Video call surfaces and changing to video UI on videoState change.

Bug: 16012946
Change-Id: I1e86b172d46d3e67eff210d9f56e03a2e6c93853

8 files changed, 675 insertions, 2 deletions

diff --git a/InCallUI/res/layout/call_card_content.xml b/InCallUI/res/layout/call_card_content.xml
index c59c1c712..07b38860d 100644
--- a/InCallUI/res/layout/call_card_content.xml
+++ b/InCallUI/res/layout/call_card_content.xml
@@ -63,6 +63,11 @@
             android:contentDescription="@string/contactPhoto"
             android:src="@drawable/picture_unknown" />
 
+        <fragment android:name="com.android.incallui.VideoCallFragment"
+            android:id="@+id/videoCallFragment"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent" />
+
         <!-- Secondary "Call info" block, for the background ("on hold") call. -->
         <include layout="@layout/secondary_call_info" />
 
diff --git a/InCallUI/res/layout/video_call_fragment.xml b/InCallUI/res/layout/video_call_fragment.xml
new file mode 100644
index 000000000..d5e11ef4a
--- /dev/null
+++ b/InCallUI/res/layout/video_call_fragment.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  ~ Copyright (C) 2014 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
+  -->
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" >
+
+    <ViewStub
+        android:id="@+id/videoCallViewsStub"
+        android:inflatedId="@+id/videoCallViews"
+        android:layout="@layout/video_call_views"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+</FrameLayout>
\ No newline at end of file
diff --git a/InCallUI/res/layout/video_call_views.xml b/InCallUI/res/layout/video_call_views.xml
new file mode 100644
index 000000000..08334b21e
--- /dev/null
+++ b/InCallUI/res/layout/video_call_views.xml
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  ~ Copyright (C) 2014 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
+  -->
+
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" >
+
+    <SurfaceView
+        android:id="@+id/incomingVideo"
+        android:layout_gravity="center_vertical"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+    <SurfaceView
+        android:id="@+id/previewVideo"
+        android:layout_gravity="bottom|right"
+        android:layout_margin="10dp"
+        android:layout_width="70dp"
+        android:layout_height="120dp" />
+</FrameLayout>
\ No newline at end of file
diff --git a/InCallUI/src/com/android/incallui/Call.java b/InCallUI/src/com/android/incallui/Call.java
index f6c039138..2ea80a300 100644
--- a/InCallUI/src/com/android/incallui/Call.java
+++ b/InCallUI/src/com/android/incallui/Call.java
@@ -335,11 +335,12 @@ public final class Call {
 
     @Override
     public String toString() {
-        return String.format(Locale.US, "[%s, %s, %s, children:%s, parent:%s]",
+        return String.format(Locale.US, "[%s, %s, %s, children:%s, parent:%s, videoState:%d]",
                 mId,
                 State.toString(mState),
                 CallCapabilities.toString(mTelecommCall.getDetails().getCapabilities()),
                 mChildCallIds,
-                mParentCallId);
+                mParentCallId,
+                mTelecommCall.getDetails().getVideoState());
     }
 }
diff --git a/InCallUI/src/com/android/incallui/CallCardFragment.java b/InCallUI/src/com/android/incallui/CallCardFragment.java
index 5080da048..f8dabf5ed 100644
--- a/InCallUI/src/com/android/incallui/CallCardFragment.java
+++ b/InCallUI/src/com/android/incallui/CallCardFragment.java
@@ -625,6 +625,16 @@ public class CallCardFragment extends BaseFragment<CallCardPresenter, CallCardPr
         mFloatingActionButtonController.setVisible(enabled);
     }
 
+    /**
+     * Changes the visibility of the contact photo.
+     *
+     * @param isVisible {@code True} if the UI should show the contact photo.
