Need function to create very large, empty bitmap file for use with FileMapping

Question for Dan Rollins - I need a function that will create a large empty bitmap file, given required dimensions.
PMH4514Asked:
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DanRollinsCommented:
The next comment contains the function I wrote to generate arbitrarily-sized 8bpp BMP files with (what is apparently) the standard grayscale palette.   The "base" of the file is the raw data from an existing grayscale file which I just converted into hex bytes.  I then overwrite a few items in that data and write out that header.  Then I wrote the "pixel data" one scanline at a time.  

I tested the function up to 40,000 x 40,000 -- which generates a 1.6 GB file.  On my computer it takes about 20 seconds to generate the file.

This is in conjunction with a related question
   http://www.experts-exchange.com/Programming/Programming_Languages/MFC/Q_21786622.html
which describes how to access portions of such large files without needing to read the entire thing into RAM -- a sot of BitBlt directly to the file.
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DanRollinsCommented:

BYTE abBmpTemplate_8bbp[] = {
      'B', 'M', 0x76,0x46,0x0f,0x00,0x00,0x00,0x00,0x00,0x36,0x04,0x00,0x00,0x28,0x00,
      0x00,0x00,0xe8,0x03,0x00,0x00,0xe8,0x03,0x00,0x00,0x01,0x00,0x08,0x00,0x00,0x00,
      0x00,0x00,0x40,0x42,0x0f,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
      0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x00,0x02,0x02,
      0x02,0x00,0x03,0x03,0x03,0x00,0x04,0x04,0x04,0x00,0x05,0x05,0x05,0x00,0x06,0x06,
      0x06,0x00,0x07,0x07,0x07,0x00,0x08,0x08,0x08,0x00,0x09,0x09,0x09,0x00,0x0a,0x0a,
      0x0a,0x00,0x0b,0x0b,0x0b,0x00,0x0c,0x0c,0x0c,0x00,0x0d,0x0d,0x0d,0x00,0x0e,0x0e,
      0x0e,0x00,0x0f,0x0f,0x0f,0x00,0x10,0x10,0x10,0x00,0x11,0x11,0x11,0x00,0x12,0x12,
      0x12,0x00,0x13,0x13,0x13,0x00,0x14,0x14,0x14,0x00,0x15,0x15,0x15,0x00,0x16,0x16,
      0x16,0x00,0x17,0x17,0x17,0x00,0x18,0x18,0x18,0x00,0x19,0x19,0x19,0x00,0x1a,0x1a,
      0x1a,0x00,0x1b,0x1b,0x1b,0x00,0x1c,0x1c,0x1c,0x00,0x1d,0x1d,0x1d,0x00,0x1e,0x1e,
      0x1e,0x00,0x1f,0x1f,0x1f,0x00,0x20,0x20,0x20,0x00,0x21,0x21,0x21,0x00,0x22,0x22,
      0x22,0x00,0x23,0x23,0x23,0x00,0x24,0x24,0x24,0x00,0x25,0x25,0x25,0x00,0x26,0x26,
