Autofocus

// Start recognition when autofocus completes (used when continuous autofocus is disabled)
    private Camera.AutoFocusCallback startRecognitionCameraAutoFocusCallback = new Camera.AutoFocusCallback() {
        @Override
        public void onAutoFocus( boolean success, Camera camera )
        {
            startRecognition();
        }
    };

    // Enable 'Start' button when autofocus completes (used when continuous autofocus is disabled)
    private Camera.AutoFocusCallback enableStartButtonCameraAutoFocusCallback = new Camera.AutoFocusCallback() {
        @Override
        public void onAutoFocus( boolean success, Camera camera )
        {
            startButton.setText( BUTTON_TEXT_START );
            startButton.setEnabled( true );
        }
    };

    // Start autofocus (used when continuous autofocus is disabled)
    private void autoFocus( Camera.AutoFocusCallback callback )
    {
        if( camera != null ) {
            try {
                camera.autoFocus( callback );
            } catch( Exception e ) {
                Log.e( getString( R.string.app_name ), "Error: " + e.getMessage() );
            }
        }
    }


// Choosing autofocus or continuous focus and whether to start recognition immediately or after autofocus or manually
        if( disableContinuousAutofocus ||
            !parameters.getSupportedFocusModes().contains( Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO ) ) {
            // No continuous focus
            if( startRecognitionWhenReady ) {
                // Start recognition (if you look inside onStartButtonClick it is actually delayed
                // till autofocus completes
                onStartButtonClick( startButton );
                startRecognitionWhenReady = false;
            } else {
                // Just focus and enable 'Start' button
                autoFocus( enableStartButtonCameraAutoFocusCallback );
            }
        } else {
            // Continuous focus. Have to use some Magic. Some devices expect preview to actually
            // start before enabling continuous focus has any effect. So we wait for the camera to
            // actually start preview
            handler.postDelayed( new Runnable() {
                public void run()
                {
                    Camera _camera = MainActivity.this.camera;
                    Camera.Parameters parameters = _camera.getParameters();
                    parameters.setFocusMode( Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO );
                    _camera.setParameters( parameters );
                    if( startRecognitionWhenReady ) {
                        // Give some time for the camera to focus and start recognition
                        handler.postDelayed( new Runnable() {
                            public void run()
                            {
                                onStartButtonClick( startButton );
                            }

                        }, 300 );
                        startRecognitionWhenReady = false;
                    } else {
                        // Just enable 'Start' button
                        startButton.setEnabled( true );
                        startButton.setText( BUTTON_TEXT_START );
                    }
                }
            }, 300 );
        }