VintaSoft Twain .NET SDK 14.1: Руководство для .NET разработчика
Vintasoft.Twain Namespace / Device Class / CancelTransfer() Method
Синтаксис Exceptions Ремарки Example Требования Смотрите также
В этом разделе
    CancelTransfer() Метод (Device)
    В этом разделе
    Отправляет на устройство команду отмены текущего процесса сканирования (процесс сканирования не будет отменен сразу после выполнения этого метода).
    Синтаксис
    'Declaration
    
    Public Sub CancelTransfer()
    
    
    public void CancelTransfer()
    
    
    public: void CancelTransfer()
    
    
    public:
    void CancelTransfer()
    Исключения
    ИсключениеОписание
    Выбрасывается, если используется .NET отладчик и для оценки функции требуется, чтобы все потоки выполнялись.
    Ремарки

    Важно: передача не будет отменена сразу после выполнения этого метода, передача будет отменена при возникновении события ScanCanceled или когда метод AcquireModal вернет AcquireModalState.None.

    Пример

    Вот C#/VB.NET код, который демонстрирует, как отменить текущую асинхронную передачу изображения.

    
    Class SyncScan_Cancel
    
            ''' <summary>
            ''' This method scans one image and cancels image scan.
            ''' </summary>
            Public Shared Sub ScanOneImageAndCancelScan()
                    Dim isScanCanceled As Boolean = False
    
                    ' create the device manager
                    Using deviceManager As New Vintasoft.Twain.DeviceManager()
                            deviceManager.IsTwain2Compatible = True
                            ' open the device manager
                            deviceManager.Open()
    
                            ' get the device
                            Dim deviceName As String = "KODAK Scanner: i5000"
                            Dim device As Vintasoft.Twain.Device = deviceManager.Devices.Find(deviceName)
                            If device Is Nothing Then
                                    Throw New ApplicationException(String.Format("Device '{0}' is not found.", deviceName))
                            End If
    
                            ' disable device UI
                            device.ShowUI = False
                            ' specify that device must be closed after scan
                            device.DisableAfterAcquire = True
    
                            ' open the device
                            device.Open()
                            ' specify that 2 images must be acquired from scanner
                            device.XferCount = 2
    
                            ' run asynchronous image acquisition
                            Dim acquireModalState1 As Vintasoft.Twain.AcquireModalState = Vintasoft.Twain.AcquireModalState.None
                            Do
                                    acquireModalState1 = device.AcquireModal()
                                    Select Case acquireModalState1
                                            Case Vintasoft.Twain.AcquireModalState.ImageAcquired
                                                    Console.WriteLine("Image is acquired.")
                                                    If device.AcquiredImage IsNot Nothing Then
                                                            device.AcquiredImage.Dispose()
                                                    End If
    
                                                    ' cancel image scan
                                                    device.CancelTransfer()
                                                    Exit Select
    
                                            Case Vintasoft.Twain.AcquireModalState.ScanCompleted
                                                    Console.WriteLine("Scan is completed.")
                                                    Exit Select
    
                                            Case Vintasoft.Twain.AcquireModalState.ScanCanceled
                                                    isScanCanceled = True
                                                    Console.WriteLine("Scan is canceled.")
                                                    Exit Select
    
                                            Case Vintasoft.Twain.AcquireModalState.ScanFailed
                                                    Console.WriteLine(String.Format("Scan is failed: {0}.", device.ErrorString))
                                                    Exit Select
                                    End Select
                            Loop While acquireModalState1 <> Vintasoft.Twain.AcquireModalState.None
    
                            If Not isScanCanceled Then
                                    Throw New ApplicationException("Scan is NOT canceled.")
                            End If
    
                            ' close the device
                            device.Close()
                    End Using
            End Sub
    
    End Class
    
    
    
    namespace TwainExamples_CSharp
    {
        class SyncScan_Cancel
        {
    
            /// <summary>
            /// This method scans one image and cancels image scan.
            /// </summary>
            public static void ScanOneImageAndCancelScan()
            {
                bool isScanCanceled = false;
    
                // create the device manager
                using (Vintasoft.Twain.DeviceManager deviceManager = new Vintasoft.Twain.DeviceManager())
                {
                    deviceManager.IsTwain2Compatible = true;
                    // open the device manager
                    deviceManager.Open();
    
                    // get the device
                    string deviceName = "KODAK Scanner: i5000";
                    Vintasoft.Twain.Device device = deviceManager.Devices.Find(deviceName);
                    if (device == null)
                        throw new System.ApplicationException(string.Format("Device '{0}' is not found.", deviceName));
    
                    // disable device UI
                    device.ShowUI = false;
                    // specify that device must be closed after scan
                    device.DisableAfterAcquire = true;
    
                    // open the device
                    device.Open();
                    // specify that 2 images must be acquired from scanner
                    device.XferCount = 2;
    
                    // run asynchronous image acquisition
                    Vintasoft.Twain.AcquireModalState acquireModalState = Vintasoft.Twain.AcquireModalState.None;
                    do
                    {
                        acquireModalState = device.AcquireModal();
                        switch (acquireModalState)
                        {
                            case Vintasoft.Twain.AcquireModalState.ImageAcquired:
                                System.Console.WriteLine("Image is acquired.");
                                if (device.AcquiredImage != null)
                                    device.AcquiredImage.Dispose();
    
                                // cancel image scan
                                device.CancelTransfer();
                                break;
    
                            case Vintasoft.Twain.AcquireModalState.ScanCompleted:
                                System.Console.WriteLine("Scan is completed.");
                                break;
    
                            case Vintasoft.Twain.AcquireModalState.ScanCanceled:
                                isScanCanceled = true;
                                System.Console.WriteLine("Scan is canceled.");
                                break;
    
                            case Vintasoft.Twain.AcquireModalState.ScanFailed:
                                System.Console.WriteLine(string.Format("Scan is failed: {0}.", device.ErrorString));
                                break;
                        }
                    }
                    while (acquireModalState != Vintasoft.Twain.AcquireModalState.None);
    
                    if (!isScanCanceled)
                        throw new System.ApplicationException("Scan is NOT canceled.");
    
                    // close the device
                    device.Close();
                }
            }
    
        }
    }
    
    

    Требования

    Целевые платформы: .NET 8; .NET 7; .NET 6; .NET Framework 4.8, 4.7, 4.6, 4.5, 4.0, 3.5

    Смотрите также