BMP文件的相关操作

 // write out a BMP file，DirectShow中例子截取的
        //m_szSnappedName 要生成的BMP文件名字
		//pBuffer BMP数据
        HANDLE hf = CreateFile(
            m_szSnappedName, GENERIC_WRITE, FILE_SHARE_READ, NULL,
            CREATE_ALWAYS, NULL, NULL );

        if( hf == INVALID_HANDLE_VALUE )
            return 0;

        // write out the file header
        //
        BITMAPFILEHEADER bfh;
        memset( &bfh, 0, sizeof( bfh ) );
        bfh.bfType = 'MB';
        bfh.bfSize = sizeof( bfh ) + lBufferSize + sizeof( BITMAPINFOHEADER );
        bfh.bfOffBits = sizeof( BITMAPINFOHEADER ) + sizeof( BITMAPFILEHEADER );

        DWORD dwWritten = 0;
        WriteFile( hf, &bfh, sizeof( bfh ), &dwWritten, NULL );

        // and the bitmap format
        //
        BITMAPINFOHEADER bih;
        memset( &bih, 0, sizeof( bih ) );
        bih.biSize = sizeof( bih );
        bih.biWidth = lWidth;
        bih.biHeight = lHeight;
        bih.biPlanes = 1;
        bih.biBitCount = 24;

        dwWritten = 0;
        WriteFile( hf, &bih, sizeof( bih ), &dwWritten, NULL );

        // and the bits themselves
        //
        dwWritten = 0;
        WriteFile( hf, pBuffer, lBufferSize, &dwWritten, NULL );
        CloseHandle( hf );
        bFileWritten = TRUE;

        // Display the bitmap bits on the dialog's preview window
		//显示，下面代码有该函数的定义
        DisplayCapturedBits(pBuffer, &bih);

//如果要防止重绘时图片被擦除，可以在OnPaint函数中在调用一次这个函数
    BOOL DisplayCapturedBits(BYTE *pBuffer, BITMAPINFOHEADER *pbih)
    {
        // If we haven't yet snapped a still, return
        if (/*!bFileWritten || !pOwner ||*/ !pBuffer)
            return FALSE;

        // put bits into the preview window with StretchDIBits
        //
        HWND hwndStill = NULL;
        pOwner->GetDlgItem( IDC_STILL, &hwndStill );//IDC_STILL显示图片的控件ID

        RECT rc;
        ::GetWindowRect( hwndStill, &rc );
        long lStillWidth = rc.right - rc.left;
        long lStillHeight = rc.bottom - rc.top;
        
        HDC hdcStill = GetDC( hwndStill );
        PAINTSTRUCT ps;
        BeginPaint(hwndStill, &ps);

        SetStretchBltMode(hdcStill, COLORONCOLOR);
        StretchDIBits( 
                    hdcStill, 0, 0, 
                    lStillWidth, lStillHeight, 
                    0, 0, lWidth, lHeight, 
                    pBuffer, 
                    (BITMAPINFO*) pbih, 
                    DIB_RGB_COLORS, 
                    SRCCOPY );

        EndPaint(hwndStill, &ps);
        ReleaseDC( hwndStill, hdcStill );    

        return TRUE;
    }