Fixes #4215 "Swiping on the last item in explore featured tab takes you to uploaded via mobile" (#4227)

* scrolling disabled on media details

* javadoc added

* javadoc modified

Author: 4D17Y4

app/src/main/java/fr/free/nrw/commons/bookmarks/BookmarkFragment.java

@@ -4,35 +4,30 @@
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.AdapterView;
 
 import android.widget.FrameLayout;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.FragmentManager;
-import androidx.viewpager.widget.ViewPager;
 
 import com.google.android.material.tabs.TabLayout;
 
-import fr.free.nrw.commons.contributions.MainActivity;
 import fr.free.nrw.commons.di.CommonsDaggerSupportFragment;
+import fr.free.nrw.commons.explore.ParentViewPager;
 import fr.free.nrw.commons.theme.BaseActivity;
 import javax.inject.Inject;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
-import fr.free.nrw.commons.Media;
 import fr.free.nrw.commons.R;
-import fr.free.nrw.commons.category.CategoryImagesCallback;
 import fr.free.nrw.commons.contributions.ContributionController;
-import fr.free.nrw.commons.media.MediaDetailPagerFragment;
 
 public class BookmarkFragment extends CommonsDaggerSupportFragment {
 
   private FragmentManager supportFragmentManager;
   private BookmarksPagerAdapter adapter;
   @BindView(R.id.viewPagerBookmarks)
-  ViewPager viewPager;
+  ParentViewPager viewPager;
   @BindView(R.id.tab_layout)
   TabLayout tabLayout;
   @BindView(R.id.fragmentContainer)
@@ -48,6 +43,10 @@ public static BookmarkFragment newInstance() {
     return fragment;
   }
 
+  public void setScroll(boolean canScroll){
+    viewPager.setCanScroll(canScroll);
+  }
+
   @Override
   public void onCreate(@Nullable final Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);

app/src/main/java/fr/free/nrw/commons/bookmarks/BookmarkListRootFragment.java

@@ -181,13 +181,14 @@ public void viewPagerNotifyDataSetChanged() {
   }
 
   public void backPressed() {
-    //check medaiDetailPage fragment is not null then we check medaiDetail.is Visible or not to avoid NullPointerException
+    //check mediaDetailPage fragment is not null then we check mediaDetail.is Visible or not to avoid NullPointerException
     if(mediaDetails!=null) {
       if (mediaDetails.isVisible()) {
         // todo add get list fragment
         ((BookmarkFragment) getParentFragment()).tabLayout.setVisibility(View.VISIBLE);
         ArrayList<Integer> removed=mediaDetails.getRemovedItems();
         removeFragment(mediaDetails);
+        ((BookmarkFragment) getParentFragment()).setScroll(true);
         setFragment(listFragment, mediaDetails);
         ((MainActivity) getActivity()).showTabs();
         if(listFragment instanceof BookmarkPicturesFragment){
@@ -217,6 +218,7 @@ public void onItemClick(AdapterView<?> parent, View view, int position, long id)
     container.setVisibility(View.VISIBLE);
     ((BookmarkFragment)getParentFragment()).tabLayout.setVisibility(View.GONE);
     mediaDetails = new MediaDetailPagerFragment(false, true);
+    ((BookmarkFragment) getParentFragment()).setScroll(false);
     setFragment(mediaDetails, listFragment);
     mediaDetails.showImage(position);
   }

app/src/main/java/fr/free/nrw/commons/explore/ExploreFragment.java

@@ -10,7 +10,6 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
-import androidx.viewpager.widget.ViewPager;
 import butterknife.BindView;
 import butterknife.ButterKnife;
 import com.google.android.material.tabs.TabLayout;
@@ -30,11 +29,15 @@ public class ExploreFragment extends CommonsDaggerSupportFragment {
     @BindView(R.id.tab_layout)
     TabLayout tabLayout;
     @BindView(R.id.viewPager)
-    ViewPager viewPager;
+    ParentViewPager viewPager;
     ViewPagerAdapter viewPagerAdapter;
     private ExploreListRootFragment featuredRootFragment;
     private ExploreListRootFragment mobileRootFragment;
 
+    public void setScroll(boolean canScroll){
+        viewPager.setCanScroll(canScroll);
+    }
+
     @NonNull
     public static ExploreFragment newInstance() {
         ExploreFragment fragment = new ExploreFragment();

app/src/main/java/fr/free/nrw/commons/explore/ExploreListRootFragment.java

@@ -118,6 +118,7 @@ public void onMediaClicked(int position) {
     ((ExploreFragment)getParentFragment()).tabLayout.setVisibility(View.GONE);
     mediaDetails = new MediaDetailPagerFragment(false, true);
     mediaDetails.showImage(position);
+    ((ExploreFragment) getParentFragment()).setScroll(false);
     setFragment(mediaDetails, listFragment);
   }
 
@@ -173,6 +174,7 @@ public void backPressed() {
       // todo add get list fragment
       ((ExploreFragment)getParentFragment()).tabLayout.setVisibility(View.VISIBLE);
       removeFragment(mediaDetails);
+      ((ExploreFragment) getParentFragment()).setScroll(true);
       setFragment(listFragment, mediaDetails);
     } else {
       ((MainActivity) getActivity()).setSelectedItemId(NavTab.CONTRIBUTIONS.code());

app/src/main/java/fr/free/nrw/commons/explore/ParentViewPager.java

@@ -0,0 +1,69 @@
+package fr.free.nrw.commons.explore;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import androidx.viewpager.widget.ViewPager;
+
+/**
+ * ParentViewPager
+ * A custom viewPager whose scrolling can be enabled and disabled.
+  */
+public class ParentViewPager extends ViewPager {
+
+  /**
+   * Boolean variable that stores the current state of pager scroll i.e(enabled or disabled)
+    */
+  private boolean canScroll = true;
+
+
+  /**
+   * Default constructors
+    */
+  public ParentViewPager(Context context) {
+    super(context);
+  }
+
+  public ParentViewPager(Context context, AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+
+  /**
+   * Setter method for canScroll.
+    */
+  public void setCanScroll(boolean canScroll) {
+    this.canScroll = canScroll;
+  }
+
+
+  /**
+   * Getter method for canScroll.
+    */
+  public boolean isCanScroll() {
+    return canScroll;
+  }
+
+
+  /**
+   * Method that prevents scrolling if canScroll is set to false.
+    */
+  @Override
+  public boolean onTouchEvent(MotionEvent ev) {
+    return canScroll && super.onTouchEvent(ev);
+  }
+
+
+  /**
+   *   A facilitator method that allows parent to intercept touch events before its children.
+   *   thus making it possible to prevent swiping parent on child end.
+    */
+  @Override
+  public boolean onInterceptTouchEvent(MotionEvent ev) {
+    return canScroll && super.onInterceptTouchEvent(ev);
+  }
+
+
+
+
+}

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

@@ -30,7 +30,7 @@
       android:orientation="horizontal"
       android:visibility="gone"/>
 
-    <androidx.viewpager.widget.ViewPager
+    <fr.free.nrw.commons.explore.ParentViewPager
       android:id="@+id/viewPagerBookmarks"
       android:layout_width="match_parent"
       android:layout_height="match_parent"

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

@@ -30,7 +30,7 @@
         android:orientation="horizontal"
         android:visibility="gone" />
 
-    <androidx.viewpager.widget.ViewPager
+    <fr.free.nrw.commons.explore.ParentViewPager
         android:id="@+id/viewPager"
         android:layout_width="match_parent"
         android:layout_height="match_parent"