Selecting ltmmConvert 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 
IltmmConvert* g_pConvert; // convert 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 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 
      IltmmConvert_get_AudioProcessors(g_pConvert, &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 
      IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
      IltmmConvert_get_VideoProcessors (g_pConvert, &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 
      IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
         IltmmConvert_get_AudioProcessors(g_pConvert, &pProcessors); 
         IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
         IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
         IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
         IltmmConvert_get_AudioProcessors(g_pConvert, &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 
         IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
            IltmmConvert_get_SelectedAudioProcessors(g_pConvert, &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 
            IltmmConvert_get_AudioProcessors(g_pConvert, &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 
         IltmmConvert_get_VideoProcessors (g_pConvert, &pProcessors); 
         IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
         IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
         IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
         IltmmConvert_get_VideoProcessors (g_pConvert, &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 
         IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
            IltmmConvert_get_SelectedVideoProcessors(g_pConvert, &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 
            IltmmConvert_get_VideoProcessors(g_pConvert, &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 SelectingltmmConvertObjectProcessors_Example ( HINSTANCE hInstance /*application instance handle*/ ) 
{ 
   HRESULT hr; 
   g_hInstance = hInstance; 
   // initialize COM library 
   hr = CoInitialize(NULL); 
   if(FAILED(hr)) 
      goto error; 
   // create the convert object 
   hr = CoCreateInstance(&CLSID_ltmmConvert, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmConvert, (void**) &g_pConvert); 
   if(FAILED(hr)) 
      goto error; 
   DialogBox(g_hInstance, (LPCTSTR)IDD_PROCESSORDLG, NULL, ProcessorDlgProc); 
error: 
   // cleanup 
   if(g_pConvert) 
      IUnknown_Release(g_pConvert); 
   CoUninitialize(); 
}