How to autofocus Android camera automatically?

I want to autofocus Android camera as soon as camera holds still. Im looking for tutorials or samples how to do it or at least small sample that shows what classes I can use to hook on such events.

For me this worked a treat:

//set camera to continually auto-focus
Camera.Parameters params = c.getParameters();
//*EDIT*//params.setFocusMode("continuous-picture");
//It is better to use defined constraints as opposed to String, thanks to AbdelHady
params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
c.setParameters(params);

Try to use Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO or Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE. See below:

Camera.Parameters params = camera.getParameters();
if (params.getSupportedFocusModes().contains(
    Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
  params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
}
camera.setParameters(params);

It's important to test whether the phone is supporting your chosen mode before attempting to use it, otherwise setParameters() will throw a runtime exception. (Edit code now working properly)

Following code works for me.

Setting autofocus (preview class):

Parameters params = camera.getParameters();
params.setFocusMode(Parameters.FOCUS_MODE_AUTO);
//some more settings
camera.setParameters(params);

Call camera for shot a picture in case that autofocus is ready (activity class):

public void butClick(View v){
	preview.camera.autoFocus(new AutoFocusCallback() {
        public void onAutoFocus(boolean success, Camera camera) {
            if(success){
                camera.takePicture(shutterCallback, rawCallback, jpegCallback);
            }
        }
    });
}

Get picture (activity class):

PictureCallback jpegCallback = new PictureCallback() {
	public void onPictureTaken(byte[] data, Camera camera) {
		//do something
	}
};

Looks like you should continuous autofocus as is discussed here.

There is a question here that you can reference.

This works perfectly for preview callback:

Camera.Parameters parameters = camera.getParameters();
if (parameters.getSupportedFocusModes().contains(
        Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
    parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
}
camera.setParameters(parameters);

you can try code:

ShutterCallback _pfnShutterCallback = new ShutterCallback() {

		@Override
		public void onShutter() {
			// TODO Auto-generated method stub

		}

	};

	PictureCallback _pfnRawPictureCallback = new PictureCallback() {

		@Override
		public void onPictureTaken(byte[] data, Camera camera) {
			// TODO Auto-generated method stub

		}
	};

	private AutoFocusCallback _pfnAutoFocusCallback = new AutoFocusCallback() {

		@Override
		public void onAutoFocus(boolean success, Camera camera) {
			// TODO Auto-generated method stub
			camera.autoFocus(null);
			camera.takePicture(_pfnShutterCallback, _pfnRawPictureCallback,
					mPicture);

		}
	};
	private PictureCallback mPicture = new PictureCallback() {

		public void onPictureTaken(byte[] data, Camera camera) {
			new SavePhotoTask().execute(data);
			camera.startPreview();

		}
	};
class SavePhotoTask extends AsyncTask<byte[], String, String> {
// Process save file image
}

call capture : mCamera.autoFocus(autoFocusCallback);

You can refer at: http://android-er.blogspot.com/2011/01/start-camera-auto-focusing-autofocus.html