Selecting ltmmPlay Object Processors for C

// define helper macros for using interfaces under C 
#ifndef COBJMACROS 
   #define COBJMACROS 
#endif 
 
#include "ltmm.h" 
#include "resource.h" 
#include "tchar.h" 
#include "stdio.h" 
 
HINSTANCE g_hInstance; // application instance handle 
IltmmPlay* g_pPlay; // play object's interface pointer 
 
// 
// BuildProcessorList 
// fills the registered processor listbox to match the contents of the collection 
// 
// pProcessors = processor collection's interface pointer 
// hwndListBox = listbox window handle 
// 
void BuildProcessorList(IltmmProcessors* pProcessors, HWND hwndListBox)  
{ 
   long i;  
   long count;  
 
   // reset the listbox contents 
   SendMessage(hwndListBox, LB_RESETCONTENT, 0, 0);  
 
   // get the collection's item count 
   IltmmProcessors_get_Count (pProcessors, &count);  
 
   for(i = 0; i < count; i++) 
   { 
      IltmmProcessor* pProcessor;  
      BSTR bstr;  
      TCHAR sz[256];  
      int index;  
 
      // retrieve collection item 
      IltmmProcessors_Item (pProcessors, i, &pProcessor);  
 
      // get displayable name 
      IltmmProcessor_get_FriendlyName (pProcessor, &bstr);  
 
      // convert from unicode 
      _stprintf(sz, _T("%ls"), bstr);  
 
      // free name 
      SysFreeString(bstr);  
 
      // add the name to the listbox 
      index = SendMessage(hwndListBox, LB_ADDSTRING, 0, (LPARAM) (LPCTSTR) sz);  
 
      // associate the listbox item with the collection item index 
      SendMessage(hwndListBox, LB_SETITEMDATA, index, i);  
 
 
      // free the collection item 
      IUnknown_Release(pProcessor);  
   } 
 
 
} 
 
// 
// BuildSelectedProcessorList 
// fills the selected processor listbox to match the contents of the collection 
// 
// pSelProcessors = selected processor collection's interface pointer 
// hwndSelListBox = selected listbox window handle 
// 
void BuildSelectedProcessorList(IltmmProcessors* pSelProcessors, HWND hwndSelListBox)  
{ 
   long i;  
   long count;  
 
   // reset the listbox contents 
   SendMessage(hwndSelListBox, LB_RESETCONTENT, 0, 0);  
 
   // get the collection's item count 
   IltmmProcessors_get_Count (pSelProcessors, &count);  
 
   for(i = 0; i < count; i++) 
   { 
      IltmmProcessor* pProcessor;  
      BSTR bstr;  
      TCHAR sz[256];  
 
      // retrieve collection item 
      IltmmProcessors_Item (pSelProcessors, i, &pProcessor);  
 
      // get displayable name 
      IltmmProcessor_get_FriendlyName (pProcessor, &bstr);  
 
      // convert from unicode 
      _stprintf(sz, _T("%ls"), bstr);  
 
      // free name 
      SysFreeString(bstr);  
 
      // add the name to the listbox 
      SendMessage(hwndSelListBox, LB_ADDSTRING, 0, (LPARAM) (LPCTSTR) sz);  
 
 
      // free the collection item 
      IUnknown_Release(pProcessor);  
   } 
 
   // add a blank entry at the end of the list and select it 
   SendMessage(hwndSelListBox, LB_ADDSTRING, 0, (LPARAM) (LPVOID) _T("")); 
   SendMessage(hwndSelListBox, LB_SETCURSEL, count, 0);  
 
} 
 
// 
// RemoveSelectedProcessor 
// removes the currently selected processor 
// 
// pSelProcessors = selected processor collection's interface pointer 
// hwndSelListBox = selected listbox window handle 
// 
void RemoveSelectedProcessor(IltmmProcessors* pSelProcessors, HWND hwndSelListBox)  
{ 
   int index;  
   int count;  
 
 
   // get the number of selected processor listbox items 
   count = (int) SendMessage(hwndSelListBox, LB_GETCOUNT, 0, 0);  
 
   // get the deletion point from the selected processor listbox 
   index = (int) SendMessage(hwndSelListBox, LB_GETCURSEL, 0, 0);  
 
