Setting up a paper size to A1 and exporting the document actually sets the paperSize to 1. 

This leads to inappropriate values when entering the Page Setup options later in Excel.

Provide a way to measure text on different platforms so the user can pass the cell value and SpreadCellFormat and get the size of the text in pixels. This way we will be able to implement auto-fit to width functionality (AutoFitWidth), at least for the .NET Framework implementation. It will be able to measure the width of all cells in a column and set the value as column width in pixels.

When calling SpreadExporter.CreateWorkbookExporter method and referencing Trial assemblies an exception is thrown: System.ArgumentException: 'An item with the same key has already been added.'

This behavior is observed both with the NuGet packages and DLLs.

It is not observed with Trial DLLs version 2020.3.1019

In addition to the fast document generation, the SpreadStreamProcessing can be adapted to import documents significantly faster than SpreadProcessing.

ArgumentException with clarification similar to "'\u001f', hexadecimal value 0x1F, is an invalid character." is thrown when trying to export document containing characters which are not supported in XML document - such as some control characters like 0x00, 0x1F, 0x1B, etc.

Such characters are described in the XML specification here: https://www.w3.org/TR/xml/#charsets.

using (var stream = File.OpenWrite("sample.xlsx"))
using (var workbook = SpreadExporter.CreateWorkbookExporter(SpreadDocumentFormat.Xlsx, stream))
using (var worksheet = workbook.CreateWorksheetExporter("My sheet"))
using (var row = worksheet.CreateRowExporter())
using (var cell = row.CreateCellExporter())
{
      cell.SetValue(string.Format("Error Value: {0} ", Encoding.ASCII.GetString(new byte[] { 8 })));
}

Provide a way to export filters.