+     */
+    @Override
+    public void setPhotoVisible(boolean isVisible) {
+        mPhoto.setVisibility(isVisible ? View.VISIBLE : View.GONE);
+    }
+
     private void dispatchPopulateAccessibilityEvent(AccessibilityEvent event, View view) {
         if (view == null) return;
         final List<CharSequence> eventText = event.getText();
diff --git a/InCallUI/src/com/android/incallui/CallCardPresenter.java b/InCallUI/src/com/android/incallui/CallCardPresenter.java
index eb4640312..cbaeda6c3 100644
--- a/InCallUI/src/com/android/incallui/CallCardPresenter.java
+++ b/InCallUI/src/com/android/incallui/CallCardPresenter.java
@@ -201,6 +201,11 @@ public class CallCardPresenter extends Presenter<CallCardPresenter.CallCardUi>
             getUi().setCallState(callState, DisconnectCause.NOT_VALID, null, null, null);
         }
 
+        // Hide/show the contact photo depending if this is a video call
+        if (mPrimary != null) {
+            getUi().setPhotoVisible(!mPrimary.isVideoCall());
+        }
+
         final boolean enableEndCallButton = Call.State.isConnected(callState) &&
                 callState != Call.State.INCOMING && mPrimary != null;
         getUi().setEndCallButtonEnabled(enableEndCallButton);
@@ -571,6 +576,7 @@ public class CallCardPresenter extends Presenter<CallCardPresenter.CallCardUi>
         void setEndCallButtonEnabled(boolean enabled);
         void setEmergencyCallbackNumber(String number);
         void setCallDetails(android.telecomm.Call.Details details);
+        void setPhotoVisible(boolean isVisible);
     }
 
     private TelecommManager getTelecommManager() {
diff --git a/InCallUI/src/com/android/incallui/VideoCallFragment.java b/InCallUI/src/com/android/incallui/VideoCallFragment.java
new file mode 100644
index 000000000..eee9643f2
--- /dev/null
+++ b/InCallUI/src/com/android/incallui/VideoCallFragment.java
@@ -0,0 +1,322 @@
+/*
+ * Copyright (C) 2014 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
+ */
+
+package com.android.incallui;
+
+import android.content.res.Configuration;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.Surface;
+import android.view.SurfaceHolder;
+import android.view.SurfaceView;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.ViewStub;
+
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
+
+/**
+ * Fragment containing video calling surfaces.
+ */
+public class VideoCallFragment extends BaseFragment<VideoCallPresenter,
+        VideoCallPresenter.VideoCallUi> implements VideoCallPresenter.VideoCallUi {
+
+    public static final int SURFACE_DISPLAY = 1;
+    public static final int SURFACE_PREVIEW = 2;
+
+    /**
+     * Listener interface used by classes interested in changed to the video telephony surfaces
+     * in the {@link CallCardFragment}.
+     */
+    public interface VideoCallSurfaceListener {
+        void onSurfaceCreated(int surface);
+        void onSurfaceDestroyed(int surface);
+        void onSurfaceChanged(int surface, int format, int width, int height);
+    }
+
+    /**
+     * Listeners to video surface changes.
+     */
+    private final Set<VideoCallSurfaceListener> mListeners = new CopyOnWriteArraySet<>();
+
+    /**
+     * {@link ViewStub} holding the video call surfaces.  This is the parent for the
+     * {@link VideoCallFragment}.  Used to ensure that the video surfaces are only inflated when
+     * required.
+     */
+    private ViewStub mVideoViewsStub;
+
+    /**
+     * Inflated view containing the video call surfaces represented by the {@link ViewStub}.
+     */
+    private View mVideoViews;
+
+    /**
+     * The display video {@link SurfaceView}.  Incoming video from the remote party of the video
+     * call is displayed here.
+     */
+    private SurfaceView mDisplayVideoSurface;
+
+    /**
+     * The surface holder for the display surface.  Provides access to the underlying
+     * {@link Surface} in the {@link SurfaceView} and allows listening to surface related events.
+     */
+    private SurfaceHolder mDisplayVideoSurfaceHolder;
+
+    /**
+     * Determines if the display surface has been created or not.
