TextSelection_onTouch.java

@Override
public boolean onTouchEvent(MotionEvent event) {
    int action = event.getActionMasked();
    float x = event.getX();
    float y = event.getY();

    switch (action) {
        case MotionEvent.ACTION_DOWN:
            startX = x;
            startY = y;
            break;
        case MotionEvent.ACTION_UP:
            break;
        case MotionEvent.ACTION_MOVE:
            currentX = x;
            currentY = y;
            invalidate();
            break;
    }
    return true;
}