C# 和 C++ (QR 代碼追蹤)

開始之前,建議您先查看 QR 代碼追蹤概觀 文章,其中包含概觀、裝置支援資料表和最佳做法。

取得 QR 套件

您可以在這裡下載 QR 代碼偵測的NuGet套件。

偵測 QR 代碼

新增網路攝影機功能

您必須將功能 webcam 新增至資訊清單,以偵測 QR 代碼。 這項功能是必要的,因為使用者環境中偵測到的代碼內的資料可能包含敏感性資訊。

您可以藉由呼叫 QRCodeWatcher.RequestAccessAsync() 來要求許可權:

C#:

await QRCodeWatcher.RequestAccessAsync();

C++:

co_await QRCodeWatcher.RequestAccessAsync();

您必須先要求許可權,才能建構 QRCodeWatcher 物件。

雖然 QR 代碼偵測需要 webcam 此功能,但偵測會使用裝置的追蹤相機進行。 相較于裝置的相片/視訊 (PV) 相機偵測,這會提供更廣泛的偵測 FOV 和更佳的電池使用時間。

在 C++ 中偵測 QR 代碼

using namespace winrt::Windows::Foundation;
using namespace winrt::Microsoft::MixedReality::QR;

class QRListHelper
{
public:
    QRListHelper(MyApplication& app) :
        m_app(app)
    {}

    IAsyncAction SetUpQRCodes()
    {
        if (QRCodeWatcher::IsSupported())
        {
            QRCodeWatcherAccessStatus status = co_await QRCodeWatcher::RequestAccessAsync();
            InitializeQR(status);
        }
    }

private:
    void OnAddedQRCode(const IInspectable&, const QRCodeAddedEventArgs& args)
    {
        m_app.OnAddedQRCode(args);
    }

    void OnUpdatedQRCode(const IInspectable&, const QRCodeUpdatedEventArgs& args)
    {
        m_app.OnUpdatedQRCode(args);
    }

    void OnEnumerationComplete(const IInspectable&, const IInspectable&)
    {
        m_app.OnEnumerationComplete();
    }

    MyApplication& m_app;
    QRCodeWatcher m_qrWatcher{ nullptr };

    void InitializeQR(QRCodeWatcherAccessStatus status)
    {
        if (status == QRCodeWatcherAccessStatus::Allowed)
        {
            m_qrWatcher = QRCodeWatcher();
            m_qrWatcher.Added({ this, &QRListHelper::OnAddedQRCode });
            m_qrWatcher.Updated({ this, &QRListHelper::OnUpdatedQRCode });
            m_qrWatcher.EnumerationCompleted({ this, &QRListHelper::OnEnumerationComplete });
            m_qrWatcher.Start();
        }
        else
        {
            // Permission denied by system or user
            // Handle the failures
        }
    }
};

取得 QR 代碼的座標系統

每個偵測到的 QR 代碼都會公開與左上角快速偵測方塊左上角的 QR 代碼一致的 空間座標系統

QR code coordinate system

直接使用 QR SDK 時,Z 軸會指向紙張 (未顯示) 。

QR 代碼的 SpatialCoordinateSystem 會對齊,如下所示。 您可以從平臺取得座標系統,方法是呼叫 SpatialGraphInteropPreview::CreateCoordinateSystemForNode ,並傳入程式碼的 SpatialGraphNodeId。

下列 C++ 程式碼示範如何建立矩形,並使用 QR 代碼的座標系統放置矩形:

// Creates a 2D rectangle in the x-y plane, with the specified properties.
std::vector<float3> MyApplication::CreateRectangle(float width, float height)
{
    std::vector<float3> vertices(4);

    vertices[0] = { 0, 0, 0 };
    vertices[1] = { width, 0, 0 };
    vertices[2] = { width, height, 0 };
    vertices[3] = { 0, height, 0 };

    return vertices;
}

您可以使用實體大小來建立 QR 矩形:

std::vector<float3> qrVertices = CreateRectangle(code.PhysicalSideLength(), code.PhysicalSideLength()); 

