How to set the capability/option value of TWAIN/SANE scanner?

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TWAIN standard defines many standard capabilities (XferCount, IPixelType, DoubleFeedDetection, IContrast, IRotation, etc), which can be supported by TWAIN device. Also TWAIN device can provide custom capabilities, which are defined by scanner manufacturer.

If you want to set the current value of TWAIN device capability, please use the WebTwainDeviceJS.setCapability function.

SANE API does not define standard options for SANE device, SANE API just defines rules, which allow to create self-describing options by device manufacturer.

If you want to set the current value of SANE device option, please use the WebTwainDeviceJS.setCapability function.

Here is JavaScript code that demonstrates how to set the value of DuplexEnabled capability of TWAIN/SANE scanner:

JavaScript

// set value of DuplexEnabled capability of TWAIN/SANE scanner
__setDuplexEnabledCapValueOfTwainScanner();



/**
 * Sets value of DuplexEnabled capability of TWAIN/SANE scanner.
 */
function __setDuplexEnabledCapValueOfTwainScanner() {
    // register the evaluation version of VintaSoft Web TWAIN service
    // please read how to get evaluation license in documentation: https://www.vintasoft.com/docs/vstwain-dotnet-web/Licensing-Twain_Web-Evaluation.html
    Vintasoft.Twain.WebTwainGlobalSettingsJS.register('REG_USER', 'REG_URL', 'REG_CODE', 'EXPIRATION_DATE');

    // URL to the VintaSoft Web TWAIN service
    var serviceUrl = 'https://localhost:25329/api/VintasoftTwainApi';
    // a Web API controller that allows to work with TWAIN and SANE devices
    var twainService = new Vintasoft.Shared.WebServiceControllerJS(serviceUrl);

    // TWAIN/SANE device manager
    var deviceManager = new Vintasoft.Twain.WebTwainDeviceManagerJS(twainService);

    // the default settings of device manager
    var deviceManagerInitSetting = new Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS();

    var device = null;
    try {
        // open device manager
        deviceManager.open(deviceManagerInitSetting);

        // get the default TWAIN/SANE device
        device = deviceManager.get_DefaultDevice();

        // open TWAIN device (do not display device UI but display dialog with image scanning progress)
        device.open(false, true);

        // if device is SANE device
        if (device.get_DeviceName().substring(0, 4) == "Sane") {
            // specify that images must be acquired from source "ADF Duplex"
            device.set_SaneScanSource("ADF Duplex");
        }
        // if device is TWAIN device
        else {
            // set value of DuplexEnabled capability of TWAIN scanner
            device.setCapability(new Vintasoft.Twain.WebDeviceCapabilityIdEnumJS("DuplexEnabled"), true);
        }

        // a collection that stores images, which are acquired from TWAIN/SANE devices and stored in memory of VintaSoft Web TWAIN service
        var acquiredImages = new Vintasoft.Twain.WebAcquiredImageCollectionJS(deviceManager);
        var acquireModalState;
        do {
            // do one step of modal image acquisition process
            var acquireModalResult = device.acquireModalSync();
            // get state of image acquisition
            acquireModalState = acquireModalResult.get_AcquireModalState().valueOf();

            switch (acquireModalState) {
                case 2:   // image is acquired
                    // get acquired image
                    var acquiredImage = acquireModalResult.get_AcquiredImage();
                    // add acquired image to the image collection
                    acquiredImages.add(acquiredImage);

                    // get image as Base64 string
                    var bitmapAsBase64String = acquiredImage.getAsBase64String();
                    // update image preview
                    var previewImageElement = document.getElementById('previewImage');
                    previewImageElement.src = bitmapAsBase64String;

                    // clear image collection (delete images from memory of VintaSoft Web TWAIN service) because image is not necessary anymore
                    acquiredImages.clear();
                    break;

                case 4:   // image scan is failed
                    alert(acquireModalResult.get_ErrorMessage());
                    break;

                case 9:   // image scan is finished
                    break;
            }
        }
        while (acquireModalState !== 0);
    }
    catch (ex) {
        alert(ex);
    }
    finally {
        if (device != null) {
            // close the device
            device.close();
        }
        // close the device manager
        deviceManager.close();
    }
}

Here is TypeScript code that demonstrates how to set the value of DuplexEnabled capability of TWAIN/SANE scanner:

