TaskController.ipynb

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   "source": [
    "import holoviews as hv\n",
    "import panel as pn\n",
    "import numpy as np\n",
    "import param\n",
    "import time\n",
    "pn.extension()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "class TaskControllerBase(param.Parameterized):\n",
    "    \"\"\" Base class for widgets of type loading\n",
    "    add method control to create start and stop buttons\n",
    "    \"\"\"\n",
    "    t=param.Number(default=0., precedence=-1)\n",
    "    interval = param.Number(default=0.1, precedence=-1, doc=\"\"\"\n",
    "    Minimal time interval in seconds between two updates of the progress bar.\"\"\")\n",
    "    start = param.Action(lambda inst : inst._start_update())\n",
    "    stop = param.Action(lambda inst : inst._stop_update())\n",
    "\n",
    "    def __init__(self, **params):\n",
    "        super(TaskControllerBase,self).__init__(**params)\n",
    "        self._stop = True\n",
    "        self._running = False\n",
    "    \n",
    "    def _update(self):\n",
    "        while not self._stop:\n",
    "            time.sleep(self.interval)\n",
    "            self.t = time.time()\n",
    "        self.t = time.time()\n",
    "        self._running = False\n",
    "        return\n",
    "    \n",
    "    def _start_update(self):\n",
    "        import threading\n",
    "        if self._running:\n",
    "            raise RuntimeError('Previous thread already running. Stop it before relaunching')\n",
    "        self._stop = False\n",
    "        self._running = True\n",
    "        self._thread = threading.Thread(target=self._update)\n",
    "        self._thread.start()\n",
    "        self.param.trigger('start')\n",
    "    \n",
    "    def _stop_update(self):\n",
    "        self._stop = True\n",
    "        self.param.trigger('stop')\n",
    "        \n",
    "    def controls(self):\n",
    "        return pn.Row(pn.Param(self,parameters=['start'],show_name=False),\n",
    "                      pn.Param(self,parameters=['stop'],show_name=False))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "class ControllerWithBar(TaskControllerBase):\n",
    "    count = param.Number(default=0., precedence=-1)\n",
    "    \n",
    "    @param.depends('t')\n",
    "    def _update_text(self):\n",
    "        if not self._stop:\n",
    "            self.count += 1\n",
    "            return pn.pane.Markdown('####Working' + ' .'*int(self.t%6), height=0, width=200)\n",
    "        else:\n",
    "            self.count = 0\n",
    "            return pn.pane.Markdown('####Idle', height=0, width=200)\n",
    "    \n",
    "    @param.depends('count')\n",
    "    def _make_pb(self):\n",
    "        return hv.Points(((0.1*self.count)%1.1,0.5)).opts(height=25,xaxis=None,yaxis=None,toolbar=None,xlim=(0.,1.),size=15)\n",
    "    \n",
    "    def view(self):\n",
    "        pb = hv.DynamicMap(self._make_pb)\n",
    "        return pn.Row(pn.Spacer(width=150), pn.Column(self._update_text, pb))\n",
    "   \n",
    "    def layout(self):\n",
    "        return pn.Column(self.controls(), self.view())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "controller = ControllerWithBar()\n",
    "controller.layout()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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