Filtering noise

app/src/main/java/no/nordicsemi/android/blinky/utils/FilterUtils.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2018, Nordic Semiconductor
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package no.nordicsemi.android.blinky.utils;
+
+import android.os.ParcelUuid;
+
+import no.nordicsemi.android.support.v18.scanner.ScanRecord;
+import no.nordicsemi.android.support.v18.scanner.ScanResult;
+
+public class FilterUtils {
+    private static final ParcelUuid EDDYSTONE_UUID
+            = ParcelUuid.fromString("0000FEAA-0000-1000-8000-00805f9b34fb");
+
+    private static final int COMPANY_ID_MICROSOFT = 0x0006;
+    private static final int COMPANY_ID_APPLE = 0x004C;
+    private static final int COMPANY_ID_NORDIC_SEMI = 0x0059;
+
+    @SuppressWarnings("RedundantIfStatement")
+    public static boolean isBeacon(final ScanResult result) {
+        if (result != null && result.getScanRecord() != null) {
+            final ScanRecord record = result.getScanRecord();
+
+            final byte[] appleData = record.getManufacturerSpecificData(COMPANY_ID_APPLE);
+            if (appleData != null) {
+                // iBeacons
+                if (appleData.length == 23 && appleData[0] == 0x02 && appleData[1] == 0x15)
+                    return true;
+            }
+
+            final byte[] nordicData = record.getManufacturerSpecificData(COMPANY_ID_NORDIC_SEMI);
+            if (nordicData != null) {
+                // Nordic Beacons
+                if (nordicData.length == 23 && nordicData[0] == 0x02 && nordicData[1] == 0x15)
+                    return true;
+            }
+
+            final byte[] microsoftData = record.getManufacturerSpecificData(COMPANY_ID_MICROSOFT);
+            if (microsoftData != null) {
+                // Microsoft Advertising Beacon
+                if (microsoftData[0] == 0x01) // Scenario Type = Advertising Beacon
+                    return true;
+            }
+
+            // Eddystone
+            final byte[] eddystoneData = record.getServiceData(EDDYSTONE_UUID);
+            if (eddystoneData != null)
+                return true;
+        }
+
+        return false;
+    }
+
+    public static boolean isAirDrop(final ScanResult result) {
+        if (result != null && result.getScanRecord() != null) {
+            final ScanRecord record = result.getScanRecord();
+
+            // iPhones and iMacs advertise with AirDrop packets
+            final byte[] appleData = record.getManufacturerSpecificData(COMPANY_ID_APPLE);
+            return appleData != null && appleData.length > 1 && appleData[0] == 0x10;
+        }
+        return false;
+    }
+}

app/src/main/java/no/nordicsemi/android/blinky/utils/Utils.java

@@ -33,7 +33,6 @@
 import android.preference.PreferenceManager;
 
 import androidx.annotation.NonNull;
-import androidx.annotation.RequiresApi;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
 import androidx.core.location.LocationManagerCompat;

app/src/main/java/no/nordicsemi/android/blinky/viewmodels/ScannerViewModel.java

@@ -37,6 +37,7 @@
 
 import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
+import no.nordicsemi.android.blinky.utils.FilterUtils;
 import no.nordicsemi.android.blinky.utils.Utils;
 import no.nordicsemi.android.support.v18.scanner.BluetoothLeScannerCompat;
 import no.nordicsemi.android.support.v18.scanner.ScanCallback;
@@ -181,7 +182,7 @@ public void onScanResult(final int callbackType, @NonNull final ScanResult resul
 			if (Utils.isLocationRequired(getApplication()) && !Utils.isLocationEnabled(getApplication()))
 				Utils.markLocationNotRequired(getApplication());
 
-			if (devicesLiveData.deviceDiscovered(result)) {
+			if (!isNoise(result) && devicesLiveData.deviceDiscovered(result)) {
 				devicesLiveData.applyFilter();
 				scannerStateLiveData.recordFound();
 			}
@@ -199,7 +200,9 @@ public void onBatchScanResults(@NonNull final List<ScanResult> results) {
 
 			boolean atLeastOneMatchedFilter = false;
 			for (final ScanResult result : results)
-				atLeastOneMatchedFilter = devicesLiveData.deviceDiscovered(result) || atLeastOneMatchedFilter;
+				atLeastOneMatchedFilter =
+						(!isNoise(result) && devicesLiveData.deviceDiscovered(result))
+								|| atLeastOneMatchedFilter;
 			if (atLeastOneMatchedFilter) {
 				devicesLiveData.applyFilter();
 				scannerStateLiveData.recordFound();
@@ -272,4 +275,42 @@ public void onReceive(final Context context, final Intent intent) {
 			}
 		}
 	};
+
+	/**
+	 * This method returns true if the scan result may be considered as noise.
+	 * This is to make the device list on the scanner screen shorter.
+	 * <p>
+	 * This implementation considers as noise devices that:
+	 * <ul>
+	 * <li>Are not connectable (Android Oreo or newer only),</li>
+	 * <li>Are far away (RSSI < -80),</li>
+	 * <li>Advertise as beacons (iBeacons, Nordic Beacons, Microsoft Advertising Beacons,
+	 * Eddystone),</li>
+	 * <li>Advertise with AirDrop footprint,</li>
+	 * </ul>
+	 * Noise devices will no the shown on the scanner screen even with all filters disabled.
+	 *
+	 * @param result the scan result.
+	 * @return true, if the device may be dismissed, false otherwise.
+	 */
+	@SuppressWarnings({"BooleanMethodIsAlwaysInverted", "RedundantIfStatement"})
+	private boolean isNoise(@NonNull final ScanResult result) {
+		// Do not show non-connectable devices.
+		// Only Android Oreo or newer can say if a device is connectable. On older Android versions
+		// the Support Scanner Library assumes all devices are connectable (compatibility mode).
+		if (!result.isConnectable())
+			return true;
+
+		// Very distant devices are noise.
+		if (result.getRssi() < -80)
+			return true;
+
+		if (FilterUtils.isBeacon(result))
+			return true;
+
+		if (FilterUtils.isAirDrop(result))
+			return true;
+
+		return false;
+	}
 }