Multipage PDFs from web twain

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Multipage PDFs from web twain

Post by newage » Wed Dec 29, 2010 05:24 PM

Hi,
Is it possible to save multipage PDFs from web twain using javascript+vb.net?
Thanks.

Re: Multipage PDFs from web twain

Post by Alex » Thu Dec 30, 2010 05:49 AM

Hello,

Yes, this is possible.

First, you need to save all acquired images as PDF document in the stream - please read description of the AcquiredImage.GetAsStream method in the documentation or see this FAQ: https://www.vintasoft.com/vstwain-dotnet ... magesAsPdf

Next, you need to upload stream to the server - please read description of the HttpUpload.AddFileField method in the documentation.

Best regards, Alexander

Re: Multipage PDFs from web twain

Post by newage » Thu Jan 06, 2011 05:34 PM

Hi, thanks for your answer.
I tried both examples from FAQs and from help documentation for GetAsStream Method.
If IвЂ™m following FAQ example, IвЂ™m getting error вЂњAquiredImgae.0 is null or not an objectвЂќ and device.AcquiredImages.Count is always 1 even if IвЂ™ve scanned 10 pages.

Help documentation example gives me error вЂњImageFileFormat is undefinedвЂќ
Thanks.

if (acquireModalState == 2) {
if (firstImage) {
// get the first image as PDF stored in the memory
mem = device.AcquiredImage[0].GetAsStream(ImageFileFormat.PDF);
firstImage = false;
}
else {
// add image to PDF stored in the memory
for (var x=1; x=device.AcquiredImages.Count-1; x++) {
device.AcquiredImages[x].SaveToStream(mem, ImageFileFormat.PDF);
}
}
}

Re: Multipage PDFs from web twain

Post by Alex » Wed Jan 12, 2011 06:57 AM

Hello,
Help documentation example gives me error вЂњImageFileFormat is undefinedвЂќ Your code has 3 mistakes:

Wrong name of property in the line "mem = device.AcquiredImage[0].GetAsStream(ImageFileFormat.PDF);". You need to use "AcquiredImages" instead of "AcquiredImage".
JavaScript cannot access Indexer of class, i.e. line "device.AcquiredImages[0]" is not correct in JavaScript
JavaScript does not know anything about the ImageFileFormat enumeration. Here are constants of ImageFileFormat enumeration: BMP - 0, JPEG - 1, TIFF - 2, PNG - 3, GIF - 4, PDF - 5.

And here is the correct code:

if (acquireModalState == 2)
{
  if (firstImage)
  {
     // get the first acquired image as PDF stored in the memory
     mem = device.AcquiredImage[0].GetAsStream(5);
     firstImage = false;
   }
  else
  {
    // add each (not first) acquired image to PDF stored in the memory
    device.AcquiredImages.Last.SaveToStream(mem, 5);
  }
}

Best regards, Alexander

Re: Multipage PDFs from web twain

Post by jimiscott » Tue Mar 08, 2011 05:05 PM

Alex, we have tried implementing the suggested code, but it seems not to work.

Our scanner is a single page scanner, but we would like to scan multiple images into a single document.

With the suggested code, after the first scan, the device.AcquireModal() method returns 3, after which the image is uploaded. Is there anyway to achieve the above?

Re: Multipage PDFs from web twain

Post by Alex » Thu Mar 17, 2011 03:14 PM

Hello,

Value 3 means that scan is completed i.e. you acquired image from flatbed scanner.

You should save acquired image to the stream, start the second/third/... scan, add acquired images to the stream, upload data of the stream to the server when this is necessary.

Best regards, Alexander

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