   // if not a valid processor, then return 
   if(index < 0 || index >= (count - 1))  
      return;  
 
   // remove the processor from the selected processor collection 
   IltmmProcessors_Remove (pSelProcessors, index);  
 
   // remove the name from the selected processor listbox 
   SendMessage(hwndSelListBox, LB_DELETESTRING, index, 0);  
 
   // select the next item in the listbox 
   SendMessage(hwndSelListBox, LB_SETCURSEL, index, 0);  
} 
 
// 
// RemoveAllSelectedProcessors 
// removes all selected processors 
// 
// pSelProcessors = selected processor collection's interface pointer 
// hwndSelListBox = selected listbox window handle 
// 
void RemoveAllSelectedProcessors(IltmmProcessors* pSelProcessors, HWND hwndSelListBox)  
{ 
   IltmmProcessors_RemoveAll (pSelProcessors);  
 
   BuildSelectedProcessorList(pSelProcessors, hwndSelListBox);  
} 
 
// 
// InsertSelectedProcessor 
// inserts the currently selected registerd processor into te selected processor collection 
// 
// pProcessors = registered processor collection's interface pointer 
// hwndListBox = registered listbox window handle 
// pSelProcessors = selected processor collection's interface pointer 
// hwndSelListBox = selected listbox window handle 
// 
void InsertSelectedProcessor(IltmmProcessors* pProcessors, HWND hwndListBox,  
                             IltmmProcessors* pSelProcessors, HWND hwndSelListBox)  
{ 
   int index;  
   int selindex;  
   long item;  
   IltmmProcessor* pProcessor;  
   BSTR bstr;  
   TCHAR sz[256];  
 
 
   // get the selection from the registered processor listbox 
   index = (int) SendMessage(hwndListBox, LB_GETCURSEL, 0, 0);  
   if(index < 0)  
      return;  
 
   // get the collection item index 
   item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, index, 0);  
 
   // get the actual item 
   IltmmProcessors_Item (pProcessors, item, &pProcessor);  
 
   // get the insertion point from the selected processor listbox 
   selindex = (int) SendMessage(hwndSelListBox, LB_GETCURSEL, 0, 0);  
 
   // insert the processor into the selected processor collection 
   IltmmProcessors_Add(pSelProcessors, pProcessor, selindex);  
 
   // get the displayable name 
   IltmmProcessor_get_FriendlyName(pProcessor, &bstr);  
 
   // release the processor 
   IUnknown_Release(pProcessor);  
 
   // convert from unicode 
   _stprintf(sz, _T("%ls"), bstr);  
 
   // free name 
   SysFreeString(bstr);  
 
   // insert the name into the selected processor listbox 
   SendMessage(hwndSelListBox, LB_INSERTSTRING, selindex, (LPARAM) (LPCTSTR) sz);  
 
 
} 
 
 
// 
// RefreshProcessorList 
// called to completely rebuild the collection 
// 
// pProcessors = processor collection's interface pointer 
// hwndListBox = listbox window handle 
// 
void RefreshProcessorList(IltmmProcessors* pProcessors, HWND hwndListBox)  
{ 
   IltmmProcessor* pProcessor;  
   long item;  
   BSTR bstr;  
   long i;  
   long count;  
 
   // get the currently selected item    
   i = (int) SendMessage(hwndListBox, LB_GETCURSEL, 0, 0);  
 
   if(i >= 0)  
   { 
      item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0);  
      // get it's unique name 
      IltmmProcessors_Item (pProcessors, item, &pProcessor);  
      IltmmProcessor_get_Name (pProcessor, &bstr);  
      IUnknown_Release(pProcessor);  
   } 
   else 
   { 
      bstr = NULL;  
   } 
 
 
   // rebuild the collection 
   IltmmProcessors_Refresh (pProcessors);  
 
 
   // rebuild the listbox 
   BuildProcessorList(pProcessors, hwndListBox);  
 
   if(bstr)  
   { 
      // find the previously selected item 
      IltmmProcessors_Find (pProcessors, bstr, &item);  
 
      // make it the current selection 
      if(item >= 0)  
      {    
         IltmmProcessors_get_Count (pProcessors, &count);  
 