      0x26,0x00,0x27,0x27,0x27,0x00,0x28,0x28,0x28,0x00,0x29,0x29,0x29,0x00,0x2a,0x2a,
      0x2a,0x00,0x2b,0x2b,0x2b,0x00,0x2c,0x2c,0x2c,0x00,0x2d,0x2d,0x2d,0x00,0x2e,0x2e,
      0x2e,0x00,0x2f,0x2f,0x2f,0x00,0x30,0x30,0x30,0x00,0x31,0x31,0x31,0x00,0x32,0x32,
      0x32,0x00,0x33,0x33,0x33,0x00,0x34,0x34,0x34,0x00,0x35,0x35,0x35,0x00,0x36,0x36,
      0x36,0x00,0x37,0x37,0x37,0x00,0x38,0x38,0x38,0x00,0x39,0x39,0x39,0x00,0x3a,0x3a,
      0x3a,0x00,0x3b,0x3b,0x3b,0x00,0x3c,0x3c,0x3c,0x00,0x3d,0x3d,0x3d,0x00,0x3e,0x3e,
      0x3e,0x00,0x3f,0x3f,0x3f,0x00,0x40,0x40,0x40,0x00,0x41,0x41,0x41,0x00,0x42,0x42,
      0x42,0x00,0x43,0x43,0x43,0x00,0x44,0x44,0x44,0x00,0x45,0x45,0x45,0x00,0x46,0x46,
      0x46,0x00,0x47,0x47,0x47,0x00,0x48,0x48,0x48,0x00,0x49,0x49,0x49,0x00,0x4a,0x4a,
      0x4a,0x00,0x4b,0x4b,0x4b,0x00,0x4c,0x4c,0x4c,0x00,0x4d,0x4d,0x4d,0x00,0x4e,0x4e,
      0x4e,0x00,0x4f,0x4f,0x4f,0x00,0x50,0x50,0x50,0x00,0x51,0x51,0x51,0x00,0x52,0x52,
      0x52,0x00,0x53,0x53,0x53,0x00,0x54,0x54,0x54,0x00,0x55,0x55,0x55,0x00,0x56,0x56,
      0x56,0x00,0x57,0x57,0x57,0x00,0x58,0x58,0x58,0x00,0x59,0x59,0x59,0x00,0x5a,0x5a,
      0x5a,0x00,0x5b,0x5b,0x5b,0x00,0x5c,0x5c,0x5c,0x00,0x5d,0x5d,0x5d,0x00,0x5e,0x5e,
      0x5e,0x00,0x5f,0x5f,0x5f,0x00,0x60,0x60,0x60,0x00,0x61,0x61,0x61,0x00,0x62,0x62,
      0x62,0x00,0x63,0x63,0x63,0x00,0x64,0x64,0x64,0x00,0x65,0x65,0x65,0x00,0x66,0x66,
      0x66,0x00,0x67,0x67,0x67,0x00,0x68,0x68,0x68,0x00,0x69,0x69,0x69,0x00,0x6a,0x6a,
      0x6a,0x00,0x6b,0x6b,0x6b,0x00,0x6c,0x6c,0x6c,0x00,0x6d,0x6d,0x6d,0x00,0x6e,0x6e,
      0x6e,0x00,0x6f,0x6f,0x6f,0x00,0x70,0x70,0x70,0x00,0x71,0x71,0x71,0x00,0x72,0x72,
      0x72,0x00,0x73,0x73,0x73,0x00,0x74,0x74,0x74,0x00,0x75,0x75,0x75,0x00,0x76,0x76,
      0x76,0x00,0x77,0x77,0x77,0x00,0x78,0x78,0x78,0x00,0x79,0x79,0x79,0x00,0x7a,0x7a,
      0x7a,0x00,0x7b,0x7b,0x7b,0x00,0x7c,0x7c,0x7c,0x00,0x7d,0x7d,0x7d,0x00,0x7e,0x7e,
      0x7e,0x00,0x7f,0x7f,0x7f,0x00,0x80,0x80,0x80,0x00,0x81,0x81,0x81,0x00,0x82,0x82,
      0x82,0x00,0x83,0x83,0x83,0x00,0x84,0x84,0x84,0x00,0x85,0x85,0x85,0x00,0x86,0x86,
      0x86,0x00,0x87,0x87,0x87,0x00,0x88,0x88,0x88,0x00,0x89,0x89,0x89,0x00,0x8a,0x8a,
      0x8a,0x00,0x8b,0x8b,0x8b,0x00,0x8c,0x8c,0x8c,0x00,0x8d,0x8d,0x8d,0x00,0x8e,0x8e,
      0x8e,0x00,0x8f,0x8f,0x8f,0x00,0x90,0x90,0x90,0x00,0x91,0x91,0x91,0x00,0x92,0x92,