+     */
+    private boolean mDisplayVideoSurfaceCreated;
+
+    /**
+     * The preview video {@link SurfaceView}.  A preview of the outgoing video to the remote party
+     * of the video call is displayed here.
+     */
+    private SurfaceView mPreviewVideoSurface;
+
+    /**
+     * The surface holder for the preview surface.  Provides access to the underlying
+     * {@link Surface} in the {@link SurfaceView} and allows listening to surface related events.
+     */
+    private SurfaceHolder mPreviewVideoSurfaceHolder;
+
+    /**
+     * Determines if the preview surface has been created or not.
+     */
+    private boolean mPreviewVideoSurfaceCreated;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+    }
+
+    /**
+     * Handles creation of the activity and initialization of the presenter.
+     *
+     * @param savedInstanceState The saved instance state.
+     */
+    @Override
+    public void onActivityCreated(Bundle savedInstanceState) {
+        super.onActivityCreated(savedInstanceState);
+
+        getPresenter().init(getActivity());
+    }
+
+    /**
+     * Handles creation of the fragment view.
+     *
+     * @param inflater The inflater.
+     * @param container The view group containing the fragment.
+     * @param savedInstanceState The saved instance state.
+     * @return
+     */
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container,
+            Bundle savedInstanceState) {
+        super.onCreateView(inflater, container, savedInstanceState);
+
+        return inflater.inflate(R.layout.video_call_fragment, container, false);
+    }
+
+    /**
+     * After creation of the fragment view, retrieves the required views.
+     *
+     * @param view The fragment view.
+     * @param savedInstanceState The saved instance state.
+     */
+    @Override
+    public void onViewCreated(View view, Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+
+        mVideoViewsStub = (ViewStub) view.findViewById(R.id.videoCallViewsStub);
+    }
+
+    /**
+     * Creates the presenter for the {@link VideoCallFragment}.
+     * @return The presenter instance.
+     */
+    @Override
+    public VideoCallPresenter createPresenter() {
+        return new VideoCallPresenter();
+    }
+
+    /**
+     * @return The user interface for the presenter, which is this fragment.
+     */
+    @Override
+    VideoCallPresenter.VideoCallUi getUi() {
+        return this;
+    }
+
+    /**
+     * SurfaceHolder callback used to track lifecycle changes to the surfaces.
+     */
+    private SurfaceHolder.Callback mSurfaceHolderCallBack = new SurfaceHolder.Callback() {
+        /**
+         * Called immediately after the surface is first created.
+         *
+         * @param holder The surface holder.
+         */
+        @Override
+        public void surfaceCreated(SurfaceHolder holder) {
+            int surfaceId = getSurfaceId(holder);
+
+            if (surfaceId == SURFACE_DISPLAY) {
+                mDisplayVideoSurfaceCreated = true;
+            } else {
+                mPreviewVideoSurfaceCreated = true;
+            }
+
+            getPresenter().onSurfaceCreated(surfaceId);
+        }
+
+        /**
+         * Called immediately after any structural changes (format or size) have been made to the
+         * surface.
+         *
+         * @param holder The surface holder.
+         * @param format
+         * @param width
+         * @param height
+         */
+        @Override
+        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
+            Log.d(this, "surfaceChanged %s", holder.getSurface().toString());
+            getPresenter().onSurfaceChanged(getSurfaceId(holder), format, width, height);
+        }
+
+        /**
+         * Called immediately before a surface is being destroyed.
+         *
+         * @param holder The surface holder.
+         */
+        @Override
+        public void surfaceDestroyed(SurfaceHolder holder) {
+            Log.d(this, "surfaceDestroyed %s", holder.getSurface().toString());
+
+            int surfaceId = getSurfaceId(holder);
+
+            if (surfaceId == SURFACE_DISPLAY) {
+                mDisplayVideoSurfaceCreated = false;
+            } else {
+                mPreviewVideoSurfaceCreated = false;
+            }
+
+            getPresenter().onSurfaceDestroyed(surfaceId);
+        }
+
+        /**
+         * Determines the surface ID for a specified surface.
