gestures.java

    float x1, x2, y1, y2, dx, dy;
    String direction;
    boolean isDown = false;
    Keyboard.Key activeKey;

    public String getDirection(MotionEvent me) {
        switch(me.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                isDown = true;
                x1 = me.getX();
                y1 = me.getY();
            }
            case MotionEvent.ACTION_UP: {
                isDown = false;
                x2 = me.getX();
                y2 = me.getY();
                dx = x2-x1;
                dy = y2-y1;

                if (dx < 2 && dy < 2) {
                    direction = "none";
                }
                else if (Math.abs(dx) > Math.abs(dy)) {
                    if (dx > 0) direction = "right";
                    else direction = "left";
                }
                else {
                    if (dy > 0) direction = "down";
                    else direction = "up";
                }
            }
        }
        return direction;
    }

    public Keyboard.Key getKeyFromCoordinates(int x, int y) {
        List<Key> keys = getKeyboard().getKeys();
        for (Key key : keys) {
            if (key.isInside(x, y)) {
                return key;
            }
        }
        return null;
    }

    @RequiresApi(api = Build.VERSION_CODES.Q)
    @Override
    public boolean onTouchEvent(MotionEvent me) {

        int action = me.getAction();
        int x = (int)me.getX();
        int y = (int)me.getY();
        getDirection(me);
        if (me.getAction() == MotionEvent.ACTION_DOWN) {
            activeKey = getKeyFromCoordinates(x, y);
        }
        if (me.getAction() != MotionEvent.ACTION_MOVE) {
            System.out.println(activeKey.label+" "+direction+" "+x+" "+y+" "+me.getAction());
        }

        switch(direction) {
            case("up"): {
                if (activeKey.popupCharacters.length() > 0) {
                    getOnKeyboardActionListener().onKey(activeKey.popupCharacters.charAt(0), null);
                }
            }
            case("down"): {
                if (activeKey.popupCharacters.length() > 1) {
                    getOnKeyboardActionListener().onKey(activeKey.popupCharacters.charAt(1), null);
                }
            }
            case("left"): {
                if (activeKey.popupCharacters.length() > 2) {
                    getOnKeyboardActionListener().onKey(activeKey.popupCharacters.charAt(2), null);
                }
            }
            case("right"): {
                if (activeKey.popupCharacters.length() > 3) {
                    getOnKeyboardActionListener().onKey(activeKey.popupCharacters.charAt(3), null);
                }
            }
        }
        getOnKeyboardActionListener().onKey(activeKey.codes[0], null);


        // ACTION_DOWN = 0
        // ACTION_UP = 1
        // ACTION_MOVE = 2

        // return isDown ? super.onTouchEvent(me) : false;
        return super.onTouchEvent(me);
    }