      0x92,0x00,0x93,0x93,0x93,0x00,0x94,0x94,0x94,0x00,0x95,0x95,0x95,0x00,0x96,0x96,
      0x96,0x00,0x97,0x97,0x97,0x00,0x98,0x98,0x98,0x00,0x99,0x99,0x99,0x00,0x9a,0x9a,
      0x9a,0x00,0x9b,0x9b,0x9b,0x00,0x9c,0x9c,0x9c,0x00,0x9d,0x9d,0x9d,0x00,0x9e,0x9e,
      0x9e,0x00,0x9f,0x9f,0x9f,0x00,0xa0,0xa0,0xa0,0x00,0xa1,0xa1,0xa1,0x00,0xa2,0xa2,
      0xa2,0x00,0xa3,0xa3,0xa3,0x00,0xa4,0xa4,0xa4,0x00,0xa5,0xa5,0xa5,0x00,0xa6,0xa6,
      0xa6,0x00,0xa7,0xa7,0xa7,0x00,0xa8,0xa8,0xa8,0x00,0xa9,0xa9,0xa9,0x00,0xaa,0xaa,
      0xaa,0x00,0xab,0xab,0xab,0x00,0xac,0xac,0xac,0x00,0xad,0xad,0xad,0x00,0xae,0xae,
      0xae,0x00,0xaf,0xaf,0xaf,0x00,0xb0,0xb0,0xb0,0x00,0xb1,0xb1,0xb1,0x00,0xb2,0xb2,
      0xb2,0x00,0xb3,0xb3,0xb3,0x00,0xb4,0xb4,0xb4,0x00,0xb5,0xb5,0xb5,0x00,0xb6,0xb6,
      0xb6,0x00,0xb7,0xb7,0xb7,0x00,0xb8,0xb8,0xb8,0x00,0xb9,0xb9,0xb9,0x00,0xba,0xba,
      0xba,0x00,0xbb,0xbb,0xbb,0x00,0xbc,0xbc,0xbc,0x00,0xbd,0xbd,0xbd,0x00,0xbe,0xbe,
      0xbe,0x00,0xbf,0xbf,0xbf,0x00,0xc0,0xc0,0xc0,0x00,0xc1,0xc1,0xc1,0x00,0xc2,0xc2,
      0xc2,0x00,0xc3,0xc3,0xc3,0x00,0xc4,0xc4,0xc4,0x00,0xc5,0xc5,0xc5,0x00,0xc6,0xc6,
      0xc6,0x00,0xc7,0xc7,0xc7,0x00,0xc8,0xc8,0xc8,0x00,0xc9,0xc9,0xc9,0x00,0xca,0xca,
      0xca,0x00,0xcb,0xcb,0xcb,0x00,0xcc,0xcc,0xcc,0x00,0xcd,0xcd,0xcd,0x00,0xce,0xce,
      0xce,0x00,0xcf,0xcf,0xcf,0x00,0xd0,0xd0,0xd0,0x00,0xd1,0xd1,0xd1,0x00,0xd2,0xd2,
      0xd2,0x00,0xd3,0xd3,0xd3,0x00,0xd4,0xd4,0xd4,0x00,0xd5,0xd5,0xd5,0x00,0xd6,0xd6,
      0xd6,0x00,0xd7,0xd7,0xd7,0x00,0xd8,0xd8,0xd8,0x00,0xd9,0xd9,0xd9,0x00,0xda,0xda,
      0xda,0x00,0xdb,0xdb,0xdb,0x00,0xdc,0xdc,0xdc,0x00,0xdd,0xdd,0xdd,0x00,0xde,0xde,
      0xde,0x00,0xdf,0xdf,0xdf,0x00,0xe0,0xe0,0xe0,0x00,0xe1,0xe1,0xe1,0x00,0xe2,0xe2,
      0xe2,0x00,0xe3,0xe3,0xe3,0x00,0xe4,0xe4,0xe4,0x00,0xe5,0xe5,0xe5,0x00,0xe6,0xe6,
      0xe6,0x00,0xe7,0xe7,0xe7,0x00,0xe8,0xe8,0xe8,0x00,0xe9,0xe9,0xe9,0x00,0xea,0xea,
      0xea,0x00,0xeb,0xeb,0xeb,0x00,0xec,0xec,0xec,0x00,0xed,0xed,0xed,0x00,0xee,0xee,
      0xee,0x00,0xef,0xef,0xef,0x00,0xf0,0xf0,0xf0,0x00,0xf1,0xf1,0xf1,0x00,0xf2,0xf2,
      0xf2,0x00,0xf3,0xf3,0xf3,0x00,0xf4,0xf4,0xf4,0x00,0xf5,0xf5,0xf5,0x00,0xf6,0xf6,
      0xf6,0x00,0xf7,0xf7,0xf7,0x00,0xf8,0xf8,0xf8,0x00,0xf9,0xf9,0xf9,0x00,0xfa,0xfa,
      0xfa,0x00,0xfb,0xfb,0xfb,0x00,0xfc,0xfc,0xfc,0x00,0xfd,0xfd,0xfd,0x00,0xfe,0xfe,
      0xfe,0x00,0xff,0xff,0xff,0x00
};


