Android RxJava 와 Lambda

MagneticPlateView.java

@EView
public class MagneticPlateView extends View {
    // ...중략...
    
    @Override
    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);

        canvas.save();
        drawIronPipe(canvas);
        drawMagneticBall(canvas);
        canvas.restore();

    }

    private void drawMagneticBall(Canvas canvas) {
        canvas.drawCircle(ballCenterPoint.x, ballCenterPoint.y, ballRadious, ballPaint);
    }


    private void drawIronPipe(Canvas canvas) {

        final int ballCenterX = ballCenterPoint.x;
        final int ballCenterY = ballCenterPoint.y;

        for (int rowIdx = 0; rowIdx < pipeRowCount; ++rowIdx) {
            for (int colIdx = 0; colIdx < pipeColumnCount; ++colIdx) {

                int startX = colIdx * (pipeLength + pipeMargin);
                int startY = rowIdx * pipeLength;

                double radian = Math.atan2(ballCenterX - startX, ballCenterY - startY);

                int stopX = (int) (startX + Math.sin(radian) * pipeLength);
                int stopY = (int) (startY + Math.cos(radian) * pipeLength);

                canvas.drawLine(startX, startY, stopX, stopY, pipePaint);
            }
        }

    }
}

MainActivity.java

@EActivity(R.layout.act_main)
public class MainActivity extends Activity {


    private PublishSubject<MotionEvent> touchDownSubject;
    private PublishSubject<MotionEvent> touchMoveSubject;
    private float lastTouchedX = -1;
    private float lastTouchedY = -1;

    @ViewById(R.id.mpv_main)
    MagneticPlateView magneticPlateView;

    @AfterInject
    void initObject() {

        touchDownSubject = initTouchDownSubject();
        touchMoveSubject = initTouchMoveSubject();

    }

    private PublishSubject<MotionEvent> initTouchMoveSubject() {


        PublishSubject<MotionEvent> touchMoveSubject = PublishSubject.create();

        touchMoveSubject
                .filter(motionEvent -> motionEvent.getAction() == MotionEvent.ACTION_MOVE)
                .map(motionEvent -> {
                    float touchX = motionEvent.getX();
                    float touchY = motionEvent.getY();

                    int[] diffTouchDistance = new int[2];

                    diffTouchDistance[0] = (int) (touchX - lastTouchedX);
                    diffTouchDistance[1] = (int) (touchY - lastTouchedY);

                    lastTouchedX = touchX;
                    lastTouchedY = touchY;
                    return diffTouchDistance;
                })
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(diffXY -> {
                    magneticPlateView.setTouchDiff(diffXY[0], diffXY[1]);
                    magneticPlateView.invalidate();
                });

        return touchMoveSubject;

    }

    private PublishSubject<MotionEvent> initTouchDownSubject() {
        PublishSubject<MotionEvent> touchDownSubject = PublishSubject.create();
        touchDownSubject
                .filter(motionEvent -> motionEvent.getAction() == MotionEvent.ACTION_DOWN)
                .observeOn(Schedulers.io())
                .subscribe(motionEvent -> {
                    lastTouchedX = motionEvent.getX();
                    lastTouchedY = motionEvent.getY();
                });
        return touchDownSubject;
    }

    @Touch(R.id.mpv_main)
    void onPlateTouch(View view, MotionEvent event) {

        touchDownSubject.onNext(event);
        touchMoveSubject.onNext(event);

    }
}