A custom view that changes icons based on current WiFi state. Uses the NetworkEvents and EventBus library.

WifiStatusIconView.java

import android.content.Context;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.util.AttributeSet;
import android.widget.ImageButton;

import com.github.pwittchen.networkevents.library.BusWrapper;
import com.github.pwittchen.networkevents.library.ConnectivityStatus;
import com.github.pwittchen.networkevents.library.NetworkEvents;
import com.github.pwittchen.networkevents.library.event.ConnectivityChanged;
import com.github.pwittchen.networkevents.library.event.WifiSignalStrengthChanged;
import com.github.pwittchen.networkevents.library.logger.Logger;
import com.optimizerhq.swipepluslibrary.R;

import de.greenrobot.event.EventBus;

/**
 * Created by okaybroda.
 */
public class WifiStatusIconView extends ImageButton {

    NetworkEvents events;
    BusWrapper busWrapper;

    WifiManager wifiManager;

    ConnectivityStatus connectivityStatus;

    public WifiStatusIconView(Context context) {
        super(context);
        init(context);
    }

    public WifiStatusIconView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public WifiStatusIconView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    public void init(Context context) {
        // Initializing icon to offline
        connectivityStatus = ConnectivityStatus.OFFLINE;
        setImageResource(R.drawable.ic_signal_wifi_off_white_36dp);

        // Get WifiManager from the system
        wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);

        // Register for WiFi events
        events = new NetworkEvents(context, busWrapper = new BusWrapper() {
            @Override
            public void register(Object o) {
                EventBus.getDefault().register(o);
            }

            @Override
            public void unregister(Object o) {
                EventBus.getDefault().unregister(o);
            }

            @Override
            public void post(Object o) {
                EventBus.getDefault().post(o);
            }
        }, new Logger() {
            @Override
            public void log(String message) {
                Utils.log("networkevents", message);
            }
        }).enableInternetCheck().enableWifiScan();

        busWrapper.register(this);
        events.register();
    }

    public void onEvent(ConnectivityChanged event) {
        // Set WiFi icon to offline
        if (event.getConnectivityStatus() == ConnectivityStatus.OFFLINE) {
            setImageResource(R.drawable.ic_signal_wifi_off_white_36dp);
        }
    }

    public void onEvent(WifiSignalStrengthChanged event) {
        // Get info about current connection
        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
        if (wifiInfo != null) {
            // Get signal strength from 0 to 4
            int signalStrength = WifiManager.calculateSignalLevel(wifiInfo.getRssi(), 5);
            int icon = R.drawable.ic_network_wifi_white_36dp; // Set default icon

            // Change icon based on strength
            switch (signalStrength) {
                case 0:
                    icon = R.drawable.ic_signal_wifi_0_bar_white_36dp;
                    break;
                case 1:
                    icon = R.drawable.ic_signal_wifi_1_bar_white_36dp;
                    break;
                case 2:
                    icon = R.drawable.ic_signal_wifi_2_bar_white_36dp;
                    break;
                case 3:
                    icon = R.drawable.ic_signal_wifi_3_bar_white_36dp;
                    break;
                case 4:
                    icon = R.drawable.ic_signal_wifi_4_bar_white_36dp;
                    break;
            }
            setImageResource(icon);
        }
    }
}