import java.util.List;

import android.hardware.Camera;
import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.util.Log;

public class CameraAccessAndroidActivity extends Activity {

    private static final String TAG = "CameraAccessAndroidActivity";

    private Camera mCamera;
    private CameraPreview mPreview;
    private int mDesiredCameraPreviewWidth = 640;

    // Retrieve an instance of the Camera object.
    public static Camera getCameraInstance() {
        Camera c = null;
        try {
            // get a Camera instance
            c = Camera.open(0);
        } catch (Exception e) {
            Log.d(TAG, "Camera not available or in use.");
        }
        // return NULL if camera is unavailable, otherwise return the Camera
        // instance
        return c;
    }

    // configure camera parameters like preview size
    private void initializeCameraParameters() {
        Camera.Parameters parameters = mCamera.getParameters();
        // Get a list of supported preview sizes.
        List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
        int currentWidth = 0;
        int currentHeight = 0;
        boolean foundDesiredWidth = false;
        for(Camera.Size s: sizes)
        {   if (s.width == mDesiredCameraPreviewWidth)
        {
            currentWidth = s.width;
            currentHeight = s.height;
            foundDesiredWidth = true;
            break;
        }
        }
        if(foundDesiredWidth) {
            parameters.setPreviewSize( currentWidth, currentHeight);

        }
        mCamera.setParameters(parameters);
    }

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

    }
    @Override
    public void onResume() {
        super.onResume();
        // Create an instance of Camera
        mCamera = getCameraInstance();
        // initialize camera parameters
        initializeCameraParameters();
        if(mCamera == null) {
            Log.d(TAG, "Camera not available");
        } else {
            // Create our Preview view and set it as the content of our activity.
            mPreview = new CameraPreview(this, mCamera);
            setContentView(mPreview);
        }
    }
    @Override
    protected void onPause() {
        super.onPause();
        releaseCamera();              // release the camera immediately on pause event
    }

    private void releaseCamera(){
        if (mCamera != null){
            mCamera.stopPreview();
            mCamera.release();        // release the camera for other applications
            mCamera = null;
        }
    }
}