fix scan on older android

Author: alerighi

library/android/src/main/java/it/iotinga/blelibrary/BleLibraryModule.java

@@ -137,34 +137,43 @@ public void cancel(String transactionId, Promise promise) {
   public void scanStart(ReadableArray filterUuid, Promise promise) {
     Log.d(NAME, String.format("scanStart(%s)", filterUuid));
 
+
     if (adapter == null) {
       promise.reject(BleError.ERROR_NOT_INITIALIZED.name(), "module is not initialized");
     } else {
-      Log.i(NAME, "starting scan");
+      boolean isFilteringSupported = adapter.isOffloadedFilteringSupported();
+      boolean isBatchingSupported = adapter.isOffloadedScanBatchingSupported();
+
+      Log.i(NAME, String.format("starting scan filter supported %b batching supported %b", isFilteringSupported, isBatchingSupported));
 
       List<ScanFilter> filters = null;
       ScanSettings.Builder settings = new ScanSettings.Builder()
         .setScanMode(ScanSettings.SCAN_MODE_BALANCED)
         .setMatchMode(ScanSettings.MATCH_MODE_AGGRESSIVE);
 
-      if (filterUuid != null && filterUuid.size() > 0) {
+      List<ParcelUuid> uuidFilter = null;
+      if (isFilteringSupported && filterUuid != null && filterUuid.size() > 0) {
         settings.setCallbackType(ScanSettings.CALLBACK_TYPE_FIRST_MATCH | ScanSettings.CALLBACK_TYPE_MATCH_LOST);
         filters = new ArrayList<>();
+        uuidFilter = new ArrayList<>();
         for (int i = 0; i < filterUuid.size(); i++) {
           String serviceUuid = filterUuid.getString(i);
           Log.d(NAME, "adding filter UUID: " + serviceUuid);
           ParcelUuid uuid = ParcelUuid.fromString(serviceUuid);
+          uuidFilter.add(uuid);
           filters.add(new ScanFilter.Builder().setServiceUuid(uuid).build());
         }
       } else {
         // avoid flooding JS with events
-        settings.setReportDelay(SCAN_REPORT_DELAY_MS);
+        if (isBatchingSupported) {
+          settings.setReportDelay(SCAN_REPORT_DELAY_MS);
+        }
         settings.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES);
       }
 
       if (scanner == null) {
         scanner = adapter.getBluetoothLeScanner();
-        scanCallback = new BleScanCallback(emitter);
+        scanCallback = new BleScanCallback(emitter, uuidFilter);
       } else {
         // stopping existing scan to restart it
         try {

library/android/src/main/java/it/iotinga/blelibrary/BleScanCallback.java

@@ -1,8 +1,10 @@
 package it.iotinga.blelibrary;
 
 import android.bluetooth.le.ScanCallback;
+import android.bluetooth.le.ScanRecord;
 import android.bluetooth.le.ScanResult;
 import android.bluetooth.le.ScanSettings;
+import android.os.ParcelUuid;
 import android.util.Log;
 
 import androidx.annotation.RequiresPermission;
@@ -12,24 +14,49 @@
 public class BleScanCallback extends ScanCallback {
   private static final String TAG = "BleScanCallback";
   private final EventEmitter eventEmitter;
+  private final List<ParcelUuid> filter;
 
-  BleScanCallback(EventEmitter eventEmitter) {
+  BleScanCallback(EventEmitter eventEmitter, List<ParcelUuid> filter) {
     super();
     this.eventEmitter = eventEmitter;
+    this.filter = filter;
+  }
+
+  private boolean resultPassesUuidFilter(ScanResult result) {
+    if (filter == null || filter.isEmpty()) {
+      return true;
+    }
+
+    ScanRecord record = result.getScanRecord();
+    if (record == null) {
+      return false;
+    }
+
+    for (ParcelUuid uuid : record.getServiceUuids()) {
+      for (ParcelUuid allowedUuid : filter) {
+        if (uuid.equals(allowedUuid)) {
+          return true;
+        }
+      }
+    }
+
+    return false;
   }
 
   @Override
   @RequiresPermission(value = "android.permission.BLUETOOTH_CONNECT")
   public void onScanResult(int callbackType, ScanResult result) {
     Log.i(TAG, String.format("got scan result: %s (callback type: %d)", result, callbackType));
 
-    boolean available = callbackType == ScanSettings.CALLBACK_TYPE_FIRST_MATCH
-      || callbackType == ScanSettings.CALLBACK_TYPE_ALL_MATCHES;
+    if (resultPassesUuidFilter(result)) {
+      boolean available = callbackType == ScanSettings.CALLBACK_TYPE_FIRST_MATCH
+        || callbackType == ScanSettings.CALLBACK_TYPE_ALL_MATCHES;
 
-    RNEventScanResult event = new RNEventScanResult();
-    event.add(result, available);
+      RNEventScanResult event = new RNEventScanResult();
+      event.add(result, available);
 
-    eventEmitter.emit(event);
+      eventEmitter.emit(event);
+    }
   }
 
   @Override
@@ -46,7 +73,9 @@ public void onBatchScanResults(List<ScanResult> results) {
 
     RNEventScanResult event = new RNEventScanResult();
     for (ScanResult result : results) {
-      event.add(result, true);
+      if (resultPassesUuidFilter(result)) {
+        event.add(result, true);
+      }
     }
 
     eventEmitter.emit(event);