Selecting ltmfCapture Object Inputs Example for C++

#include "ltmf.h"
#include "resource.h"
#include "tchar.h"
#include "stdio.h"
HINSTANCE g_hInstance;
// application instance handle
IltmfCapture* g_pCapture;
// convert object's interface pointer
//
// BuildCaptureInputList
// fills a listbox to match the contents of the collection
//
// pCaptureInputs = input collection's interface pointer
// hwndListBox = listbox window handle
//
void BuildCaptureInputList(IltmfCaptureInputs* pCaptureInputs, 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
   pCaptureInputs->get_Count(&count);
   for(i = 0; i < count; i++)
   {
      IltmfCaptureInput* pCaptureInput;
      BSTR bstr;
      TCHAR sz[256];
      int index;
      VARIANT_BOOL f;
      // retrieve collection item
      pCaptureInputs->Item(i, &pCaptureInput);
      // get displayable name
      pCaptureInput->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
      pCaptureInput->get_Selected(&f);
      if(f)
         selected = i;
      // free the collection item
      pCaptureInput->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;
      }
   }
}
//
// CaptureInputSelectionChanged
// called to reflect changes in the listbox selection
//
// pCaptureInputs = input collection's interface pointer
// hwndListBox = listbox window handle
//
void CaptureInputSelectionChanged(IltmfCaptureInputs* pCaptureInputs, 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
      pCaptureInputs->put_Selection(-1);
   }
   else
   {  
      // get the collection item index
      item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, index, 0);
      // select the item
#ifdef _DEBUG
      {  
         IltmfCaptureInput* pCaptureInput;
         pCaptureInputs->Item(item, &pCaptureInput);
         hr = pCaptureInput->put_Selected(VARIANT_TRUE);
         pCaptureInput->Release();
      }
#else
      hr = pCaptureInputs->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
         pCaptureInputs->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;
            }  
         }  
      }  
   }
}
//
// SelectCompositeVideo
// selects composite video, if available
//
// pCaptureInputs = input collection's interface pointer
// hwndListBox = listbox window handle
//
void SelectCompositeVideo(IltmfCaptureInputs* pCaptureInputs, HWND hwndListBox)
{
   long item;
   BSTR bstr;
   long i;
   long count;
   // Find the composite video input
   bstr = SysAllocString(L"Video Composite");
   pCaptureInputs->Find(bstr, &item);
   SysFreeString(bstr);
   // make it the current selection
   if(item >= 0)
   {
      pCaptureInputs->put_Selection(item);
      pCaptureInputs->get_Count(&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;
         }  
      }
   }
}
//
// CaptureInputDlgProc
// selects object inputs
//
BOOL CALLBACK CaptureInputDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
   IltmfCaptureInputs* pCaptureInputs;
   switch (msg)
   {
   case WM_INITDIALOG:
      // initialize the video input listbox
      g_pCapture->get_VideoInputs(&pCaptureInputs);
      BuildCaptureInputList(pCaptureInputs, GetDlgItem(hwnd, IDC_VIDEOINPUTS));
      pCaptureInputs->Release();
      return TRUE;
      break;
   case WM_COMMAND:
      switch(LOWORD(wParam))
      {  
      case IDC_SELECTCOMPOSITEVIDEO:
         // select composite video
         g_pCapture->get_VideoInputs(&pCaptureInputs);
         SelectCompositeVideo(pCaptureInputs, GetDlgItem(hwnd, IDC_VIDEOINPUTS));
         pCaptureInputs->Release();
         return TRUE;
         break;
      case IDC_VIDEOINPUTS:
         if(HIWORD(wParam) == LBN_SELCHANGE)
         {  
            // select the video input
            g_pCapture->get_VideoInputs(&pCaptureInputs);
            CaptureInputSelectionChanged(pCaptureInputs, GetDlgItem(hwnd, IDC_VIDEOINPUTS));
            pCaptureInputs->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;
   IltmfDevices* pDevices;
   g_hInstance = hInstance;
   // initialize COM library
   hr = CoInitialize(NULL);
   if(FAILED(hr))
      goto error;
   // create the capture object
   hr = CoCreateInstance(CLSID_ltmfCapture, NULL, CLSCTX_INPROC_SERVER, IID_IltmfCapture, (void**) &g_pCapture);
   if(FAILED(hr))
      goto error;
   // select the first audio device available
   g_pCapture->get_AudioDevices(&pDevices);
   pDevices->put_Selection(0);
   pDevices->Release();
   // select the first video device available
   g_pCapture->get_VideoDevices(&pDevices);
   pDevices->put_Selection(0);
   pDevices->Release();
   DialogBox(g_hInstance, (LPCTSTR)IDD_INPUTDLG, NULL, CaptureInputDlgProc); error:
   // cleanup
   if(g_pCapture)
      g_pCapture->Release();
   CoUninitialize();
   return 0;
}