Selecting ltmmCapture Object Sizes for C++

The following example shows how to enumerate and select ltmmCapture object sizes.

#include "ltmm.h" 
#include "resource.h" 
#include "tchar.h" 
#include "stdio.h" 
 
HINSTANCE g_hInstance;         // application instance handle 
IltmmCapture* g_pCapture;      // capture object's interface pointer 
 
// 
// BuildSizeList 
// fills a listbox to match the contents of the collection 
// 
// pSizes = size collection's interface pointer 
// hwndListBox = listbox window handle 
// 
void BuildSizeList(IltmmCaptureSizes* pSizes, 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 
   pSizes->get_Count(&count); 
 
   for(i = 0; i < count; i++) 
   { 
      IltmmCaptureSize* pSize; 
      TCHAR sz[256]; 
      int index; 
      VARIANT_BOOL f; 
      long width; 
      long height; 
 
      // retrieve collection item 
      pSizes->Item(i, &pSize); 
    
      // get displayable name 
      pSize->get_Width(&width); 
      pSize->get_Height(&height); 
      _stprintf(sz, _T("%d x %d"), width, height); 
 
      // 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 
      pSize->get_Selected(&f); 
      if(f) 
         selected = i; 
    
      // free the collection item 
      pSize->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; 
      } 
   } 
 
} 
 
// 
// SizeSelectionChanged 
// called to reflect changes in the listbox selection 
// 
// pSizes = size collection's interface pointer 
// hwndListBox = listbox window handle 
// 
void SizeSelectionChanged(IltmmCaptureSizes* pSizes, 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) 
   { 
 
      // get the collection item index 
      item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, index, 0); 
    
      // select the item 
#ifdef _DEBUG 
      { 
         IltmmCaptureSize* pSize; 
         pSizes->Item(item, &pSize); 
         hr = pSize->put_Selected(VARIANT_TRUE); 
         pSize->Release(); 
      } 
#else 
      hr = pSizes->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 
         pSizes->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; 
            } 
         } 
 
      } 
    
   } 
 
} 
 
// 
// SizeDlgProc 
// selects object sizes 
// 
BOOL CALLBACK SizeDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) 
{ 
   IltmmDevices* pDevices; 
   IltmmCaptureSizes* pSizes; 
   long index; 
 
   switch (msg)  
   { 
   case WM_INITDIALOG: 
      // select the first video capture device 
      g_pCapture->get_VideoDevices( &pDevices); 
      pDevices->put_Selection( 0); 
      pDevices->Release(); 
 
      g_pCapture->get_VideoCaptureSizes(&pSizes); 
 
      // setup an initial size of 320 x 240 
      pSizes->Find( 320, 240, &index); 
      pSizes->put_Selection(index); 
 
      // initialize the video size listbox 
      BuildSizeList(pSizes, GetDlgItem(hwnd, IDC_CAPTURESIZES)); 
      pSizes->Release(); 
 
      return TRUE; 
      break; 
 
   case WM_COMMAND: 
      switch(LOWORD(wParam)) 
      { 
      case IDC_CAPTURESIZES: 
         if(HIWORD(wParam) == LBN_SELCHANGE) 
         { 
            // select the video size 
            g_pCapture->get_VideoCaptureSizes(&pSizes); 
            SizeSelectionChanged(pSizes, GetDlgItem(hwnd, IDC_CAPTURESIZES)); 
            pSizes->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_ltmmCapture, NULL, CLSCTX_INPROC_SERVER, IID_IltmmCapture, (void**) &g_pCapture); 
   if(FAILED(hr)) 
      goto error; 
    
    
   DialogBox(g_hInstance, (LPCTSTR)IDD_SIZEDLG, NULL, SizeDlgProc); 
 
 
error: 
   // cleanup 
 
   if(g_pCapture) 
      g_pCapture->Release(); 
 
   CoUninitialize(); 
    
   return 0; 
} 

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