Capabilities + Extensions + Cast Host Extension Support for Android client

remoting/android/cast/src/org/chromium/chromoting/CastExtensionHandler.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chromoting;
+
+import android.app.Activity;
+import android.content.Context;
+import android.os.Bundle;
+import android.support.v4.view.MenuItemCompat;
+import android.support.v7.app.MediaRouteActionProvider;
+import android.support.v7.media.MediaRouteSelector;
+import android.support.v7.media.MediaRouter;
+import android.support.v7.media.MediaRouter.RouteInfo;
+import android.util.Log;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+import com.google.android.gms.cast.Cast;
+import com.google.android.gms.cast.Cast.Listener;
+import com.google.android.gms.cast.CastDevice;
+import com.google.android.gms.cast.CastMediaControlIntent;
+import com.google.android.gms.cast.CastStatusCodes;
+import com.google.android.gms.common.ConnectionResult;
+import com.google.android.gms.common.api.GoogleApiClient;
+import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
+import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener;
+import com.google.android.gms.common.api.ResultCallback;
+import com.google.android.gms.common.api.Status;
+
+import org.chromium.chromoting.jni.JniInterface;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A handler that interacts with the Cast Extension of the Chromoting host using extension messages.
+ * It uses the Cast Android Sender API to start our registered Cast Receiver App on a nearby Cast
+ * device, if the user chooses to do so.
+ */
+public class CastExtensionHandler implements ClientExtension, ActivityLifecycleListener {
+
+    /** Extension messages of this type will be handled by the CastExtensionHandler. */
+    public static final String EXTENSION_MSG_TYPE = "cast_message";
+
+    /** Tag used for logging. */
+    private static final String TAG = "CastExtensionHandler";
+
+    /** Application Id of the Cast Receiver App that will be run on the Cast device. */
+    private static final String RECEIVER_APP_ID = "8A1211E3";
+
+    /** Custom namespace that will be used to communicate with the Cast device. */
+    private static final String CHROMOTOCAST_NAMESPACE = "urn:x-cast:com.chromoting.cast.all";

[Lambros, 2014/08/14 23:54:24]

This should use "com.google.chromeremotedesktop" for official builds. You can
add a TODO for this - don't need to fix it right now.

[aiguha, 2014/08/15 03:37:29]

Done.

+
+    /** Context that wil be used to initialize the MediaRouter and the GoogleApiClient. */
+    private Context mContext = null;
+
+    /** True if the application has been launched on the Cast device. */
+    private boolean mApplicationStarted;
+
+    /** True if the client is temporarily in a disconnected state. */
+    private boolean mWaitingForReconnect;
+
+    /** Object that allows routing of media to external devices including Google Cast devices. */
+    private MediaRouter mMediaRouter;
+
+    /** Describes the capabilities of routes that the application might want to use. */
+    private MediaRouteSelector mMediaRouteSelector;
+
+    /** Cast device selected by the user. */
+    private CastDevice mSelectedDevice;
+
+    /** Object to receive callbacks about media routing changes. */
+    private MediaRouter.Callback mMediaRouterCallback;
+
+    /** Listener for events related to the connected Cast device.*/
+    private Listener mCastClientListener;
+
+    /** Object that handles Google Play Services integration. */
+    private GoogleApiClient mApiClient;
+
+    /** Callback objects for connection changes with Google Play Services. */
+    private ConnectionCallbacks mConnectionCallbacks;
+    private OnConnectionFailedListener mConnectionFailedListener;
+
+    /** Channel for receiving messages from the Cast device. */
+    private ChromotocastChannel mChromotocastChannel;
+
+    /** Current session ID, if there is one. */
+    private String mSessionId;
+
+    /** Queue of messages that are yet to be delivered to the Receiver App. */
+    private List<String> mChromotocastMessageQueue;
+
+    /** Current status of the application, if any. */
+    private String mApplicationStatus;
+
+    /**
+     * A callback class for receiving events about media routing.
+     */
+    private class CustomMediaRouterCallback extends MediaRouter.Callback {
+        @Override
+        public void onRouteSelected(MediaRouter router, RouteInfo info) {
+            mSelectedDevice = CastDevice.getFromBundle(info.getExtras());
+            connectApiClient();
+        }
+
+        @Override
+        public void onRouteUnselected(MediaRouter router, RouteInfo info) {
+            tearDown();
+            mSelectedDevice = null;
+        }
+    }
+
+    /**
+     * A callback class for receiving the result of launching an application on the user-selected
+     * Google Cast device.
+     */
+    private class ApplicationConnectionResultCallback implements
+            ResultCallback<Cast.ApplicationConnectionResult> {
+        @Override
+        public void onResult(Cast.ApplicationConnectionResult result) {
+            Status status = result.getStatus();
+            if (!status.isSuccess()) {
+                tearDown();
+                return;
+            }
+
+            mSessionId = result.getSessionId();
+            mApplicationStatus = result.getApplicationStatus();
+            mApplicationStarted = result.getWasLaunched();
+            mChromotocastChannel = new ChromotocastChannel();
+
+            try {
+                Cast.CastApi.setMessageReceivedCallbacks(mApiClient,
+                        mChromotocastChannel.getNamespace(), mChromotocastChannel);
+                sendPendingMessagesToCastDevice();
+            } catch (IOException e) {
+                showToast("Failed to connect.", Toast.LENGTH_SHORT);

