Request draw over other apps permission

Author: Luis Correa

android/app/src/main/AndroidManifest.xml

@@ -8,6 +8,7 @@
 
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.CALL_PHONE" />
+    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
 
     <application
         android:name="io.flutter.app.FlutterApplication"

android/app/src/main/kotlin/com/cubanopensource/todo/MainActivity.kt

@@ -1,6 +1,41 @@
 package com.cubanopensource.todo
 
+import android.content.Intent
+import android.net.Uri
+import android.os.Build
+import android.provider.Settings
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodChannel
 
 class MainActivity: FlutterActivity() {
+    private val CHANNEL = "todoappchannel_android"
+
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        super.configureFlutterEngine(flutterEngine)
+
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler {
+            call, result ->
+
+            when {
+                call.method == "getDrawPermissionState" -> result.success(getDrawPermissionState())
+                call.method == "reqDrawPermission" -> result.success(reqDrawPermission())
+                else -> result.notImplemented()
+            }
+        }
+    }
+
+    private fun getDrawPermissionState(): Boolean {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
+            return (Settings.canDrawOverlays(this))
+
+        return true
+    }
+
+    private fun reqDrawPermission() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            val intent = Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:${packageName}"))
+            startActivityForResult(intent, 1)
+        }
+    }
 }

lib/pages/home_page.dart

@@ -1,15 +1,16 @@
+import 'package:connectivity/connectivity.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
+import 'package:provider/provider.dart';
+import 'package:quick_actions/quick_actions.dart';
 import 'package:shared_preferences/shared_preferences.dart';
-import 'package:todo/pages/login_page.dart';
-import 'package:todo/components/ussd_widget.dart';
 import 'package:todo/components/disclaim.dart';
-import 'package:connectivity/connectivity.dart';
+import 'package:todo/components/ussd_widget.dart';
+import 'package:todo/pages/account_page.dart';
+import 'package:todo/pages/login_page.dart';
 import 'package:todo/pages/settings_page.dart';
-import 'package:provider/provider.dart';
 import 'package:todo/services/AppStateNotifier.dart';
-import 'package:todo/pages/account_page.dart';
-import 'package:quick_actions/quick_actions.dart';
+import 'package:todo/services/PlatformService.dart';
 import 'package:todo/services/phone.dart';
 
 class HomePage extends StatefulWidget {
@@ -117,6 +118,8 @@ class _HomePageState extends State<HomePage> {
         );
     });
 
+    showReqDrawDialog(context);
+
     return Scaffold(
       floatingActionButton: FloatingActionButton(
         backgroundColor: Theme.of(context).focusColor,
@@ -205,4 +208,37 @@ class _HomePageState extends State<HomePage> {
       ),
     );
   }
+
+  showReqDrawDialog(BuildContext context) async {
+    if (await getDrawPermissionState()) {
+      return;
+    }
+
+    Widget continueButton = FlatButton(
+      child: Text("Continuar"),
+      onPressed: () async {
+        await reqDrawPermission();
+        Navigator.pop(context);
+      },
+    );
+
+    // set up the AlertDialog
+    AlertDialog alert = AlertDialog(
+      title: Text("Solicitud de permiso"),
+      content: Text(
+          "Hola, perdona la molestia pero necesito permiso para poder mostrarte información sobre tu velocidad de conexión,"
+          " por favor toca en el botón de continuar y habilita la superposición de pantalla"),
+      actions: [
+        continueButton,
+      ],
+    );
+
+    // show the dialog
+    await showDialog(
+      context: context,
+      builder: (BuildContext context) {
+        return alert;
+      },
+    );
+  }
 }

lib/services/PlatformService.dart

@@ -0,0 +1,26 @@
+import 'package:flutter/services.dart';
+
+const platform = const MethodChannel("todoappchannel_android");
+
+Future<bool> getDrawPermissionState() async {
+  bool drawPermission;
+
+  try {
+    final result = await platform.invokeMethod("getDrawPermissionState");
+    drawPermission = result;
+  } catch (e) {
+    drawPermission = false;
+  }
+
+  return drawPermission;
+}
+
+Future<void> reqDrawPermission() async {
+  if(! await getDrawPermissionState()) {
+    try {
+      await platform.invokeMethod("reqDrawPermission");
+    } catch (e) {
+      print(e.message);
+    }
+  }
+}