我正在编写一个 Android 应用程序，其中一个功能是 map 将根据指南针旋转(即，如果手机指向东方，则 map 将被定向，以便 map 的东侧位于顶部) .我发现以前的答案建议在 mapView 中编写 onDraw() 方法，但是，api 将方法更改为 final，因此它不能被覆盖。结果，我尝试像这样覆盖 dispatchDraw() 方法:

注意:

-compass 是一个 bool 值，如果为真，则旋转 View

-bearing 是一个浮点变量，具有 View 应旋转的度数

protected void dispatchDraw(Canvas canvas) {
    canvas.save();
         if (compass) {
             final float w = this.getWidth();
             final float h = this.getHeight();

             final float scaleFactor = (float)(Math.sqrt(h * h + w * w) / Math.min(w, h));

             final float centerX = w / 2.0f;
             final float centerY = h / 2.0f;

             canvas.rotate(bearing, centerX, centerY);
             canvas.scale(scaleFactor, scaleFactor, centerX, centerY);

         }
         super.dispatchDraw(canvas);
         canvas.restore();
}

最佳答案

感谢 pheelick 和 Nikita Koksharov 的回答，我设法根据指南针打开/关闭 map View 的旋转。

首先，您需要 MapViewCompassDemo.java 的 两个内部 类，该类位于:Android_SDK_ Tools\add-ons\addon-google_apis-google-#\samples\MapsDemo\src\com\example\android\apis\view\

RotateView
SmoothCanvas

提取内部类RotateView到RotateView.java并添加 SmoothCanvas作为RotateView.java的内部类而不是MapViewCompassDemo.java

public class RotateView extends ViewGroup implements SensorListener {
...
   static final class SmoothCanvas extends Canvas {
...
   }//end SmoothCanvas 
}//end RotateView 

maplayout.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map_layout_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<LinearLayout
    android:id="@+id/rotating_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.google.android.maps.MapView
        android:id="@+id/map_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:apiKey="##### YOUR MAP KEY HERE ######"
        android:clickable="true" />
</LinearLayout>

<ToggleButton
    android:id="@+id/button_compass"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:onClick="onClick"
    android:textOff="compass off"
    android:textOn="compass on" />

</RelativeLayout>

map Activity

 /**
 * Example activity on how to display a google map view rotation with compass
 * To make it work you need to add:
 *  - <uses-library android:name="com.google.android.maps" /> in the manifest.xml file
 *  - Your Android Maps API Key from https://developers.google.com/android/maps-api- signup
 *  - Set the project build target to "Google APIs"
 *  - Extract/Add the two inner classes RotateView and SmoothCanvas of MapViewCompassDemo.java found at: 
 * ..\Android\Android SDK Tools\add-ons\addon-google_apis-google-#\samples\MapsDemo\src\com\example\android\apis\view\
 * 
 * @author hsigmond - touchboarder.com - 
 *
 */
public class MapViewRotationWithCompass extends MapActivity {

private MapView mMapView;
private MyLocationOverlay mMyLocationOverlay = null;
private boolean mModeCompass = false;
private SensorManager mSensorManager;
private LinearLayout mRotateViewContainer;
private RotateView mRotateView;


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

    setContentView(R.layout.maplayout);
    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    mRotateViewContainer = (LinearLayout) findViewById(R.id.rotating_view);
    mRotateView = new RotateView(this);

    // Sign Up for the Android Maps API at:
    // https://developers.google.com/android/maps-api-signup
    // Add the Android Maps API key to the MapView in the maplayout.xml file 
    mMapView = (MapView) findViewById(R.id.map_view);
    mMyLocationOverlay = new MyLocationOverlay(this, mMapView);     

}

@SuppressWarnings("deprecation")
public void onClick(View v) {

    switch (v.getId()) {

    case R.id.button_compass:
        if (mMyLocationOverlay.isCompassEnabled()) {
            mSensorManager.unregisterListener(mRotateView);
            mRotateView.removeAllViews();
            mRotateViewContainer.removeAllViews();
            mRotateViewContainer.addView(mMapView);
            mMyLocationOverlay.disableCompass();
            mModeCompass = false;
        } else {
            mRotateViewContainer.removeAllViews();
            mRotateView.removeAllViews();
            mRotateView.addView(mMapView);
            mRotateViewContainer.addView(mRotateView);
            mMapView.setClickable(true);
            mSensorManager.registerListener(mRotateView,
                    SensorManager.SENSOR_ORIENTATION,
                    SensorManager.SENSOR_DELAY_UI);
            mMyLocationOverlay.enableCompass();
            mModeCompass = true;
        }
        break;
    }
}

@SuppressWarnings("deprecation")
@Override
public void onResume() {
    super.onResume();
    if (mModeCompass) {
        mMyLocationOverlay.enableCompass();
        mSensorManager.registerListener(mRotateView,
                SensorManager.SENSOR_ORIENTATION,
                SensorManager.SENSOR_DELAY_UI);
    }
}

@Override
public void onPause() {
    super.onPause();
    mMyLocationOverlay.disableCompass();
}

@SuppressWarnings("deprecation")
@Override
protected void onStop() {
    mSensorManager.unregisterListener(mRotateView);
    super.onStop();
}

@Override
protected boolean isRouteDisplayed() {
    return (false);// Don't display a route
}

}

更新: 使用 Compass 示例项目旋转 Google MapView:https://www.dropbox.com/sh/c1encbc2lr63qd9/6C1C4hsrlT

关于android - 在 Android 中旋转 MapView，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1830391/