TYPESCRIPT

import { Component } from '@angular/core';

@Component({
  selector: 'twain-scanning-demo',
  templateUrl: './twain-scanning-demo.component.html'
})
export class TwainScanningDemoComponent {

  ngOnInit() {
    // set value of DuplexEnabled capability of TWAIN/SANE scanner
    this.__setDuplexEnabledCapValueOfTwainScanner();
  }


  /**
   * Sets value of DuplexEnabled capability of TWAIN/SANE scanner.
   */
  __setDuplexEnabledCapValueOfTwainScanner() {
    // register the evaluation version of VintaSoft Web TWAIN service
    // please read how to get evaluation license in documentation: https://www.vintasoft.com/docs/vstwain-dotnet-web/Licensing-Twain_Web-Evaluation.html
    Vintasoft.Twain.WebTwainGlobalSettingsJS.register('REG_USER', 'REG_URL', 'REG_CODE', 'EXPIRATION_DATE');

    // URL to the VintaSoft Web TWAIN service
    let serviceUrl: string = 'https://localhost:25329/api/VintasoftTwainApi';
    // a Web API controller that allows to work with TWAIN and SANE devices
    let twainService: Vintasoft.Shared.WebServiceControllerJS = new Vintasoft.Shared.WebServiceControllerJS(serviceUrl);

    // TWAIN/SANE device manager
    let deviceManager: Vintasoft.Twain.WebTwainDeviceManagerJS = new Vintasoft.Twain.WebTwainDeviceManagerJS(twainService);

    // the default settings of device manager
    let deviceManagerInitSetting: Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS = new Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS();

    try {
      // open device manager
      deviceManager.open(deviceManagerInitSetting);
    }
    catch (ex) {
      alert(ex);
      return;
    }

    let device: Vintasoft.Twain.WebTwainDeviceJS = null;
    try {
      // get the default TWAIN/SANE device
      device = deviceManager.get_DefaultDevice();

      // open TWAIN device (do not display device UI but display dialog with image scanning progress)
      device.open(false, true);

      // if device is SANE device
      if (device.get_DeviceName().substring(0, 4) == "Sane") {
        // specify that images must be acquired from source "ADF Duplex"
        device.set_SaneScanSource("ADF Duplex");
      }
      // if device is TWAIN device
      else {
        // set value of DuplexEnabled capability of TWAIN scanner
        device.setCapability(new Vintasoft.Twain.WebDeviceCapabilityIdEnumJS("DuplexEnabled"), true);
      }

      // a collection that stores images, which are acquired from TWAIN/SANE devices and stored in memory of VintaSoft Web TWAIN service
      let acquiredImages: Vintasoft.Twain.WebAcquiredImageCollectionJS = new Vintasoft.Twain.WebAcquiredImageCollectionJS(deviceManager);
      let acquireModalState: number;
      do {
        // do one step of modal image acquisition process
        let acquireModalResult: Vintasoft.Twain.WebTwainDeviceAcquireModalResultJS = device.acquireModalSync();
        // get state of image acquisition
        acquireModalState = acquireModalResult.get_AcquireModalState().valueOf() as number;

        switch (acquireModalState) {
          case 2:   // image is acquired
            // get acquired image
            let acquiredImage: Vintasoft.Twain.WebAcquiredImageJS = acquireModalResult.get_AcquiredImage();
            // add acquired image to the image collection
            acquiredImages.add(acquiredImage);

            // get image as Base64 string
            let bitmapAsBase64String: string = acquiredImage.getAsBase64String();
            // update image preview
            let previewImageElement: HTMLImageElement = document.getElementById('previewImage') as HTMLImageElement;
            previewImageElement.src = bitmapAsBase64String;

            // clear image collection (delete images from memory of VintaSoft Web TWAIN service) because image is not necessary anymore
            acquiredImages.clear();
            break;

          case 4:   // image scan is failed
            alert(acquireModalResult.get_ErrorMessage());
            break;

          case 9:   // image scan is finished
            break;
        }
      }
      while (acquireModalState !== 0);
    }
    catch (ex) {
      alert(ex);
    }
    finally {
      if (device != null) {
        // close the device
        device.close();
      }
      // close the device manager
      deviceManager.close();
    }
  }

}

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