座標系統可用來繪製 QR 代碼,或將全像投影附加至位置:

using namespace winrt::Windows::Perception::Spatial;
using namespace winrt::Windows::Perception::Spatial::Preview;
SpatialCoordinateSystem qrCoordinateSystem = SpatialGraphInteropPreview::CreateCoordinateSystemForNode(code.SpatialGraphNodeId());

您的 QRCodeAddedHandler 看起來可能像這樣:

void MyApplication::OnAddedQRCode(const QRCodeAddedEventArgs& args)
{
    QRCode code = args.Code();
    std::vector<float3> qrVertices = CreateRectangle(code.PhysicalSideLength(), code.PhysicalSideLength());
    std::vector<unsigned short> qrCodeIndices = TriangulatePoints(qrVertices);
    XMFLOAT3 qrAreaColor = XMFLOAT3(DirectX::Colors::Aqua);

    SpatialCoordinateSystem qrCoordinateSystem = SpatialGraphInteropPreview::CreateCoordinateSystemForNode(code.SpatialGraphNodeId());
    std::shared_ptr<SceneObject> m_qrShape =
        std::make_shared<SceneObject>(
            m_deviceResources,
            qrVertices,
            qrCodeIndices,
            qrAreaColor,
            qrCoordinateSystem);

    m_sceneController->AddSceneObject(m_qrShape);
}

QR 代碼追蹤 API 參考

namespace Microsoft.MixedReality.QR
{
    /// <summary>
    /// Represents a detected QR code.
    /// </remarks>
    public class QRCode
    {
        /// <summary>
        /// Unique id that identifies this QR code for this session.
        /// </summary>
        public Guid Id { get; }

        /// <summary>
        /// Spatial graph node id for this QR code to create a coordinate system.
        /// </summary>
        public Guid SpatialGraphNodeId { get; }

        /// <summary>
        /// Version of this QR code. Version 1-40 are regular QR codes and M1 to M4 are Micro QR code formats 1-4.
        /// </summary>
        public QRVersion Version { get; }

        /// <summary>
        /// Physical width and height of this QR code in meters.
        /// </summary>
        public float PhysicalSideLength { get; }

        /// <summary>
        /// Decoded QR code data.
        /// </summary>
        public String Data { get; }

        /// <summary>
        /// Size of the RawData of this QR code.
        /// </summary>
        public UInt32 RawDataSize { get; }

        /// <summary>
        /// Gets the error-corrected raw data bytes.
        /// Used when the platform is unable to decode the code's format,
        /// allowing your app to decode as needed.
        /// </summary>
        public void GetRawData(byte[] buffer);

        /// <summary>
        /// The last detected time in 100ns QPC ticks.
        /// </summary>
        public System.TimeSpan SystemRelativeLastDetectedTime { get; }

        /// <summary>
        /// The last detected time.
        /// </summary>
        public System.DateTimeOffset LastDetectedTime { get; }
    }

    /// <summary>
    /// Event arguments for a QRCodeWatcher's Added event.
    /// </summary>
    public class QRCodeAddedEventArgs
    {
        /// <summary>
        /// Gets the QR Code that was added
        /// </summary>
        public QRCode Code { get; }
    }

    /// <summary>
    /// Event arguments for a QRCodeWatcher's Removed event.
    /// </summary>
    public class QRCodeRemovedEventArgs
    {
        /// <summary>
        /// Gets the QR Code that was removed.
        /// </summary>
        public QRCode Code { get; }
    }

    /// <summary>
    /// Event arguments for a QRCodeWatcher's Updated event.
    /// </summary>
    public class QRCodeUpdatedEventArgs
    {
        /// <summary>
        /// Gets the QR Code that was updated.
        /// </summary>
        public QRCode Code { get; }
    }

