Xamarin.Essentials: Flashlight
The Flashlight class has the ability to turn on or off the device's camera flash to turn it into a flashlight.
Get started
To start using this API, read the getting started guide for Xamarin.Essentials to ensure the library is properly installed and set up in your projects.
To access the Flashlight functionality the following platform specific setup is required.
The Flashlight and Camera permissions are required and must be configured in the Android project. This can be added in the following ways:
Open the AssemblyInfo.cs file under the Properties folder and add:
[assembly: UsesPermission(Android.Manifest.Permission.Flashlight)]
[assembly: UsesPermission(Android.Manifest.Permission.Camera)]
OR Update Android Manifest:
Open the AndroidManifest.xml file under the Properties folder and add the following inside of the manifest node.
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-permission android:name="android.permission.CAMERA" />
Or right click on the Android project and open the project's properties. Under Android Manifest find the Required permissions: area and check the FLASHLIGHT and CAMERA permissions. This will automatically update the AndroidManifest.xml file.
By adding these permissions Google Play will automatically filter out devices without specific hardware. You can get around this by adding the following to your AssemblyInfo.cs file in your Android project:
[assembly: UsesFeature("android.hardware.camera", Required = false)]
[assembly: UsesFeature("android.hardware.camera.autofocus", Required = false)]
This API uses runtime permissions on Android. Please ensure that Xamarin.Essentials is fully initialized and permission handling is setup in your app.
In the Android project's MainLauncher or any Activity that is launched Xamarin.Essentials must be initialized in the OnCreate method:
protected override void OnCreate(Bundle savedInstanceState)
{
//...
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState); // add this line to your code, it may also be called: bundle
//...
}
To handle runtime permissions on Android, Xamarin.Essentials must receive any OnRequestPermissionsResult. Add the following code to all Activity classes:
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Android.Content.PM.Permission[] grantResults)
{
Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
Using Flashlight
Add a reference to Xamarin.Essentials in your class:
using Xamarin.Essentials;
The flashlight can be turned on and off through the TurnOnAsync and TurnOffAsync methods:
try
{
// Turn On
await Flashlight.TurnOnAsync();
// Turn Off
await Flashlight.TurnOffAsync();
}
catch (FeatureNotSupportedException fnsEx)
{
// Handle not supported on device exception
}
catch (PermissionException pEx)
{
// Handle permission exception
}
catch (Exception ex)
{
// Unable to turn on/off flashlight
}
Platform Implementation Specifics
The Flashlight class has been optimized based on the device's operating system.
API Level 23 and Higher
On newer API levels, Torch Mode will be used to turn on or off the flash unit of the device.
API Level 22 and Lower
A camera surface texture is created to turn on or off the FlashMode of the camera unit.