android: move a view on touch move (ACTION_MOVE)

I'd like to do a simple control: a container with a view inside. If I touch the container and I move the finger, I want to move the view to follow my finger.

What kind of container (layout) should I use? How to do this?

I don't need to use a surface, but a simple layout.

Solution 1:

I've found an easy approach to do that with the ViewPropertyAnimator:

float dX, dY;

@Override
public boolean onTouch(View view, MotionEvent event) {

    switch (event.getAction()) {

        case MotionEvent.ACTION_DOWN:

            dX = view.getX() - event.getRawX();
            dY = view.getY() - event.getRawY();
            break;

        case MotionEvent.ACTION_MOVE:

            view.animate()
                    .x(event.getRawX() + dX)
                    .y(event.getRawY() + dY)
                    .setDuration(0)
                    .start();
            break;
        default:
            return false;
    }
    return true;
}

Solution 2:

Something like this:

public class MyActivity extends Activity implements View.OnTouchListener {

TextView _view;
ViewGroup _root;
private int _xDelta;
private int _yDelta;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    _root = (ViewGroup)findViewById(R.id.root);

    _view = new TextView(this);
    _view.setText("TextView!!!!!!!!");

    RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 50);
    layoutParams.leftMargin = 50;
    layoutParams.topMargin = 50;
    layoutParams.bottomMargin = -250;
    layoutParams.rightMargin = -250;
    _view.setLayoutParams(layoutParams);

    _view.setOnTouchListener(this);
    _root.addView(_view);
}

public boolean onTouch(View view, MotionEvent event) {
    final int X = (int) event.getRawX();
    final int Y = (int) event.getRawY();
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
            _xDelta = X - lParams.leftMargin;
            _yDelta = Y - lParams.topMargin;
            break;
        case MotionEvent.ACTION_UP:
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            break;
        case MotionEvent.ACTION_POINTER_UP:
            break;
        case MotionEvent.ACTION_MOVE:
            RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
            layoutParams.leftMargin = X - _xDelta;
            layoutParams.topMargin = Y - _yDelta;
            layoutParams.rightMargin = -250;
            layoutParams.bottomMargin = -250;
            view.setLayoutParams(layoutParams);
            break;
    }
    _root.invalidate();
    return true;
}}

In main.xml just RelativeLayout with @+id/root

Solution 3:

Touch the container and the view will follow your finger.

xml code

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:id="@+id/floating_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    >

    <ImageView
      android:id="@+id/btn_chat"
      android:layout_width="42dp"
      android:layout_height="42dp"
      />
    
<LinearLayout>

Java code

public class DashBoardActivity extends Activity implements View.OnClickListener, View.OnTouchListener {
    
    float dX;
    float dY;
    int lastAction;
    LinearLayout floatingLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_dashboard);

        floatingLayout = findViewById(R.id.floating_layout);
        floatingLayout.setOnTouchListener(this);    
    
    
    
     @Override
    public boolean onTouch(View view, MotionEvent event) {
        switch (event.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                dX = view.getX() - event.getRawX();
                dY = view.getY() - event.getRawY();
                lastAction = MotionEvent.ACTION_DOWN;
                break;

            case MotionEvent.ACTION_MOVE:
                view.setY(event.getRawY() + dY);
                view.setX(event.getRawX() + dX);
                lastAction = MotionEvent.ACTION_MOVE;
                break;

            case MotionEvent.ACTION_UP:
                if (lastAction == MotionEvent.ACTION_DOWN)
                    Toast.makeText(DashBoardActivity.this, "Clicked!", Toast.LENGTH_SHORT).show();
                break;

            default:
                return false;
        }
        return true;
    }
}

Solution 4:

Following the @Andrey approach, if you want to move the view from its center, you only have to substract the view's half height and width to the movement.

float dX, dY;

@Override
public boolean onTouchEvent(View view, MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            dX = view.getX() - event.getRawX();
            dY = view.getY() - event.getRawY();
            break;
        case MotionEvent.ACTION_MOVE:
            view.animate()
                .x(event.getRawX() + dX - (view.getWidth() / 2))
                .y(event.getRawY() + dY - (view.getHeight() / 2))
                .setDuration(0)
                .start();
            break;
        default:
            return false;
    }
    return true;
}