X and YRESOLUTION in TIFF

[bbailie]

Okay, I'm new to TIFF but I get that you're supposed to be able to set XResolution to some number like 300/1.
The cast shown is a double, which I thought would be something like:

BYTE buff[] = { 2c 01 00 00 01 00 00 00 }
int rtx = IS40_SetTIFFTag_TW(hTIFF, 282, 0, (double)*buff);

(rtx always returns 0, even on things that do work)

It seems to ignore every byte but the 2c.

So clearly I'm missing something obvious.
I would like to set the resolution to 300pix per cm.

Please help!
Thanks in advance,
Brian

[Admin]

try it like this:

double dpi = 3.1415925;
int rtx = IS40_SetTIFFTag_TW(hTIFF, 282, 0, dpi);

if the tag is expecting a double, it's going to try to pop a double off the argument stack.

[bbailie]

Thanks, it works as you say. That should have been obvious, but the LibTIFF docs on the tag appear to say it requires two integers, which led me into a dark alley. Appreciate the help!
-brian