VintaSoft Twain .NET SDK v10.2
How to save acquired images in the database?

Example: Here is an example that shows how to save acquired images as multipage PDF document in memory. Later, PDF document can be saved in the database or transferred onto the server.

Imports System.IO
Imports System.Windows.Forms
Imports Vintasoft.Twain
Imports Vintasoft.Twain.ImageEncoders

''' <summary>
''' Class allows to scan and save image as PDF document to a database.
''' </summary>
Partial Public Class How_to_save_acquired_images_to_database_as_PDF_document
    Inherits Form

    ''' <summary>
    ''' TWAIN device manager.
    ''' </summary>
    Private _deviceManager As DeviceManager

    ''' <summary>
    ''' Memory stream for PDF document.
    ''' </summary>
    Private _memoryStream As MemoryStream



    Public Sub New()
        InitializeComponent()

        ' create and open device manager
        _deviceManager = New DeviceManager(Me)
        _deviceManager.Open()
    End Sub



    ''' <summary>
    ''' Acquire images asynchronously.
    ''' </summary>
    Public Sub AcquireImagesAsynchronously()
        Try
            ' get reference to the default device
            Dim device1 As Device = _deviceManager.DefaultDevice

            ' subscribe to the device events
            AddHandler device1.ImageAcquired, New EventHandler(Of ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
            AddHandler device1.ScanCompleted, New EventHandler(AddressOf device_ScanCompleted)
            AddHandler device1.ScanCanceled, New EventHandler(AddressOf device_ScanCanceled)
            AddHandler device1.ScanFailed, New EventHandler(Of ScanFailedEventArgs)(AddressOf device_ScanFailed)
            AddHandler device1.ScanFinished, New EventHandler(AddressOf device_ScanFinished)

            ' disable UI
            device1.ShowUI = False
            ' set Memory (or Native) transfer mode
            device1.TransferMode = TransferMode.Memory

            ' acquire images asynchronously
            device1.Acquire()
        Catch ex As TwainException
            MessageBox.Show(ex.Message)
        End Try
    End Sub

    ''' <summary>
    ''' Image is acquired.
    ''' </summary>
    Private Sub device_ImageAcquired(ByVal sender As Object, ByVal e As Vintasoft.Twain.ImageAcquiredEventArgs)
        ' if memory stream is empty
        If _memoryStream Is Nothing Then
            ' get the first image as PDF stored in the memory
            _memoryStream = e.Image.GetAsStream(New TwainPdfEncoderSettings())
        Else
            ' add image to PDF stored in the memory
            e.Image.Save(_memoryStream, New TwainPdfEncoderSettings())
        End If

        ' dispose the acquired image
        e.Image.Dispose()
    End Sub

    ''' <summary>
    ''' Scan is completed.
    ''' </summary>
    Private Sub device_ScanCompleted(ByVal sender As Object, ByVal e As EventArgs)
        ' save memory stream to a database
    End Sub

    ''' <summary>
    ''' Scan is canceled.
    ''' </summary>
    Private Sub device_ScanCanceled(ByVal sender As Object, ByVal e As EventArgs)
        MessageBox.Show("Scan is canceled.")
    End Sub

    ''' <summary>
    ''' Scan is failed.
    ''' </summary>
    Private Sub device_ScanFailed(ByVal sender As Object, ByVal e As Vintasoft.Twain.ScanFailedEventArgs)
        MessageBox.Show("Scan is failed: " + Convert.ToString(e.ErrorString))
    End Sub

    ''' <summary>
    ''' Scan is finished.
    ''' </summary>
    Private Sub device_ScanFinished(ByVal sender As Object, ByVal e As EventArgs)
        Dim device1 As Device = DirectCast(sender, Device)

        ' unsubscribe from device events
        RemoveHandler device1.ImageAcquired, New EventHandler(Of ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
        RemoveHandler device1.ScanCompleted, New EventHandler(AddressOf device_ScanCompleted)
        RemoveHandler device1.ScanCanceled, New EventHandler(AddressOf device_ScanCanceled)
        RemoveHandler device1.ScanFailed, New EventHandler(Of ScanFailedEventArgs)(AddressOf device_ScanFailed)
        RemoveHandler device1.ScanFinished, New EventHandler(AddressOf device_ScanFinished)

