[PAINTROID - 776] Second instance of app is opened when catrobat image is opened from files

android/app/src/main/AndroidManifest.xml

@@ -29,12 +29,19 @@
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:exported="true"
             android:hardwareAccelerated="true"
-            android:launchMode="singleTop"
+            android:launchMode="singleTask"
             android:theme="@style/LaunchTheme"
             android:windowSoftInputMode="adjustResize">
             <meta-data
                 android:name="io.flutter.embedding.android.NormalTheme"
                 android:resource="@style/NormalTheme" />
+            <intent-filter android:label="Pocket Paint">
+                <action android:name="android.intent.action.VIEW" />
+                <action android:name="android.intent.action.EDIT" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:mimeType="image/*" />
+            </intent-filter>
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />

android/app/src/main/kotlin/org/catrobat/paintroid/MainActivity.kt

@@ -2,7 +2,9 @@ package org.catrobat.paintroid
 
 import android.Manifest
 import android.content.ContentValues
+import android.content.Intent
 import android.content.pm.PackageManager
+import android.net.Uri
 import android.os.Build
 import android.provider.MediaStore
 import androidx.annotation.NonNull
@@ -15,6 +17,7 @@ import io.flutter.plugin.common.MethodChannel
 import java.io.IOException
 
 class MainActivity : FlutterActivity() {
+    private var initialFileUri: String? = null
     private val hasWritePermission: Boolean
         get() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q ||
                 ContextCompat.checkSelfPermission(
@@ -26,22 +29,64 @@ class MainActivity : FlutterActivity() {
         super.configureFlutterEngine(flutterEngine)
         setupPhotoLibraryChannel(flutterEngine)
         setupDeviceChannel(flutterEngine)
+        setupFileHandlerChannel(flutterEngine)
+        handleIntent(intent)
+    }
+    override fun onNewIntent(intent: Intent) {
+        super.onNewIntent(intent)
+        handleIntent(intent)
+    }
+
+    private fun handleIntent(intent: Intent?) {
+        val action = intent?.action
+        val data: Uri? = intent?.data
+        if ((Intent.ACTION_VIEW == action || Intent.ACTION_EDIT == action) && data != null) {
+            initialFileUri = data.toString()
+        }
+    }
+
+    private fun setupFileHandlerChannel(flutterEngine: FlutterEngine) {
+        MethodChannel(
+            flutterEngine.dartExecutor.binaryMessenger, "org.catrobat.paintroid/file_handler"
+        ).setMethodCallHandler { call, result ->
+            when (call.method) {
+                "getInitialFile" -> {
+                    result.success(initialFileUri)
+                    initialFileUri = null
+                }
+                "getFileBytes" -> {
+                    val uriString = call.argument<String>("uri")
+                    if (uriString != null) {
+                        try {
+                            val uri = Uri.parse(uriString)
+                            val bytes = contentResolver.openInputStream(uri)?.use { it.readBytes() }
+                            result.success(bytes)
+                        } catch (e: Exception) {
+                            result.error("IO_ERROR", "Failed to read URI: ${e.message}", null)
+                        }
+                    } else {
+                        result.error("INVALID_ARGUMENT", "URI is null", null)
+                    }
+                }
+                else -> result.notImplemented()
+            }
+        }
     }
 
     private fun setupDeviceChannel(flutterEngine: FlutterEngine) {
         MethodChannel(
             flutterEngine.dartExecutor.binaryMessenger, "org.catrobat.paintroid/device"
         ).apply {
-            setMethodCallHandler { call, result ->
-                when (call.method) {
-                    "getHeightInPixels" -> {
-                        val windowMetrics = WindowMetricsCalculator.getOrCreate()
-                            .computeMaximumWindowMetrics(activity)
-                        val height = windowMetrics.bounds.height()
-                        result.success(height.toDouble())
-                    }
-                    else -> result.notImplemented()
+        setMethodCallHandler { call, result ->
+            when (call.method) {
+                "getHeightInPixels" -> {
+                    val windowMetrics = WindowMetricsCalculator.getOrCreate()
+                        .computeMaximumWindowMetrics(activity)
+                    val height = windowMetrics.bounds.height()
+                    result.success(height.toDouble())
                 }
+               else -> result.notImplemented()
+            }
             }
         }
     }
@@ -50,24 +95,24 @@ class MainActivity : FlutterActivity() {
         MethodChannel(
             flutterEngine.dartExecutor.binaryMessenger, "org.catrobat.paintroid/photo_library"
         ).apply {
-            setMethodCallHandler { call, result ->
-                when (call.method) {
-                    "saveToPhotos" -> {
-                        if (!hasWritePermission) {
-                            result.error(
-                                "PERMISSION_DENIED",
-                                "User explicitly denied WRITE_EXTERNAL_STORAGE permission",
-                                null
-                            )
-                            return@setMethodCallHandler
-                        }
-                        val (filename, imageData) = extractImageData(call, result)
-                            ?: return@setMethodCallHandler
+        setMethodCallHandler { call, result ->
+            when (call.method) {
+                "saveToPhotos" -> {
+                    if (!hasWritePermission) {
+                        result.error(
+                            "PERMISSION_DENIED",
+                            "User explicitly denied WRITE_EXTERNAL_STORAGE permission",
+                            null
+                        )
+                        return@setMethodCallHandler
+                    }
+                    val (filename, imageData) = extractImageData(call, result)
+                        ?: return@setMethodCallHandler
                         saveImageToPictures(filename, imageData)
                         result.success(null)
-                    }
-                    else -> result.notImplemented()
                 }
+                else -> result.notImplemented()
+            }
             }
         }
     }
@@ -99,7 +144,7 @@ class MainActivity : FlutterActivity() {
             return null
         }
         val imageData = call.argument<ByteArray>("data") ?: run {
-            result.error(
+          result.error(
                 "INVALID_IMAGE_DATA",
                 "Image data is either not supplied or not of type UInt8List",
                 null

lib/app.dart

@@ -11,8 +11,9 @@ import 'package:paintroid/ui/theme/theme.dart';
 
 class App extends StatelessWidget {
   final bool showOnboardingPage;
+  final String? initialFileUri;
 
