On Sat, 3 Jun 2000, Hans Breuer wrote:
> There is structure packaging with M$VC as well and there is the
> #pragma pack directive to fix or produce problems with it.
Generally, it is not a good idea to write structures directly to a file
unless you will be reading them again on the same architecture. If you
are writing cross platform code, it is not really a good idea to rely on
the structure packing rules of the compiler.
>
> The main reason it appears to work here: it wasn't used, because it's
> only needed for single objects with size > 32767 (My test bitmaps
> were smaller).
> I'm still investigating a related documentation problem. There seems
> to be no way to detect if a WPGHead16 or WPGHead32 was used, while
> reading a wpg file. Maybe the 32 bit version was never used.
The Encyclopedia of Graphics Formats (from oreilly) has a bit of sample
code for reading the header of a WPG record. The code looks like it is
written for dos or windows use, so it requires a little modification to
work correctly on both little endian and big endian machines (the
GINT16_{TO,FROM}_LE macros (is it little endian?) should help):
BYTE RecordType;
DWORD RecordLength;
FILE *fp;
RecordType = GetByte(fp); /* read RecordType */
RecordLength = GetByte(fp); /* read RecordLength */
if (RecordLength == 0xFF) { /* not a BYTE value */
RecordLength = GetWord(fp); /* read next WORD */
if (RecordLength & 0x800) { /* not a WORD value */
RecordLength <<= 16; /* shift value to high WORD */
RecordLength += GetWord(fp); /* read in LOW word value */
}
}
>
> Hans
>
James.
--
Email: [EMAIL PROTECTED]
WWW: http://www.daa.com.au/~james/