+         *
+         * @param holder The surface holder.
+         * @return The surface ID.
+         */
+        private int getSurfaceId(SurfaceHolder holder) {
+            int surface;
+            if (holder == mDisplayVideoSurface.getHolder()) {
+                Log.d(this, "surfaceCreated: DISPLAY");
+                surface = SURFACE_DISPLAY;
+            } else {
+                Log.d(this, "surfaceCreated: PREVIEW");
+                surface = SURFACE_PREVIEW;
+            }
+            return surface;
+        }
+    };
+
+    /**
+     * Toggles visibility of the video UI.
+     *
+     * @param show {@code True} if the video surfaces should be shown.
+     */
+    @Override
+    public void showVideoUi(boolean show) {
+        getView().setVisibility(show ? View.VISIBLE : View.GONE);
+
+        Log.d(this, "Show video call UI: " + show);
+        if (show) {
+            inflateVideoCallViews();
+        }
+
+        if (mVideoViews != null ) {
+            int newVisibility = show ? View.VISIBLE : View.GONE;
+            mVideoViews.setVisibility(newVisibility);
+            mDisplayVideoSurface.setVisibility(newVisibility);
+            mPreviewVideoSurface.setVisibility(newVisibility);
+            mPreviewVideoSurface.setZOrderOnTop(show);
+        }
+    }
+
+    /**
+     * @return {@code True} if the display video surface has been created.
+     */
+    @Override
+    public boolean isDisplayVideoSurfaceCreated() {
+        return mDisplayVideoSurfaceCreated;
+    }
+
+    /**
+     * @return {@code True} if the preview video surface has been created.
+     */
+    @Override
+    public boolean isPreviewVideoSurfaceCreated() {
+        return mPreviewVideoSurfaceCreated;
+    }
+
+    /**
+     * {@link android.view.Surface} on which incoming video for a video call is displayed.
+     * {@code Null} until the video views {@link android.view.ViewStub} is inflated.
+     */
+    public Surface getDisplayVideoSurface() {
+        if (mDisplayVideoSurfaceHolder != null) {
+            return mDisplayVideoSurfaceHolder.getSurface();
+        }
+        return null;
+    }
+
+    /**
+     * {@link android.view.Surface} on which a preview of the outgoing video for a video call is
+     * displayed.  {@code Null} until the video views {@link android.view.ViewStub} is inflated.
+     */
+    public Surface getPreviewVideoSurface() {
+        if (mPreviewVideoSurfaceHolder != null) {
+            return mPreviewVideoSurfaceHolder.getSurface();
+        }
+        return null;
+    }
+
+    /**
+     * Inflates the {@link ViewStub} containing the incoming and outgoing video surfaces and sets
+     * up a callback to listen for lifecycle changes to the surface.
+     */
+    private void inflateVideoCallViews() {
+        if (mDisplayVideoSurface == null && mPreviewVideoSurface == null && mVideoViews == null ) {
+            mVideoViews = mVideoViewsStub.inflate();
+
+            if (mVideoViews != null) {
+                mDisplayVideoSurface = (SurfaceView) mVideoViews.findViewById(R.id.incomingVideo);
+                mDisplayVideoSurfaceHolder = mDisplayVideoSurface.getHolder();
+                mDisplayVideoSurfaceHolder.addCallback(mSurfaceHolderCallBack);
+
+                mPreviewVideoSurface = (SurfaceView) mVideoViews.findViewById(R.id.previewVideo);
+                mPreviewVideoSurfaceHolder = mPreviewVideoSurface.getHolder();
+                mPreviewVideoSurfaceHolder.addCallback(mSurfaceHolderCallBack);
+                mPreviewVideoSurface.setZOrderOnTop(true);
+            }
+        }
+    }
+}
diff --git a/InCallUI/src/com/android/incallui/VideoCallPresenter.java b/InCallUI/src/com/android/incallui/VideoCallPresenter.java
new file mode 100644
index 000000000..0c8034cb3
--- /dev/null
+++ b/InCallUI/src/com/android/incallui/VideoCallPresenter.java
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2014 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
+ */
+
+package com.android.incallui;
+
+import com.android.internal.util.Preconditions;
+
+import android.content.Context;
+import android.telecomm.RemoteCallVideoProvider;
+import android.view.Surface;
+
+import java.util.Objects;
+
+/**
+ * Logic related to the {@link VideoCallFragment} and for managing changes to the video calling
+ * surfaces based on other user interface events and incoming events from the
+ * {@class CallVideoClient}.