-  App({super.key, required this.showOnboardingPage});
+  App({super.key, required this.showOnboardingPage,this.initialFileUri});
 
   final _lightTheme = LightPaintroidThemeData();
   final _darkTheme = DarkPaintroidThemeData();
@@ -42,7 +43,7 @@ class App extends StatelessWidget {
                     ? const OnboardingPage(
                         navigateTo: LandingPage(title: 'Pocket Paint'),
                       )
-                    : const LandingPage(title: 'Pocket Paint'),
+                    :LandingPage(title: 'Pocket Paint',initialFileUri:initialFileUri),                   
               );
             case '/PocketPaint':
               return MaterialPageRoute(
@@ -66,7 +67,7 @@ class App extends StatelessWidget {
               child: child,
             );
           },
-          child: const LandingPage(title: 'Pocket Paint'),
+          child:  LandingPage(title: 'Pocket Paint',initialFileUri:initialFileUri),          
         ),
       ),
     );

lib/main.dart

@@ -1,7 +1,7 @@
 import 'dart:developer';
 
 import 'package:flutter/material.dart';
-
+import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:logging/logging.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -25,8 +25,17 @@ void main() async {
   );
 
   WidgetsFlutterBinding.ensureInitialized();
+  const platform = MethodChannel('org.catrobat.paintroid/file_handler');
+  String? initialFileUri;
+
+  try {
+    initialFileUri = await platform.invokeMethod('getInitialFile');
+  } on PlatformException catch (e) {
+    log("Failed to get initial file: '${e.message}'.");
+  }
+
   final prefs = await SharedPreferences.getInstance();
   final showOnboarding = prefs.getBool('showOnboarding') ?? true;
 
-  runApp(ProviderScope(child: App(showOnboardingPage: showOnboarding)));
+  runApp(ProviderScope(child: App(showOnboardingPage: showOnboarding,initialFileUri: initialFileUri)));
 }

lib/ui/pages/landing_page/landing_page.dart

@@ -1,4 +1,7 @@
+import 'dart:developer';
+import 'dart:ui' as ui;
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart'; 
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:oxidized/oxidized.dart';
 import 'package:paintroid/core/database/project_database.dart';
@@ -23,8 +26,9 @@ import 'package:toast/toast.dart';
 
 class LandingPage extends ConsumerStatefulWidget {
   final String title;
-
-  const LandingPage({super.key, required this.title});
+  final String? initialFileUri;
+
+  const LandingPage({super.key, required this.title,this.initialFileUri});
 
   @override
   ConsumerState<LandingPage> createState() => _LandingPageState();
@@ -35,13 +39,65 @@ class _LandingPageState extends ConsumerState<LandingPage> {
   late IFileService fileService;
   late IImageService imageService;
 
+  @override
+  void initState() {
+    super.initState();
+
+    final platform = MethodChannel('org.catrobat.paintroid/file_handler');
+    SystemChannels.lifecycle.setMessageHandler((msg) async {
+      if (msg == AppLifecycleState.resumed.toString()) {
+        final String? newUri = await platform.invokeMethod('getInitialFile');
+        if (newUri != null) {
+          _handleInitialFile(newUri);
+        }
+      }
+      return null;
+    });
+
+    if (widget.initialFileUri != null) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        _handleInitialFile(widget.initialFileUri!);
+      });
+    }
+  }
+
+  Future<void> _handleInitialFile(String uri) async {
+    if (mounted) {
+      final ioHandler = ref.read(IOHandler.provider);
+      final shouldContinue = await ioHandler.handleUnsavedChanges(context, this);
+      if (!shouldContinue) return;
+    }
+
+    ref.read(workspaceStateProvider.notifier).performIOTask(() async {
+      try {
+        final platform = const MethodChannel('org.catrobat.paintroid/file_handler');
+        final Uint8List? imageBytes = await platform.invokeMethod('getFileBytes', {'uri': uri});
+
+        if (imageBytes != null && mounted) {
+          _clearCanvas();
+          final ui.Image image = await decodeImageFromList(imageBytes);
+          ref.read(canvasStateProvider.notifier).setBackgroundImage(image);
+          if (!mounted) return;
+          final currentRoute = ModalRoute.of(context)?.settings.name;
+          if (currentRoute != '/PocketPaint') {
+             await _navigateToPocketPaint();
+          } else {
+             setState(() {});
+          }
+        }
+      } catch (e) {
+        log('error in loading file from Intent: $e');
+        ToastUtils.showShortToast(message: 'failed to open image from file.');
+      }
+    });
+  }
   Future<List<Project>> _getProjects() async {
     return database.projectDAO.getProjects();
   }
 
   Future<void> _navigateToPocketPaint() async {
     await Navigator.pushNamed(context, '/PocketPaint');
-    setState(() {});
+     if (mounted){setState(() {});}
   }
 
   Future<bool> _loadProject(IOHandler ioHandler, Project project) async {