    /// <summary>
    /// Represents the status of an access request for QR code detection.
    /// </summary>
    public enum QRCodeWatcherAccessStatus
    {
        /// <summary>
        /// The system has denied permission for the app to detect QR codes.
        /// </summary>
        DeniedBySystem = 0,
        /// <summary>
        /// The app has not declared the webcam capability in its manifest.
        /// </summary>
        NotDeclaredByApp = 1,
        /// <summary>
        /// The user has denied permission for the app to detect QR codes.
        /// </summary>
        DeniedByUser = 2,
        /// <summary>
        /// A user prompt is required to get permission to detect QR codes.
        /// </summary>
        UserPromptRequired = 3,
        /// <summary>
        /// The user has given permission to detect QR codes.
        /// </summary>
        Allowed = 4,
    }

    /// <summary>
    /// Detects QR codes in the user's environment.
    /// </summary>
    public class QRCodeWatcher
    {
        /// <summary>
        /// Gets whether QR code detection is supported on the current device.
        /// </summary>
        public static bool IsSupported();

        /// <summary>
        /// Request user consent before using QR code detection.
        /// </summary>
        public static IAsyncOperation<QRCodeWatcherAccessStatus> RequestAccessAsync();

        /// <summary>
        /// Constructs a new QRCodeWatcher.
        /// </summary>
        public QRCodeWatcher();

        /// <summary>
        /// Starts detecting QR codes.
        /// </summary>
        /// <remarks>
        /// Start should only be called once RequestAccessAsync has succeeded.
        /// Start should not be called if QR code detection is not supported.
        /// Check that IsSupported returns true before calling Start.
        /// </remarks>
        public void Start();

        /// <summary>
        /// Stops detecting QR codes.
        /// </summary>
        public void Stop();

        /// <summary>
        /// Get the list of QR codes detected.
        /// </summary>
        /// <remarks>
        /// </remarks>
        public IList<QRCode> GetList();

        /// <summary>
        /// Event representing the addition of a QR Code.
        /// </summary>
        public event EventHandler<QRCodeAddedEventArgs> Added;

        /// <summary>
        /// Event representing the removal of a QR Code.
        /// </summary>
        public event EventHandler<QRCodeRemovedEventArgs> Removed;

        /// <summary>
        /// Event representing the update of a QR Code.
        /// </summary>
        public event EventHandler<QRCodeUpdatedEventArgs> Updated;

        /// <summary>
        /// Event representing the enumeration of QR Codes completing after a Start call.
        /// </summary>
        public event EventHandler<Object> EnumerationCompleted;
    }

    /// <summary>
    /// Version info for QR codes, including Micro QR codes.
    /// </summary>
    public enum QRVersion
    {
        QR1 = 1,
        QR2 = 2,
        QR3 = 3,
        QR4 = 4,
        QR5 = 5,
        QR6 = 6,
        QR7 = 7,
        QR8 = 8,
        QR9 = 9,
        QR10 = 10,
        QR11 = 11,
        QR12 = 12,
        QR13 = 13,
        QR14 = 14,
        QR15 = 15,
        QR16 = 16,
        QR17 = 17,
        QR18 = 18,
        QR19 = 19,
        QR20 = 20,
        QR21 = 21,
        QR22 = 22,
        QR23 = 23,
        QR24 = 24,
        QR25 = 25,
        QR26 = 26,
        QR27 = 27,
        QR28 = 28,
        QR29 = 29,
        QR30 = 30,
        QR31 = 31,
        QR32 = 32,
        QR33 = 33,
        QR34 = 34,
        QR35 = 35,
        QR36 = 36,
        QR37 = 37,
        QR38 = 38,
        QR39 = 39,
        QR40 = 40,
        MicroQRM1 = 41,
        MicroQRM2 = 42,
        MicroQRM3 = 43,
        MicroQRM4 = 44,
    }
}

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