Implement intro screen for offline app sharing

briar-android/src/main/AndroidManifest.xml

@@ -441,6 +441,11 @@
 			android:label="@string/pending_contact_requests"
 			android:theme="@style/BriarTheme" />
 
+		<activity
+			android:name=".android.hotspot.HotspotActivity"
+			android:label="@string/hotspot_title"
+			android:theme="@style/BriarTheme" />
+
 	</application>
 
 	<queries>

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -35,6 +35,7 @@ import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.attachment.media.MediaModule;
 import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
+import org.briarproject.briar.android.hotspot.HotspotIntroFragment;
 import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.settings.ConnectionsFragment;
@@ -210,4 +211,6 @@ public interface AndroidComponent
 	void inject(SecurityFragment securityFragment);
 
 	void inject(NotificationsFragment notificationsFragment);
+
+	void inject(HotspotIntroFragment hotspotIntroFragment);
 }

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -35,6 +35,7 @@ import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactModule;
 import org.briarproject.briar.android.forum.ForumModule;
+import org.briarproject.briar.android.hotspot.HotspotModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
@@ -92,6 +93,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		GroupListModule.class,
 		GroupConversationModule.class,
 		SharingModule.class,
+		HotspotModule.class
 })
 public class AppModule {
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -38,6 +38,7 @@ import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
+import org.briarproject.briar.android.hotspot.HotspotActivity;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.introduction.IntroductionMessageFragment;
@@ -176,6 +177,8 @@ public interface ActivityComponent {
 
 	void inject(CrashReportActivity crashReportActivity);
 
+	void inject(HotspotActivity hotspotActivity);
+
 	// Fragments
 
 	void inject(SetupFragment fragment);

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotActivity.java

@@ -0,0 +1,62 @@
+package org.briarproject.briar.android.hotspot;
+
+import android.os.Bundle;
+import android.view.MenuItem;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BriarActivity;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.ActionBar;
+import androidx.lifecycle.ViewModelProvider;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class HotspotActivity extends BriarActivity {
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private HotspotViewModel viewModel;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(HotspotViewModel.class);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+		setContentView(R.layout.activity_fragment_container);
+
+		ActionBar ab = getSupportActionBar();
+		if (ab != null) {
+			ab.setDisplayHomeAsUpEnabled(true);
+		}
+
+		if (state == null) {
+			getSupportFragmentManager().beginTransaction()
+					.replace(R.id.fragmentContainer, new HotspotIntroFragment(),
+							HotspotIntroFragment.TAG)
+					.commit();
+		}
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
+		}
+		return super.onOptionsItemSelected(item);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotIntroFragment.java

@@ -0,0 +1,67 @@
+package org.briarproject.briar.android.hotspot;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.ProgressBar;
+import android.widget.TextView;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static androidx.transition.TransitionManager.beginDelayedTransition;
+import static org.briarproject.briar.android.AppModule.getAndroidComponent;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class HotspotIntroFragment extends Fragment {
+
+	public final static String TAG = HotspotIntroFragment.class.getName();
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private HotspotViewModel viewModel;
+
+	@Override
+	public void onAttach(Context context) {
+		super.onAttach(context);
+		getAndroidComponent(requireContext()).inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(HotspotViewModel.class);
+	}
+
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		View v = inflater
+				.inflate(R.layout.fragment_hotspot_intro, container, false);
+
+		Button startButton = v.findViewById(R.id.startButton);
+		ProgressBar progressBar = v.findViewById(R.id.progressBar);
+		TextView progressTextView = v.findViewById(R.id.progressTextView);
+
+		startButton.setOnClickListener(button -> {
+			beginDelayedTransition((ViewGroup) v);
+			startButton.setVisibility(INVISIBLE);
+			progressBar.setVisibility(VISIBLE);
+			progressTextView.setVisibility(VISIBLE);
+		});
+
+		return v;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotModule.java

@@ -0,0 +1,18 @@
+package org.briarproject.briar.android.hotspot;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public interface HotspotModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(HotspotViewModel.class)
+	ViewModel bindHotspotViewModel(HotspotViewModel hotspotViewModel);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotViewModel.java

