How to get a width and a height from an SWF

SIZE GetFlashMovieSize(LPCTSTR szSWFPath)
{
    SIZE size = { 0 };
    HANDLE hFile = CreateFile(szSWFPath, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL); 
 
    if (INVALID_HANDLE_VALUE != hFile)
    {
        DWORD dwNumberOfBytesRead; 
        char chFirstByte;
        ReadFile(hFile, (LPVOID)&chFirstByte, sizeof(chFirstByte), &dwNumberOfBytesRead, NULL); 
 
        const DWORD dwOffset = 3 + 1 + 4;
        SetFilePointer(hFile, dwOffset, NULL, FILE_BEGIN); 
 
        char outbuffer[256]; 
 
        if (chFirstByte == 'C') // Compressed
        {
            char buffer[256];
            ReadFile(hFile, buffer, sizeof(buffer), &dwNumberOfBytesRead, NULL); 
 
            z_stream stream = { 0 };
            stream.next_in = (Bytef*)buffer;
            stream.avail_in = 256;
            stream.next_out = (Bytef*)outbuffer;
            stream.avail_out = 256;
            inflateInit(&stream); 
            inflate(&stream, Z_SYNC_FLUSH); 
            inflateEnd(&stream);
        }
        else
        {
            ReadFile(hFile, outbuffer, sizeof(outbuffer), &dwNumberOfBytesRead, NULL);
        } 
 
        unsigned char nByte = outbuffer[0]; 
        unsigned char intBits = nByte >> 3; 
        int intTotalBits = intBits * 4 + 5;
        int intTotalBytes = (intTotalBits + 7) / 8; 
 
        unsigned char* pnBytes = new unsigned char[intTotalBytes];
        CopyMemory(pnBytes, outbuffer, min(intTotalBytes, sizeof(outbuffer))); 
 
        int intOffset = 5;
        int intXMin = GetIntegerFromBits(pnBytes, intOffset, intBits) / 20;
        int intXMax = GetIntegerFromBits(pnBytes, intOffset + intBits, intBits) / 20;
        int intYMin = GetIntegerFromBits(pnBytes, intOffset + 2 * intBits, intBits) / 20;
        int intYMax = GetIntegerFromBits(pnBytes, intOffset + 3 * intBits, intBits) / 20; 
 
        size.cx = intXMax - intXMin;
        size.cy = intYMax - intYMin; 
 
        delete[] pnBytes; 
        CloseHandle(hFile);
    } 
 
    return size;
}
 
int GetIntegerFromBits(LPVOID lpData, int intOffset, int intLength)
{
    int intResult = 0;
    LPBYTE lpBytes = static_cast<LPBYTE>(lpData); 
 
    int intBitIndex = 0;
    int intSign; 
 
    for (int intBitPos = intOffset; intBitPos < intOffset + intLength; intBitPos++, intBitIndex++)
    {
        int intByteIndex = intBitPos / 8;
        __int8 nByte = lpBytes[intByteIndex];
        int intLocalBitIndex = 7 - intBitPos % 8;
        int intBitValue = ((nByte >> intLocalBitIndex) & 1); 
 
        if (intBitIndex == 0)
            intSign = (intBitValue == 1) ? -1 : +1;
        else
        {
            intResult <<= 1;
            intResult += intBitValue;
        }
    }
 
    intResult *= intSign;
    return intResult;
}