Technical FAQs

How do I ensure temp files are deleted when closing ImageGear .NET?

All PDF objects are based on underlying low-level PDF objects that are not controlled by .NET resource manager and garbage collector. Because of this, each PDF object that is created from scratch should be explicitly disposed of using that object’s Dispose() method.

Also, any ImGearPDEContent object obtained from ImGearPDFPage should be released using the ImGearPDFPage.ReleaseContent() in all cases.

This should cause all temp files to be cleared when the application is closed.

ImageGear .NET v24.6 added support for viewing PDF documents with XFA content. I’m using v24.8, and upon trying to open an XFA PDF, I get a SEHException for some reason…

Why might this be happening?

One reason could be because you need to execute the following lines after initializing the PDF component, and prior to loading an XFA PDF:

// Allow opening of PDF documents that contain XFA form data.
IImGearFormat pdfFormat = ImGearFileFormats.Filters.Get(ImGearFormats.PDF);
pdfFormat.Parameters.GetByName("XFAAllowed").Value = true;

This will enable XFA PDFs to be opened by the ImageGear .NET toolkit.

I am combining multiple PDF documents together, and I need to create a new bookmark collection, placed at the beginning of the new document. Each bookmark should go to a specific page or section of the new document.
Example structure:

• Section 1
  • Document 1
• Section 2
  • Document 2

How might I do this using ImageGear .NET?

You are adding section dividers to the result document. So, for example, if you are to merge two documents, you might have, say, two sections, each with a single document, like so…

• Section 1
  • Document 1
• Section 2
  • Document 2

…The first page will be the first header page, and then the pages of Document 1, then another header page, then the pages of Document 2. So, the first header page is at index 0, the first page of Document 1 is at index 1, the second header is at 1 + firstDocumentPageCount, etc.

The following code demonstrates adding some blank pages to igResultDocument, inserting pages from other ImGearPDFDocuments, and modifying the bookmark tree such that it matches the outline above, with "Section X" pointing to the corresponding divider page and "Document X" pointing to the appropriate starting page number…

// Create new document, add pages
ImGearPDFDocument igResultDocument = new ImGearPDFDocument();
igResultDocument.CreateNewPage((int)ImGearPDFPageNumber.BEFORE_FIRST_PAGE, new ImGearPDFFixedRect(0, 0, 300, 300));
igResultDocument.InsertPages((int)ImGearPDFPageNumber.LAST_PAGE, igFirstDocument, 0, (int)ImGearPDFPageRange.ALL_PAGES, ImGearPDFInsertFlags.DEFAULT);
igResultDocument.CreateNewPage(igFirstDocument.Pages.Count, new ImGearPDFFixedRect(0, 0, 300, 300));
igResultDocument.InsertPages((int)ImGearPDFPageNumber.LAST_PAGE, igSecondDocument, 0, (int)ImGearPDFPageRange.ALL_PAGES, ImGearPDFInsertFlags.DEFAULT);

// Add first Section
ImGearPDFBookmark resultBookmarkTree = igResultDocument.GetBookmark();
resultBookmarkTree.AddNewChild("Section 1");
var child = resultBookmarkTree.GetLastChild();
int targetPageNumber = 0;
setNewDestination(igResultDocument, targetPageNumber, child);

// Add first Document
child.AddNewChild("Document 1");
child = child.GetLastChild();
targetPageNumber = 1;
setNewDestination(igResultDocument, targetPageNumber, child);

// Add second Section
resultBookmarkTree.AddNewChild("Section 2");
child = resultBookmarkTree.GetLastChild();
targetPageNumber = 1 + igFirstDocument.Pages.Count;
setNewDestination(igResultDocument, targetPageNumber, child);

// Add second Document
child.AddNewChild("Document 2");
child = child.GetLastChild();
targetPageNumber = 2 + igFirstDocument.Pages.Count;
setNewDestination(igResultDocument, targetPageNumber, child);

// Save
using (FileStream stream = File.OpenWrite(@"C:\path\here\test.pdf"))
{
    igResultDocument.Save(stream, ImGearSavingFormats.PDF, 0, 0, igResultDocument.Pages.Count, ImGearSavingModes.OVERWRITE);
}

...

private ImGearPDFDestination setNewDestination(ImGearPDFDocument igPdfDocument, int targetPageNumber, ImGearPDFBookmark targetNode)
{
    ImGearPDFAction action = targetNode.GetAction();
    if (action == null)
    {
        action = new ImGearPDFAction(
            igPdfDocument,
            new ImGearPDFDestination(
                igPdfDocument,
                igPdfDocument.Pages[targetPageNumber] as ImGearPDFPage,
                new ImGearPDFAtom("XYZ"),
                new ImGearPDFFixedRect(), 0, targetPageNumber));
        targetNode.SetAction(action);
    }
    return action.GetDestination();
}

(The setNewDestination method is a custom method that abstracts the details of adding the new destination.)

