Using AutoSize with ltmmCapture for C

The following example demonstrates automatically sizing the ltmmCapture object’s video frame window to the actual size of the media.

// define helper macros for using interfaces under C
#define COBJMACROS

// include the LEAD Multimedia TOOLKIT header
#include "ltmm.h"

#include "resource.h"
#include <tchar.h>
#include <stdio.h>
#include <assert.h>

#define SZ_WNDCLASS_CAPTURE _T("CAPTURE WNDCLASS")
#define WM_CAPTURENOTIFY (WM_USER + 1000)

HINSTANCE g_hInstance;  // application instance handle
HWND g_hwndCapture; // video frame window
IltmmCapture* g_pCapture; // capture object interface pointer


//
// CaptureWndProc
// video frame window procedure
//
LRESULT CALLBACK CaptureWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
   IltmmDevices* pDevices;

   switch (message) 
   {
   case WM_CREATE:
      g_hwndCapture = hwnd;

      // window is the video window frame
      IltmmCapture_put_VideoWindowFrame(g_pCapture, (long) hwnd);

      // force the frame window to be automatically resized to the video
      IltmmCapture_put_AutoSize(g_pCapture, VARIANT_TRUE);
#ifdef _DEBUG
      {
         VARIANT_BOOL f;
         IltmmCapture_get_AutoSize(g_pCapture, &f);
         assert(f != 0);
      }
#endif

      // set preview source video only
      IltmmCapture_put_PreviewSource(g_pCapture, ltmmCapture_Preview_Video);

      // enable preview
      IltmmCapture_put_Preview(g_pCapture, VARIANT_TRUE);
      

      // select the first video device available
      IltmmCapture_get_VideoDevices(g_pCapture, &pDevices);
      IltmmDevices_put_Selection(pDevices, 0);
      IUnknown_Release(pDevices);

      return 0;
      break;
   case WM_DESTROY:
      PostQuitMessage(0);
      break;
   }
   return DefWindowProc(hwnd, message, wParam, lParam);

}

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
   MSG msg;
   HRESULT hr;
   WNDCLASSEX wcex;
   
   g_hInstance = hInstance;

   // initialize COM library
   hr = CoInitialize(NULL);
   if(FAILED(hr))
      goto error;
   
   
   // register the video frame window class
   wcex.cbSize = sizeof(WNDCLASSEX); 
   wcex.style         = CS_HREDRAW | CS_VREDRAW;
   wcex.lpfnWndProc   = CaptureWndProc;
   wcex.cbClsExtra    = 0;
   wcex.cbWndExtra    = 0;
   wcex.hInstance      = g_hInstance;
   wcex.hIcon         = NULL;
   wcex.hCursor      = LoadCursor(NULL, IDC_ARROW);
   wcex.hbrBackground   = (HBRUSH) (COLOR_APPWORKSPACE + 1);
   wcex.lpszMenuName   = NULL;
   wcex.lpszClassName   = SZ_WNDCLASS_CAPTURE;
   wcex.hIconSm      = NULL;
   
   if(!RegisterClassEx(&wcex))
      goto error;

   
   // create the capture object
   hr = CoCreateInstance(&CLSID_ltmmCapture, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmCapture, (void**) &g_pCapture);
   if(FAILED(hr))
      goto error;
   
   // create the video frame window
   if(!CreateWindow(SZ_WNDCLASS_CAPTURE, _T("Capture"), WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, g_hInstance, NULL))
      goto error;
   
   ShowWindow(g_hwndCapture, nCmdShow);

   UpdateWindow(g_hwndCapture);

   // process until done
   while (GetMessage(&msg, NULL, 0, 0)) 
   {
      TranslateMessage(&msg);
      DispatchMessage(&msg);
   }
   
error:
   if(g_pCapture)
      IUnknown_Release(g_pCapture);

   CoUninitialize();

   return 0;   
}