Add MSVC support for Bluetooth

Qt5 doen't implement some bluetooth functions in the WinRT backend. I
guess it's caused by the C++ minimum standard requirement. I have to
port some functions from Qt6 to make the Bluetooth function on MSVC
builds.

Limitations:
1. BLE Central doesn't work well on MinGW builds.
2. Bluetooth Client discovery doesn't work well on MSVC builds. Users
can still specify the Bluetooth address and connect to a server
manually.
3. Bluetooth Client reconnect might causes crashes on MSVC builds.

src/SerialTest.pro

@@ -6,7 +6,16 @@ android {
 
 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
 
-CONFIG += c++11
+win32-msvc*: {
+    # For Bluetooth LE in WinRT
+    CONFIG += c++17
+    SOURCES += winrtbluetooth.cpp
+    HEADERS += winrtbluetooth.h
+    LIBS += -lwindowsapp
+} else {
+    CONFIG += c++11
+}
+
 
 # The following define makes your compiler emit warnings if you use
 # any Qt feature that has been marked deprecated (the exact warnings

src/devicetab.cpp

@@ -13,6 +13,9 @@
 #include <QtAndroid>
 #include <QAndroidJniEnvironment>
 #endif
+#ifdef _MSC_VER
+#include <winrtbluetooth.h>
+#endif
 
 const QMap<QString, QString> DeviceTab::m_historyPrefix =
 {
@@ -424,19 +427,28 @@ qint64 DeviceTab::updateBTAdapterList()
     // need modify
     getRequiredPermission();
 #endif
+#ifdef _MSC_VER
+    // Only powered on adapters
+    auto BTAdapterList = WinRTBluetooth::allLocalDevices(true);
+#else
+    // All adapters
     auto BTAdapterList = QBluetoothLocalDevice::allDevices();
+#endif
     for(auto it = BTAdapterList.cbegin(); it != BTAdapterList.cend(); ++it)
     {
         qDebug() << "dev:" << it->name() << it->address();
+#ifndef _MSC_VER
         QBluetoothLocalDevice dev(it->address());
-        if(dev.isValid() && dev.hostMode() != QBluetoothLocalDevice::HostPoweredOff)
+        if(!dev.isValid() || dev.hostMode() == QBluetoothLocalDevice::HostPoweredOff)
         {
-            QString name = QString("%1:%2").arg(adapterID + 1).arg(it->name());
-            ui->BTClient_adapterBox->addItem(name, it->address().toString());
-            ui->BTServer_adapterBox->addItem(name, it->address().toString());
-            ui->BLEC_adapterBox->addItem(name, it->address().toString());
-            adapterID++;
+            continue;
         }
+#endif
+        QString name = QString("%1:%2").arg(adapterID + 1).arg(it->name());
+        ui->BTClient_adapterBox->addItem(name, it->address().toString());
+        ui->BTServer_adapterBox->addItem(name, it->address().toString());
+        ui->BLEC_adapterBox->addItem(name, it->address().toString());
+        adapterID++;
     }
     return adapterID; // adapter count
 }
@@ -1277,9 +1289,13 @@ void DeviceTab::on_refreshButton_clicked()
 
 void DeviceTab::on_BTClient_adapterBox_activated(int index)
 {
+    // This function is actually useless.
+    // According to the source code of Qt Connectivity (v5.9.0, v5.15.2 and v6.7.0),
+    // the constructor of QBluetoothDeviceDiscoveryAgent only checks if the adapter address exists
+    // in QBluetoothLocalDevice::allDevices(). It ignores null address and won't specify which adapter to be used.
     Q_UNUSED(index)
     ui->BTClient_localAddrLabel->setText(ui->BTClient_adapterBox->currentData().toString());
-    setBTClientDiscoveryAgent(QBluetoothAddress(ui->BTClient_adapterBox->currentData().toString()));
+    setBTClientDiscoveryAgent(QBluetoothAddress());
 #ifdef Q_OS_ANDROID
     // invalid MAC address, ignore
     ui->BTClient_localAddrLabel->setHidden(ui->BTClient_localAddrLabel->text() == "02:00:00:00:00:00");

