Added async variants of RequestPermission function that don't freeze …

…the app unnecessarily

.github/README.md

@@ -131,6 +131,11 @@ There are two functions to handle permissions with this plugin:
 
 `NativeGallery.Permission NativeGallery.RequestPermission( PermissionType permissionType, MediaType mediaTypes )`: requests permission to access Gallery/Photos 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 the SaveImageToGallery/SaveVideoToGallery and GetImageFromGallery/GetVideoFromGallery functions call RequestPermission internally and execute only if the permission is granted (the result of RequestPermission is also returned).
 
+`void NativeGallery.RequestPermissionAsync( PermissionCallback callback, PermissionType permissionType, MediaType mediaTypes )`: 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 `NativeGallery.Permission permission` parameter
+
+`Task<NativeGallery.Permission> NativeGallery.RequestPermissionAsync( PermissionType permissionType, MediaType mediaTypes )`: Another asynchronous variant of *RequestPermission* (requires Unity 2018.4 or later).
+
 `NativeGallery.OpenSettings()`: opens the settings for this app, from where the user can manually grant permission in case current permission state is *Permission.Denied* (on Android, the necessary permission is named *Storage* and on iOS, the necessary permission is named *Photos*).
 
 `bool NativeGallery.CanOpenSettings()`: on iOS versions prior to 8.0, opening settings from within app is not possible and in this case, this function returns *false*. Otherwise, it returns *true*.
@@ -197,6 +202,14 @@ 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 NativeGallery functions
+private async void RequestPermissionAsynchronously( NativeGallery.PermissionType permissionType, NativeGallery.MediaType mediaTypes )
+{
+	NativeGallery.Permission permission = await NativeGallery.RequestPermissionAsync( permissionType, mediaTypes );
+	Debug.Log( "Permission result: " + permission );
+}
+
 private IEnumerator TakeScreenshotAndSave()
 {
 	yield return new WaitForEndOfFrame();

Plugins/NativeGallery/Android/NGCallbackHelper.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/NativeGallery/Android/NGMediaReceiveCallbackAndroid.cs

@@ -19,7 +19,7 @@ public NGMediaReceiveCallbackAndroid( NativeGallery.MediaPickCallback callback,
 
 		public void OnMediaReceived( string path )
 		{
-			callbackHelper.CallOnMainThread( () => MediaReceiveCallback( path ) );
+			callbackHelper.CallOnMainThread( () => callback( !string.IsNullOrEmpty( path ) ? path : null ) );
 		}
 
 		public void OnMultipleMediaReceived( string paths )
@@ -53,39 +53,7 @@ public void OnMultipleMediaReceived( string paths )
 				result = pathsSplit;
 			}
 
-			callbackHelper.CallOnMainThread( () => MediaReceiveMultipleCallback( result ) );
-		}
-
-		private void MediaReceiveCallback( string path )
-		{
-			if( string.IsNullOrEmpty( path ) )
-				path = null;
-
-			try
-			{
-				if( callback != null )
-					callback( path );
-			}
-			finally
-			{
-				Object.Destroy( callbackHelper.gameObject );
-			}
-		}
-
-		private void MediaReceiveMultipleCallback( string[] paths )
-		{
-			if( paths != null && paths.Length == 0 )
-				paths = null;
-
-			try
-			{
-				if( callbackMultiple != null )
-					callbackMultiple( paths );
-			}
-			finally
-			{
-				Object.Destroy( callbackHelper.gameObject );
-			}
+			callbackHelper.CallOnMainThread( () => callbackMultiple( ( result != null && result.Length > 0 ) ? result : null ) );
 		}
 	}
 }

Plugins/NativeGallery/Android/NGPermissionCallbackAndroid.cs

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

Plugins/NativeGallery/NativeGallery.cs

@@ -55,6 +55,7 @@ public enum MediaType { Image = 1, Video = 2, Audio = 4 };
 	// 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 MediaSaveCallback( bool success, string path );
 	public delegate void MediaPickCallback( string path );
 	public delegate void MediaPickMultipleCallback( string[] paths );
@@ -94,7 +95,7 @@ private static AndroidJavaObject Context
 	private static extern int _NativeGallery_CheckPermission( int readPermission, int permissionFreeMode );
 
 	[System.Runtime.InteropServices.DllImport( "__Internal" )]
-	private static extern int _NativeGallery_RequestPermission( int readPermission, int permissionFreeMode );
+	private static extern int _NativeGallery_RequestPermission( int readPermission, int permissionFreeMode, int asyncMode );
 
