Add support for recyclerview-selection

example/build.gradle

@@ -41,6 +41,7 @@ dependencies {
     implementation project(':example-shared')
     implementation project(':library')
     implementation project(':library-kotlin-android-extensions')
+    implementation "androidx.recyclerview:recyclerview-selection:1.1.0-rc01"
 }
 
 repositories {

example/src/main/java/com/xwray/groupie/example/MainActivity.kt

@@ -9,33 +9,21 @@ import android.view.View
 import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
+import androidx.recyclerview.selection.SelectionPredicates
+import androidx.recyclerview.selection.SelectionTracker
+import androidx.recyclerview.selection.StableIdKeyProvider
+import androidx.recyclerview.selection.StorageStrategy
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.RecyclerView
-import com.xwray.groupie.ExpandableGroup
-import com.xwray.groupie.Group
-import com.xwray.groupie.GroupAdapter
-import com.xwray.groupie.GroupieViewHolder
-import com.xwray.groupie.OnItemClickListener
-import com.xwray.groupie.OnItemLongClickListener
-import com.xwray.groupie.Section
+import com.xwray.groupie.*
 import com.xwray.groupie.example.core.InfiniteScrollListener
 import com.xwray.groupie.example.core.Prefs
 import com.xwray.groupie.example.core.SettingsActivity
 import com.xwray.groupie.example.core.decoration.CarouselItemDecoration
 import com.xwray.groupie.example.core.decoration.DebugItemDecoration
 import com.xwray.groupie.example.core.decoration.SwipeTouchCallback
-import com.xwray.groupie.example.item.CardItem
-import com.xwray.groupie.example.item.CarouselCardItem
-import com.xwray.groupie.example.item.CarouselItem
-import com.xwray.groupie.example.item.ColumnItem
-import com.xwray.groupie.example.item.FAVORITE
-import com.xwray.groupie.example.item.FullBleedCardItem
-import com.xwray.groupie.example.item.HeaderItem
-import com.xwray.groupie.example.item.HeartCardItem
-import com.xwray.groupie.example.item.SmallCardItem
-import com.xwray.groupie.example.item.SwipeToDeleteItem
-import com.xwray.groupie.example.item.UpdatableItem
+import com.xwray.groupie.example.item.*
 import com.xwray.groupie.groupiex.plusAssign
 import kotlinx.android.synthetic.main.activity_main.*
 
@@ -57,6 +45,8 @@ class MainActivity : AppCompatActivity() {
     private val infiniteLoadingSection = Section(HeaderItem(R.string.infinite_loading))
     private val swipeSection = Section(HeaderItem(R.string.swipe_to_delete))
 
+    private var tracker: SelectionTracker<Long>? = null
+
     // Normally there's no need to hold onto a reference to this list, but for demonstration
     // purposes, we'll shuffle this list and post an update periodically
     private val updatableItems: ArrayList<UpdatableItem> by lazy {
@@ -102,6 +92,16 @@ class MainActivity : AppCompatActivity() {
             })
         }
 
+        tracker = SelectionTracker.Builder<Long>(
+                GroupieLookup.GROUPIE_SELECTION_ID,
+                recyclerView,
+                StableIdKeyProvider(recyclerView),
+                GroupieLookup(recyclerView),
+                StorageStrategy.createLongStorage()
+        ).withSelectionPredicate(SelectionPredicates.createSelectAnything())
+                .build()
+        groupAdapter.setSelectionTracker(tracker)
+
         ItemTouchHelper(touchCallback).attachToRecyclerView(recyclerView)
 
         fab.setOnClickListener { startActivity(Intent(this@MainActivity, SettingsActivity::class.java)) }
@@ -112,6 +112,7 @@ class MainActivity : AppCompatActivity() {
 
     private fun recreateAdapter() {
         groupAdapter.clear()
+        groupAdapter.setHasStableIds(true)
 
         if (prefs.useAsync) {
             populateAdapterAsync()

example/src/main/java/com/xwray/groupie/example/item/CardItem.kt

@@ -1,5 +1,6 @@
 package com.xwray.groupie.example.item
 
+import android.graphics.Color
 import androidx.annotation.ColorInt
 import com.xwray.groupie.example.INSET
 import com.xwray.groupie.example.INSET_TYPE_KEY
@@ -17,7 +18,11 @@ open class CardItem (@ColorInt private val colorInt: Int, val text: CharSequence
     override fun getLayout() = R.layout.item_card
 
     override fun bind(viewHolder: GroupieViewHolder, position: Int) {
-        viewHolder.root.setBackgroundColor(colorInt)
+        if (isSelectable) {
+            viewHolder.root.setBackgroundColor(Color.GRAY)
+        } else {
+            viewHolder.root.setBackgroundColor(colorInt)
+        }
         viewHolder.text.text = text
     }
 }

library/build.gradle

@@ -35,6 +35,7 @@ android {
 
 dependencies {
     implementation "androidx.recyclerview:recyclerview:1.1.0"
+    compileOnly "androidx.recyclerview:recyclerview-selection:1.1.0-rc01"
     testImplementation "junit:junit:$junit_version"
     testImplementation "org.mockito:mockito-core:$mockito_version"
 }

library/src/main/java/com/xwray/groupie/GroupAdapter.java

@@ -6,6 +6,7 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.GridLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
@@ -22,6 +23,7 @@ public class GroupAdapter<VH extends GroupieViewHolder> extends RecyclerView.Ada
     private final List<Group> groups = new ArrayList<>();
     private OnItemClickListener onItemClickListener;
     private OnItemLongClickListener onItemLongClickListener;
+    private SelectionTracker<Long> selectionTracker;
     private int spanCount = 1;
     private Item lastItemForViewTypeLookup;
 
