2003.08.07 01:12 "[Tiff] Custom tags", by Ashley Dreier

2003.08.07 06:36 "[Tiff] Custom tags", by Ashley Dreier

Hi again.

Further to my previous email, I find that things work okay for TIFF_ASCII tags (as in I can read/modify/write them). Still having the same problem for other custom tags though which are either TIFF_SHORT or TIFF_LONG. Looks like it's perhaps a pointer addressing/casting problem somewhere.

The TIFFFieldInfo contains something like the following:

static const TIFFFieldInfo myFieldInfo[] = {
     { TIFFTAG_NAME,         4, 4, TIFF_ASCII, FIELD_CUSTOM, FALSE, FALSE, "Name" },

To read them, I use:

        void *data;
     short count;

        if (!TIFFGetField(tif, TIFFTAG_NAME, &data))
        printf("Unable to get TIFFTAG_NAME\n");
        printf("NAME = %s\n", (char *) data;

        if (!TIFFGetField(tif, TIFFTAG_SEQUENCENUMBER, &count, &data))
      warning(": Unable to get TIFFTAG_SEQUENCENUMBER\n");
           printf("SEQUENCENUMBER = ");
            for (i = 0; i < count; i++)
         printf("%d ", ((long *) data)[0]);

Once I specify the FieldInfo structure for the TIFF_LONG tag, then calling TIFFRewriteDirectory() causes a segfault, even without trying to read/modify any of the custom tags. Hence it sounds like an internal TIFF library error.



Ashley J. Dreier.                     Email: Ashley.Dreier@csiro.au
CSIRO Manufacturing and Infrastructure Tech, Phone: +61 3 9662 7799
Locked Bag No. 9,                            Fax:   +61 3 9662 7851
Preston, Vic, 3072, Australia.
URL: http://www.msa.cmst.csiro.au/cmst/automation/staff/ajd