src/winrtbluetooth.cpp

@@ -0,0 +1,90 @@
+#include "winrtbluetooth.h"
+
+#include <winrt/Windows.Foundation.Collections.h>
+#include <winrt/Windows.Devices.Enumeration.h>
+#include <winrt/Windows.Devices.Bluetooth.h>
+#include <winrt/Windows.Devices.Radios.h>
+
+#include <QCoreApplication>
+#include <QElapsedTimer>
+
+using namespace winrt::Windows::Foundation;
+using namespace winrt::Windows::Foundation::Collections;
+using namespace winrt::Windows::Devices::Enumeration;
+using namespace winrt::Windows::Devices::Bluetooth;
+using namespace winrt::Windows::Devices::Radios;
+
+template <typename T>
+static bool await(IAsyncOperation<T> &&asyncInfo, T &result, uint timeout = 0)
+{
+    using WinRtAsyncStatus = winrt::Windows::Foundation::AsyncStatus;
+    WinRtAsyncStatus status;
+    QElapsedTimer timer;
+    if(timeout)
+        timer.start();
+    do
+    {
+        QCoreApplication::processEvents();
+        status = asyncInfo.Status();
+    }
+    while(status == WinRtAsyncStatus::Started && (!timeout || !timer.hasExpired(timeout)));
+    if(status == WinRtAsyncStatus::Completed)
+    {
+        result = asyncInfo.GetResults();
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static DeviceInformationCollection getAvailableAdapters()
+{
+    const auto btSelector = BluetoothAdapter::GetDeviceSelector();
+    DeviceInformationCollection deviceInfoCollection(nullptr);
+    await(DeviceInformation::FindAllAsync(btSelector), deviceInfoCollection);
+    return deviceInfoCollection;
+}
+
+static Radio getRadioFromAdapterId(winrt::hstring id)
+{
+    BluetoothAdapter a(nullptr);
+    bool res = await(BluetoothAdapter::FromIdAsync(id), a);
+    if(res && a)
+    {
+        Radio r(nullptr);
+        res = await(a.GetRadioAsync(), r);
+        if(res && r)
+            return r;
+    }
+    return nullptr;
+}
+
+WinRTBluetooth::WinRTBluetooth(QObject *parent)
+    : QObject{parent}
+{
+
+}
+
+QList<QBluetoothHostInfo> WinRTBluetooth::allLocalDevices(bool PoweredOnOnly)
+{
+    QList<QBluetoothHostInfo> devices;
+    const auto deviceInfoCollection = getAvailableAdapters();
+    if(deviceInfoCollection)
+    {
+        for(const auto &devInfo : deviceInfoCollection)
+        {
+            BluetoothAdapter adapter(nullptr);
+            const bool res = await(BluetoothAdapter::FromIdAsync(devInfo.Id()), adapter);
+            if(res && adapter && (!PoweredOnOnly || getRadioFromAdapterId(devInfo.Id()).State() == RadioState::On))
+            {
+                QBluetoothHostInfo info;
+                info.setName(QString::fromStdString(winrt::to_string(devInfo.Name())));
+                info.setAddress(QBluetoothAddress(adapter.BluetoothAddress()));
+                devices.push_back(std::move(info));
+            }
+        }
+    }
+    return devices;
+}

src/winrtbluetooth.h

@@ -0,0 +1,17 @@
+#ifndef WINRTBLUETOOTH_H
+#define WINRTBLUETOOTH_H
+
+#include <QObject>
+#include <QBluetoothHostInfo>
+
+class WinRTBluetooth : public QObject
+{
+    Q_OBJECT
+public:
+    explicit WinRTBluetooth(QObject *parent = nullptr);
+    static QList<QBluetoothHostInfo> allLocalDevices(bool PoweredOnOnly = false);
+signals:
+
+};
+
+#endif // WINRTBLUETOOTH_H