DeviceListActivity.cs

/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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.
*/

using System;
using Android.App;
using Android.Bluetooth;
using Android.Content;
using Android.OS;
using Android.Util;
using Android.Views;
using Android.Widget;

namespace BluetoothChat
{
	
	/// <summary>
	/// This Activity appears as a dialog. It lists any paired devices and
	/// devices detected in the area after discovery. When a device is chosen
	/// by the user, the MAC address of the device is sent back to the parent
	/// Activity in the result Intent.
	/// </summary>
	[Activity (Label = "@string/select_device", 
				Theme = "@android:style/Theme.Dialog",
				ConfigurationChanges=Android.Content.PM.ConfigChanges.KeyboardHidden | Android.Content.PM.ConfigChanges.Orientation)]			
	public class DeviceListActivity : Activity
	{
		// Debugging
		private const string TAG = "DeviceListActivity";
		private const bool Debug = true;
	
		// Return Intent extra
		public const string EXTRA_DEVICE_ADDRESS = "device_address";
	
		// Member fields
		private BluetoothAdapter btAdapter;
		private static ArrayAdapter<string> pairedDevicesArrayAdapter;
		private static ArrayAdapter<string> newDevicesArrayAdapter;
		private Receiver receiver;
		
		protected override void OnCreate (Bundle bundle)
		{
			base.OnCreate (bundle);
			
			// Setup the window
			RequestWindowFeature (WindowFeatures.IndeterminateProgress);
			SetContentView (Resource.Layout.device_list);
			
			// Set result CANCELED incase the user backs out
			SetResult (Result.Canceled);

			// Initialize the button to perform device discovery			
			var scanButton = FindViewById<Button> (Resource.Id.button_scan);
			scanButton.Click += (sender, e) => {
				DoDiscovery ();
				(sender as View).Visibility = ViewStates.Gone;
			};
			
			// Initialize array adapters. One for already paired devices and
			// one for newly discovered devices
			pairedDevicesArrayAdapter = new ArrayAdapter<string> (this, Resource.Layout.device_name);
			newDevicesArrayAdapter = new ArrayAdapter<string> (this, Resource.Layout.device_name);
			
			// Find and set up the ListView for paired devices
			var pairedListView = FindViewById<ListView> (Resource.Id.paired_devices);
			pairedListView.Adapter = pairedDevicesArrayAdapter;
			pairedListView.ItemClick += DeviceListClick;
			
			// Find and set up the ListView for newly discovered devices
			var newDevicesListView = FindViewById<ListView> (Resource.Id.new_devices);
			newDevicesListView.Adapter = newDevicesArrayAdapter;
			newDevicesListView.ItemClick += DeviceListClick;
			
			// Register for broadcasts when a device is discovered
			receiver = new Receiver (this);
			var filter = new IntentFilter (BluetoothDevice.ActionFound);
			RegisterReceiver (receiver, filter);
			
			// Register for broadcasts when discovery has finished
			filter = new IntentFilter (BluetoothAdapter.ActionDiscoveryFinished);
			RegisterReceiver (receiver, filter);
			
			// Get the local Bluetooth adapter
			btAdapter = BluetoothAdapter.DefaultAdapter;
			
			// Get a set of currently paired devices
			var pairedDevices = btAdapter.BondedDevices;
			
			// If there are paired devices, add each one to the ArrayAdapter
			if (pairedDevices.Count > 0) {
				FindViewById<View> (Resource.Id.title_paired_devices).Visibility = ViewStates.Visible;
				foreach (var device in pairedDevices) {
					pairedDevicesArrayAdapter.Add (device.Name + "\n" + device.Address);
				}
			} else {
				String noDevices = Resources.GetText (Resource.String.none_paired);
				pairedDevicesArrayAdapter.Add (noDevices);	
			}
			
		}
		
		protected override void OnDestroy ()
		{
			base.OnDestroy ();
			
			// Make sure we're not doing discovery anymore
			if (btAdapter != null) {
				btAdapter.CancelDiscovery();
			}
	
			// Unregister broadcast listeners
			UnregisterReceiver(receiver);
		}
		
		/// <summary>
		/// Start device discover with the BluetoothAdapter
		/// </summary>
		private void DoDiscovery ()
		{
			if (Debug)
				Log.Debug (TAG, "doDiscovery()");
			
			// Indicate scanning in the title
			SetProgressBarIndeterminateVisibility (true);
			SetTitle (Resource.String.scanning);
	
			// Turn on sub-title for new devices
			FindViewById<View> (Resource.Id.title_new_devices).Visibility = ViewStates.Visible;	

			// If we're already discovering, stop it
			if (btAdapter.IsDiscovering) {
				btAdapter.CancelDiscovery ();
			}
	
			// Request discover from BluetoothAdapter
			btAdapter.StartDiscovery ();
		}
		
	
		/// <summary>
		/// The on-click listener for all devices in the ListViews
		/// </summary>
		void DeviceListClick (object sender, AdapterView.ItemClickEventArgs e)
		{
			// Cancel discovery because it's costly and we're about to connect
			btAdapter.CancelDiscovery ();
			
			// Get the device MAC address, which is the last 17 chars in the View
			var info = (e.View as TextView).Text.ToString ();
			var address = info.Substring (info.Length - 17);
			
			// Create the result Intent and include the MAC address
			Intent intent = new Intent ();
			intent.PutExtra (EXTRA_DEVICE_ADDRESS, address);
			
			// Set result and finish this Activity
			SetResult (Result.Ok, intent);
			Finish ();
		}
		
		public class Receiver : BroadcastReceiver
		{ 
			Activity _chat;

			public Receiver (Activity chat)
			{
				_chat = chat;
			}
			
			public override void OnReceive (Context context, Intent intent)
			{ 
				string action = intent.Action;

				// When discovery finds a device
				if (action == BluetoothDevice.ActionFound) {
					// Get the BluetoothDevice object from the Intent
					BluetoothDevice device = (BluetoothDevice)intent.GetParcelableExtra (BluetoothDevice.ExtraDevice);
					// If it's already paired, skip it, because it's been listed already
					if (device.BondState != Bond.Bonded) {
						newDevicesArrayAdapter.Add (device.Name + "\n" + device.Address);
					}
					// When discovery is finished, change the Activity title
				} else if (action == BluetoothAdapter.ActionDiscoveryFinished) {
					_chat.SetProgressBarIndeterminateVisibility (false);
					_chat.SetTitle (Resource.String.select_device);
					if (newDevicesArrayAdapter.Count == 0) {
						var noDevices = _chat.Resources.GetText (Resource.String.none_found).ToString ();
						newDevicesArrayAdapter.Add (noDevices);
					}
				}
			} 
		}
	}
}