subiquity/subiquitycore/ui/spinner.py

# Copyright 2017 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import asyncio

from urwid import Text

styles = {
    "dots": {
        "texts": [
            t.replace("*", "\N{bullet}")
            for t in [
                "|*----|",
                "|-*---|",
                "|--*--|",
                "|---*-|",
                "|----*|",
                "|---*-|",
                "|--*--|",
                "|-*---|",
            ]
        ],
        "rate": 0.2,
    },
    "spin": {
        "texts": ["-", "\\", "|", "/"],
        "rate": 0.1,
    },
}


class Spinner(Text):
    def __init__(self, style="spin", align="center"):
        self.spin_index = 0
        self.spin_text = styles[style]["texts"]
        self.rate = styles[style]["rate"]
        super().__init__("", align=align)
        self._spin_task = None

    def spin(self):
        self.spin_index = (self.spin_index + 1) % len(self.spin_text)
        self.set_text(self.spin_text[self.spin_index])

    async def _spin(self):
        while True:
            self.spin()
            await asyncio.sleep(self.rate)

    def start(self):
        self.stop()
        self._spin_task = asyncio.create_task(self._spin())

    def stop(self):
        self.set_text("")
        if self._spin_task is not None:
            self._spin_task.cancel()
            self._spin_task = None