         // select the appropriate listbox item 
         for(i = 0; i < count; i++) 
         { 
            if(item == (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0))  
            { 
               SendMessage(hwndListBox, LB_SETCURSEL, i, 0);  
               break;  
            } 
         } 
 
      }       
      SysFreeString(bstr);  
   } 
 
 
} 
 
 
// 
// ProcessorSelectionChanged 
// called when the registered processor selection has changed 
// 
// pProcessors = processor collection's interface pointer 
// hwndListBox = listbox window handle 
// hwndAddBtn = add button window handle 
// 
void ProcessorSelectionChanged(IltmmProcessors* pProcessors, HWND hwndListBox, HWND hwndAddBtn)  
{ 
   int index;  
 
   pProcessors = pProcessors ; 
 
   // get the currently selected listbox item 
   index = (int) SendMessage(hwndListBox, LB_GETCURSEL, 0, 0);  
 
   // enable add, if a filter is selected 
   EnableWindow(hwndAddBtn, index >= 0);  
} 
 
// 
// SelectedProcessorSelectionChanged 
// called when the selected processor selection has changed 
// 
// pSelProcessors = processor collection's interface pointer 
// hwndSelListBox = listbox window handle 
// hwndRemoveBtn = remove button window handle 
// hwndRemoveAllBtn = remove all button window handle 
// hwndPropBtn = properties button window handle 
// 
void SelectedProcessorSelectionChanged(IltmmProcessors* pSelProcessors, HWND hwndSelListBox, HWND hwndRemoveBtn, HWND hwndRemoveAllBtn, HWND hwndPropBtn)  
{ 
   int index;  
   int count;  
   BOOL fFilter;  
   VARIANT_BOOL fHasDialog = VARIANT_FALSE;  
   HRESULT hr;  
 
   // get the currently selected listbox item 
   index = (int) SendMessage(hwndSelListBox, LB_GETCURSEL, 0, 0);  
 
   // get the total item count 
   count = (int) SendMessage(hwndSelListBox, LB_GETCOUNT, 0, 0);  
 
   // is this a filter?  
   fFilter = (index >= 0 && index < (count - 1));  
 
   // enable remove all button, if there is a filter in the list 
   EnableWindow(hwndRemoveAllBtn, count > 1);  
 
   // enable remove button, if it is a filter 
   EnableWindow(hwndRemoveBtn, fFilter);  
 
   if(fFilter)  
   { 
      // check for the availablility of a filter property dialog box 
      IltmmProcessor* pProcessor;  
      hr = IltmmProcessors_Item (pSelProcessors, index, &pProcessor);  
      if(SUCCEEDED(hr))  
      { 
         IltmmProcessor_HasDialog (pProcessor, ltmmProcessor_Dlg_Properties, &fHasDialog);  
         IUnknown_Release(pProcessor);  
      } 
   } 
   else 
   { 
      fHasDialog = VARIANT_FALSE;  
   } 
 
   // enable properties button, if dialog box is available 
   EnableWindow(hwndPropBtn, fHasDialog != VARIANT_FALSE);  
} 
 
// 
// InvokeProcessorProperties 
// invokes the currently selected processor's properties dialog box 
// 
// pSelProcessors = processor collection's interface pointer 
// hwndSelListBox = listbox window handle 
// hwndParent = parent window handle 
// 
void InvokeProcessorProperties(IltmmProcessors* pSelProcessors, HWND hwndSelListBox, HWND hwndParent)  
{ 
   int index;  
   int count;  
   IltmmProcessor* pProcessor;  
   HRESULT hr;  
 
   // get the currently selected listbox item 
   index = (int) SendMessage(hwndSelListBox, LB_GETCURSEL, 0, 0);  
 
   // get the total item count 
   count = (int) SendMessage(hwndSelListBox, LB_GETCOUNT, 0, 0);  
 
   // is this a filter?  
   if(index >= 0 && index < (count - 1))  
   { 
      // invoke the processor's dialog 
      hr = IltmmProcessors_Item (pSelProcessors, index, &pProcessor);  
      if(SUCCEEDED(hr))  
      { 
         IltmmProcessor_ShowDialog (pProcessor, ltmmProcessor_Dlg_Properties, (long) hwndParent);  
         IUnknown_Release(pProcessor);  
      } 
   } 
 
