MAX_ZOOM_LEVEL;
    startZoomLevel = START_ZOOM_LEVEL;

        mapView = new MapView(this);

        mapView.setBuiltInZoomControls(false);
        mapView.setEnabled(true);
        mapView.setClickable(true);
        mapView.setFocusable(true);
        MapScaleBar mapScaleBar = mapView.getMapScaleBar();
    mapScaleBar.setShowMapScaleBar(true);

    mRotateView = new RotateView(this);

        mRotateView.addView(mapView);   //   if i use this 2 lines, the activity start with the map rotation
        setContentView(mRotateView);   //


    mapView.addView(mRotateView);   //   if i use this 2 lines, the activity start with normal map ( no rotation)
        setContentView(mapView);





        FrameLayout rootLayout = (FrameLayout)findViewById(android.R.id.content); // this is where i call my xml layout with my buttons
        View.inflate(this, R.layout.map, rootLayout);

    configureMapViewFlorence();



    ImageButton compass = (ImageButton) findViewById(R.id.compass);
            compass.setBackgroundResource(R.drawable.action_click_gps);
            compass.setEnabled(true);




    compass.setOnClickListener(new View.OnClickListener() {   // i would like to use this button to switch from  normal map to rotate map
        public void onClick(View v) {


        }
    });


}

这是你的建议

public class CommandActivity extends MapViewCompassDemo{
protected  MapView mapView;
protected MyLocationOverlay myLocationOverlay;


protected static final File MAP_FLORENCE = new File(Environment.getExternalStorageDirectory().getPath() + “/folder/map/", "florence.map");

private static final Byte MIN_ZOOM_LEVEL = new Byte("12");
private static final Byte MAX_ZOOM_LEVEL = new Byte("22");
private static final Byte START_ZOOM_LEVEL = new Byte("12");

private byte zoomLevelMax;
private byte zoomLevelMin;
private byte startZoomLevel;




public void configureMapViewFlorence() {
    FileOpenResult fileOpenResult = this.mapView.setMapFile(MAP_FLORENCE);
    GeoPoint geoPoint = new GeoPoint(43.7874, 11.2499);
    this.mapView.getMapViewPosition().setCenter(geoPoint);

    if (!fileOpenResult.isSuccess()) {
        Toast.makeText(this, fileOpenResult.getErrorMessage(), Toast.LENGTH_LONG).show();

    }

}



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

        zoomLevelMin = MIN_ZOOM_LEVEL;
    zoomLevelMax = MAX_ZOOM_LEVEL;
    startZoomLevel = START_ZOOM_LEVEL;

        FrameLayout rootLayout = (FrameLayout)findViewById(android.R.id.content); 
        View.inflate(this, R.layout.map, rootLayout);

    configureMapViewFlorence();

    ImageButton compass = (ImageButton) findViewById(R.id.compass);
            compass.setBackgroundResource(R.drawable.action_click_gps);
            compass.setEnabled(true);

    compass.setOnClickListener(new View.OnClickListener() {  
        public void onClick(View v) {
        if (isNnormal)
            RotateMap();                     
        else 
            NnormalMap();


        isNnormal = !isNormal;

        }
    });

    boolean isNormal = true;

    private void RotateMap()
    {
      mRotateView = new RotateView(this);
      mRotateView.addView(mapView);  
      setContentView(mRotateView); 

    }

     private void NnormalMap()
    {
     mapView = new MapView(this);
     mapView.setBuiltInZoomControls(false);
     mapView.setEnabled(true);
     mapView.setClickable(true);
     mapView.setFocusable(true);
     MapScaleBar mapScaleBar = mapView.getMapScaleBar();
     mapScaleBar.setShowMapScaleBar(true);
     mapView.addView(mRotateView);  
     setContentView(mapView);
    }
}