[Lambros, 2014/08/14 23:54:24]

Please localize any toasts. Maybe have a look through
remoting/resources/remoting_strings.grd to see if there's already a generic
"connection failed" message?

Also, do you need to call tearDown() here?

[aiguha, 2014/08/15 03:37:28]

Done.

+            } catch (IllegalStateException e) {
+                showToast("Failed to connect.", Toast.LENGTH_SHORT);
+            }
+        }
+    }
+
+    /**
+     * A callback class for receiving events about client connections and disconnections from
+     * Google Play Services.
+     */
+    private class ConnectionCallbacks implements GoogleApiClient.ConnectionCallbacks {
+        @Override
+        public void onConnected(Bundle connectionHint) {
+            if (mWaitingForReconnect) {
+                mWaitingForReconnect = false;
+                reconnectChannels();
+                return;
+            }
+            Cast.CastApi.launchApplication(mApiClient, RECEIVER_APP_ID, false).setResultCallback(
+                    new ApplicationConnectionResultCallback());
+        }
+
+        @Override
+        public void onConnectionSuspended(int cause) {
+            mWaitingForReconnect = true;
+        }
+    }
+
+    /**
+     * A listener for failures to connect with Google Play Services.
+     */
+    private class ConnectionFailedListener implements GoogleApiClient.OnConnectionFailedListener {
+        @Override
+        public void onConnectionFailed(ConnectionResult result) {
+            Log.e(TAG, String.format("Google Play Service connection failed: %s", result));
+
+            tearDown();
+        }
+
+    }
+
+    /**
+     * A channel for communication with the Cast device on the CHROMOTOCAST_NAMESPACE.
+     */
+    private class ChromotocastChannel implements Cast.MessageReceivedCallback {
+
+        /**
+         * Returns the namespace associated with this channel.
+         */
+        public String getNamespace() {
+            return CHROMOTOCAST_NAMESPACE;
+        }
+
+        @Override
+        public void onMessageReceived(CastDevice castDevice, String namespace, String message) {
+            if (namespace.equals(CHROMOTOCAST_NAMESPACE)) {
+                sendMessageToHost(message);
+            }
+        }
+    }
+
+    /**
+     * A listener for changes when connected to a Google Cast device.
+     */
+    private class CastClientListener extends Cast.Listener {
+        @Override
+        public void onApplicationStatusChanged() {
+            try {
+                if (mApiClient != null) {
+                    mApplicationStatus = Cast.CastApi.getApplicationStatus(mApiClient);
+                }
+            } catch (IllegalStateException e) {
+                showToast("Lost connection to Cast device.", Toast.LENGTH_SHORT);
+                tearDown();
+            }
+        }
+
+        @Override
+        public void onVolumeChanged() {} // Changes in volume do not affect us.

[Lambros, 2014/08/14 23:54:24]

nit: two spaces before //

[aiguha, 2014/08/15 03:37:28]

Done.

