Android 视频播放但没有出现 VideoView

Question

当用户更改位置时，我正在尝试在 Google 地图上播放视频。最初在 activity_main.xml 中，videoview 设置为不可见。当视频即将播放时，我将 videoview 设置为可见并 setZOrderOnTop(true)。

当视频由 onLocationChanged 触发时，视频视图不会出现。但我可以听到视频中的音频，所以我知道它正在播放。

但是，如果我首先在 onCreate 中播放视频，该视频会成功播放并出现在屏幕上。并且 onLocationChanged 视频也会播放并出现在屏幕上。

为什么我在onCreate中不播放视频，videovideo视图没有出现？

activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" 
android:layout_height="fill_parent"
android:gravity="center" >

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView android:id="@+id/top_message"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:minWidth="110sp" android:textColor="#66CCFF"
        android:textStyle="bold" android:textSize="20sp" android:text="Default Text" />

    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/map"
        android:layout_below="@id/top_message"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal" /> 

</RelativeLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <VideoView 
        android:visibility="invisible"
        android:layout_height="fill_parent"
        android:layout_width="fill_parent"
        android:id="@+id/myVideo"
        android:gravity="center"
        android:layout_centerInParent="true" />

    </RelativeLayout>

</FrameLayout>

MainActivity.java

public class MainActivity extends FragmentActivity implements LocationListener {

private GoogleMap googleMap;
private TextView distanceTextView;
private VideoView videoView;
private LocationManager locationManager;

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

    setContentView(R.layout.activity_main);        

    // setup overlay for text
    distanceTextView = (TextView)findViewById(R.id.top_message);
    distanceTextView.setText("Text set onCreate");

    // setup overlay for video
    videoView = (VideoView) findViewById(R.id.myVideo);

    // setup google map data
    googleMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
    googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    googleMap.getUiSettings().setCompassEnabled(true);
    googleMap.getUiSettings().setZoomControlsEnabled(true);
    googleMap.setMyLocationEnabled(true);

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5000, 1, this);
    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

    // set current location and move map to that location
    if (location != null) {
        LatLng myPosition = new LatLng(location.getLatitude(),location.getLongitude());
        googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(myPosition, 15));
    }

    // if below is uncommented then secondvideo will also appear 
    //playVideo(new String("android.resource://" + getPackageName() + "/" + R.raw.firstvideo));

}

public void onLocationChanged(Location location) {
    locationManager.removeUpdates(this);
    distanceTextView.setText("Location has changed");
    playVideo(new String("android.resource://" + getPackageName() + "/" + R.raw.secondvideo));          
}

private void playVideo(String videoFile) {
    videoView.setVisibility(View.VISIBLE);
    videoView.setZOrderOnTop(true);

    MediaController mediaController = new MediaController(this);
    mediaController.setAnchorView(videoView);
    videoView.setMediaController(mediaController);
    videoView.setVideoPath(videoFile);
    videoView.start();
    videoView.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            videoView.setVisibility(View.INVISIBLE);
            videoView.setZOrderOnTop(false);
            videoView.stopPlayback();
            return false;
        }
    });
}

@Override
public void onProviderDisabled(String arg0) {
    // TODO Auto-generated method stub
}

@Override
public void onProviderEnabled(String arg0) {
    // TODO Auto-generated method stub
}

@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
    // TODO Auto-generated method stub

}

}

Answer 1

setZOrderOnTop() 不能用于动态更改 z 水平。来自docs，

请注意，这必须在表面视图的包含窗口之前设置 附加到窗口管理器。

一旦附加了视图，对setZOrderOnTop() 的调用就没有任何效果。一种解决方案是始终将VideoView 放在顶部并控制它是否像您已经在做的那样与.setVisibility() 一起看到。您可以在onCreate() 中使用一个呼叫setZOrderOnTop()，这可能是您在onCreate 中播放视频时起作用的原因。