wfd_scan - kensuke/How-to-Miracast-on-AOSP GitHub Wiki

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Wireless Display Scanning (p2p) & Device Filtering

Sequence Diagram

Method Flow

1. Settings App

    125     public void onResume() {
    126         super.onResume();
    127 
    128         Context context = getActivity();
    129         IntentFilter filter = new IntentFilter();
    130         filter.addAction(DisplayManager.ACTION_WIFI_DISPLAY_STATUS_CHANGED);
    131         context.registerReceiver(mReceiver, filter);
    132 
    133         getContentResolver().registerContentObserver(Settings.Secure.getUriFor(
    134                 Settings.Global.WIFI_DISPLAY_ON), false, mSettingsObserver);
    135 
    136         mDisplayManager.scanWifiDisplays();
    137 
    138         update();
    139     }

2. DisplayManager.java

    200     public void scanWifiDisplays() {
    201         mGlobal.scanWifiDisplays();
    202     }

3. DisplayManagerGlobal.java

    256     public void scanWifiDisplays() {
    257         try {
    258             mDm.scanWifiDisplays();
    259         } catch (RemoteException ex) {
    260             Log.e(TAG, "Failed to scan for Wifi displays.", ex);
    261         }
    262     }

4. DisplayManagerService.java

    407     public void scanWifiDisplays() {
    408         final long token = Binder.clearCallingIdentity();
    409         try {
    410             synchronized (mSyncRoot) {
    411                 if (mWifiDisplayAdapter != null) {
    412                     mWifiDisplayAdapter.requestScanLocked();
    413                 }
    414             }
    415         } finally {
    416             Binder.restoreCallingIdentity(token);
    417         }
    418     }

5. WifiDisplayAdapter.java

    151     public void requestScanLocked() {
    152         if (DEBUG) {
    153             Slog.d(TAG, "requestScanLocked");
    154         }
    155 
    156         getHandler().post(new Runnable() {
    157             @Override
    158             public void run() {
    159                 if (mDisplayController != null) {
    160                     mDisplayController.requestScan();
    161                 }
    162             }
    163         });
    164     }

6. WifiDisplayController.java

    217     public void requestScan() {
    218         discoverPeers();
    219     }

    294     private void discoverPeers() {
    295         if (!mDiscoverPeersInProgress) {
    296             mDiscoverPeersInProgress = true;
    297             mDiscoverPeersRetriesLeft = DISCOVER_PEERS_MAX_RETRIES;
    298             handleScanStarted();
    299             tryDiscoverPeers();
    300         }
    301     }

    303     private void tryDiscoverPeers() {
    304         mWifiP2pManager.discoverPeers(mWifiP2pChannel, new ActionListener() {
    305             @Override
    306             public void onSuccess() {
    307                 if (DEBUG) {
    308                     Slog.d(TAG, "Discover peers succeeded.  Requesting peers now.");
    309                 }
    310 
    311                 mDiscoverPeersInProgress = false;
    312                 requestPeers();
    313             }
    314 
    315             @Override
    316             public void onFailure(int reason) {
      // ...

    350     private void requestPeers() {
    351         mWifiP2pManager.requestPeers(mWifiP2pChannel, new PeerListListener() {
    352             @Override
    353             public void onPeersAvailable(WifiP2pDeviceList peers) {
    354                 if (DEBUG) {
    355                     Slog.d(TAG, "Received list of peers.");
    356                 }
    357 
    358                 mAvailableWifiDisplayPeers.clear();
    359                 for (WifiP2pDevice device : peers.getDeviceList()) {
    360                     if (DEBUG) {
    361                         Slog.d(TAG, "  " + describeWifiP2pDevice(device));
    362                     }
    363 
    364                     if (isWifiDisplay(device)) {
    365                         mAvailableWifiDisplayPeers.add(device);
    366                     }
    367                 }
    368 
    369                 handleScanFinished();
    370             }
    371         });
    372     }

    819     private static boolean isWifiDisplay(WifiP2pDevice device) {
    820         return device.wfdInfo != null
    821                 && device.wfdInfo.isWfdEnabled()
    822                 && isPrimarySinkDeviceType(device.wfdInfo.getDeviceType());
    823     }

    825     private static boolean isPrimarySinkDeviceType(int deviceType) {
    826         return deviceType == WifiP2pWfdInfo.PRIMARY_SINK
    827                 || deviceType == WifiP2pWfdInfo.SOURCE_OR_PRIMARY_SINK;
    828     }

7. WifiP2pManager.java

    959     public void discoverPeers(Channel c, ActionListener listener) {
    960         checkChannel(c);
    961         c.mAsyncChannel.sendMessage(DISCOVER_PEERS, 0, c.putListener(listener));
    962     }

8. WifiP2pService.java

    847                 case WifiP2pManager.DISCOVER_PEERS:
    848                     // do not send service discovery request while normal find operation.
    849                     clearSupplicantServiceRequest();
    850                     if (mWifiNative.p2pFind(DISCOVER_TIMEOUT_S)) {
    851                         replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_SUCCEEDED);
    852                         sendP2pDiscoveryChangedBroadcast(true);
    853                     } else {
    854                         replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_FAILED,
    855                                 WifiP2pManager.ERROR);
    856                     }
    857                     break;

9. WifiNative.java

    522     public boolean p2pFind() {
    523         return doBooleanCommand("P2P_FIND");
    524     }

     99     private boolean doBooleanCommand(String command) {
    100         if (DBG) Log.d(mTAG, "doBoolean: " + command);
    101         return doBooleanCommand(mInterface, command);
    102     }

     76     private native boolean doBooleanCommand(String iface, String command);

10. wpa_supplicant_8

   1652 static int wpa_cli_cmd_p2p_find(struct wpa_ctrl *ctrl, int argc, char *argv[])
   1653 {
   1654 	return wpa_cli_cmd(ctrl, "P2P_FIND", 0, argc, argv);
   1655 }

11. // ..., wlan driver

// ...

12. // other p2p device

// ...