/// <include file='doc\StyleBuilderSite.uex' path='docs/doc[@for="StyleBuilderSite.QueryService"]/*' />
/// <devdoc>
/// </devdoc>
public object QueryService(Type serviceType)
{
Debug.Assert(serviceType != null, "null service type");
Guid serviceGuid = serviceType.GUID;
object service = null;
if ((site != null) && !serviceGuid.Equals(Guid.Empty))
{
IntPtr pUnk;
int hr = site.QueryService(ref serviceGuid, ref NativeMethods.IID_IUnknown, out pUnk);
if (NativeMethods.Succeeded(hr))
{
service = Marshal.GetObjectForIUnknown(pUnk);
Marshal.Release(pUnk);
}
else
{
service = null;
}
}
return(service);
}
/// <include file='doc\ServiceProvider.uex' path='docs/doc[@for="ServiceProvider.GetService2"]/*' />
/// <devdoc>
/// Retrieves the requested service. The guid must be specified; the class is only
/// used when debugging and it may be null.
/// </devdoc>
private object GetService(Guid guid, Type serviceClass)
{
object service = null;
// No valid guid on the passed in class, so there is no service for it.
//
if (guid.Equals(Guid.Empty))
{
Debug.WriteLineIf(Switches.TRACESERVICE.TraceVerbose, "\tNo SIDSystem.Runtime.InteropServices.Guid");
return(null);
}
// We provide a couple of services of our own.
//
if (guid.Equals(IID_IServiceProvider))
{
return(serviceProvider);
}
if (guid.Equals(IID_IObjectWithSite))
{
return((NativeMethods.IObjectWithSite) this);
}
IntPtr pUnk;
int hr = serviceProvider.QueryService(ref guid, ref NativeMethods.IID_IUnknown, out pUnk);
if (NativeMethods.Failed(hr) || pUnk == (IntPtr)0)
{
Debug.Assert(NativeMethods.Failed(hr), "QueryService succeeded but reurned a NULL pointer.");
service = null;
// These may be interesting to log.
//
Debug.WriteLineIf(Switches.TRACESERVICE.TraceVerbose, "\tQueryService failed: " + hr.ToString());
#if DEBUG
// Ensure that this service failure was not the result of a bad QI implementation.
// In C++, 99% of a service query uses SID == IID, but for us, we always use IID = IUnknown
// first. If the service didn't implement IUnknown correctly, we'll fail the service request
// and it's very difficult to track this down.
//
hr = serviceProvider.QueryService(ref guid, ref guid, out pUnk);
if (NativeMethods.Succeeded(hr))
{
object obj = Marshal.GetObjectForIUnknown(pUnk);
Marshal.Release(pUnk);
// Note that I do not return this service if we succeed -- I don't
// want to make debug work correctly when retail doesn't!
Debug.Assert(!System.Runtime.InteropServices.Marshal.IsComObject(obj),
"The service " + (serviceClass != null ? serviceClass.Name : guid.ToString()) +
" implements it's own interface, but does not implelement IUnknown!\r\n" +
"This is a bad service implemementation, not a problem in the CLR service provider mechanism." + obj.ToString());
}
#endif
}
else
{
service = Marshal.GetObjectForIUnknown(pUnk);
Marshal.Release(pUnk);
}
return(service);
}
