Currently, Telerik Document Processing is available only for .NET Framework and (partially) for Silverlight. Create version targeting .NET Core.

Update: There is a version of Telerik Document Processing compatible with .NET Core 3.0 in the UI for WPF suite. You can use this version in .NET Core projects running on Windows. The assemblies can be downloaded from telerik.com, the Downloads section of UI for WPF -> Betas tab. Please, note that you should have a valid license for UI for WPF in order to be able to see this version. In case you don't, you can use the Trial license by downloading a trial version of the suite. More information about this version of UI for WPF and how it can be used is available in the related blog post.

Add support for preserving and exporting the macros in a macro-enabled workbook.

Macros are pieces of code written in Visual Basic for Applications (VBA) which are used to automate repetitive tasks in excel. The macros are part of the excel file. When a file contains a macro its extension becomes xlsm.

SpreadProcessing should be able to import and export xlsm files and edit the macros in them.

These file formats are very similar to DOCX, and can be easily imported with loss of some information (e.g. macros).

Implement nested mail merge and master-detail scenario.

Implement support for cell references to columns and rows, e.g. $1:$2, A:D, etc.

Currently, CellSelection.SetValue throws ParseException, and CellSelection.SetValueAsFormula throws InvalidOperationException. 

If the lookup_value parameter and lookup_vector parameters refer cells containing text values, the function returns a Not available error ("#N/A").

When a list is just before the table, all of its list items are inserted in the first cell of the table while exporting to HTML.

Workaround: Add a paragraph between the list and the table

By specification, the document AcroForm contains fields with no parents. However, some documents may have child fields in the AcroForm. This leads to ArgumentException when importing the child and parent fields - 'An item with the same key has already been added.' since the child field is added twice.

Exporting document with a missing image is caused by handled Exception on import for DecodeParms containing null or stream object. Currently, PdfProcessing supports only decode parameters containing simple types. The case when some dictionary value is null or stream object should be implemented.

Another case is when the whole dictionary/stream is null. In this case, an ArgumentNullException is thrown.

The current implementation uses System.Windows.Media.Imaging.BitmapImage class in order to take the image pixels for the PDF export. However, BitmapImage class throws NotSupportedException when being initialized with a WMF or EMF image.

WORKAROUND: WMF and EMF images may be converted to PNG images before the PDF export. The following code snippet shows how to convert all inline WMF image to PNG images by using System.Drawing.Image class:

private static void ConvertInlineWmfImagesToPng(RadFlowDocument document)
{
    foreach (ImageInline image in document.EnumerateChildrenOfType<ImageInline>())
    {
        if (image.Image.ImageSource.Extension.Equals("wmf", StringComparison.InvariantCultureIgnoreCase))
        {
            using (MemoryStream wmfImageStream = new MemoryStream(image.Image.ImageSource.Data))
            {
                using (MemoryStream pngImageStream = new MemoryStream())
                {
                    var imageDrawing = System.Drawing.Image.FromStream(wmfImageStream);
                    imageDrawing.Save(pngImageStream, ImageFormat.Png);
                    byte[] pngBytes = pngImageStream.ToArray();
 
                    image.Image.ImageSource = new ImageSource(pngBytes, "png");
                }
            }
        }
    }
}

Table and table cell borders are not evaluated according to inheritance and conflict resolution rules. A conflict will occur when different borders from the table and table cell are overlapping. 

The GetActualValue method of the TableBorders and TableCellBorders could potentially return an incorrect value in some of the following scenarios:

Scenario 1:
A table has cell spacing set to 0. Meaning that the table and table cell borders will overlap.
The table borders have defined all of its borders with border style "Single".
The table cell borders have all of its borders defined with border style "None".

Expected result: the resulting borders should have the border style set to "None" for the location where the table and the cell borders are overlapping.

Scenario 2:
A table has explicitly defined that its right border is with border style "None".
The table has a table style applied with defined border style of type "Single" for all table borders.

Expected result: All of the table borders except the right border should have border style of "Single".

The problem is mostly visible when exporting to PDF and RTF format.

RadPdfProcessing cannot find startxref keyword at the end of a document if the document contains many zero bytes at its end. NotSupportedException is thrown with "Startxref keyword cannot be found" message. 
Workaround: Trim the ending zero bytes before loading the document to PdfProcessing. Example showing this approach can be found in the following KB article:
http://www.telerik.com/support/kb/winforms/details/notsupportedexception-startxref-keyword-cannot-be-found-when-loading-pdf-file-in-radpdfviewer-for-winforms

ArgumentException is thrown when importing documents containing empty values

Form fields are the legacy way to insert an editable controls in a document (text boxes, checkboxes, dropdowns) by using the FORMTEXT, FORMCHECKBOX and FORMDROPDOWN fields.

Do not confuse with content controls (structured document tags) (see https://feedback.telerik.com/Project/184/Feedback/Details/190057 ) and with ActiveX controls.

By specification, the src attribute for images in the HTML content must be present and must contain a valid non-empty URL potentially surrounded by spaces.

However when embedded images with leading white spaces are imported, UriFormatException: 'Invalid URI: The Uri string is too long.', is thrown.

The calculations are wrong, leading to single lines on a page. As a result, the content of the PDF document is laid out on a bigger number of pages.

Workaround: Change the line spacing and its type before exporting to PDF:

When this type of section break is used, the next section should start on the same page instead on the next one.

This API should provide a method for removing all fields and widgets in the document and draw the default widget appearance in place of the removed widgets.

WORKAROUND: Sample implementation for flattening form fields may be seen in the FlattenFormFields method from the attached demo project.