BOOL CreateEmptyBitmap_8bbp( LPCSTR sFilename, int nWide, int nHigh )
{
      BITMAPFILEHEADER* pBMFH;
      BITMAPINFO*       pBMI;    

      pBMFH= (BITMAPFILEHEADER*)abBmpTemplate_8bbp;  
      pBMI=  (BITMAPINFO*)      (pBMFH+1);

      int nBytesPerLine= nWide;
      if (nBytesPerLine & 1) nBytesPerLine++;  // WORD alignment

      int nTotalPixels= nBytesPerLine * nHigh;

      pBMFH->bfSize = 1078 + nTotalPixels;
      pBMI->bmiHeader.biWidth=     nWide;
      pBMI->bmiHeader.biHeight=    nHigh;
      pBMI->bmiHeader.biSizeImage= nTotalPixels;

      HANDLE hFile= CreateFile( sFilename,GENERIC_WRITE,0,0,CREATE_ALWAYS,0,NULL );
      DWORD nActual;
      WriteFile( hFile, abBmpTemplate_8bbp, 1078, &nActual, 0 );

      BYTE* pabOneLine= new BYTE[nBytesPerLine];
      for (int x=0; x<nBytesPerLine; x++ ) {
            pabOneLine[x]= 0; // 196;    // a black pixel (196= gray for testing)
      }
      for ( int y=0; y<nHigh; y++ ) {
            WriteFile( hFile, pabOneLine, nBytesPerLine, &nActual, 0 );
      }

      CloseHandle( hFile );
      return( TRUE);
}
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DanRollinsCommented:
Strictly speaking, it would be simple to generate most or even all of that "hard-coded" data in the
  abBmpTemplate_8bbp[]
array... for instance, the pallette is just a series like:
    0x00 0x00 0x00 0x00
    0x02 0x02 0x02 0x00
    0x03 0x03 0x03 0x00
    ...
    0xFF 0xFF 0xFF 0xFF0

And the fn might be sped up by writing larger blocks of scan-line data (though in a 40,000x40,000 BMP, it is already wring 40K at a whack)... Anyway, there is room for improvement in that code but it seems to work fine as is. :-)

-- Dan
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DanRollinsCommented:
IMPORTANT change to the above function.  I failed to delete the temporary scanline buffer.  Change the end of the function to:
      ...

      delete  pabOneLine; // free the allocated scanline buffer
      return( TRUE);
}
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PMH4514Author Commented:
wow, nice work again Dan! I'm learning alot from your responses
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DanRollinsCommented:
Glad to help.  Thanks for the points and the grade :-)
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