+ */
+public class VideoCallPresenter extends Presenter<VideoCallPresenter.VideoCallUi>  implements
+        InCallPresenter.IncomingCallListener, InCallPresenter.InCallStateListener {
+
+    /**
+     * The current context.
+     */
+    private Context mContext;
+
+    /**
+     * The call the video surfaces are currently related to
+     */
+    private Call mCall;
+
+    /**
+     * The {@link RemoteCallVideoProvider} used to inform the video telephony layer of changes
+     * to the video surfaces.
+     */
+    private RemoteCallVideoProvider mCallVideoProvider;
+
+    /**
+     * Determines if the current UI state represents a video call.
+     */
+    private boolean mIsVideoCall;
+
+    /**
+     * Initializes the presenter.
+     *
+     * @param context The current context.
+     */
+    public void init(Context context) {
+        mContext = Preconditions.checkNotNull(context);
+    }
+
+    /**
+     * Called when the user interface is ready to be used.
+     *
+     * @param ui The Ui implementation that is now ready to be used.
+     */
+    @Override
+    public void onUiReady(VideoCallUi ui) {
+        super.onUiReady(ui);
+
+        // Register for call state changes last
+        InCallPresenter.getInstance().addListener(this);
+        InCallPresenter.getInstance().addIncomingCallListener(this);
+        mIsVideoCall = false;
+    }
+
+    /**
+     * @return The {@link RemoteCallVideoProvider}.
+     */
+    private RemoteCallVideoProvider getCallVideoProvider() {
+        return mCallVideoProvider;
+    }
+
+    /**
+     * Handles the creation of a surface in the {@link VideoCallFragment}.
+     *
+     * @param surface The surface which was created.
+     */
+    public void onSurfaceCreated(int surface) {
+        final VideoCallUi ui = getUi();
+        final RemoteCallVideoProvider callVideoProvider = getCallVideoProvider();
+
+        if (ui == null || callVideoProvider == null) {
+            return;
+        }
+
+        if (surface == VideoCallFragment.SURFACE_DISPLAY) {
+            mCallVideoProvider.setDisplaySurface(ui.getDisplayVideoSurface());
+        } else if (surface == VideoCallFragment.SURFACE_PREVIEW) {
+            mCallVideoProvider.setPreviewSurface(ui.getPreviewVideoSurface());
+        }
+    }
+
+    /**
+     * Handles structural changes (format or size) to a surface.
+     *
+     * @param surface The surface which changed.
+     * @param format The new PixelFormat of the surface.
+     * @param width The new width of the surface.
+     * @param height The new height of the surface.
+     */
+    public void onSurfaceChanged(int surface, int format, int width, int height) {
+        //Do stuff
+    }
+
+    /**
+     * Handles the destruction of a surface in the {@link VideoCallFragment}.
+     *
+     * @param surface The surface which was destroyed.
+     */
+    public void onSurfaceDestroyed(int surface) {
+        final VideoCallUi ui = getUi();
+        final RemoteCallVideoProvider callVideoProvider = getCallVideoProvider();
+
+        if (ui == null || callVideoProvider == null) {
+            return;
+        }
+
+        if (surface == VideoCallFragment.SURFACE_DISPLAY) {
+            mCallVideoProvider.setDisplaySurface(null);
+        } else if (surface == VideoCallFragment.SURFACE_PREVIEW) {
+            mCallVideoProvider.setPreviewSurface(null);
+        }
+    }
+
+    /**
+     * Handles incoming calls.
