1# Flip Clock
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3### Introduction
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5 This sample uses the Feature Ability (FA) model and related APIs to implement a simple flip clock app. Below shows the sample app.
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7![FlipClock](screenshots/devices/FlipClock.png)  ![CountDown](screenshots/devices/CountDown.png)
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9### Concepts
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11**reminderAgent**: a class that provides APIs to create scheduled reminders for countdown timers, calendar events, and alarm clocks. When the created reminders are published, the timing and pop-up notification functions of your application will be taken over by the reminder agent in the background when your application is frozen or exits.
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13### Required Permissions
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15ohos.permission.PUBLISH_AGENT_REMINDER (permission for the reminder agent)
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17ohos.permission.RUNNING_LOCK (permission for the running lock)
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19ohos.permission.NOTIFICATION_CONTROLLER (permission for send notification)
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21### Usage
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231. There are four tab bars (**Clock**, **Alarm**, **Countdown**, and **Settings**) at the bottom of the home page of the sample app. The **Clock** tab page displays a flip clock.
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252. On the **Alarm** tab page, you can touch **+** to create an alarm record. When the alarm time arrives, a notification will be displayed.
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273. The **Countdown** tab page provides the countdown function.
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294. The **Settings** tab page provides the following functions: full screen, screen brightness adjustment, and screen-on.
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31### Constraints
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331. This sample can only be run on standard-system devices.
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352. This sample requires DevEco Studio 3.1 Canary1 (Build Version: 3.1.0.100, built on November 3, 2022) to compile and run.