Develop Reference

Is it possible to programatically convert a Cell Range in Excel to HTML

I don't mind using any external libraries in order to achieve this. I need to get the HTML representation of a Cell Range in Excel (including all formatting such as borders, font style, etc) inside my C# application. We're trying to automate a process where the user copies certain ranges from some excel files to another system.
I've tried using NPOI, COM Interop, OpenXML, and it seems there are no built-in ways to export just a smaller part of a workbook to HTML. NPOI does have a converter for old formats though, but it converts the entire file. And I could use a XLST transformation to convert the OpenXML representation to HTML. But it would take a lot of time which I don't exactly have right now.
Am I missing something? How does Excel itself save its files to HTML format? Can I use this to my advantage somehow? Are there any libraries out there able to do this?
I've done a lot of research but found nothing.

How to save excel chart as an image using c#?

I have excel files which contains few charts, and I must display these charts on the web page. Additionally I can't install excel on server machine.
I've checked the following free libraries:
epplus, closedxml, spreadsheetlight.
But they are not support that kind of operation.
Do you know any free library which can help me with that?

I'm just going to put this here in case there are no other responses...
Without Excel and therefore interop -- you could have it extract the chart XML files from the XLXS (as if it were a ZIP) to parse/recreate the charts (possibly using System.Windows.Forms.DataVisualization.Charting?) and then save.

Is there Any way to change the colour of an Excel Cell using C#?

I am working on an ASP project where I need to Change the color of the cells based on some validation Checks and return it to user.
Currently I have successfully Implemented this functionality using Excel 12.0 Object Library.
But the problem is that I need to improve performance. InterOp library is very slower than what I expected.
Is there any way that I can Format the cells on an Excel sheet without using InterOp library.
(Something like connecting using OleDb connection and formatting) ??
Please Share Your Knowledge

Try using ExcelPlusPlus library from codeplex. It is not using OleDB
EPPlus link
From codeplex:
Create advanced Excel 2007/2010 spreadsheets on the server
EPPlus is a .net library that reads and writes Excel 2007/2010 files using the Open Office Xml format (xlsx).
EPPlus supports:
Cell Ranges
Cell styling (Border, Color, Fill, Font, Number, Alignments)
Charts
Pictures
Shapes
Comments
Tables
Protection
Encryption
Pivot tables
Data validation
Conditional formatting
VBA
Many more...

export to excel from sharepoint - complex

There is some code/werbparts on our site that display a lot of data in a grid on our site. In addition, they have another page with a few charts.
I need a way to create functionality to export this to excel so the user can click a button and save everything.
The chart will actually have to be built in excel, I can't just grab the picture from the website and display it.
Also, the data from the grid will have to be put into a spreadhseet. I am not as worried about this part.
I have exported to excel before, but it was just basically printing some data which was tab delimited with a certain doc type .
This actually will need to use different work sheets and use some excel functionality.
(I need a better answer than use excel services)
Thanks!

Use Epplus is a third party library for creating and manipulating excel files(xlsx)

Dunno about sharepoint, but the OpenXML SDK might be what you're after:-
http://msdn.microsoft.com/en-us/library/bb448854.aspx

importing excel data while retaining formatting

Is it possible to import excel data to display using C# in any view(data grid etc ..) while retaining formatting like Bold, italic and strikethrough, throughout the document? I am making a Windows form application. My data is in an excel sheet, I want to display it in grid view or any other while retaining the formatting.

Well, there are some ways that I can think of but neither of them are very pretty at all and they would not be very effecient.
1) Parse the excel file cell by cell using Excel Interop. (Very nasty)
2) If you can convert the excel file to Excel XML you could then write say a XSLT to parse the file to pull styling data much more quickly.
Of course getting the styling data out is one thing. Applying it can be a whole other experience. Once you get the styling you have to make sure you apply the values to all the correct columns. Again very nasty and alot of parsing.
However since you did not say whether this was a web or desktop app you could always just embedd an excel control (on the web side) to display the data which may solve your problem. On a desktop app you are probably in for a world of pain trying to do what I describe above.
Maybe somebody will have a better answer but that's what I got.

SpreadsheetGear for .NET can load Excel workbooks and provides access to formatted text values as well as cell formatting such as fonts and colors.
SpreadsheetGear also comes with a Windows Forms spreadsheet control which will allow users to display, edit, format, calculate, print, etc... workbooks with formatting, charts, etc... intact.
If you are building an ASP.NET application, you can use SpreadsheetGear to open a workbook and generate an image of cells and / or charts as shown on our "Excel Chart and Range Imaging Samples" page here
You can download the free trial here if you want to try it out.
Disclaimer: I own SpreadsheetGear LLC