+     *
+     * @param state The in call state.
+     * @param call The call.
+     */
+    @Override
+    public void onIncomingCall(InCallPresenter.InCallState state, Call call) {
+        // same logic should happen as with onStateChange()
+        onStateChange(state, CallList.getInstance());
+    }
+
+    /**
+     * Handles state changes (including incoming calls)
+     *
+     * @param state The in call state.
+     * @param callList The call list.
+     */
+    @Override
+    public void onStateChange(InCallPresenter.InCallState state, CallList callList) {
+        Call call = null;
+        if (state == InCallPresenter.InCallState.INCOMING) {
+            call = callList.getIncomingCall();
+        } else if (state == InCallPresenter.InCallState.OUTGOING) {
+            call = callList.getOutgoingCall();
+        }
+
+        if (call == null || getUi() == null) {
+            return;
+        }
+        final boolean callChanged = !Objects.equals(mCall, call);
+
+        // If the call changed track it now.
+        if (callChanged) {
+            mCall = call;
+        }
+
+        RemoteCallVideoProvider callVideoProvider =
+                mCall.getTelecommCall().getCallVideoProvider();
+        if (callVideoProvider != mCallVideoProvider) {
+            changeCallVideoProvider(callVideoProvider);
+        }
+
+        boolean newVideoState = call.isVideoCall();
+
+        // Check if video state changed
+        if (mIsVideoCall != newVideoState) {
+            mIsVideoCall = newVideoState;
+
+            if (mIsVideoCall) {
+                enterVideoState();
+            } else {
+                exitVideoState();
+            }
+        }
+    }
+
+    /**
+     * Handles a change to the call video provider.  Sets the surfaces on the previous provider
+     * to null and sets the surfaces on the new provider accordingly.
+     *
+     * @param callVideoProvider The new call video provider.
+     */
+    private void changeCallVideoProvider(RemoteCallVideoProvider callVideoProvider) {
+        // Null out the surfaces on the previous provider
+        if (mCallVideoProvider != null) {
+            mCallVideoProvider.setDisplaySurface(null);
+            mCallVideoProvider.setPreviewSurface(null);
+        }
+
+        mCallVideoProvider = callVideoProvider;
+        setSurfaces();
+
+    }
+
+    /**
+     * Enters video mode by showing the video surfaces.
+     * TODO(vt): Need to adjust size and orientation of preview surface here.
+     */
+    private void enterVideoState() {
+        VideoCallUi ui = getUi();
+        if (ui == null) {
+            return;
+        }
+
+        ui.showVideoUi(true);
+    }
+
+    /**
+     * Sets the surfaces on the specified {@link RemoteCallVideoProvider}.
+     */
+    private void setSurfaces() {
+        VideoCallUi ui = getUi();
+        if (ui == null || mCallVideoProvider == null) {
+            return;
+        }
+
+        if (getUi().isDisplayVideoSurfaceCreated()) {
+            mCallVideoProvider.setDisplaySurface(ui.getDisplayVideoSurface());
+        }
+
+        if (getUi().isPreviewVideoSurfaceCreated()) {
+            mCallVideoProvider.setPreviewSurface(ui.getPreviewVideoSurface());
+        }
+    }
+
+    /**
+     * Exits video mode by hiding the video surfaces.
+     */
+    private void exitVideoState() {
+        VideoCallUi ui = getUi();
+        if (ui == null) {
+            return;
+        }
+
+        ui.showVideoUi(false);
+    }
+
+    /**
+     * Defines the VideoCallUI interactions.
+     */
+    public interface VideoCallUi extends Ui {
+        void showVideoUi(boolean show);
+        boolean isDisplayVideoSurfaceCreated();
+        boolean isPreviewVideoSurfaceCreated();
+        Surface getDisplayVideoSurface();
+        Surface getPreviewVideoSurface();
+    }
+}