+
+        @Override
+        public void onApplicationDisconnected(int errorCode) {
+            if (errorCode != CastStatusCodes.SUCCESS) {
+                Log.e(TAG, String.format("Application disconnected with: %d", errorCode));
+            }
+            tearDown();
+        }
+    }
+
+    /**
+     * Constructs a CastExtensionHandler with an empty message queue.
+     */
+    public CastExtensionHandler() {
+        mChromotocastMessageQueue = new ArrayList<String>();
+    }
+
+    //
+    // ClientExtension implementation.
+    //
+
+    @Override
+    public String getCapability() {
+        return Capabilities.CAST_CAPABILITY;
+    }
+
+    @Override
+    public boolean onExtensionMessage(String type, String data) {
+        if (type.equals(EXTENSION_MSG_TYPE)) {
+            mChromotocastMessageQueue.add(data);
+            if (mApplicationStarted) {
+                sendPendingMessagesToCastDevice();
+            }
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public ActivityLifecycleListener onActivityAcceptingListener(Activity activity) {
+        return this;
+    }
+    //

[Lambros, 2014/08/14 23:54:24]

nit: blank line above this comment block

[aiguha, 2014/08/15 03:37:29]

Done.

+    // ActivityLifecycleListener implementation.
+    //
+
+    /** Initializes the MediaRouter and related objects using the provided activity Context. */
+    @Override
+    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
+        if (activity == null) {
+            return;
+        }
+        mContext = activity;
+        mMediaRouter = MediaRouter.getInstance(activity);
+        mMediaRouteSelector = new MediaRouteSelector.Builder()
+                .addControlCategory(CastMediaControlIntent.categoryForCast(RECEIVER_APP_ID))
+                .build();
+        mMediaRouterCallback = new CustomMediaRouterCallback();
+    }
+
+    @Override
+    public void onActivityDestroyed(Activity activity) {
+        tearDown();
+    }
+
+    @Override
+    public void onActivityPaused(Activity activity) {
+        removeMediaRouterCallback();
+    }
+
+    @Override
+    public void onActivityResumed(Activity activity) {
+        addMediaRouterCallback();
+    }
+
+    @Override
+    public void onActivitySaveInstanceState (Activity activity, Bundle outState) {}
+
+    @Override
+    public void onActivityStarted(Activity activity) {
+        addMediaRouterCallback();
+    }
+
+    @Override
+    public void onActivityStopped(Activity activity) {
+        removeMediaRouterCallback();
+    }
+
+    @Override
+    public boolean onActivityCreatedOptionsMenu(Activity activity, Menu menu) {
+

[Lambros, 2014/08/14 23:54:24]

nit: blank line not needed

[aiguha, 2014/08/15 03:37:29]

Acknowledged.

+        // Find the cast button in the menu.
+        MenuItem mediaRouteMenuItem = menu.findItem(R.id.media_route_menu_item);
+        if (mediaRouteMenuItem == null) {
+            return false;
+        }
+
+        // Setup a MediaRouteActionProvider using the button.
+        MediaRouteActionProvider mediaRouteActionProvider =
+                (MediaRouteActionProvider) MenuItemCompat.getActionProvider(mediaRouteMenuItem);
+        mediaRouteActionProvider.setRouteSelector(mMediaRouteSelector);
+
+        return true;
+    }
+
+    @Override
+    public boolean onActivityOptionsItemSelected(Activity activity, MenuItem item) {
+        if (item.getItemId() == R.id.actionbar_disconnect) {
+            removeMediaRouterCallback();
+            showToast("Closing connection to Cast device.", Toast.LENGTH_SHORT);

[Lambros, 2014/08/14 23:54:24]

Do we need this toast? If so, localize it.

[aiguha, 2014/08/15 03:37:28]

Acknowledged.

