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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 计时器\n",
    "\n",
    "创建 NiceGUI 的主要动力之一是需要一个简单方法来定期更新界面，例如显示带有传入测量值的图表。计时器将使用给定的时间间隔重复执行回调函数。\n",
    "\n",
    "- `interval`：调用计时器的间隔（可以在运行时更改）\n",
    "- `callback`：当时间间隔过去时要执行的函数或协程\n",
    "- `active`：是否应执行回调函数（可以在运行时更改）\n",
    "- `once`：是否仅在间隔指定的延迟后执行一次回调（默认：`False`）"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<nicegui.elements.timer.Timer at 0x258b168de10>"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from datetime import datetime\n",
    "from nicegui import ui\n",
    "\n",
    "label = ui.label()\n",
    "ui.timer(1.0, lambda: label.set_text(f'{datetime.now():%X}'))\n",
    "\n",
    "# ui.run()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 激活、停用和取消计时器\n",
    "\n",
    "您可以使用 `active` 属性来激活和停用计时器。您可以使用 `cancel` 方法来取消计时器。取消计时器后，它将无法再次激活。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<nicegui.elements.button.Button at 0x258c4884a90>"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from nicegui import ui\n",
    "\n",
    "slider = ui.slider(min=0, max=1, value=0.5)\n",
    "timer = ui.timer(0.1, lambda: slider.set_value((slider.value + 0.01) % 1.0))\n",
    "ui.switch('active').bind_value_to(timer, 'active')\n",
    "ui.button('Cancel', on_click=timer.cancel)\n",
    "\n",
    "# ui.run()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 在延迟后调用函数\n",
    "\n",
    "您可以使用带有 `once` 参数的计时器在延迟后调用函数。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<nicegui.elements.button.Button at 0x258c4878710>"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from nicegui import ui\n",
    "\n",
    "def handle_click():\n",
    "    ui.timer(1.0, lambda: ui.notify('Hi!'), once=True)\n",
    "ui.button('Notify after 1 second', on_click=handle_click)\n",
    "\n",
    "# ui.run()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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