@@ -200,6 +202,10 @@ public void setOnItemLongClickListener(@Nullable OnItemLongClickListener onItemL
         this.onItemLongClickListener = onItemLongClickListener;
     }
 
+    public void setSelectionTracker(@Nullable SelectionTracker<Long> selectionTracker) {
+        this.selectionTracker = selectionTracker;
+    }
+
     @Override
     @NonNull
     public VH onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
@@ -217,7 +223,11 @@ public void onBindViewHolder(@NonNull VH holder, int position) {
     @Override
     public void onBindViewHolder(@NonNull VH holder, int position, @NonNull List<Object> payloads) {
         Item contentItem = getItem(position);
-        contentItem.bind(holder, position, payloads, onItemClickListener, onItemLongClickListener);
+        if (selectionTracker != null) {
+            contentItem.bind(holder, position, payloads, onItemClickListener, onItemLongClickListener, selectionTracker.isSelected(contentItem.getId()));
+        }else {
+            contentItem.bind(holder, position, payloads, onItemClickListener, onItemLongClickListener, false);
+        }
     }
 
     @Override

library/src/main/java/com/xwray/groupie/GroupieLookup.java

@@ -0,0 +1,33 @@
+package com.xwray.groupie;
+
+import android.view.MotionEvent;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class GroupieLookup extends ItemDetailsLookup<Long> {
+
+    public final static String GROUPIE_SELECTION_ID = "groupie-selection";
+    private RecyclerView recyclerView;
+
+    public GroupieLookup(RecyclerView recyclerView) {
+        this.recyclerView = recyclerView;
+    }
+
+    @Nullable
+    @Override
+    public ItemDetails<Long> getItemDetails(@NonNull MotionEvent e) {
+        View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
+        if (view != null) {
+            RecyclerView.ViewHolder viewHolder = recyclerView.getChildViewHolder(view);
+            if (viewHolder instanceof GroupieViewHolder) {
+                return ((GroupieViewHolder) viewHolder).getItemDetails();
+            }
+        }
+
+        return null;
+    }
+}

library/src/main/java/com/xwray/groupie/GroupieViewHolder.java

@@ -2,6 +2,7 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
 import androidx.recyclerview.widget.RecyclerView;
 import android.view.View;
 
@@ -94,4 +95,19 @@ public Item getItem() {
     public View getRoot() {
         return itemView;
     }
+
+    public ItemDetailsLookup.ItemDetails<Long> getItemDetails() {
+        return new ItemDetailsLookup.ItemDetails<Long>(){
+            @Override
+            public int getPosition() {
+                return getAdapterPosition();
+            }
+
+            @Nullable
+            @Override
+            public Long getSelectionKey() {
+                return getItemId();
+            }
+        };
+    }
 }

library/src/main/java/com/xwray/groupie/Item.java

@@ -4,6 +4,7 @@
 import androidx.annotation.LayoutRes;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.RecyclerView;
 import android.view.View;
 
@@ -18,6 +19,7 @@ public abstract class Item<VH extends GroupieViewHolder> implements Group, SpanS
     protected GroupDataObserver parentDataObserver;
     private final long id;
     private Map<String, Object> extras = new HashMap<>();
+    private boolean isSelectable = false;
 
     public Item() {
         this(ID_COUNTER.decrementAndGet());
@@ -40,11 +42,14 @@ public VH createViewHolder(@NonNull View itemView) {
      * @param payloads            Any payloads (this list may be empty)
      * @param onItemClickListener An optional adapter-level click listener
      * @param onItemLongClickListener An optional adapter-level long click listener
+     * @param isSelected          An optional property stating if a selectable item is selected
      */
     @CallSuper
     public void bind(@NonNull VH viewHolder, int position, @NonNull List<Object> payloads,
                      @Nullable OnItemClickListener onItemClickListener,
-                     @Nullable OnItemLongClickListener onItemLongClickListener) {
+                     @Nullable OnItemLongClickListener onItemLongClickListener,
+                     boolean isSelected) {
+        isSelectable = isSelected;
         viewHolder.bind(this, onItemClickListener, onItemLongClickListener);
         bind(viewHolder, position, payloads);
     }
@@ -70,6 +75,7 @@ public void bind(@NonNull VH viewHolder, int position, @NonNull List<Object> pay
      */
     @CallSuper
     public void unbind(@NonNull VH viewHolder) {
+        isSelectable = false;
         viewHolder.unbind();
     }
 
@@ -152,6 +158,10 @@ public boolean isLongClickable() {
         return true;
     }
 
+    public boolean isSelectable() {
+        return isSelectable;
+    }
+
     public void notifyChanged() {
         if (parentDataObserver != null) {
             parentDataObserver.onItemChanged(this, 0);