XlsFormatProvider: Add support for hidden rows.

Add support for the FILTER function.

Add support for setting the Axis Type to Automatic.

At this point the culture used by RadSpreadProcessing (in the FormatHelper and internally in SpreadsheetCultureHelper) is determined by the current thread culture on startup. Provide ability to:
- to change the culture at runtime. Currently, when the thread culture is changed, RadSpreadProcessing is "stuck" with the original one.
- set this culture independently of the current thread's one.

In Excel formulas, the double minus (--) is known as the "double unary operator." Its main purpose is to convert Boolean values (TRUE/FALSE) into numeric values (1/0).
How it works:
• TRUE becomes 1
• FALSE becomes 0
Example: Suppose you have an array formula like:

=SUM(--(B2:B20="Gamma"))

• (B2:B20="Gamma") produces an array of TRUE/FALSE.
• --(B2:B20="Gamma") converts that array to 1/0.
• SUM(...) then adds up the number of matches.

Some Excel functions (like SUM, SUMPRODUCT) require numbers, not Booleans.
The double unary is a concise way to force this conversion.

 

 

SEARCH function with the following format is valid only in Excel 365/2021 or later (with dynamic array support).
"=SEARCH({"Alpha","Beta","Gamma","Delta","Omega","Sigma","Zeta"}, "Omega")"

• It returns an array of numbers or errors, showing the position of each substring in "Omega".
• If a substring is found, you get its position (e.g., 1 for "Omega"); if not, you get #VALUE!.

Add support for the RANDBETWEEN function.

Provide the ability to work with images in headers/footers of a worksheet. Note that large images put in headers are visualized as watermarks on printing/exporting to PDF.
Watermark in Excel: https://support.office.com/en-us/article/add-a-watermark-in-excel-a372182a-d733-484e-825c-18ddf3edf009
 

Add support for Stock charts (StockChart).

Add support for pivot tables.

Charts in excel have support for minor grid lines. This is not supported here.

The COUNTA function counts cells containing any type of information, including error values and empty text ("")

https://support.microsoft.com/en-us/office/counta-function-7dc98875-d5c1-46f1-9a82-53f3219e2509 

Expose the argument values of existing conditional formatting rules. Currently, the argument values from the SingleArgumentConditionalFormattingRule and DoubleArgumentConditionalFormattingRule classes are internal.

https://support.microsoft.com/en-us/office/eomonth-function-7314ffa1-2bc9-4005-9d66-f49db127d628 

Add support for creating Tables and applying tables styles (predefined ones or custom).

Introduce import/export of a single sheet.

Add support for "Of Pie" charts (ofPieChart).

Handle import of documents containing XLSX-incompatible names.

For the Telerik Spreadsheet control, XlsxFormatProvider.Export() API is used for saving the .xlsx file manually without the UI command(Save As dialog) invocation. This API is currently returning a byte stream.

The requirement is that the API should also intimate the user whether the export is successful or not by returning a boolean value.

Note: I think we can implement this requirement at the base level which is for the BinaryFormatProviderBase class or atleast at the FormatProviderBase class.