 	[System.Runtime.InteropServices.DllImport( "__Internal" )]
 	private static extern void _NativeGallery_ShowLimitedLibraryPicker();
@@ -186,16 +187,18 @@ public static Permission CheckPermission( PermissionType permissionType, MediaTy
 
 		return result;
 #elif !UNITY_EDITOR && UNITY_IOS
-		// result == 3: LimitedAccess permission on iOS, no need to handle it when PermissionFreeMode is set to true
-		int result = _NativeGallery_CheckPermission( permissionType == PermissionType.Read ? 1 : 0, PermissionFreeMode ? 1 : 0 );
-		return result == 3 ? Permission.Granted : (Permission) result;
+		return ProcessPermission( (Permission) _NativeGallery_CheckPermission( permissionType == PermissionType.Read ? 1 : 0, PermissionFreeMode ? 1 : 0 ) );
 #else
 		return Permission.Granted;
 #endif
 	}
 
 	public static Permission RequestPermission( PermissionType permissionType, MediaType mediaTypes )
 	{
+		// Don't block the main thread if the permission is already granted
+		if( CheckPermission( permissionType, mediaTypes ) == Permission.Granted )
+			return Permission.Granted;
+
 #if !UNITY_EDITOR && UNITY_ANDROID
 		object threadLock = new object();
 		lock( threadLock )
@@ -216,14 +219,40 @@ public static Permission RequestPermission( PermissionType permissionType, Media
 			return (Permission) nativeCallback.Result;
 		}
 #elif !UNITY_EDITOR && UNITY_IOS
-		// result == 3: LimitedAccess permission on iOS, no need to handle it when PermissionFreeMode is set to true
-		int result = _NativeGallery_RequestPermission( permissionType == PermissionType.Read ? 1 : 0, PermissionFreeMode ? 1 : 0 );
-		return result == 3 ? Permission.Granted : (Permission) result;
+		return ProcessPermission( (Permission) _NativeGallery_RequestPermission( permissionType == PermissionType.Read ? 1 : 0, PermissionFreeMode ? 1 : 0, 0 ) );
 #else
 		return Permission.Granted;
 #endif
 	}
 
+	public static void RequestPermissionAsync( PermissionCallback callback, PermissionType permissionType, MediaType mediaTypes )
+	{
+#if !UNITY_EDITOR && UNITY_ANDROID
+		NGPermissionCallbackAsyncAndroid nativeCallback = new NGPermissionCallbackAsyncAndroid( callback );
+		AJC.CallStatic( "RequestPermission", Context, nativeCallback, permissionType == PermissionType.Read, (int) mediaTypes, (int) Permission.ShouldAsk );
+#elif !UNITY_EDITOR && UNITY_IOS
+		NGPermissionCallbackiOS.Initialize( ( result ) => callback( ProcessPermission( result ) ) );
+		_NativeGallery_RequestPermission( permissionType == PermissionType.Read ? 1 : 0, PermissionFreeMode ? 1 : 0, 1 );
+#else
+		callback( Permission.Granted );
+#endif
+	}
+
+#if UNITY_2018_4_OR_NEWER && !NATIVE_GALLERY_DISABLE_ASYNC_FUNCTIONS
+	public static Task<Permission> RequestPermissionAsync( PermissionType permissionType, MediaType mediaTypes )
+	{
+		TaskCompletionSource<Permission> tcs = new TaskCompletionSource<Permission>();
+		RequestPermissionAsync( ( permission ) => tcs.SetResult( permission ), permissionType, mediaTypes );
+		return tcs.Task;
+	}
+#endif
+
+	private static Permission ProcessPermission( Permission permission )
+	{
+		// result == 3: LimitedAccess permission on iOS, no need to handle it when PermissionFreeMode is set to true
+		return ( PermissionFreeMode && (int) permission == 3 ) ? Permission.Granted : permission;
+	}
+
 	// This function isn't needed when PermissionFreeMode is set to true
 	private static void TryExtendLimitedAccessPermission()
 	{

Plugins/NativeGallery/README.txt

@@ -1,4 +1,4 @@
-= Native Gallery for Android & iOS (v1.7.3) =
+= Native Gallery for Android & iOS (v1.7.4) =
 
 Online documentation & example code available at: https://github.com/yasirkula/UnityNativeGallery
 E-mail: [email protected]
@@ -57,6 +57,7 @@ enum NativeGallery.Permission { Denied = 0, Granted = 1, ShouldAsk = 2 };
 enum NativeGallery.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)
 enum MediaType { Image = 1, Video = 2, Audio = 4 };
 
+delegate void PermissionCallback( NativeGallery.Permission permission );
 delegate void MediaSaveCallback( bool success, string path );
 delegate void NativeGallery.MediaPickCallback( string path );
 delegate void MediaPickMultipleCallback( string[] paths );
@@ -113,6 +114,10 @@ bool NativeGallery.IsMediaPickerBusy();
 NativeGallery.Permission NativeGallery.CheckPermission( PermissionType permissionType, MediaType mediaTypes );
 NativeGallery.Permission NativeGallery.RequestPermission( PermissionType permissionType, MediaType mediaTypes );
 
+// 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 NativeGallery.RequestPermissionAsync( PermissionCallback callback, PermissionType permissionType, MediaType mediaTypes );
+Task<NativeGallery.Permission> NativeGallery.RequestPermissionAsync( PermissionType permissionType, MediaType mediaTypes );
+
 // If permission state is Permission.Denied, user must grant the necessary permission (Storage on Android and Photos on iOS) manually from the Settings. These functions help you open the Settings directly from within the app
 void NativeGallery.OpenSettings();
 bool NativeGallery.CanOpenSettings();

Plugins/NativeGallery/iOS/NGPermissionCallbackiOS.cs

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