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May 2007
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2007.05.04 13:13 "Re: TIFFSetField and float values", by Toby Thain
On 4-May-07, at 10:02 AM, Joris wrote: > mikk, > > mikk wrote: >> Oh, my, I've found the reason. Digging into the source code I >> realized >> that TIFFSetField >> gets the parameter from va_arg as double: >> (From tif_dir.c,v 1.72 2006/03/15 12:49:35, line 234:) >> // ... >> case TIFFTAG_XRESOLUTION: >> td->td_xresolution = (float) va_arg(ap, double); >> break; >> // ... >> >> When I pass argument of type double, the tag saves the value >> properly. >> Looks like an error in documentation (TIFFSetField.3tiff.html)? > > I would agree... but I suspect other compilers may behave > differently. I suspect that passing a float, as per documentation, > would work for most, but passing a double will work for all. In standard C, floats are always promoted to double in function arguments. --Toby > I've also tried changing the code you quote from tif_dir.c to va_arg > (ap,float), but that doesn't work on our Borland compilers at all > (and likely it will not work on most other compilers either, I > think). So I'm about to propose to change the documention to > specify a double parameter as part of the next update. > > > Best regards, > > Joris Van Damme > info@awaresystems.be > http://www.awaresystems.be/ > Download your free TIFF tag viewer for windows here: > http://www.awaresystems.be/imaging/tiff/astifftagviewer.html > > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/