Googlemaps Coded screenshot returns black image

问题:

I am trying to take a screenshot of Googlemaps after I set a market so I can use image decomposition on it and differentiate land from the ocean. But the return result I get is a black screenshot of the maps it does not take the stream here is the data My API level on the manifest.xml is 15

import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.view.View;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import java.io.File;
import java.io.FileOutputStream;
import java.util.Date;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    GPSTracker gps;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }


    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    final Handler handler = new Handler();
    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        // Add a marker in Sydney and move the camera
        gps = new GPSTracker(MapsActivity.this);
        double latitude = gps.getLatitude();
        double longitude = gps.getLongitude();
        LatLng sydney = new LatLng(latitude, longitude);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Cyprus"));

        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney) );
        mMap.animateCamera( CameraUpdateFactory.zoomTo( 19.0f ) );
        mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
            //Here's a runnable/handler combo

            @Override
            public void onMapClick(LatLng point) {

                MarkerOptions marker = new MarkerOptions().position(
                        new LatLng(point.latitude, point.longitude)).title("New Marker");

               mMap.addMarker(marker);

                System.out.println(point.latitude+"---"+ point.longitude);


            }
        });
        takeScreenshot();
    }

    private void takeScreenshot() {
        Date now = new Date();
        android.text.format.DateFormat.format("yyyy-MM-dd_hh:mm:ss", now);

        try {
            // image naming and path  to include sd card  appending name you choose for file
            String mPath = Environment.getExternalStorageDirectory().toString() + "/" + now + ".jpg";

            // create bitmap screen capture
            View v1 = getWindow().getDecorView().getRootView();
            v1.setDrawingCacheEnabled(true);
            Bitmap bitmap = Bitmap.createBitmap(v1.getDrawingCache());
            v1.setDrawingCacheEnabled(false);

            File imageFile = new File(mPath);

            FileOutputStream outputStream = new FileOutputStream(imageFile);
            int quality = 100;
            bitmap.compress(Bitmap.CompressFormat.JPEG, quality, outputStream);
            outputStream.flush();
            outputStream.close();

            openScreenshot(imageFile);
        } catch (Throwable e) {
            // Several error may come out with file handling or OOM
            e.printStackTrace();
        }
    }
    private void openScreenshot(File imageFile) {
        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_VIEW);
        Uri uri = Uri.fromFile(imageFile);
        intent.setDataAndType(uri, "image/*");
        startActivity(intent);
    }
}

回答1:

You can use the GoogleMap.snapshot method to take snapshots of the map (documentation)

You will need to implement a GoogleMap.SnapshotReadyCallback to manage the snapshot taken.

Also, take into account that, according to the documentation:

Note: Images of the map must not be transmitted to your servers, or otherwise used outside of the application. If you need to send a map to another application or user, send data that allows them to reconstruct the map for the new user instead of a snapshot.