@@ -0,0 +1,28 @@
+package org.briarproject.briar.android.hotspot;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+@NotNullByDefault
+class HotspotViewModel extends DbViewModel {
+
+	@Inject
+	HotspotViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+	}
+
+}

briar-android/src/main/res/drawable/ic_wifi_tethering.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M12,11c-1.1,0 -2,0.9 -2,2s0.9,2 2,2 2,-0.9 2,-2 -0.9,-2 -2,-2zM18,13c0,-3.31 -2.69,-6 -6,-6s-6,2.69 -6,6c0,2.22 1.21,4.15 3,5.19l1,-1.74c-1.19,-0.7 -2,-1.97 -2,-3.45 0,-2.21 1.79,-4 4,-4s4,1.79 4,4c0,1.48 -0.81,2.75 -2,3.45l1,1.74c1.79,-1.04 3,-2.97 3,-5.19zM12,3C6.48,3 2,7.48 2,13c0,3.7 2.01,6.92 4.99,8.65l1,-1.73C5.61,18.53 4,15.96 4,13c0,-4.42 3.58,-8 8,-8s8,3.58 8,8c0,2.96 -1.61,5.53 -4,6.92l1,1.73c2.99,-1.73 5,-4.95 5,-8.65 0,-5.52 -4.48,-10 -10,-10z" />
+</vector>

briar-android/src/main/res/layout/fragment_hotspot_intro.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	tools:context=".android.hotspot.HotspotIntroFragment">
+
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:layout_marginStart="64dp"
+		android:layout_marginLeft="64dp"
+		android:layout_marginTop="32dp"
+		android:layout_marginEnd="64dp"
+		android:layout_marginRight="64dp"
+		android:layout_marginBottom="32dp"
+		app:layout_constraintBottom_toTopOf="@+id/introView"
+		app:layout_constraintDimensionRatio="1,1"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		app:layout_constraintVertical_chainStyle="spread_inside"
+		app:srcCompat="@drawable/ic_nickname"
+		tools:ignore="ContentDescription" />
+
+	<TextView
+		android:id="@+id/introView"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_margin="16dp"
+		android:text="@string/hotspot_intro"
+		app:layout_constraintBottom_toTopOf="@+id/startButton"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_bias="0.5"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/imageView" />
+
+	<Button
+		android:id="@+id/startButton"
+		style="@style/BriarButton"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_margin="16dp"
+		android:drawablePadding="6dp"
+		android:text="@string/hotspot_button_start_sharing"
+		app:drawableLeftCompat="@drawable/ic_wifi_tethering"
+		app:drawableStartCompat="@drawable/ic_wifi_tethering"
+		app:drawableTint="@color/button_text"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_bias="0.812"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/introView"
+		app:layout_constraintVertical_bias="1.0"
+		tools:visibility="visible" />
+
+	<ProgressBar
+		android:id="@+id/progressBar"
+		style="?android:attr/progressBarStyle"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:visibility="invisible"
+		app:layout_constraintBottom_toBottomOf="@+id/startButton"
+		app:layout_constraintEnd_toStartOf="@+id/progressTextView"
+		app:layout_constraintHorizontal_chainStyle="packed"
+		app:layout_constraintStart_toStartOf="@+id/startButton"
+		app:layout_constraintTop_toTopOf="@+id/startButton"
+		tools:visibility="visible" />
+
+	<TextView
+		android:id="@+id/progressTextView"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:text="@string/hotspot_progress_text_start"
+		android:visibility="invisible"
+		app:layout_constraintBottom_toBottomOf="@+id/startButton"
+		app:layout_constraintEnd_toEndOf="@+id/startButton"
+		app:layout_constraintStart_toEndOf="@+id/progressBar"
+		app:layout_constraintTop_toTopOf="@+id/startButton"
+		tools:visibility="visible" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

briar-android/src/main/res/values/strings.xml

@@ -689,6 +689,14 @@
 	<!-- Connections Screen -->
 	<string name="transports_help_text">Briar can connect to your contacts via the Internet, Wi-Fi or Bluetooth.\n\nAll Internet connections go through the Tor network for privacy.\n\nIf a contact can be reached by multiple methods, Briar uses them in parallel.</string>
 
+	<!-- Share app offline -->
+	<string name="hotspot_title">Share Briar offline</string>
+	<string name="hotspot_intro">Share this app with someone nearby without internet connection
+		by using your phone\'s Wi-Fi.
+		\n\nYour phone will open a local hotspot and provide a small website with a download of this app.</string>
+	<string name="hotspot_button_start_sharing">Start sharing</string>
+	<string name="hotspot_progress_text_start">Setting up hotspot…</string>
+
 	<!-- Screenshots -->
 
 	<!-- This is a name to be used in screenshots. Feel free to change it to a local name. -->