        ' if device is not closed
        If device1.State <> DeviceState.Closed Then
            ' close the device
            device1.Close()
        End If

        MessageBox.Show("Scan is finished.")
    End Sub

End Class
              
using System;
using System.IO;
using System.Windows.Forms;
using Vintasoft.Twain;
using Vintasoft.Twain.ImageEncoders;

namespace TwainExamples_CSharp
{
    /// <summary>
    /// Class allows to scan and save image as PDF document to a database.
    /// </summary>
    public partial class How_to_save_acquired_images_to_database_as_PDF_document : Form
    {

        /// <summary>
        /// TWAIN device manager.
        /// </summary>
        DeviceManager _deviceManager;

        /// <summary>
        /// Memory stream for PDF document.
        /// </summary>
        MemoryStream _memoryStream;



        public How_to_save_acquired_images_to_database_as_PDF_document()
        {
            InitializeComponent();

            // create and open device manager
            _deviceManager = new DeviceManager(this);
            _deviceManager.Open();
        }



        /// <summary>
        /// Acquire images asynchronously.
        /// </summary>
        public void AcquireImagesAsynchronously()
        {
            try
            {
                // get reference to the default device
                Device device = _deviceManager.DefaultDevice;

                // subscribe to the device events
                device.ImageAcquired += new EventHandler(device_ImageAcquired);
                device.ScanCompleted += new EventHandler(device_ScanCompleted);
                device.ScanCanceled += new EventHandler(device_ScanCanceled);
                device.ScanFailed += new EventHandler(device_ScanFailed);
                device.ScanFinished -= new EventHandler(device_ScanFinished);

                // disable UI
                device.ShowUI = false;
                // set Memory (or Native) transfer mode
                device.TransferMode = TransferMode.Memory;

                // acquire images asynchronously
                device.Acquire();
            }
            catch (TwainException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        /// <summary>
        /// Image is acquired.
        /// </summary>
        private void device_ImageAcquired(object sender, Vintasoft.Twain.ImageAcquiredEventArgs e)
        {
            // if memory stream is empty
            if (_memoryStream == null)
                // get the first image as PDF stored in the memory
                _memoryStream = e.Image.GetAsStream(new TwainPdfEncoderSettings());
            else
                // add image to PDF stored in the memory
                e.Image.Save(_memoryStream, new TwainPdfEncoderSettings());

            // dispose the acquired image
            e.Image.Dispose();
        }

        /// <summary>
        /// Scan is completed.
        /// </summary>
        private void device_ScanCompleted(object sender, EventArgs e)
        {
            // save memory stream to a database
        }

        /// <summary>
        /// Scan is canceled.
        /// </summary>
        private void device_ScanCanceled(object sender, EventArgs e)
        {
            MessageBox.Show("Scan is canceled.");
        }

        /// <summary>
        /// Scan is failed.
        /// </summary>
        private void device_ScanFailed(object sender, Vintasoft.Twain.ScanFailedEventArgs e)
        {
            MessageBox.Show("Scan is failed: " + e.ErrorString);
        }

        /// <summary>
        /// Scan is finished.
        /// </summary>
        void device_ScanFinished(object sender, EventArgs e)
        {
            Device device = (Device)sender;

            // unsubscribe from device events
            device.ImageAcquired -= new EventHandler(device_ImageAcquired);
            device.ScanCompleted -= new EventHandler(device_ScanCompleted);
            device.ScanCanceled -= new EventHandler(device_ScanCanceled);
            device.ScanFailed -= new EventHandler(device_ScanFailed);
            device.ScanFinished -= new EventHandler(device_ScanFinished);

            // if device is not closed
            if (device.State != DeviceState.Closed)
                // close the device
                device.Close();

            MessageBox.Show("Scan is finished.");
        }

    }
}