+            tearDown();
+            return true;
+        }
+        return false;
+    }
+
+    //
+    // Extension Message Handling logic
+    //
+
+    /** Sends a message to the Chromoting host. */
+    private void sendMessageToHost(String data) {
+        JniInterface.sendExtensionMessage(EXTENSION_MSG_TYPE, data);
+    }
+
+    /** Sends any messages in the message queue to the Cast device. */
+    private void sendPendingMessagesToCastDevice() {
+        for (String msg : mChromotocastMessageQueue) {
+            sendMessageToCastDevice(msg);
+        }
+        mChromotocastMessageQueue.clear();
+    }
+
+    //
+    // Cast Sender API logic
+    //
+
+    /**
+     * Initializes and connects to Google Play Services.
+     */
+    private void connectApiClient() {
+        if (mContext == null) {
+            return;
+        }
+        mCastClientListener = new CastClientListener();
+        mConnectionCallbacks = new ConnectionCallbacks();
+        mConnectionFailedListener = new ConnectionFailedListener();
+
+        Cast.CastOptions.Builder apiOptionsBuilder = Cast.CastOptions
+                .builder(mSelectedDevice, mCastClientListener)
+                .setVerboseLoggingEnabled(true);
+
+        mApiClient = new GoogleApiClient.Builder(mContext)
+                .addApi(Cast.API, apiOptionsBuilder.build())
+                .addConnectionCallbacks(mConnectionCallbacks)
+                .addOnConnectionFailedListener(mConnectionFailedListener)
+                .build();
+        mApiClient.connect();
+    }
+
+    /**
+     * Adds the callback object to the MediaRouter. Called when the owning activity starts/resumes.
+     */
+    private void addMediaRouterCallback() {
+        if (mMediaRouter != null && mMediaRouteSelector != null && mMediaRouterCallback != null) {
+            mMediaRouter.addCallback(mMediaRouteSelector, mMediaRouterCallback,
+                    MediaRouter.CALLBACK_FLAG_PERFORM_ACTIVE_SCAN);
+        }
+    }
+
+    /**
+     * Removes the callback object from the MediaRouter. Called when the owning activity
+     * stops/pauses.
+     */
+    private void removeMediaRouterCallback() {
+        if (mMediaRouter != null && mMediaRouterCallback != null) {
+            mMediaRouter.removeCallback(mMediaRouterCallback);
+        }
+    }
+
+    /**
+     * Sends a message to the Cast device on the CHROMOTOCAST_NAMESPACE.
+     */
+    private void sendMessageToCastDevice(String message) {
+        if (mApiClient == null || mChromotocastChannel == null) {
+            return;
+        }
+        Cast.CastApi.sendMessage(mApiClient, mChromotocastChannel.getNamespace(), message)
+                .setResultCallback(new ResultCallback<Status>() {
+                    @Override
+                    public void onResult(Status result) {
+                        if (!result.isSuccess()) {
+                            Log.e(TAG, "Failed to send message to cast device.");
+                        }
+                    }
+                });
+
+    }
+
+    /**
+     * Restablishes the chromotocast message channel, so we can continue communicating with the
+     * Google Cast device. This must be called when resuming a connection.
+     */
+    private void reconnectChannels() {
+        if (mApiClient == null && mChromotocastChannel == null) {
+            return;
+        }
+        try {
+            Cast.CastApi.setMessageReceivedCallbacks(
+                    mApiClient,mChromotocastChannel.getNamespace(),mChromotocastChannel);
+            sendPendingMessagesToCastDevice();
+        } catch (IOException e) {
+            showToast("Error connecting to Cast device.", Toast.LENGTH_SHORT);
+        } catch (IllegalStateException e) {
+            showToast("Not connected to a Cast device.", Toast.LENGTH_SHORT);
+        }
+    }
+
+    /**
+     * Stops the running application on the Google Cast device and performs the required tearDown
+     * sequence.
+     */
+    private void tearDown() {
+        if (mApiClient != null && mApplicationStarted && mApiClient.isConnected()) {

[Lambros, 2014/08/14 23:54:24]

I'm not exactly sure about the logic here. If mApplicationStarted == true, but
isConnected() == false, what should happen?

[aiguha, 2014/08/15 03:37:29]

We should just have to change the mApplicationStarted to false. This tearDown()
is based off of the teardown() method here:
https://developers.google.com/cast/docs/android_sender. But flattened out at the
cost of nulling some objects that are already null or setting a false bit to
false again.

+            Cast.CastApi.stopApplication(mApiClient, mSessionId);
+            if (mChromotocastChannel != null) {
+                try {
+                    Cast.CastApi.removeMessageReceivedCallbacks(
+                            mApiClient, mChromotocastChannel.getNamespace());
+                } catch (IOException e) {
+                    Log.e(TAG, "Failed to remove chromotocast channel.");
+                }
+            }
+            mApiClient.disconnect();
+        }
+        mChromotocastChannel = null;
+        mApplicationStarted = false;
+        mApiClient = null;
+        mSelectedDevice = null;
+        mWaitingForReconnect  = false;
+        mSessionId = null;
+    }
+
+    /**
+     * Makes a toast using the given message and duration.
+     */
+    private void showToast(String message, int duration) {

[Lambros, 2014/08/14 23:54:24]

Change this to take a resource ID instead of a String message.

[aiguha, 2014/08/15 03:37:29]

Done.

+        if (mContext != null) {
+            Toast.makeText(mContext, message, duration).show();
+        }
+    }
+}