但是它抛出一个 NullPointerException

有了这个，它就可以工作了，但是当我调用旋转 map 时，我的按钮布局消失了

public class CommandActivity extends MapViewCompassDemo{
protected  MapView mapView;
protected MyLocationOverlay myLocationOverlay;
protected static final File MAP_FLORENCE = new     File(Environment.getExternalStorageDirectory().getPath() + “/folder/map/", "florence.map");

private static final Byte MIN_ZOOM_LEVEL = new Byte("12");
private static final Byte MAX_ZOOM_LEVEL = new Byte("22");
private static final Byte START_ZOOM_LEVEL = new Byte("12");

private byte zoomLevelMax;
private byte zoomLevelMin;
private byte startZoomLevel;

 boolean isNormal = true;

private void RotateMap()
{
  mapView = new MapView(this);
  mapView.setBuiltInZoomControls(false);
  mapView.setEnabled(true);
  mapView.setClickable(true);
  mapView.setFocusable(true);
  MapScaleBar mapScaleBar = mapView.getMapScaleBar();
  mapScaleBar.setShowMapScaleBar(true);
  mRotateView = new RotateView(this);
  mRotateView.addView(mapView);  
  setContentView(mRotateView); 

}

 private void NnormalMap()
{
 mapView = new MapView(this);
 mapView.setBuiltInZoomControls(false);
 mapView.setEnabled(true);
 mapView.setClickable(true);
 mapView.setFocusable(true);
 MapScaleBar mapScaleBar = mapView.getMapScaleBar();
 mapScaleBar.setShowMapScaleBar(true);
 mRotateView = new RotateView(this);
 mapView.addView(mRotateView);  
 setContentView(mapView);
}


public void configureMapViewFlorence() {
    FileOpenResult fileOpenResult = this.mapView.setMapFile(MAP_FLORENCE);
    GeoPoint geoPoint = new GeoPoint(43.7874, 11.2499);
    this.mapView.getMapViewPosition().setCenter(geoPoint);

    if (!fileOpenResult.isSuccess()) {
    Toast.makeText(this, fileOpenResult.getErrorMessage(), Toast.LENGTH_LONG).show();

}

}



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

    zoomLevelMin = MIN_ZOOM_LEVEL;
    zoomLevelMax = MAX_ZOOM_LEVEL;
    startZoomLevel = START_ZOOM_LEVEL;

    NnormalMap();


    FrameLayout rootLayout = (FrameLayout)findViewById(android.R.id.content); 
    View.inflate(this, R.layout.map, rootLayout);

    ImageButton compass = (ImageButton) findViewById(R.id.compass);
        compass.setBackgroundResource(R.drawable.action_click_gps);
        compass.setEnabled(true);

compass.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                 if (isNormal)
                        RotateMap();                     
                    else 
                        NnormalMap();



                    isNormal = !isNormal;


            }
        });

configureMapViewFlorence();



}

Answer 1

您需要一个 boolean 值来检查女巫布局是否显示:

boolean isNormal = true;

在 onClick 方法中:

compass.setOnClickListener(new View.OnClickListener() {   // i would like to use this button to switch from  normal map to rotate map
        public void onClick(View v) {

            if (isNormal)
                RotateMap();                     
            else 
                NormalMap();


            isNormal = !isNormal;

        }
    });

法线贴图:

private void NnormalMap()
{
        mapView = new MapView(this);

        mapView.setBuiltInZoomControls(false);
        mapView.setEnabled(true);
        mapView.setClickable(true);
        mapView.setFocusable(true);
        MapScaleBar mapScaleBar = mapView.getMapScaleBar();
        mapScaleBar.setShowMapScaleBar(true);


        mapView.addView(mRotateView);   //   if i use this 2 lines, the activity start with normal map ( no rotation)
        setContentView(mapView);
}

旋转 map :

private void RotateMap()
{
     mRotateView = new RotateView(this);

     mRotateView.addView(mapView);   //   if i use this 2 lines, the activity start with the map rotation
     setContentView(mRotateView); 

}