Android: Camera with SurfaceView

Question

I am trying to use Android's Camera with a SurfaceView, so the the user can preview the camera. I followed various tutorials on StackOverflow, and finally ended up with Google's own tutorial, but my app crashed. Here is my code. I am using Eclipse's Android Virtual Device, emulated camera (which I don't think would affect anything) and 100mb sd card space alloted.

There are two classes, a CameraPreview object and the CameraActivity.

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback{

    private SurfaceHolder mHolder;
    private Camera mCamera;
    private final String TAG = "TAG";

    public CameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}


public class CameraActivity extends Activity{
 private Camera mCamera;
    private CameraPreview mPreview;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Create an instance of Camera
        mCamera = getCameraInstance();

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e){
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }
}

06-04 14:28:07.726: W/dalvikvm(6115): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 06-04 14:28:07.956: E/AndroidRuntime(6115): FATAL EXCEPTION: main 06-04 14:28:07.956: E/AndroidRuntime(6115): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mobilequote/com.example.mobilequote.CameraActivity}: java.lang.NullPointerException 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread.access$600(ActivityThread.java:141) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.os.Handler.dispatchMessage(Handler.java:99) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.os.Looper.loop(Looper.java:137) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread.main(ActivityThread.java:5041) 06-04 14:28:07.956: E/AndroidRuntime(6115): at java.lang.reflect.Method.invokeNative(Native Method) 06-04 14:28:07.956: E/AndroidRuntime(6115): at java.lang.reflect.Method.invoke(Method.java:511) 06-04 14:28:07.956: E/AndroidRuntime(6115): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 06-04 14:28:07.956: E/AndroidRuntime(6115): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 06-04 14:28:07.956: E/AndroidRuntime(6115): at dalvik.system.NativeStart.main(Native Method) 06-04 14:28:07.956: E/AndroidRuntime(6115): Caused by: java.lang.NullPointerException 06-04 14:28:07.956: E/AndroidRuntime(6115): at com.example.mobilequote.CameraActivity.onCreate(CameraActivity.java:24) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.Activity.performCreate(Activity.java:5104) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 06-04 14:28:07.956: E/AndroidRuntime(6115): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 06-04 14:28:07.956: E/AndroidRuntime(6115): ... 11 more

The line CameraActivity.java:24 is preview.addView(mPreview);

Android: Camera with SurfaceView

Answers (1)

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