Programmatically apply a Theme to a Web in Sharepoint 2010

We can manage the theme from UI of Sharepoint also but sometimes we have a requirement like we need to manage theme through a feature i.e. on feature activation we need to apply some theme and on deactivation remove that theme and apply the default no-theme of Sharepoint.

Add the Microsoft.SharePoint.Utilities reference.

Below is the code by which we can iterate through all the themes and apply to the web

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using Microsoft.SharePoint;

using Microsoft.SharePoint.Utilities;

using System.Collections.ObjectModel;

using Microsoft.SharePoint.Utilities;

namespace GetThemes

{

    class Program

    {

        static void Main(string[] args)

        {

            using (SPSite objSite = new SPSite("http://<Site Url>/"))

            {

                using (SPWeb objWeb = objSite.OpenWeb())

                {

                    ReadOnlyCollection<ThmxTheme> objThmxThemeList;

                    objThmxThemeList = ThmxTheme.GetManagedThemes(objSite);

                    foreach (ThmxTheme objThmxTheme in objThmxThemeList)

                    {

                        if (objThmxTheme.Name == "Graham")

                        {

                            ThmxTheme.SetThemeUrlForWeb(objWeb, objThmxTheme.ServerRelativeUrl);

                            break;

                        }

                    }

                 }           

            }

        }

    }

}

Now if you want to remove the applied theme from the web than pass NULL  instead of theme url as shown below.

ThmxTheme.SetThemeUrlForWeb(objWeb, null);

This will apply the default no theme to Sharepoint site.