Question

I’ve written a litte Camera-Appliction after I have read this tutorial:

http://www.brighthub.com/mobile/google-android/articles/43414.aspx

In the emulator everything works fine (ok, there’s no camera, but at least there are no errors 😉 )

Then I tried to get it run on my HTC Wildfire S. But immediately after the start the app crashes.

Here’s the code of my Activity, maybe somebody has an idea, how to solve the problem:

public class CameraView extends Activity implements SurfaceHolder.Callback {

    android.hardware.Camera mCamera;
    boolean mPreviewRunning = false;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.camera_surface);
        SurfaceView mSurfaceView = (SurfaceView)findViewById(R.id.surface_camera);
        SurfaceHolder mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }


    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mCamera = android.hardware.Camera.open();
    }


    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        if(mPreviewRunning) {
            mCamera.stopPreview();
        }

        android.hardware.Camera.Parameters params = mCamera.getParameters();
        params.setPreviewSize(width, height);
        mCamera.setParameters(params);

        try {
            mCamera.setPreviewDisplay(holder);
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        mCamera.startPreview();
        mPreviewRunning = true;
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mCamera.stopPreview();
        mPreviewRunning = false;
        mCamera.release();
    }

    android.hardware.Camera.PictureCallback mPictureCallback = new android.hardware.Camera.PictureCallback() {

        @Override
        public void onPictureTaken(byte[] data, android.hardware.Camera camera) {

        }
    };
}

Answer 1

You are getting an exception because you are trying to make the camera use a width and height it doesn’t support. You are asking it to use the width and height of the SurfaceView, which rarely matches one of the supported preview sizes. Instead, try using the following:

   public class CameraView extends Activity implements SurfaceHolder.Callback {

android.hardware.Camera mCamera;
boolean mPreviewRunning = false;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    getWindow().setFormat(PixelFormat.TRANSLUCENT);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.camera_surface);
    SurfaceView mSurfaceView = (SurfaceView)findViewById(R.id.surface_camera);
    SurfaceHolder mSurfaceHolder = mSurfaceView.getHolder();
    mSurfaceHolder.addCallback(this);
    mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}


@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
        mCamera.setPreviewDisplay(previewHolder);   
    }
    catch (Throwable t) {
        Log.e(TAG, "Exception in setPreviewDisplay()", t);
    }
}


@Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    Camera.Parameters parameters=camera.getParameters();
    Camera.Size size=getBestPreviewSize(width, height, parameters);

    if (size!=null) {
        parameters.setPreviewSize(size.width, size.height);
        camera.setParameters(parameters);
        camera.startPreview();
        inPreview=true;
    }
  }

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCamera.stopPreview();
    mPreviewRunning = false;
    mCamera.release();
}

android.hardware.Camera.PictureCallback mPictureCallback = new android.hardware.Camera.PictureCallback() {

    @Override
    public void onPictureTaken(byte[] data, android.hardware.Camera camera) {

    }
};

    private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters) {
    Camera.Size result=null;

    for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
        if (size.width<=width && size.height<=height) {
            if (result==null) {
                result=size;
            }
            else {
                int resultArea=result.width*result.height;
                int newArea=size.width*size.height;

                if (newArea>resultArea) {
                    result=size;
                }
            }
        }
    }

    return(result);
}
}

This code is all adapted from the one I wrote for my book. I changed some of your code, so some variable names and imports might need to be fixed, but it should work fine.

getBestPreviewSize() is the magic method here which calculates the optimum and best camera preview size to use.