Selecting ltmmConvert Object Target Formats for C++

The following code demonstrates how to enumerate, add, and select ltmmConvert object target formats:

#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

//
// BuildTargetFormatList
// fills a listbox to match the contents of the collection
//
// pTargetFormats = format collection's interface pointer
// hwndListBox = listbox window handle
//
void BuildTargetFormatList(IltmmTargetFormats* pTargetFormats, HWND hwndListBox)
{
   long i;
   long count;
   int selected = -1;

   // reset the listbox contents
   SendMessage(hwndListBox, LB_RESETCONTENT, 0, 0);

   // get the collection's item count
   pTargetFormats->get_Count(&count);

   for(i = 0; i < count; i++)
   {
      IltmmTargetFormat* pTargetFormat;
      BSTR bstr;
      TCHAR sz[256];
      int index;
      VARIANT_BOOL f;

      // retrieve collection item
      pTargetFormats->Item(i, &pTargetFormat);
   
      // get displayable name
      pTargetFormat->get_Name(&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);

      // remember this listbox item, if it is selected in the collection
      pTargetFormat->get_Selected(&f);
      if(f)
         selected = i;
   
      // free the collection item
      pTargetFormat->Release();
   }

   // select the appropriate listbox item
   for(i = 0; i < count; i++)
   {
      if(selected == (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0))
      {
         SendMessage(hwndListBox, LB_SETCURSEL, i, 0);
         break;
      }
   }
}

//
// TargetFormatSelectionChanged
// called to reflect changes in the listbox selection
//
// pTargetFormats = format collection's interface pointer
// hwndListBox = listbox window handle
//
void TargetFormatSelectionChanged(IltmmTargetFormats* pTargetFormats, HWND hwndListBox)
{
   int index;
   long item;
   int i;
   int count;
   HRESULT hr;

   // get the index of current listbox selection
   index = (int) SendMessage(hwndListBox, LB_GETCURSEL, 0, 0);
   
   if(index < 0)
   {
      // clear selection
      pTargetFormats->put_Selection(-1);
   }
   else
   {
      // get the collection item index
      item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, index, 0);
   
      // select the item
#ifdef _DEBUG
      {
         IltmmTargetFormat* pTargetFormat;
         pTargetFormats->Item(item, &pTargetFormat);
         hr = pTargetFormat->put_Selected(VARIANT_TRUE);
         pTargetFormat->Release();
      }
#else
      hr = pTargetFormats->put_Selection(item);
#endif
      // if new selection failed, we need to force the listbox to match the actual selection
      if(FAILED(hr))
      {
         // get the real selection
         pTargetFormats->get_Selection(&item);   
   
         // find the matching listbox item
         count = (int) SendMessage(hwndListBox, LB_GETCOUNT, 0, 0);

         for(i = 0; i < count; i++)
         {
            if(item == (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0))
            {
               SendMessage(hwndListBox, LB_SETCURSEL, i, 0);
               break;
            }
         }
      }
   }
#ifdef _DEBUG
   {
      long item;
      pTargetFormats->get_Selection(&item);
      if(item >= 0)
      {
         IltmmTargetFormat* pTargetFormat;
         TCHAR sz[2048];
         LPTSTR p;
         VARIANT_BOOL b;
         BSTR bstr;
         
         sz[0] = _T('\0');
         p = sz;
         pTargetFormats->Item(item, &pTargetFormat);
      

         pTargetFormat->get_AudioCompressor(&bstr);
         p += _stprintf(p, _T("AComp = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_VideoCompressor(&bstr);
         p += _stprintf(p, _T(", VComp = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_AVMux(&bstr);
         p += _stprintf(p, _T(", AVMux = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_Mux(&bstr);
         p += _stprintf(p, _T(", Mux = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_SinkSubType(&bstr);
         p += _stprintf(p, _T(", SubType = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_Sink(&bstr);
         p += _stprintf(p, _T(", Sink = %ls"), bstr);
         SysFreeString(bstr);

         pTargetFormat->get_ReadOnly(&b);
         p += _stprintf(p, _T(", ReadOnly = %s"), b != 0 ? _T("Yes") : _T("No"));
         
         pTargetFormat->Release();

