1 files changed, 214 insertions, 0 deletions
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/util/HeaderViewRecyclerAdapter.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/util/HeaderViewRecyclerAdapter.java
new file mode 100644
index 00000000..4de15531
--- /dev/null
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/util/HeaderViewRecyclerAdapter.java
@@ -0,0 +1,214 @@
+package org.fox.ttrss.util;
+
+/*
+ * Copyright (C) 2014 darnmason
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * <p>
+ * RecyclerView adapter designed to wrap an existing adapter allowing the addition of
+ * header views and footer views.
+ * </p>
+ * <p>
+ * I implemented it to aid with the transition from ListView to RecyclerView where the ListView's
+ * addHeaderView and addFooterView methods were used. Using this class you may initialize your
+ * header views in the Fragment/Activity and add them to the adapter in the same way you used to
+ * add them to a ListView.
+ * </p>
+ * <p>
+ * I also required to be able to swap out multiple adapters with different content, therefore
+ * setAdapter may be called multiple times.
+ * </p>
+ * Created by darnmason on 07/11/2014.
+ */
+public class HeaderViewRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
+
+    private static final int HEADERS_START = Integer.MIN_VALUE;
+    private static final int FOOTERS_START = Integer.MIN_VALUE + 10;
+    private static final int ITEMS_START = Integer.MIN_VALUE + 20;
+    private static final int ADAPTER_MAX_TYPES = 100;
+
+    private RecyclerView.Adapter mWrappedAdapter;
+    private List<View> mHeaderViews, mFooterViews;
+    private Map<Class, Integer> mItemTypesOffset;
+
+    /**
+     * Construct a new header view recycler adapter
+     * @param adapter The underlying adapter to wrap
+     */
+    public HeaderViewRecyclerAdapter(RecyclerView.Adapter adapter) {
+        mHeaderViews = new ArrayList<View>();
+        mFooterViews = new ArrayList<View>();
+        mItemTypesOffset = new HashMap<Class, Integer>();
+        setWrappedAdapter(adapter);
+    }
+
+    /**
+     * Replaces the underlying adapter, notifying RecyclerView of changes
+     * @param adapter The new adapter to wrap
+     */
+    public void setAdapter(RecyclerView.Adapter adapter) {
+        if(mWrappedAdapter != null && mWrappedAdapter.getItemCount() > 0) {
+            notifyItemRangeRemoved(getHeaderCount(), mWrappedAdapter.getItemCount());
+        }
+        setWrappedAdapter(adapter);
+        notifyItemRangeInserted(getHeaderCount(), mWrappedAdapter.getItemCount());
+    }
+
+    @Override
+    public int getItemViewType(int position) {
+        int hCount = getHeaderCount();
+        if (position < hCount) return HEADERS_START + position;
+        else {
+            int itemCount = mWrappedAdapter.getItemCount();
+            if (position < hCount + itemCount) {
+                return getAdapterTypeOffset() + mWrappedAdapter.getItemViewType(position - hCount);
+            }
+            else return FOOTERS_START  + position - hCount - itemCount;
+        }
+    }
+
+    @Override
+    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
+        if (viewType < HEADERS_START + getHeaderCount())
+            return new StaticViewHolder(mHeaderViews.get(viewType - HEADERS_START));
+        else if (viewType < FOOTERS_START + getFooterCount())
+            return new StaticViewHolder(mFooterViews.get(viewType - FOOTERS_START));
+        else {
+            return mWrappedAdapter.onCreateViewHolder(viewGroup, viewType - getAdapterTypeOffset());
+        }
+    }
+
+    @Override
+    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
+        int hCount = getHeaderCount();
+        if (position >= hCount && position < hCount + mWrappedAdapter.getItemCount())
+            mWrappedAdapter.onBindViewHolder(viewHolder, position - hCount);
+    }
+
+    /**
+     * Add a static view to appear at the start of the RecyclerView. Headers are displayed in the
+     * order they were added.
+     * @param view The header view to add
+     */
+    public void addHeaderView(View view) {
+        mHeaderViews.add(view);
+    }
+
+    /**
+     * Add a static view to appear at the end of the RecyclerView. Footers are displayed in the
+     * order they were added.
+     * @param view The footer view to add
+     */
+    public void addFooterView(View view) {
+        mFooterViews.add(view);
+    }
+
+    public void removeFooterView(View view) {
+        mFooterViews.remove(view);
+    }
+
+    @Override
+    public int getItemCount() {
+        return getHeaderCount() + getFooterCount() + getWrappedItemCount();
+    }
+
+    /**
+     * @return The item count in the underlying adapter
+     */
+    public int getWrappedItemCount() {
+        return mWrappedAdapter.getItemCount();
+    }
+
+    /**
+     * @return The number of header views added
+     */
+    public int getHeaderCount() {
+        return mHeaderViews.size();
+    }
+
+    /**
+     * @return The number of footer views added
+     */
+    public int getFooterCount() {
+        return mFooterViews.size();
+    }
+
+    private void setWrappedAdapter(RecyclerView.Adapter adapter) {
+        if (mWrappedAdapter != null) mWrappedAdapter.unregisterAdapterDataObserver(mDataObserver);
+        mWrappedAdapter = adapter;
+        Class adapterClass = mWrappedAdapter.getClass();
+        if(!mItemTypesOffset.containsKey(adapterClass)) putAdapterTypeOffset(adapterClass);
+        mWrappedAdapter.registerAdapterDataObserver(mDataObserver);
+    }
+
+    private void putAdapterTypeOffset(Class adapterClass) {
+        mItemTypesOffset.put(adapterClass, ITEMS_START + mItemTypesOffset.size() * ADAPTER_MAX_TYPES);
+    }
+
+    private int getAdapterTypeOffset() {
+        return mItemTypesOffset.get(mWrappedAdapter.getClass());
+    }
+
+    private RecyclerView.AdapterDataObserver mDataObserver = new RecyclerView.AdapterDataObserver() {
+        @Override
+        public void onChanged() {
+            super.onChanged();
+            notifyDataSetChanged();
+        }
+
+        @Override
+        public void onItemRangeChanged(int positionStart, int itemCount) {
+            super.onItemRangeChanged(positionStart, itemCount);
+            notifyItemRangeChanged(positionStart + getHeaderCount(), itemCount);
+        }
+
+        @Override
+        public void onItemRangeInserted(int positionStart, int itemCount) {
+            super.onItemRangeInserted(positionStart, itemCount);
+            notifyItemRangeInserted(positionStart + getHeaderCount(), itemCount);
+        }
+
+        @Override
+        public void onItemRangeRemoved(int positionStart, int itemCount) {
+            super.onItemRangeRemoved(positionStart, itemCount);
+            notifyItemRangeRemoved(positionStart + getHeaderCount(), itemCount);
+        }
+
+        @Override
+        public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
+            super.onItemRangeMoved(fromPosition, toPosition, itemCount);
+            int hCount = getHeaderCount();
+            // TODO: No notifyItemRangeMoved method?
+            notifyItemRangeChanged(fromPosition + hCount, toPosition + hCount + itemCount);
+        }
+    };
+
+    private static class StaticViewHolder extends RecyclerView.ViewHolder {
+
+        public StaticViewHolder(View itemView) {
+            super(itemView);
+        }
+    }
+}