ASP.NET Control Snapshot Renderer

ControlRenderer.cs

public class ControlRenderer : IDisposable
{
	public static string RenderContents(Control control)
	{
		using (var renderer = new ControlRenderer(control))
		{
			return renderer.Render();
		}
	}

	private string Render()
	{
		try
		{
			RememberAspNetValidation();
			DisableAspNetValidation();
			InvokeRender();
		}
		finally 
		{
			ResetAspNetValidation();
		}
		return RenderedContents();
	}

	private string RenderedContents()
	{
		return builder.ToString();
	}

	private void InvokeRender()
	{
		renderMethod.Invoke(control, new object[] {htmlWriter});
	}

	private void RememberAspNetValidation()
	{
		originalInOnFormRender = (bool)inOnFormRenderField.GetValue(control.Page);
		originalEnableEventValidation = (bool)enableEventValidationField.GetValue(control.Page);
	}

	private void ResetAspNetValidation()
	{
		inOnFormRenderField.SetValue(control.Page, originalInOnFormRender);
		enableEventValidationField.SetValue(control.Page, originalEnableEventValidation);
	}

	private void DisableAspNetValidation()
	{
		inOnFormRenderField.SetValue(control.Page, true);
		enableEventValidationField.SetValue(control.Page, false);
	}

	private ControlRenderer(Control controlToRender)
	{
		control = controlToRender;
		builder = new StringBuilder();
		writer = new StringWriter(builder);
		htmlWriter = new HtmlTextWriter(writer);
	}

	void IDisposable.Dispose()
	{
		writer.Dispose();
		htmlWriter.Dispose();
	}

	private const BindingFlags PrivateInstance = BindingFlags.NonPublic | BindingFlags.Instance;
	private static readonly Type pageType = typeof(Page);
	private static readonly Type controlType = typeof(Control);
	private static readonly FieldInfo inOnFormRenderField = pageType.GetField("_inOnFormRender", PrivateInstance);
	private static readonly FieldInfo enableEventValidationField = pageType.GetField("_enableEventValidation", PrivateInstance);
	private static readonly MethodInfo renderMethod = controlType.GetMethod("Render", PrivateInstance);

	private readonly StringBuilder builder;
	private readonly StringWriter writer;
	private readonly HtmlTextWriter htmlWriter;
	private readonly Control control;
	private bool originalInOnFormRender;
	private bool originalEnableEventValidation;
}

Makes it possible to render a snapshot of an ASP.NET control even if you don't render a containing Form and/or outside the main Render chain.

Just do ControlRenderer.Render(this) from anywhere, and you get a string representing the current output of this, being a Control or a Page.