         MessageBox(NULL, sz, _T("Target Format"), MB_OK);
      }
   }
#endif
}

//
// AddCustomTargetFormats
// called to append custom target formats
//
// pTargetFormats = format collection's interface pointer
//
void AddCustomTargetFormats(IltmmTargetFormats* pTargetFormats)
{
   BSTR bstr;
   long index;
   IltmmTargetFormat* pTargetFormat;

   // remove all custom formats
#ifdef _DEBUG
   pTargetFormats->get_Count(&index);
   pTargetFormats->Remove(index - 1);
#else
   pTargetFormats->RemoveAll();
#endif

   bstr = SysAllocString(L"CUSTOM FORMAT 1");
   pTargetFormats->Add(bstr, -1);
   pTargetFormats->Find(bstr, &index);
   SysFreeString(bstr);

   pTargetFormats->Item(index, &pTargetFormat);

   // assign an optional audio compressor
   // this case: MP3
   bstr = SysAllocString(L"@device:cm:{33D9A761-90C8-11D0-BD43-00A0C911CE86}\\85MPEG Layer-3");
   pTargetFormat->put_AudioCompressor(bstr);
   SysFreeString(bstr);

   // assign an optional video compressor
   // this case: LEAD MCMP
   bstr = SysAllocString(L"@device:sw:{33D9A760-90C8-11D0-BD43-00A0C911CE86}\\LEAD MCMP/MJPEG Codec (2.0)");
   pTargetFormat->put_VideoCompressor(bstr);
   SysFreeString(bstr);

   // assign an optional AVMux compressor
   // this case: no premux
   bstr = SysAllocString(L"");
   pTargetFormat->put_AVMux(bstr);
   SysFreeString(bstr);

   // assign the required Mux
   // this case: AVI
   bstr = SysAllocString(L"@device:sw:{083863F1-70DE-11D0-BD40-00A0C911CE86}\\{E2510970-F137-11CE-8B67-00AA00A3F1A6}");
   pTargetFormat->put_Mux(bstr);
   SysFreeString(bstr);

   // assign the optional SinkSubType
   // this case: MEDIASUBTYPE_Avi
   bstr = SysAllocString(L"{E436EB88-524F-11CE-9F53-0020AF0BA770}");
   pTargetFormat->put_SinkSubType(bstr);
   SysFreeString(bstr);

   // assign an optional Sink
   // this case: default
   bstr = SysAllocString(L"");
   pTargetFormat->put_Sink(bstr);
   SysFreeString(bstr);
   
   pTargetFormat->Release();
}
   
//
// TargetFormatDlgProc
// selects object formats
//
BOOL CALLBACK TargetFormatDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
   IltmmTargetFormats* pTargetFormats;
   
   switch (msg) 
   {
   case WM_INITDIALOG:
      // initialize the target format listbox
      g_pConvert->get_TargetFormats(&pTargetFormats);
      AddCustomTargetFormats(pTargetFormats);
      BuildTargetFormatList(pTargetFormats, GetDlgItem(hwnd, IDC_TARGETFORMATS));
      pTargetFormats->Release();
      
      return TRUE;
      break;

   case WM_COMMAND:
      switch(LOWORD(wParam))
      {
      case IDC_TARGETFORMATS:
         if(HIWORD(wParam) == LBN_SELCHANGE)
         {
            // select the target format
            g_pConvert->get_TargetFormats(&pTargetFormats);
            TargetFormatSelectionChanged(pTargetFormats, GetDlgItem(hwnd, IDC_TARGETFORMATS));
            pTargetFormats->Release();
         }
         break;

      case IDOK:
         EndDialog(hwnd, IDOK);
         return TRUE;
         break;
      }
      break;
   }
   return FALSE;
   
}

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
   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_TARGETFORMATDLG, NULL, TargetFormatDlgProc);

error:
   // cleanup
   if(g_pConvert)
      g_pConvert->Release();

   CoUninitialize();
   
   return 0;
}