Screen Lock Plugin #

A Flutter plugin that allows you to programmatically lock the Android device screen.

Features #

• Lock the device screen programmatically
• Check device admin permission status
• Request device admin permissions
• Check current screen state (isScreenOn)
• Stream screen on/off events (onScreenStateChanged)
• Simple and easy-to-use API

Platform Support #

Android Setup #

No additional setup is required. The plugin automatically configures the necessary permissions and device admin receiver.

Usage #

Import the package #

import 'package:screen_lock_plugin/screen_lock_plugin.dart';

Create an instance #

final screenLockPlugin = ScreenLockPlugin();

Check if device admin is enabled #

bool? isEnabled = await screenLockPlugin.isDeviceAdminEnabled();
if (isEnabled == true) {
  print('Device admin is enabled');
} else {
  print('Device admin is not enabled');
}

Request device admin permissions #

await screenLockPlugin.requestDeviceAdmin();

This will show a system dialog asking the user to grant device admin permissions to your app.

Lock the screen #

bool? result = await screenLockPlugin.lockScreen();
if (result == true) {
  print('Screen locked successfully');
} else {
  print('Failed to lock screen. Device admin may not be enabled.');
}

How It Works #

This plugin uses Android's DevicePolicyManager API to lock the screen. Here's what happens:

1. Device Admin Permissions: The app must be registered as a device administrator to lock the screen. This is a security requirement by Android.

2. User Consent: Users must explicitly grant device admin permissions through a system dialog. This cannot be done automatically.

3. Screen Lock: Once permissions are granted, the plugin can lock the screen immediately using DevicePolicyManager.lockNow().

Important Notes #

• User Permission Required: Users must manually grant device admin permissions. This is a security feature and cannot be bypassed.

• Revoking Permissions: Users can revoke device admin permissions at any time through:

  • Settings → Security → Device administrators

• Uninstalling: If users want to uninstall your app, they must first disable device admin permissions in Settings.

• Best Practices:

  • Always check if device admin is enabled before attempting to lock the screen
  • Provide clear UI feedback about permission status
  • Explain why your app needs this permission

Permissions #

The plugin automatically adds the following permission to your AndroidManifest.xml:

<uses-permission android:name="android.permission.BIND_DEVICE_ADMIN" />

Troubleshooting #

Screen doesn't lock when button is pressed #

• Verify device admin is enabled by checking isDeviceAdminEnabled()
• If not enabled, call requestDeviceAdmin() to prompt the user

App won't uninstall #

• Users must disable device admin permissions before uninstalling
• Go to Settings → Security → Device administrators → Disable your app

Contributing #

Contributions are welcome! Please feel free to submit a Pull Request.

Support #

If you encounter any issues or have questions, please file an issue on the GitHub repository.

Changelog #

See CHANGELOG.md for a list of changes in each version.