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NAME

       im_incheck, im_outcheck, im_iocheck - checks image descriptors for WIO

SYNOPSIS

       #include <vips.h>

       int im_incheck( in )
       IMAGE *in;

       int im_outcheck( out )
       IMAGE *out;

       int im_iocheck( in, out)
       IMAGE *in, *out;

DESCRIPTION

       im_incheck(3) checks that an image descriptor is suitable for WIO input
       (ie. all of its pels can be  found  from  im->data).  If  possible,  it
       transforms  the  descriptor  to  make  WIO input ok using the following
       rules:

       IM_PARTIAL: the  descriptor  is  magically  turned  into  an  IM_SETBUF
       descriptor.  Memory is allocated and the image generated into that. The
       old partial callbacks are closed down, and the descriptor reformed as a
       IM_SETBUF.

       IM_OPENOUT:  if the descriptor has been written to, it is automatically
       ‘rewound,‘  that  is,  it  is  closed  and  reopened  as  an  IM_MMAPIN
       descriptor.

       IM_SETBUF: just checks that the descriptor has been written to.

       See the manual page for im_setupout(3) for a skeleton program.

       im_outcheck(3) checks that a descriptor is suitable for WIO output with
       im_writeline(3). If it sees an IM_PARTIAL image, it turns it  magically
       into an IM_SETBUF image.

       im_iocheck(3)   simply   calls   in_incheck(3)   for   image   in   and
       im_outcheck(3) for image out.

RETURN VALUE

       All functions returns 0 on success and -1 on error.

SEE ALSO

       im_open(3), im_cp_desc(3), im_setupout(3), im_makerw(3).

COPYRIGHT

       National Gallery

AUTHOR

       J. Cupitt - 23/7/93

                                 11 April 1990