"All images" view for conversations

// FREEBIE

src/org/thoughtcrime/securesms/database/CursorRecyclerViewAdapter.java

@@ -0,0 +1,125 @@
+/**
+ * Copyright (C) 2015 Open Whisper Systems
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.thoughtcrime.securesms.database;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.database.DataSetObserver;
+import android.support.v7.widget.RecyclerView;
+
+/**
+ * RecyclerView.Adapter that manages a Cursor, comparable to the CursorAdapter usable in ListView/GridView.
+ */
+public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
+  private final Context         context;
+  private final DataSetObserver observer = new AdapterDataSetObserver();
+
+  private Cursor  cursor;
+  private boolean valid;
+
+  protected CursorRecyclerViewAdapter(Context context, Cursor cursor) {
+    this.context = context;
+    this.cursor = cursor;
+    if (cursor != null) {
+      valid = true;
+      cursor.registerDataSetObserver(observer);
+    }
+
+    setHasStableIds(true);
+  }
+
+  public Context getContext() {
+    return context;
+  }
+
+  public Cursor getCursor() {
+    return cursor;
+  }
+
+  public void changeCursor(Cursor cursor) {
+    Cursor old = swapCursor(cursor);
+    if (old != null) {
+      old.close();
+    }
+  }
+
+  public Cursor swapCursor(Cursor newCursor) {
+    if (newCursor == cursor) {
+      return null;
+    }
+
+    final Cursor oldCursor = cursor;
+    if (oldCursor != null) {
+      oldCursor.unregisterDataSetObserver(observer);
+    }
+
+    cursor = newCursor;
+    if (cursor != null) {
+      cursor.registerDataSetObserver(observer);
+    }
+
+    valid = cursor != null;
+    notifyDataSetChanged();
+    return oldCursor;
+  }
+
+
+  @Override
+  public int getItemCount() {
+    return isActiveCursor() ? cursor.getCount() : 0;
+  }
+
+  @Override
+  public long getItemId(int position) {
+    return isActiveCursor() && cursor.moveToPosition(position)
+           ? cursor.getLong(cursor.getColumnIndexOrThrow("_id"))
+           : 0;
+  }
+
+  public abstract void onBindViewHolder(VH viewHolder, Cursor cursor);
+
+  @Override
+  public void onBindViewHolder(VH viewHolder, int position) {
+    if (!isActiveCursor()) {
+      throw new IllegalStateException("this should only be called when the cursor is valid");
+    }
+    if (!cursor.moveToPosition(position)) {
+      throw new IllegalStateException("couldn't move cursor to position " + position);
+    }
+    onBindViewHolder(viewHolder, cursor);
+  }
+
+  private boolean isActiveCursor() {
+    return valid && cursor != null;
+  }
+
+  private class AdapterDataSetObserver extends DataSetObserver {
+    @Override
+    public void onChanged() {
+      super.onChanged();
+      valid = true;
+      notifyDataSetChanged();
+    }
+
+    @Override
+    public void onInvalidated() {
+      super.onInvalidated();
+      valid = false;
+      notifyDataSetChanged();
+    }
+  }
+}