C / C++ / MFC

Christian Graus wrote:

That's way to broad a question for a forum. You should google for articles on what is a huge topic.

G Haranadh wrote:

pbyCmd = new BYTE[byCount+1];

G Haranadh wrote:

if (pbyCmd) delete pbyCmd;

Christian Graus wrote:

Why +1 ?

Christian Graus wrote:

if (pbyCmd) delete [] pbyCmd;

---

Nice talking to you.
If you judge people, you have no time to love them. -- Mother Teresa

BYTE *pbyCmd <code>= NULL</code>;   //Always allocate a default value,
                       // or directly assign a value
 
pbyCmd = new BYTE[byCount+1];    //why +1 ?
 
if (pbyCmd) {
    delete<code>[]</code> pbyCmd;
    <code>pbyCmd = NULL;</code>    //this is not done automatically by delete
                      // but you should do it for security, and if
                      // you want to be able to test if NULL or not
}

Thanks. After long time we met .

delete pbyCmd; //or<br />
delete[] pbyCmd;

---

Nice talking to you.
If you judge people, you have no time to love them. -- Mother Teresa

toxcct wrote:

if (pbyCmd) { delete[] pbyCmd;

Aniket Salunkhe wrote:

What is use of Abstract Class? What it's advantage over normal Class?

Aniket Salunkhe wrote:

In VC6, how to get Pixels of a JPEG Image?

Aniket Salunkhe wrote:

What is use of Abstract Class? What it's advantage over normal Class?

#include <Ole2.h>
#include <olectl.h>
#define HIMETRIC_INCH 2540
HBITMAP LoadJpgFile(LPCTSTR filename)
{
  HBITMAP hBmp = NULL;

  if(filename && *filename)
  {
    HANDLE hFile = CreateFile(filename, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
    if(hFile)
    {
      DWORD dwFileSize = GetFileSize(hFile, NULL);
      HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize);
      if(hGlobal)
      {
        LPVOID pvData = GlobalLock(hGlobal);
        if(pvData)
        {
          DWORD dwBytesRead = 0;
          BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL);
          GlobalUnlock(hGlobal);

          if(bRead && (dwBytesRead==dwFileSize))
          {
            LPSTREAM pstm = NULL;
            HRESULT hr = ::CreateStreamOnHGlobal(hGlobal, TRUE, &pstm);
            if(pstm)
            {
              LPPICTURE pPic = NULL;
              hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID*)&pPic);
              if(pPic)
              {
                // Retrieve logical dimensions
                long lWidth=0, lHeight=0;
                pPic->get_Width(&lWidth);
                pPic->get_Height(&lHeight);

                HDC hMemDC = CreateCompatibleDC(NULL);
                if(hMemDC)
                {
                  // Map logical dimensions to physical device
                  int nWidth = MulDiv(lWidth, GetDeviceCaps(hMemDC, LOGPIXELSX), HIMETRIC_INCH);
                  int nHeight = MulDiv(lHeight, GetDeviceCaps(hMemDC, LOGPIXELSY), HIMETRIC_INCH);
                  if((nWidth>=0) && (nHeight>=0))
                  {
                    HDC dcScreen = GetDC(NULL);
                    if(dcScreen)
                    {
                      HBITMAP hJpgBmp = ::CreateCompatibleBitmap(dcScreen, nWidth, nHeight);
                      if(hJpgBmp)
                      {
                        HBITMAP hPrevBmp = (HBITMAP)::SelectObject(hMemDC, hJpgBmp);

                        RECT rect = {0,0, nWidth,nHeight};
                        hr = pPic->Render(hMemDC, 0, 0, nWidth, nHeight, 0, lHeight, lWidth, -lHeight, &rect);

                        ::SelectObject(hMemDC, hPrevBmp);

                        if(SUCCEEDED(hr))
                          hBmp = hJpgBmp;
                        else
                          DeleteObject(hJpgBmp);
                      }
                      DeleteDC(dcScreen);
                    }
                  }
                  DeleteDC(hMemDC);
                }
                pPic->Release();
              }
              pstm->Release();
            }
          }
        }
        // Note: BoundChecker may say that 'hGlobal' is bad after it's been passed to CreateStreamOnHGlobal().
        // CreateStreamOnHGlobal() docs say that the fcn doesn't  modify the hdl, but BoundsChecker seems to think something is wrong.
        GlobalFree(hGlobal);  
      }
      CloseHandle(hFile);
    }
  }

  return hBmp;
}

void DrawBitmap(HDC hDC, HBITMAP hBitmap, int nXDest, int nYDest)
{
  BITMAP bm;
  if (GetObject(hBitmap, sizeof(bm), &bm))
  {
    HDC hMemDC = CreateCompatibleDC(hDC);

    HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);

    BitBlt(hDC, nXDest, nYDest, bm.bmWidth, bm.bmHeight, hMemDC, 0, 0, SRCCOPY);

    SelectObject(hMemDC, hOldBitmap);
    DeleteDC(hMemDC);
  }
}

void somefcn()
{
  // You supply szJpgFile, hDC, x, y
  HBITMAP hBmp = LoadJpgFile(szJpgFile);
  DrawBitmap(hDC, hBmp, x, y);
  DeleteObject(hBmp);
}

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