Create custom BriarRecyclerView and use it for the contact list.

It is a common pattern to have a list with an empty view and a progress bar.
This commit introduces a custom BriarRecyclerView and uses it for the
contact list.

No more manually hiding and showing empty views and progress bars is
necessary when using the new BriarRecyclerView instead of RecyclerView.

Please note that this conflicts with !44 at the moment and needs to be
implemented for !36 once merged.

Closes #198

briar-android/src/org/briarproject/android/util/BriarRecyclerView.java

@@ -0,0 +1,112 @@
+package org.briarproject.android.util;
+
+import android.content.Context;
+import android.support.v7.widget.RecyclerView;
+import android.util.AttributeSet;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.FrameLayout;
+import android.widget.ProgressBar;
+import android.widget.TextView;
+
+import org.briarproject.R;
+
+public class BriarRecyclerView extends FrameLayout {
+
+	private RecyclerView recyclerView;
+	private TextView emptyView;
+	private ProgressBar progressBar;
+	private RecyclerView.AdapterDataObserver emptyObserver;
+
+	public BriarRecyclerView(Context context) {
+		super(context);
+
+		initViews();
+	}
+
+	public BriarRecyclerView(Context context, AttributeSet attrs) {
+		super(context, attrs);
+
+		initViews();
+	}
+
+	public BriarRecyclerView(Context context, AttributeSet attrs,
+			int defStyle) {
+		super(context, attrs, defStyle);
+
+		initViews();
+	}
+
+	private void initViews() {
+		if (isInEditMode()) {
+			return;
+		}
+
+		View v = LayoutInflater.from(getContext()).inflate(
+				R.layout.briar_recycler_view, this, true);
+
+		recyclerView = (RecyclerView) v.findViewById(R.id.recyclerView);
+		emptyView = (TextView) v.findViewById(R.id.emptyView);
+		progressBar = (ProgressBar) v.findViewById(R.id.progressBar);
+
+		recyclerView.setVisibility(View.INVISIBLE);
+		emptyView.setVisibility(View.INVISIBLE);
+		progressBar.setVisibility(View.VISIBLE);
+
+		emptyObserver = new RecyclerView.AdapterDataObserver() {
+			@Override
+			public void onChanged() {
+				showData();
+			}
+
+			@Override
+			public void onItemRangeInserted(int positionStart, int itemCount) {
+				super.onItemRangeInserted(positionStart, itemCount);
+				onChanged();
+			}
+		};
+	}
+
+	public void setLayoutManager(RecyclerView.LayoutManager layout) {
+		recyclerView.setLayoutManager(layout);
+	}
+
+	public void setAdapter(RecyclerView.Adapter adapter) {
+		recyclerView.setAdapter(adapter);
+
+		if (adapter != null) {
+			adapter.registerAdapterDataObserver(emptyObserver);
+
+			if (adapter.getItemCount() > 0) {
+				// only show data if adapter has data already
+				// otherwise progress bar is shown
+				emptyObserver.onChanged();
+			}
+		}
+	}
+
+	public void setEmptyText(String text) {
+		emptyView.setText(text);
+	}
+
+	public void showProgressBar() {
+		recyclerView.setVisibility(View.INVISIBLE);
+		emptyView.setVisibility(View.INVISIBLE);
+		progressBar.setVisibility(View.VISIBLE);
+	}
+
+	private void showData() {
+		RecyclerView.Adapter<?> adapter = recyclerView.getAdapter();
+		if (adapter != null) {
+			if (adapter.getItemCount() == 0) {
+				emptyView.setVisibility(View.VISIBLE);
+				recyclerView.setVisibility(View.INVISIBLE);
+			} else {
+				emptyView.setVisibility(View.INVISIBLE);
+				recyclerView.setVisibility(View.VISIBLE);
+			}
+			progressBar.setVisibility(View.INVISIBLE);
+		}
+	}
+
+}