Selecting ltmfConvert Object Target Formats Example for C++

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

#include "ltmf.h"
#include "resource.h"
#include "tchar.h"
#include "stdio.h"
HINSTANCE g_hInstance; // application instance handle
IltmfConvert* 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(IltmfTargetFormats* 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++)
   {
      IltmfTargetFormat* 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(IltmfTargetFormats* 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
      {
         IltmfTargetFormat* 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;
            }
         }
      }
   }
}
   
//
// TargetFormatDlgProc
// selects object formats
//
BOOL CALLBACK TargetFormatDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
   IltmfTargetFormats* pTargetFormats;
   
   switch (msg) 
   {
   case WM_INITDIALOG:
      // initialize the target format listbox
      g_pConvert->get_TargetFormats(&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_ltmfConvert, NULL, CLSCTX_INPROC_SERVER, IID_IltmfConvert, (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;
}