// collect filters of specified category
private void CollectFilters(Guid category)
{
object comObj = null;
ICreateDevEnum enumDev = null;
IEnumMoniker enumMon = null;
IMoniker[] devMon = new IMoniker[1];
int hr;
try
{
// Get the system device enumerator
Type srvType = Type.GetTypeFromCLSID(Clsid.SystemDeviceEnum);
if (srvType == null)
throw new ApplicationException("Failed creating device enumerator");
// create device enumerator
comObj = Activator.CreateInstance(srvType);
enumDev = (ICreateDevEnum) comObj;
// Create an enumerator to find filters of specified category
hr = enumDev.CreateClassEnumerator(category, out enumMon, CDef.None);
if (hr != 0)
throw new ApplicationException("No devices of the category");
// Collect all filters
IntPtr n = IntPtr.Zero;
while (true)
{
// Get next filter
hr = enumMon.Next(1, devMon, n);
if ((hr != 0) || (devMon[0] == null))
break;
// Add the filter
Filter filter = new Filter(devMon[0]);
InnerList.Add(filter);
// Release COM object
Marshal.ReleaseComObject(devMon[0]);
devMon[0] = null;
}
// Sort the collection
InnerList.Sort();
}
finally
{
// release all COM objects
enumDev = null;
if (comObj != null)
{
Marshal.ReleaseComObject(comObj);
comObj = null;
}
if (enumMon != null)
{
Marshal.ReleaseComObject(enumMon);
enumMon = null;
}
if (devMon[0] != null)
{
Marshal.ReleaseComObject(devMon[0]);
devMon[0] = null;
}
}
}
public static Filter CreateFromMonikerString(string monikerString)
{
Filter aFilter = new Filter(monikerString);
return aFilter;
}
