Test view pager and tab layout with support map fragment to see it works, it works!

app/src/main/java/fr/free/nrw/commons/nearby/NearbyTestFragmentLayersActivity.java

@@ -1,14 +1,183 @@
 package fr.free.nrw.commons.nearby;
 
 import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
 
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentPagerAdapter;
+import androidx.viewpager.widget.ViewPager;
+
+import com.google.android.material.tabs.TabLayout;
+
+import butterknife.BindView;
+import butterknife.ButterKnife;
 import fr.free.nrw.commons.R;
+import fr.free.nrw.commons.contributions.UnswipableViewPager;
 import fr.free.nrw.commons.theme.NavigationBaseActivity;
+import timber.log.Timber;
 
 public class NearbyTestFragmentLayersActivity extends NavigationBaseActivity {
+
+    @BindView(R.id.tab_layout)
+    TabLayout tabLayout;
+    @BindView(R.id.pager)
+    UnswipableViewPager viewPager;
+    public static final int CONTRIBUTIONS_TAB_POSITION = 0;
+    public static final int NEARBY_TAB_POSITION = 1;
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_nearby_test_fragment_layers);
+        ButterKnife.bind(this);
+        addTabsAndFragments();
+
     }
+
+    private void addTabsAndFragments() {
+        ContributionsActivityPagerAdapter contributionsActivityPagerAdapter = new ContributionsActivityPagerAdapter(getSupportFragmentManager());
+        viewPager.setAdapter(contributionsActivityPagerAdapter);
+
+        tabLayout.addTab(tabLayout.newTab().setText(getResources().getString(R.string.contributions_fragment)));
+        tabLayout.addTab(tabLayout.newTab().setText(getResources().getString(R.string.nearby_fragment)));
+
+        // Set custom view to add nearby info icon next to text
+        View nearbyTabLinearLayout = LayoutInflater.from(this).inflate(R.layout.custom_nearby_tab_layout, null);
+        tabLayout.getTabAt(1).setCustomView(nearbyTabLinearLayout);
+
+        setTabAndViewPagerSynchronisation();
+    }
+
+    private void setTabAndViewPagerSynchronisation() {
+        //viewPager.canScrollHorizontally(false);
+        viewPager.setFocusableInTouchMode(true);
+
+        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
+            @Override
+            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+
+            }
+
+            @Override
+            public void onPageSelected(int position) {
+                switch (position) {
+                    case CONTRIBUTIONS_TAB_POSITION:
+                        Timber.d("Contributions tab selected");
+                        tabLayout.getTabAt(CONTRIBUTIONS_TAB_POSITION).select();
+
+                        break;
+                    case NEARBY_TAB_POSITION:
+                        Timber.d("Nearby tab selected");
+                        tabLayout.getTabAt(NEARBY_TAB_POSITION).select();
+                        break;
+                    default:
+                        tabLayout.getTabAt(CONTRIBUTIONS_TAB_POSITION).select();
+                        break;
+                }
+            }
+
+            @Override
+            public void onPageScrollStateChanged(int state) {
+
+            }
+        });
+
+        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
+            @Override
+            public void onTabSelected(TabLayout.Tab tab) {
+                viewPager.setCurrentItem(tab.getPosition());
+            }
+
+            @Override
+            public void onTabUnselected(TabLayout.Tab tab) {
+
+            }
+
+            @Override
+            public void onTabReselected(TabLayout.Tab tab) {
+
+            }
+        });
+    }
+
+
+    public class ContributionsActivityPagerAdapter extends FragmentPagerAdapter {
+        FragmentManager fragmentManager;
+        private boolean isContributionsListFragment = true; // to know what to put in first tab, Contributions of Media Details
+
+
+        public ContributionsActivityPagerAdapter(FragmentManager fragmentManager) {
+            super(fragmentManager);
+            this.fragmentManager = fragmentManager;
+        }
+
+        @Override
+        public int getCount() {
+            return 2;
+        }
+
+        /*
+         * Do not use getItem method to access fragments on pager adapter. User reference variables
+         * instead.
+         * */
+        @Override
+        public Fragment getItem(int position) {
+            switch (position){
+                case 0:
+                    NearbyTestLayersFragment retainedContributionsFragment = getContributionsFragment(0);
+                    if (retainedContributionsFragment != null) {
+                        return retainedContributionsFragment;
+                    } else {
+                        // If we reach here, retainedContributionsFragment is null
+                        return new NearbyTestLayersFragment();
+
+                    }
+
+                case 1:
+                    NearbyTestLayersFragment retainedNearbyFragment = getNearbyFragment(1);
+                    if (retainedNearbyFragment != null) {
+                        return retainedNearbyFragment;
+                    } else {
+                        // If we reach here, retainedNearbyFragment is null
+                        return new NearbyTestLayersFragment();
+                    }
+                default:
+                    return null;
+            }
+        }
+
+        /**
+         * Generates fragment tag with makeFragmentName method to get retained contributions fragment
+         * @param position index of tabs, in our case 0 or 1
+         * @return
+         */
+        private NearbyTestLayersFragment getContributionsFragment(int position) {
+            String tag = makeFragmentName(R.id.pager, position);
+            return (NearbyTestLayersFragment)fragmentManager.findFragmentByTag(tag);
+        }
+
+        /**
+         * Generates fragment tag with makeFragmentName method to get retained nearby fragment
+         * @param position index of tabs, in our case 0 or 1
+         * @return
+         */
+        private NearbyTestLayersFragment getNearbyFragment(int position) {
+            String tag = makeFragmentName(R.id.pager, position);
+            return (NearbyTestLayersFragment)fragmentManager.findFragmentByTag(tag);
+        }
+
+        /**
+         * A simple hack to use retained fragment when getID is called explicitly, if we don't use
+         * this method, a new fragment will be initialized on each explicit calls of getID
+         * @param viewId id of view pager
+         * @param index index of tabs, in our case 0 or 1
+         * @return
+         */
+        public String makeFragmentName(int viewId, int index) {
+            return "android:switcher:" + viewId + ":" + index;
+        }
+
+    }
+
 }

app/src/main/res/layout/activity_nearby_test_fragment_layers.xml

@@ -1,12 +1,46 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    android:orientation="vertical" android:layout_width="match_parent"
-    android:layout_height="match_parent">
+<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/drawer_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="?attr/contributionsListBackground"
+    >
 
-    <fragment android:name="fr.free.nrw.commons.nearby.NearbyTestLayersFragment"
-        android:id="@+id/fragment"
+    <RelativeLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        />
+        android:gravity="center_horizontal"
+        >
+        <include layout="@layout/toolbar"/>
 
-</LinearLayout>
+        <com.google.android.material.tabs.TabLayout
+            android:id="@+id/tab_layout"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:background="?attr/tabBackground"
+            app:tabIndicatorColor="?attr/tabIndicatorColor"
+            app:tabSelectedTextColor="?attr/tabSelectedTextColor"
+            app:tabTextColor="?attr/tabTextColor"
+            android:layout_below="@id/toolbar"
+            app:tabMode="fixed" />
+
+        <FrameLayout android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:id="@+id/contributionsFragmentContainer"
+            android:orientation="horizontal"
+            android:layout_below="@id/tab_layout">
+
+            <fr.free.nrw.commons.contributions.UnswipableViewPager
+                xmlns:android="http://schemas.android.com/apk/res/android"
+                android:id="@+id/pager"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent" />
+
+        </FrameLayout>
+
+    </RelativeLayout>
+
+    <include layout="@layout/drawer_view" />
+
+</androidx.drawerlayout.widget.DrawerLayout>