}    
 
// 
// ProcessorDlgProc 
// selects object processors 
// 
BOOL CALLBACK ProcessorDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)  
{ 
   IltmmProcessors* pProcessors;  
   IltmmProcessors* pSelProcessors;  
 
   lParam = lParam ; 
 
   switch (msg)  
   { 
   case WM_INITDIALOG:  
      // initialize the audio processor listbox 
      IltmmPlay_get_AudioProcessors(g_pPlay, &pProcessors);  
      BuildProcessorList(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS));  
      ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS),  
         GetDlgItem(hwnd, IDC_ADDAUDIOPROCESSOR));  
      IUnknown_Release(pProcessors);  
 
      // initialize the selected audio processor listbox 
      IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
      BuildSelectedProcessorList(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS));  
      SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS),  
         GetDlgItem(hwnd, IDC_REMOVEAUDIOPROCESSOR),  
         GetDlgItem(hwnd, IDC_REMOVEALLAUDIOPROCESSORS),  
         GetDlgItem(hwnd, IDC_AUDIOPROCESSORPROPERTIES));  
      IUnknown_Release(pSelProcessors);  
 
      // initialize the video processor listbox 
      IltmmPlay_get_VideoProcessors (g_pPlay, &pProcessors);  
      BuildProcessorList(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS));  
      ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS),  
         GetDlgItem(hwnd, IDC_ADDVIDEOPROCESSOR));  
      IUnknown_Release(pProcessors);  
 
      // initialize the selected video processor listbox 
      IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
      BuildSelectedProcessorList(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS));  
      SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS),  
         GetDlgItem(hwnd, IDC_REMOVEVIDEOPROCESSOR),  
         GetDlgItem(hwnd, IDC_REMOVEALLVIDEOPROCESSORS),  
         GetDlgItem(hwnd, IDC_VIDEOPROCESSORPROPERTIES));  
      IUnknown_Release(pSelProcessors);  
 
      return TRUE;  
      break;  
 
