Android WiFi Display Implementation

Introduction

Android devices provide the functionality to display the screen wirelessly on a larger external display through a technology called WiFi Display or Miracast. This feature allows users to share their mobile screen with a TV, monitor, or projector without the need for any physical connection. In this article, we will explore the implementation of WiFi Display in Android and provide code examples to demonstrate how it can be achieved.

WiFi Display Protocol

WiFi Display is based on the Miracast standard, which is a wireless display standard developed by the Wi-Fi Alliance. It utilizes the Wi-Fi Direct technology to establish a peer-to-peer connection between the Android device (source) and the external display (sink). The protocol used for communication is based on the Real-Time Streaming Protocol (RTSP) and the Real-Time Transport Protocol (RTP) over the User Datagram Protocol (UDP).

WiFi Display API

Android provides a set of classes and interfaces to interact with the WiFi Display feature. The main classes involved in the implementation are:

  1. WifiP2pManager: This class provides the APIs to discover and connect to nearby WiFi Direct devices. It also handles the negotiation and establishment of a WiFi Display session.

  2. WifiP2pDevice: This class represents a WiFi Direct device that can be discovered and connected to. It contains information such as the device name, MAC address, and device capabilities.

  3. WifiP2pConnectionInfo: This class provides information about the current WiFi Direct connection, including the group owner (GO) IP address and the group owner MAC address.

  4. WifiP2pDnsSdServiceInfo: This class allows the Android device to advertise itself as a WiFi Display source or discover nearby WiFi Display sinks.

Implementing WiFi Display

To implement WiFi Display in an Android app, follow these steps:

  1. Request the necessary permissions in the manifest file:

    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

  2. Create an instance of the WifiP2pManager class and register a WifiP2pManager.ActionListener to handle the WiFi Direct operations:

    WifiP2pManager manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
Channel channel = manager.initialize(this, getMainLooper(), null);
WifiP2pManager.ActionListener actionListener = new WifiP2pManager.ActionListener() {
    @Override
    public void onSuccess() {
        // Handle success
    }

    @Override
    public void onFailure(int reason) {
        // Handle failure
    }
};

  3. Register a WifiP2pManager.PeerListListener to receive the list of nearby WiFi Direct devices:

    WifiP2pManager.PeerListListener peerListListener = new WifiP2pManager.PeerListListener() {
    @Override
    public void onPeersAvailable(WifiP2pDeviceList peers) {
        // Handle the list of peers
        List<WifiP2pDevice> deviceList = new ArrayList<>(peers.getDeviceList());
        // Display device list in a RecyclerView or ListView
    }
};

  4. Discover nearby WiFi Direct devices using the discoverPeers() method:

    manager.discoverPeers(channel, actionListener);

  5. Connect to a specific WiFi Direct device using the connect() method:

    WifiP2pDevice device = deviceList.get(position);
WifiP2pConfig config = new WifiP2pConfig();
config.deviceAddress = device.deviceAddress;
manager.connect(channel, config, actionListener);

  6. Implement the necessary callbacks to handle the WiFi Direct events, such as connection success or failure, group owner information, and data transfer.

Conclusion

In this article, we have explored the implementation of WiFi Display in Android. We have discussed the WiFi Display protocol, the WiFi Display API, and provided code examples to demonstrate how to implement WiFi Display in an Android app. With the WiFi Display feature, users can enjoy the convenience of wirelessly sharing their mobile screen with a larger external display.