Android: Wie Video-Vorschau nach dem surfaceDestroyed neu zu starten ()?

Question

Ich habe eine CapturePreview Klasse und CameraManager Klasse die folgende Art und Weise erstellt:

CapturePreview:

public class CaptureView extends SurfaceView implements Callback{

private final SurfaceHolder surfaceHolder;
FileReaderWriter fileRW;
int frameCount;

private static final int MSG_FRAME_REFRESHED = 1;
private static final int MSG_AUTOFOCUS = 2;

private final CameraManager mCameraManager;

private boolean mRecording;

public CaptureView(Context context, AttributeSet attrs)
{
    super(context, attrs);

    surfaceHolder = getHolder();
    surfaceHolder.addCallback(this);
    surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    CameraManager.init(context);
    mCameraManager = CameraManager.get();

    init(context);
}

public CaptureView(Context context, AttributeSet attrs, int defStyle)
{
    super(context, attrs, defStyle);

    surfaceHolder = getHolder();
    surfaceHolder.addCallback(this);
    surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    surfaceHolder.setSizeFromLayout();

    CameraManager.init(context);
    mCameraManager = CameraManager.get();

    init(context);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
        int height) {

    mCameraManager.startPreview();

    //mCameraManager.requestPreviewFrame(mCameraHandler, MSG_FRAME_REFRESHED);
    mCameraManager.requestAutoFocus(mCameraHandler, MSG_AUTOFOCUS);
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    try
    {
        mCameraManager.openDriver(surfaceHolder);
    }
    catch(Exception e)
    {
        //TODO: display error
    }

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCameraManager.stopPreview();
}

private void init(Context context)
{
    setFocusable(true);
    mRecording = false;
    fileRW = new FileReaderWriter();
    frameCount = 0;
}



public void setRecording(boolean isRecording) {
    this.mRecording = isRecording;
}

public boolean isRecording() {
    return mRecording;
}

private Handler mCameraHandler = new CameraHandler();

private class CameraHandler extends Handler
{
    @Override
    public void handleMessage(Message msg)
    {
        switch(msg.what)
        {
        case MSG_FRAME_REFRESHED:
//              String path = "JPGFrame" + frameCount;
//              fileRW.setPath(path);
//              fileRW.WriteToFile((byte[]) msg.obj);
//              frameCount++;

            break;
        }
    }
}

}

CameraManager:

public final class CameraManager {

@Override
protected void finalize() throws Throwable {
    closeDriver();
    super.finalize();
}

private static final String TAG = "CameraManager";

private static CameraManager mCameraManager;
private Camera mCamera;
private final Context mContext;
private Point mScreenResolution;
private Rect mFramingRect;
private Handler mPreviewHandler;
private int mPreviewMessage;
private Handler mAutoFocusHandler;
private int mAutoFocusMessage;
private boolean mPreviewing;

public static synchronized void init(Context context) {
    if (mCameraManager == null) {
      mCameraManager = new CameraManager(context);
      mCameraManager.getScreenResolution();
    }
  }

  public static CameraManager get() {
    return mCameraManager;
  }

  private CameraManager(Context context) {
    mContext = context;
    mCamera = null;
    mPreviewing = false;
  }

  public void openDriver(SurfaceHolder holder) throws IOException {
    // "throws IOException added to accommodate Android 1.5
    if (mCamera == null) {
      mCamera = Camera.open();
      setCameraParameters();
      mCamera.setPreviewDisplay(holder);
    }
  }

  public void closeDriver() {
    if (mCamera != null) {
      mCamera.release();
      mCamera = null;
    }
  }

  public void startPreview() {
    if (mCamera != null && !mPreviewing) {
      mCamera.startPreview();
      mPreviewing = true;
    }
  }

  public void stopPreview() {
    if (mCamera != null && mPreviewing) {
      mCamera.setPreviewCallback(null);
      mCamera.stopPreview();
      mPreviewHandler = null;
      mAutoFocusHandler = null;
      mPreviewing = false;
    }
  }


  public void requestPreviewFrame(Handler handler, int message) {
    if (mCamera != null && mPreviewing) {
      mPreviewHandler = handler;
      mPreviewMessage = message;
      mCamera.setPreviewCallback(previewCallback);
    }
  }

  public void requestAutoFocus(Handler handler, int message) {
    if (mCamera != null && mPreviewing) {
      mAutoFocusHandler = handler;
      mAutoFocusMessage = message;
      mCamera.autoFocus(autoFocusCallback);
    }
  }


  public Rect getFramingRect() {
    if (mFramingRect == null) {
      int size = ((mScreenResolution.x < mScreenResolution.y) ? mScreenResolution.x :
          mScreenResolution.y) * 3 / 4;
      int leftOffset = (mScreenResolution.x - size) / 2;
      int topOffset = (mScreenResolution.y - size) / 2;
      mFramingRect = new Rect(leftOffset, topOffset, leftOffset + size, topOffset + size);
    }
    return mFramingRect;
  }


  PreviewCallback previewCallback = new PreviewCallback()
  {

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        if(mPreviewHandler != null)
        {
            Message message = mPreviewHandler.obtainMessage(mPreviewMessage,
                mScreenResolution.x, mScreenResolution.y, data);
                message.sendToTarget();
        }
    } 
  };

  AutoFocusCallback autoFocusCallback = new AutoFocusCallback()
  {

    @Override
    public void onAutoFocus(boolean success, Camera camera) {
        if(mAutoFocusHandler != null)
        {
            Message message = mAutoFocusHandler.obtainMessage(mAutoFocusMessage, success);
            message.sendToTarget();
        }   
    }  
  };

  private void setCameraParameters() {
    Camera.Parameters parameters = mCamera.getParameters();
    parameters.setPreviewSize(mScreenResolution.x, mScreenResolution.y);
    parameters.setPictureFormat(PixelFormat.JPEG);
    parameters.setPreviewFormat(PixelFormat.JPEG);
    mCamera.setParameters(parameters);
  }

  private Point getScreenResolution() {
    if (mScreenResolution == null) {
      WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
      Display display = wm.getDefaultDisplay();
      mScreenResolution = new Point(display.getWidth(), display.getHeight());
    }
    return mScreenResolution;
  }

}

Die Video-Vorschau funktioniert so lange gut, bis die Unteraktivität in der Haupttätigkeit beginnt. Wenn Subaktivität beginnt, wird der CaptureView.surfaceDestroyed(SurfaceHolder holder) genannt und die Videovorschau stoppt. Dann, wenn die Unteraktivität der CaptureView.surfaceCreated(SurfaceHolder holder) schließt ausgeführt wird, aber die Videovorschau nicht startet.

Wer weiß, wie das Problem zu fixieren, um erfolgreich Video-Vorschau neu starten, nachdem surfaceDestroyed (SurfaceHolder Halter) ausgeführt wird?

Danke!

Answer 1

Sie müssen die Kamera freigeben auf ‚surfaceDestroyed‘ zu sehen, wie Sie versuchen, den Zugriff darauf wieder in ‚surfaceCreated‘ zu erwerben, die Sie eine Ausnahme werfen würde, wenn die Kamera bereits erworben wird.