source: branches/WebApplication/MVC2/HLWebPluginHost/PluginLib/PluginViewEngine.cs @ 4606

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Diagnostics;

namespace HLWebPluginHost.PluginLib {

  /// <summary>
  /// This implementation of the view engine takes view inside of plugins into account and removes the need to provide the full
  /// path of a view from within a controller inside a view.
  /// Use Global.asax to register this engine to the framework
  /// </summary>
  public class PluginViewEngine : System.Web.Mvc.WebFormViewEngine {
    public PluginViewEngine(string[] viewLocations)
      : base() {
      string[] tempArray = new string[ViewLocationFormats.Length + viewLocations.Length];
      ViewLocationFormats.CopyTo(tempArray, 0);

      for (int i = 0; i < viewLocations.Length; i++) {

        tempArray[ViewLocationFormats.Length + i] = viewLocations[i];
      }

      ViewLocationFormats = tempArray;

      PartialViewLocationFormats = ViewLocationFormats;
    }

    private bool IsAppResourcePath(string virtualPath) {

      String checkPath = VirtualPathUtility.ToAppRelative(virtualPath);
      return checkPath.StartsWith("~/Plugins/", StringComparison.InvariantCultureIgnoreCase);
    }

    //If we have a virtual path, we need to override the super class behavior,
    //its implementation ignores custom VirtualPathProviders, unlike the super's super class. 
    //This code basically just reimplements the super-super class (VirtualPathProviderViewEngine) behavior for virtual paths.
    protected override bool FileExists(ControllerContext controllerContext, string virtualPath) {

      if (IsAppResourcePath(virtualPath)) {

        return System.Web.Hosting.HostingEnvironment.VirtualPathProvider.FileExists(virtualPath);
      } else
        return base.FileExists(controllerContext, virtualPath);
    }
  }
}