from nbdev import *
# default_exp navi_widget

Navi Widget

#export

class Navi(NaviGUI):
    """
    Represents simple navigation module with slider.

    on_navi_clicked: callable
        A callback that runs after every navigation
        change. The callback should have, as a
        parameter the navi's index.
    """

    def __init__(self, max_im_num: int = 1, on_navi_clicked: Callable = None):
        super().__init__(max_im_num)
        self._max_im_num = max_im_num
        self.on_navi_clicked = on_navi_clicked
        self._index = 0

        self.model = NaviLogic(gui=self)

        self._listen_next_click()
        self._listen_prev_click()
        self._listen_slider_changes()

    @property
    def index(self) -> int:
        return self._index

    @index.setter
    def index(self, value: int):
        self.model.set_slider_value(value)
        self._index = value
        self._external_call()

    @property
    def max_im_num(self) -> int:
        return self._max_im_num

    @max_im_num.setter
    def max_im_num(self, value: int):
        self.model.set_slider_max(value - 1)
        self._max_im_num = value

    def _next_clicked(self, *args):
        self.model._increment_state_index(1)

    def _slider_updated(self, value: dict):
        self.model.slider_updated(value)
        self._external_call()

    def _prev_clicked(self, *args):
        self.model._increment_state_index(-1)

    def _listen_slider_changes(self):
        self._im_number_slider.observe(
            self._slider_updated, names='value'
        )

    def _listen_next_click(self):
        self._next_btn.on_click(self._next_clicked)

    def _listen_prev_click(self):
        self._prev_btn.on_click(self._prev_clicked)

    def _external_call(self):
        if self.on_navi_clicked:
            self.on_navi_clicked(self._index)
        else:
            warnings.warn(
                "Navi callable was not defined."
                "The navigation will not trigger any action!"
            )

# it start navi with slider index at 0

navi = Navi(6)

assert navi._im_number_slider.value == 0

# it changes state if slider.value changes

navi._im_number_slider.value = 2

assert navi._index == 2

# it changes state and slider.value if button is clicked

navi._next_btn.click()

assert navi._index == 3
assert navi._im_number_slider.value == 3

navi._prev_btn.click()

assert navi._index == 2
assert navi._im_number_slider.value == 2

# it changes slider.max if navi changes max im num
navi.max_im_num = 6
assert navi._im_number_slider.max == 5

# it changes slider.index if navi changes its index
navi.index = 3
assert navi._im_number_slider.value == 3

# testing callback
callback_index = 0


def increment_callback(index):
    global callback_index
    callback_index = index


navi.on_navi_clicked = increment_callback

navi._next_btn.click()
assert callback_index == 4

navi._prev_btn.click()
assert callback_index == 3

navi.index = 2
assert callback_index == 2

<ipython-input-6-72704c14ee75>:69: UserWarning: Navi callable was not defined.The navigation will not trigger any action!
  warnings.warn(

navi

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