Implement introduction screen.

Fixes #1316.

src/main/java/de/dennisguse/opentracks/AboutActivity.java

@@ -33,4 +33,10 @@ public class AboutActivity extends AbstractActivity {
         viewBinding = AboutBinding.inflate(getLayoutInflater());
         return viewBinding.getRoot();
     }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+    }
 }

src/main/java/de/dennisguse/opentracks/TrackListActivity.java

@@ -159,8 +159,6 @@ public class TrackListActivity extends AbstractTrackDeleteActivity implements Co
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
-        SplashScreen.installSplashScreen(this);
-
         super.onCreate(savedInstanceState);
         setDefaultKeyMode(DEFAULT_KEYS_SEARCH_LOCAL);
 

src/main/java/de/dennisguse/opentracks/introduction/IntroductionActivity.java

@@ -0,0 +1,93 @@
+package de.dennisguse.opentracks.introduction;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.core.splashscreen.SplashScreen;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.viewpager2.adapter.FragmentStateAdapter;
+
+import java.util.List;
+
+import de.dennisguse.opentracks.AbstractActivity;
+import de.dennisguse.opentracks.TrackListActivity;
+import de.dennisguse.opentracks.databinding.IntroductionBinding;
+import de.dennisguse.opentracks.settings.PreferencesUtils;
+import de.dennisguse.opentracks.util.IntentUtils;
+
+public class IntroductionActivity extends AbstractActivity {
+
+    private IntroductionBinding viewBinding;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        SplashScreen.installSplashScreen(this);
+
+        super.onCreate(savedInstanceState);
+
+        if (!PreferencesUtils.shouldShowIntroduction()) {
+            startActivity(new Intent(this, TrackListActivity.class));
+            finish();
+        }
+
+        viewBinding.nextButton.setOnClickListener(v -> {
+            int nextItemId = viewBinding.introductionViewPager.getCurrentItem() + 1;
+            if (nextItemId < viewBinding.introductionViewPager.getAdapter().getItemCount()) {
+                viewBinding.introductionViewPager.setCurrentItem(nextItemId);
+            } else {
+                PreferencesUtils.setShowIntroduction(false);
+                startActivity(IntentUtils.newIntent(this, TrackListActivity.class));
+                finish();
+            }
+        });
+        viewBinding.introductionViewPager.setAdapter(new CustomFragmentPagerAdapter(this));
+        viewBinding.introductionViewPager.setUserInputEnabled(false);
+    }
+
+    @Override
+    protected View getRootView() {
+        viewBinding = IntroductionBinding.inflate(getLayoutInflater());
+        return viewBinding.getRoot();
+    }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+    }
+
+    private static class CustomFragmentPagerAdapter extends FragmentStateAdapter {
+
+        private static final List<FragmentCreator> fragmentCreators = List.of(
+                (FragmentCreator) WelcomeFragment::newInstance,
+                (FragmentCreator) OSMDashboardFragment::newInstance
+        );
+
+        public CustomFragmentPagerAdapter(@NonNull FragmentActivity fa) {
+            super(fa);
+        }
+
+        @NonNull
+        @Override
+        public Fragment createFragment(int position) {
+            FragmentCreator fc = fragmentCreators.get(position);
+            if (fc != null) {
+                return fc.newInstance();
+            }
+
+            throw new RuntimeException("There isn't Fragment associated with the position: " + position);
+        }
+
+        @Override
+        public int getItemCount() {
+            return fragmentCreators.size();
+        }
+    }
+
+    private interface FragmentCreator {
+        Fragment newInstance();
+    }
+}

src/main/java/de/dennisguse/opentracks/introduction/OSMDashboardFragment.java

@@ -0,0 +1,32 @@
+package de.dennisguse.opentracks.introduction;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+
+import de.dennisguse.opentracks.databinding.OsmDashboardBinding;
+
+public class OSMDashboardFragment extends Fragment {
+
+    public static OSMDashboardFragment newInstance() {
+        return new OSMDashboardFragment();
+    }
+
+    private OsmDashboardBinding viewBinding;
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        viewBinding = OsmDashboardBinding.inflate(inflater, container, false);
+        return viewBinding.getRoot();
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+    }
+}

src/main/java/de/dennisguse/opentracks/introduction/WelcomeFragment.java

@@ -0,0 +1,37 @@
+package de.dennisguse.opentracks.introduction;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+
+import de.dennisguse.opentracks.databinding.WelcomeBinding;
+
+public class WelcomeFragment extends Fragment {
+
+    public static WelcomeFragment newInstance() {
+        return new WelcomeFragment();
+    }
+
+    private WelcomeBinding viewBinding;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+    }
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        viewBinding = WelcomeBinding.inflate(inflater, container, false);
+        return viewBinding.getRoot();
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+    }
+}

src/main/java/de/dennisguse/opentracks/settings/PreferencesUtils.java

@@ -197,6 +197,14 @@ public class PreferencesUtils {
         return getBoolean(R.string.publicapi_dashboard_enabled_key, resources.getBoolean(R.bool.publicapi_dashboard_enabled_default));
     }
 
+    public static boolean shouldShowIntroduction() {
+        return getBoolean(R.string.show_introduction_screen_key, resources.getBoolean(R.bool.show_introduction_screen_default));
+    }
+
+    public static void setShowIntroduction(boolean introduction) {
+        setBoolean(R.string.show_introduction_screen_key, introduction);
+    }
+
     public static UnitSystem getUnitSystem() {
         final String STATS_UNIT_DEFAULT = resources.getString(R.string.stats_units_default);