How to use camera in Android?

This article teaches how to use Android camera.

Step1:Camera preview needs a surface to show.And needs some callback function to handle the take picture processes.
We create a class named CameraPreivew, and implement the SurfaceHolder.Callback and CameraPreviewCallback.

public class CameraPreview implements SurfaceHolder.Callback, Camera.PreviewCallback
{
 public CameraPreview(int PreviewlayoutWidth, int PreviewlayoutHeight)
 {
  // TODO
 } 
 @Override
 public void onPreviewFrame(byte[] arg0, Camera arg1) 
 {
  // At preview mode, the frame data will push to here.
  // But we do not want these data.
 }

 @Override
 public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) 
 {
  // TODO Auto-generated method stub
 }

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

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

 // Take picture interface
 public void CameraTakePicture(String FileName)
 {
  // TODO 
 }
 
 // Set auto-focus interface
 public void CameraStartAutoFocus()
 {
  // TODO 
 }
}

Step2: At the class constructor, we set the preview size.

 
public CameraPreview(int PreviewlayoutWidth, int PreviewlayoutHeight)
{
 PreviewSizeWidth = PreviewlayoutWidth;
 PreviewSizeHeight = PreviewlayoutHeight;
}

Step3:At the SurfaceHolder callback functions, we handle the camera instance.

 
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) 
{
  Parameters parameters;
  mSurfHolder = arg0;
  
  parameters = mCamera.getParameters();
  // Set the camera preview size
  parameters.setPreviewSize(PreviewSizeWidth, PreviewSizeHeight);
  // Set the take picture size, you can set the large size of the camera supported.
  parameters.setPictureSize(PreviewSizeWidth, PreviewSizeHeight);
  
  // Turn on the camera flash. 
  String NowFlashMode = parameters.getFlashMode();
  if ( NowFlashMode != null )
   parameters.setFlashMode(Parameters.FLASH_MODE_ON);
  // Set the auto-focus. 
  String NowFocusMode = parameters.getFocusMode ();
  if ( NowFocusMode != null )
   parameters.setFocusMode("auto");
  
  mCamera.setParameters(parameters);
  
  mCamera.startPreview();
}

@Override
public void surfaceCreated(SurfaceHolder arg0) 
{
 mCamera = Camera.open();
 try
 {
  // If did not set the SurfaceHolder, the preview area will be black.
  mCamera.setPreviewDisplay(arg0);
  mCamera.setPreviewCallback(this);
 } 
 catch (IOException e)
 {
  mCamera.release();
  mCamera = null;
 }
}

@Override
public void surfaceDestroyed(SurfaceHolder arg0) 
{
 mCamera.setPreviewCallback(null);
 mCamera.stopPreview();
 mCamera.release();
 mCamera = null;
}

Step4:In the PreviewCallback, we call the myAutoFocusCallback to handle the take picture processes after the auto-focus.

 
// Take picture interface
public void CameraTakePicture(String FileName)
{
 TakePicture = true;
 NowPictureFileName = FileName;
 mCamera.autoFocus(myAutoFocusCallback);
}
 
// Set auto-focus interface
public void CameraStartAutoFocus()
{
 TakePicture = false;
 mCamera.autoFocus(myAutoFocusCallback);
}

Step5:Create a instance to implement the AutoFocusCallback.

 
AutoFocusCallback myAutoFocusCallback = new AutoFocusCallback()
{
 public void onAutoFocus(boolean arg0, Camera NowCamera) 
 {
  if ( TakePicture )
  {
   NowCamera.stopPreview();//fixed for Samsung S2
   NowCamera.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);
   TakePicture = false;
  }
 }
};

Step6:Implement 3 callback instance to handle the takepicture processes.

 
ShutterCallback shutterCallback = new ShutterCallback()
{
 public void onShutter() 
 {
  // Just do nothing.
 }
};
   
PictureCallback rawPictureCallback = new PictureCallback()
{
 public void onPictureTaken(byte[] arg0, Camera arg1) 
 {
  // Just do nothing.
 }
};
   
PictureCallback jpegPictureCallback = new PictureCallback()
{
 public void onPictureTaken(byte[] data, Camera arg1) 
 {
  // Save the picture.
  try {
   Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0,data.length);
   FileOutputStream out = new FileOutputStream(NowPictureFileName);
   bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
  } 
  catch (IOException e) 
  {
   e.printStackTrace();
  }
 }
}; 

Step7:The camera basic function we all implemented, now we go back to the main activity to use the CameraPreview.

 
public class MyCamera extends Activity
{
 private CameraPreview camPreview; 
 private FrameLayout mainLayout;
     
 private Handler mHandler = new Handler(Looper.getMainLooper());
 
 @Override
 public void onCreate(Bundle savedInstanceState) 
 {
  super.onCreate(savedInstanceState);
  //Set this SPK Full screen
  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,  
  WindowManager.LayoutParams.FLAG_FULLSCREEN);
  //Set this APK no title
  requestWindowFeature(Window.FEATURE_NO_TITLE);  
  setContentView(R.layout.main);
        
  SurfaceView camView = new SurfaceView(this);
  SurfaceHolder camHolder = camView.getHolder();
  camPreview = new CameraPreview(640, 480);
        
  camHolder.addCallback(camPreview);
  camHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        
  mainLayout = (FrameLayout) findViewById(R.id.frameLayout1);
  mainLayout.addView(camView, new LayoutParams(640, 480));
 }

 @Override 
 public boolean onTouchEvent(MotionEvent event) 
 { 
  if (event.getAction() == MotionEvent.ACTION_DOWN) 
  { 
   int X = (int)event.getX(); 
   if ( X >= 640 )
    mHandler.postDelayed(TakePicture, 300);
   else
    camPreview.CameraStartAutoFocus();
  }
  return true;
 };
    
 private Runnable TakePicture = new Runnable() 
 {
  String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
  String MyDirectory_path = extStorageDirectory;
  String PictureFileName;
  public void run() 
  {
   File file = new File(MyDirectory_path);
   if (!file.exists()) 
    file.mkdirs();
   PictureFileName = MyDirectory_path + "/MyPicture.jpg";
   camPreview.CameraTakePicture(PictureFileName);
 }
 };    
}

Step8:The code is all done here, now is to setup the Android configuration to active the Camera hardware.Edit AndroidManifest.xml to active the function we need.

Step9:And the layout file main.xml should be simple like this.