Added async variants of RequestPermission function that don't freeze the app unnecessarily

Author: yasirkula

.github/README.md

@@ -82,6 +82,11 @@ Beginning with *6.0 Marshmallow*, Android apps must request runtime permissions
 
 `NativeCamera.Permission NativeCamera.RequestPermission( bool isPicturePermission )`: requests permission to access the camera from the user and returns the result. It is recommended to show a brief explanation before asking the permission so that user understands why the permission is needed and doesn't click Deny or worse, "Don't ask again". Note that TakePicture and RecordVideo functions call RequestPermission internally and execute only if the permission is granted (the result of RequestPermission is then returned).
 
+`void NativeCamera.RequestPermissionAsync( PermissionCallback callback, bool isPicturePermission )`: Asynchronous variant of *RequestPermission*. Unlike RequestPermission, this function doesn't freeze the app unnecessarily before the permission dialog is displayed. So it's recommended to call this function instead.
+- **PermissionCallback** takes `NativeCamera.Permission permission` parameter
+
+`Task<NativeCamera.Permission> NativeCamera.RequestPermissionAsync( bool isPicturePermission )`: Another asynchronous variant of *RequestPermission* (requires Unity 2018.4 or later).
+
 `NativeCamera.OpenSettings()`: opens the settings for this app, from where the user can manually grant permission in case current permission state is *Permission.Denied* (Android requires *Storage* and, if declared in AndroidManifest, *Camera* permissions; iOS requires *Camera* permission).
 
 `bool NativeCamera.CanOpenSettings()`: on iOS versions prior to 8.0, opening settings from within the app is not possible and in this case, this function returns *false*. Otherwise, it returns *true*.
@@ -137,6 +142,14 @@ void Update()
 	}
 }
 
+// Example code doesn't use this function but it is here for reference. It's recommended to ask for permissions manually using the
+// RequestPermissionAsync methods prior to calling NativeCamera functions
+private async void RequestPermissionAsynchronously( bool isPicturePermission )
+{
+	NativeCamera.Permission permission = await NativeCamera.RequestPermissionAsync( isPicturePermission );
+	Debug.Log( "Permission result: " + permission );
+}
+
 private void TakePicture( int maxSize )
 {
 	NativeCamera.Permission permission = NativeCamera.TakePicture( ( path ) =>

Plugins/NativeCamera/Android/NCCallbackHelper.cs

@@ -16,9 +16,16 @@ private void Update()
 		{
 			if( mainThreadAction != null )
 			{
-				System.Action temp = mainThreadAction;
-				mainThreadAction = null;
-				temp();
+				try
+				{
+					System.Action temp = mainThreadAction;
+					mainThreadAction = null;
+					temp();
+				}
+				finally
+				{
+					Destroy( gameObject );
+				}
 			}
 		}
 

Plugins/NativeCamera/Android/NCCameraCallbackAndroid.cs

@@ -16,23 +16,7 @@ public NCCameraCallbackAndroid( NativeCamera.CameraCallback callback ) : base( "
 
 		public void OnMediaReceived( string path )
 		{
-			callbackHelper.CallOnMainThread( () => MediaReceiveCallback( path ) );
-		}
-
-		private void MediaReceiveCallback( string path )
-		{
-			if( string.IsNullOrEmpty( path ) )
-				path = null;
-
-			try
-			{
-				if( callback != null )
-					callback( path );
-			}
-			finally
-			{
-				Object.Destroy( callbackHelper.gameObject );
-			}
+			callbackHelper.CallOnMainThread( () => callback( !string.IsNullOrEmpty( path ) ? path : null ) );
 		}
 	}
 }

Plugins/NativeCamera/Android/NCPermissionCallbackAndroid.cs

@@ -25,5 +25,22 @@ public void OnPermissionResult( int result )
 			}
 		}
 	}
+
+	public class NCPermissionCallbackAsyncAndroid : AndroidJavaProxy
+	{
+		private readonly NativeCamera.PermissionCallback callback;
+		private readonly NCCallbackHelper callbackHelper;
+
+		public NCPermissionCallbackAsyncAndroid( NativeCamera.PermissionCallback callback ) : base( "com.yasirkula.unity.NativeCameraPermissionReceiver" )
+		{
+			this.callback = callback;
+			callbackHelper = new GameObject( "NCCallbackHelper" ).AddComponent<NCCallbackHelper>();
+		}
+
+		public void OnPermissionResult( int result )
+		{
+			callbackHelper.CallOnMainThread( () => callback( (NativeCamera.Permission) result ) );
+		}
+	}
 }
 #endif

Plugins/NativeCamera/NativeCamera.cs

@@ -53,6 +53,7 @@ public enum PreferredCamera { Default = -1, Rear = 0, Front = 1 }
 	// EXIF orientation: http://sylvana.net/jpegcrop/exif_orientation.html (indices are reordered)
 	public enum ImageOrientation { Unknown = -1, Normal = 0, Rotate90 = 1, Rotate180 = 2, Rotate270 = 3, FlipHorizontal = 4, Transpose = 5, FlipVertical = 6, Transverse = 7 };
 