   case WM_COMMAND:  
      switch(LOWORD(wParam))  
      { 
      case IDC_ADDAUDIOPROCESSOR:  
         // insert processor into selected audio processor collection 
         IltmmPlay_get_AudioProcessors(g_pPlay, &pProcessors);  
         IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
         InsertSelectedProcessor(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS),  
            pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEAUDIOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_AUDIOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         IUnknown_Release(pProcessors);  
         return TRUE;  
         break;  
      case IDC_REMOVEAUDIOPROCESSOR:  
         // remove processor from the selected audio processor collection 
         IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
         RemoveSelectedProcessor(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEAUDIOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_AUDIOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_REMOVEALLAUDIOPROCESSORS:  
         // remove all selected audio processors 
         IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
         RemoveAllSelectedProcessors(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEAUDIOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLAUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_AUDIOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_REFRESHAUDIOPROCESSORS:  
         // rebuild the registered audio processor collection 
         IltmmPlay_get_AudioProcessors(g_pPlay, &pProcessors);  
         RefreshProcessorList(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS));  
         ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS),  
            GetDlgItem(hwnd, IDC_ADDAUDIOPROCESSOR));  
         IUnknown_Release(pProcessors);  
         return TRUE;  
         break;  
      case IDC_AUDIOPROCESSORPROPERTIES:  
         // invoke the selected audio processor's properties dialog box 
         IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
         InvokeProcessorProperties(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS), hwnd);  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_SELAUDIOPROCESSORS:  
         if(HIWORD(wParam) == LBN_SELCHANGE)  
         { 
            // selection changed, update buttons 
            IltmmPlay_get_SelectedAudioProcessors(g_pPlay, &pSelProcessors);  
            SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELAUDIOPROCESSORS),  
               GetDlgItem(hwnd, IDC_REMOVEAUDIOPROCESSOR),  
               GetDlgItem(hwnd, IDC_REMOVEALLAUDIOPROCESSORS),  
               GetDlgItem(hwnd, IDC_AUDIOPROCESSORPROPERTIES));  
            IUnknown_Release(pSelProcessors);  
         } 
         break;  
      case IDC_AUDIOPROCESSORS:  
         if(HIWORD(wParam) == LBN_SELCHANGE)  
         { 
            // selection changed, update buttons 
            IltmmPlay_get_AudioProcessors(g_pPlay, &pProcessors);  
            ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_AUDIOPROCESSORS),  
               GetDlgItem(hwnd, IDC_ADDAUDIOPROCESSOR));  
            IUnknown_Release(pProcessors);  
         } 
         break;  
      case IDC_ADDVIDEOPROCESSOR:  
         // insert processor into selected video processor collection 
         IltmmPlay_get_VideoProcessors (g_pPlay, &pProcessors);  
         IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
         InsertSelectedProcessor(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS),  
            pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEVIDEOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_VIDEOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         IUnknown_Release(pProcessors);  
         return TRUE;  
         break;  
      case IDC_REMOVEVIDEOPROCESSOR:  
         // remove processor from the selected video processor collection 
         IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
         RemoveSelectedProcessor(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEVIDEOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_VIDEOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_REMOVEALLVIDEOPROCESSORS:  
         // remove all selected video processors 
         IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
         RemoveAllSelectedProcessors(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS));  
         SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_REMOVEVIDEOPROCESSOR),  
            GetDlgItem(hwnd, IDC_REMOVEALLVIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_VIDEOPROCESSORPROPERTIES));  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_REFRESHVIDEOPROCESSORS:  
         // rebuild the registered video processor collection 
         IltmmPlay_get_VideoProcessors (g_pPlay, &pProcessors);  
         RefreshProcessorList(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS));  
         ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS),  
            GetDlgItem(hwnd, IDC_ADDVIDEOPROCESSOR));  
         IUnknown_Release(pProcessors);  
         return TRUE;  
         break;  
      case IDC_VIDEOPROCESSORPROPERTIES:  
         // invoke the selected video processor's properties dialog box 
         IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
         InvokeProcessorProperties(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS), hwnd);  
         IUnknown_Release(pSelProcessors);  
         return TRUE;  
         break;  
      case IDC_SELVIDEOPROCESSORS:  
         if(HIWORD(wParam) == LBN_SELCHANGE)  
         { 
            // selection changed, update buttons 
            IltmmPlay_get_SelectedVideoProcessors(g_pPlay, &pSelProcessors);  
            SelectedProcessorSelectionChanged(pSelProcessors, GetDlgItem(hwnd, IDC_SELVIDEOPROCESSORS),  
               GetDlgItem(hwnd, IDC_REMOVEVIDEOPROCESSOR),  
               GetDlgItem(hwnd, IDC_REMOVEALLVIDEOPROCESSORS),  
               GetDlgItem(hwnd, IDC_VIDEOPROCESSORPROPERTIES));  
            IUnknown_Release(pSelProcessors);  
         } 
         break;  
      case IDC_VIDEOPROCESSORS:  
         if(HIWORD(wParam) == LBN_SELCHANGE)  
         { 
            // selection changed, update buttons 
            IltmmPlay_get_VideoProcessors (g_pPlay, &pProcessors);  
            ProcessorSelectionChanged(pProcessors, GetDlgItem(hwnd, IDC_VIDEOPROCESSORS),  
               GetDlgItem(hwnd, IDC_ADDVIDEOPROCESSOR));  
            IUnknown_Release(pProcessors);  
         } 
         break;  
 
      case IDOK:  
         EndDialog(hwnd, IDOK);  
         return TRUE;  
         break;  
      } 
      break;  
   } 
   return FALSE;  
 
} 
 
void SelectingltmmPlayObjectProcessors_Example ( HINSTANCE hInstance /*application instance handle*/ ) 
{ 
   HRESULT hr;  
 
   g_hInstance = hInstance;  
 
   // initialize COM library 
   hr = CoInitialize(NULL);  
   if(FAILED(hr))  
      goto error;  
 
   // create the play object 
   hr = CoCreateInstance(&CLSID_ltmmPlay, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmPlay, (void**) &g_pPlay);  
   if(FAILED(hr))  
      goto error;  
 
 
   DialogBox(g_hInstance, (LPCTSTR)IDD_PROCESSORDLG, NULL, ProcessorDlgProc);  
 
 
error:  
   // cleanup 
 
   if(g_pPlay)  
      IUnknown_Release(g_pPlay);  
 
   CoUninitialize(); 
}