Essentially, the GetBookmark() method will allow you to get an instance representing the root of the bookmark tree, with its children being subtrees themselves. Thus, we can add a new child to an empty tree, then get the last child with GetLastChild(). Then, we can set the action for that node to be a new "GoTo" action that will navigate to the specified destination. Upon save to the file system, this should produce a PDF with the below bookmark structure…

Note that you may need to use the native Save method (NOT SaveDocument) described in the product documentation here in order to save a PDF file with the bookmark tree included. Also, you can read more about Actions in the PDF Specification.

How do I remove XMP Data from my image using ImageGear .NET?

When removing XMP data in ImageGear, the simplest way to do this is to set the XMP Metadata node to null, like so:

ImGearSimplifiedMetadata.Initialize(); 
doc.Metadata.XMP = new ImGearXMPMetadataRoot();

Or, you can traverse through the metadata tree and remove each node from the tree:

// Example code. Not thoroughly tested
private static void RemoveXmp(ImGearMetadataTree tree)
{
ArrayList toRemove = new ArrayList();
foreach (ImGearMetadataNode node in tree.Children)
{
    if (node is ImGearMetadataTree)
        RemoveXmp((ImGearMetadataTree)node);

    if (node.Format != ImGearMetadataFormats.XMP)
        continue;

    toRemove.Add(node);
}

foreach (ImGearMetadataNode node in toRemove)
    tree.Children.Remove(node);
}

Why do I get a “File Format Unrecognized” exception when trying to load a PDF document in ImageGear .NET?

You will need to set up your project to include PDF support if you want to work with PDF documents. Add a reference to ImageGear24.Formats.Pdf (if you’re using another version of ImageGear, make sure you’re adding the correct reference). Add the following line of code where you specify other resources:

using ImageGear.Formats.PDF;

Add the following lines of code before you begin working with PDFs:

ImGearFileFormats.Filters.Insert(0, ImGearPDF.CreatePDFFormat());
ImGearPDF.Initialize();

The documentation page linked here shows how to add PDF support to a project.

When using OCR in ImageGear .NET, is there any way to distinguish between a capital/uppercase letter O and the number 0?

Not without context or a font that makes the difference clear (such as one with a slashed 0). ImageGear will properly recognize Oliver and 1530 as containing O and 0, respectively, but cannot reliably distinguish it when letters and numbers are mixed. That is, ImageGear may not reliably distinguish between 1ABO0F3 and 1AB0OF3.

How do I remove XMP Data from my image using ImageGear .NET?

When removing XMP data in ImageGear, the simplest way to do this is to set the XMP Metadata node to null, like so:

ImGearSimplifiedMetadata.Initialize(); 
doc.Metadata.XMP = new ImGearXMPMetadataRoot();

Or, you can traverse through the metadata tree and remove each node from the tree:

// Example code. Not thoroughly tested
private static void RemoveXmp(ImGearMetadataTree tree)
{
ArrayList toRemove = new ArrayList();
foreach (ImGearMetadataNode node in tree.Children)
{
    if (node is ImGearMetadataTree)
        RemoveXmp((ImGearMetadataTree)node);

    if (node.Format != ImGearMetadataFormats.XMP)
        continue;

    toRemove.Add(node);
}

foreach (ImGearMetadataNode node in toRemove)
    tree.Children.Remove(node);
}

Why do I get a “File Format Unrecognized” exception when trying to load a PDF document in ImageGear .NET?

You will need to set up your project to include PDF support if you want to work with PDF documents. Add a reference to ImageGear24.Formats.Pdf (if you’re using another version of ImageGear, make sure you’re adding the correct reference). Add the following line of code where you specify other resources:

using ImageGear.Formats.PDF;

Add the following lines of code before you begin working with PDFs:

ImGearFileFormats.Filters.Insert(0, ImGearPDF.CreatePDFFormat());
ImGearPDF.Initialize();

The documentation page linked here shows how to add PDF support to a project.