+	public delegate void PermissionCallback( Permission permission );
 	public delegate void CameraCallback( string path );
 
 	#region Platform Specific Elements
@@ -90,7 +91,7 @@ private static AndroidJavaObject Context
 	private static extern int _NativeCamera_CheckPermission();
 
 	[System.Runtime.InteropServices.DllImport( "__Internal" )]
-	private static extern int _NativeCamera_RequestPermission();
+	private static extern int _NativeCamera_RequestPermission( int asyncMode );
 
 	[System.Runtime.InteropServices.DllImport( "__Internal" )]
 	private static extern int _NativeCamera_CanOpenSettings();
@@ -173,6 +174,10 @@ public static Permission CheckPermission( bool isPicturePermission )
 
 	public static Permission RequestPermission( bool isPicturePermission )
 	{
+		// Don't block the main thread if the permission is already granted
+		if( CheckPermission( isPicturePermission ) == Permission.Granted )
+			return Permission.Granted;
+
 #if !UNITY_EDITOR && UNITY_ANDROID
 		object threadLock = new object();
 		lock( threadLock )
@@ -193,12 +198,34 @@ public static Permission RequestPermission( bool isPicturePermission )
 			return (Permission) nativeCallback.Result;
 		}
 #elif !UNITY_EDITOR && UNITY_IOS
-		return (Permission) _NativeCamera_RequestPermission();
+		return (Permission) _NativeCamera_RequestPermission( 0 );
 #else
 		return Permission.Granted;
 #endif
 	}
 
+	public static void RequestPermissionAsync( PermissionCallback callback, bool isPicturePermission )
+	{
+#if !UNITY_EDITOR && UNITY_ANDROID
+		NCPermissionCallbackAsyncAndroid nativeCallback = new NCPermissionCallbackAsyncAndroid( callback );
+		AJC.CallStatic( "RequestPermission", Context, nativeCallback, isPicturePermission, (int) Permission.ShouldAsk );
+#elif !UNITY_EDITOR && UNITY_IOS
+		NCPermissionCallbackiOS.Initialize( callback );
+		_NativeCamera_RequestPermission( 1 );
+#else
+		callback( Permission.Granted );
+#endif
+	}
+
+#if UNITY_2018_4_OR_NEWER && !NATIVE_CAMERA_DISABLE_ASYNC_FUNCTIONS
+	public static Task<Permission> RequestPermissionAsync( bool isPicturePermission )
+	{
+		TaskCompletionSource<Permission> tcs = new TaskCompletionSource<Permission>();
+		RequestPermissionAsync( ( permission ) => tcs.SetResult( permission ), isPicturePermission );
+		return tcs.Task;
+	}
+#endif
+
 	public static bool CanOpenSettings()
 	{
 #if !UNITY_EDITOR && UNITY_IOS

Plugins/NativeCamera/README.txt

@@ -1,4 +1,4 @@
-= Native Camera for Android & iOS (v1.3.9) =
+= Native Camera for Android & iOS (v1.4.0) =
 
 Online documentation & example code available at: https://github.com/yasirkula/UnityNativeCamera
 E-mail: yasirkula@gmail.com
@@ -38,6 +38,7 @@ enum NativeCamera.Permission { Denied = 0, Granted = 1, ShouldAsk = 2 };
 enum NativeCamera.Quality { Default = -1, Low = 0, Medium = 1, High = 2 };
 enum NativeCamera.ImageOrientation { Unknown = -1, Normal = 0, Rotate90 = 1, Rotate180 = 2, Rotate270 = 3, FlipHorizontal = 4, Transpose = 5, FlipVertical = 6, Transverse = 7 }; // EXIF orientation: http://sylvana.net/jpegcrop/exif_orientation.html (indices are reordered)
 
+delegate void PermissionCallback( NativeCamera.Permission permission );
 delegate void CameraCallback( string path );
 
 //// Accessing Camera ////
@@ -66,6 +67,10 @@ bool NativeCamera.IsCameraBusy(); // returns true if the camera is currently ope
 NativeCamera.Permission NativeCamera.CheckPermission( bool isPicturePermission );
 NativeCamera.Permission NativeCamera.RequestPermission( bool isPicturePermission );
 
+// Asynchronous variants of RequestPermission. Unlike RequestPermission, these functions don't freeze the app unnecessarily before the permission dialog is displayed. So it's recommended to call these functions instead
+void NativeCamera.RequestPermissionAsync( PermissionCallback callback, PermissionType permissionType, MediaType mediaTypes );
+Task<NativeCamera.Permission> NativeCamera.RequestPermissionAsync( PermissionType permissionType, MediaType mediaTypes );
+
 // If permission state is Permission.Denied, user must grant the necessary permission(s) manually from the Settings (Android requires Storage and, if declared in AndroidManifest, Camera permissions; iOS requires Camera permission). These functions help you open the Settings directly from within the app
 void NativeCamera.OpenSettings();
 bool NativeCamera.CanOpenSettings();

Plugins/NativeCamera/iOS/NCPermissionCallbackiOS.cs

@@ -0,0 +1,34 @@
+#if UNITY_EDITOR || UNITY_IOS
+using UnityEngine;
+
+namespace NativeCameraNamespace
+{
+	public class NCPermissionCallbackiOS : MonoBehaviour
+	{
+		private static NCPermissionCallbackiOS instance;
+		private NativeCamera.PermissionCallback callback;
+
+		public static void Initialize( NativeCamera.PermissionCallback callback )
+		{
+			if( instance == null )
+			{
+				instance = new GameObject( "NCPermissionCallbackiOS" ).AddComponent<NCPermissionCallbackiOS>();
+				DontDestroyOnLoad( instance.gameObject );
+			}
+			else if( instance.callback != null )
+				instance.callback( NativeCamera.Permission.ShouldAsk );
+
+			instance.callback = callback;
+		}
+
+		public void OnPermissionRequested( string message )
+		{
+			NativeCamera.PermissionCallback _callback = callback;
+			callback = null;
+
+			if( _callback != null )
+				_callback( (NativeCamera.Permission) int.Parse( message ) );
+		}
+	}
+}
+#endif

Plugins/NativeCamera/iOS/NCPermissionCallbackiOS.cs.meta

@@ -14,7 +14,7 @@
 
 @interface UNativeCamera:NSObject
 + (int)checkPermission;
-+ (int)requestPermission;
++ (int)requestPermission:(BOOL)asyncMode;
 + (int)canOpenSettings;
 + (void)openSettings;
 + (int)hasCamera;
@@ -55,7 +55,16 @@ + (int)checkPermission
 }
 
 // Credit: https://stackoverflow.com/a/20464727/2373034
-+ (int)requestPermission
++ (int)requestPermission:(BOOL)asyncMode
+{
+	int result = [self requestPermissionInternal:asyncMode];
+	if( asyncMode && result >= 0 ) // Result returned immediately, forward it
+		UnitySendMessage( "NCPermissionCallbackiOS", "OnPermissionRequested", [self getCString:[NSString stringWithFormat:@"%d", result]] );
+		
+	return result;
+}
+
++ (int)requestPermissionInternal:(BOOL)asyncMode
 {
 	if( CHECK_IOS_VERSION( @"7.0" ) )
 	{
@@ -64,17 +73,28 @@ + (int)requestPermission
 			return 1;
 		else if( status == AVAuthorizationStatusNotDetermined )
 		{
-			__block BOOL authorized = NO;
-			
-			dispatch_semaphore_t sema = dispatch_semaphore_create( 0 );
-			[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^( BOOL granted )
+			if( asyncMode )
 			{
-				authorized = granted;
-				dispatch_semaphore_signal( sema );
-			}];
-			dispatch_semaphore_wait( sema, DISPATCH_TIME_FOREVER );
-			
-			return authorized ? 1 : 0;
+				[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^( BOOL granted )
+				{
+					UnitySendMessage( "NCPermissionCallbackiOS", "OnPermissionRequested", granted ? "1" : "0" );
+				}];
+				
+				return -1;
+			}
+			else
+			{
+				__block BOOL authorized = NO;
+				dispatch_semaphore_t sema = dispatch_semaphore_create( 0 );
+				[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^( BOOL granted )
+				{
+					authorized = granted;
+					dispatch_semaphore_signal( sema );
+				}];
+				dispatch_semaphore_wait( sema, DISPATCH_TIME_FOREVER );
+				
+				return authorized ? 1 : 0;
+			}
 		}
 		else
 			return 0;
@@ -552,9 +572,9 @@ + (char *)getCString:(NSString *)source
 	return [UNativeCamera checkPermission];
 }
 
-extern "C" int _NativeCamera_RequestPermission()
+extern "C" int _NativeCamera_RequestPermission( int asyncMode )
 {
-	return [UNativeCamera requestPermission];
+	return [UNativeCamera requestPermission:( asyncMode == 1 )];
 }
 
 extern "C" int _NativeCamera_CanOpenSettings()

Plugins/NativeCamera/iOS/NativeCamera.mm

@@ -1,7 +1,7 @@
 {
   "name": "com.yasirkula.nativecamera",
   "displayName": "Native Camera",
-  "version": "1.3.9",
+  "version": "1.4.0",
   "documentationUrl": "https://github.com/yasirkula/UnityNativeCamera",
   "changelogUrl": "https://github.com/yasirkula/UnityNativeCamera/releases",
   "licensesUrl": "https://github.com/yasirkula/UnityNativeCamera/blob/master/LICENSE.txt",